Publications by authors named "Sungwoo Ryoo"

76 Publications

Arginase inhibition by rhaponticin increases L-arginine concentration that contributes to Ca2+-dependent eNOS activation.

BMB Rep 2021 Jun 3. Epub 2021 Jun 3.

Department of Biological Sciences, Kangwon National University, Chuncheon 24341, Korea.

Although arginase primarily participates in the last reaction of the urea cycle, we have previously demonstrated that arginase II is an important cytosolic calcium regulator through spermine production in a p32-dependent manner. Here, we demonstrated that rhaponticin (RPT) is a novel medicinal-plant arginase inhibitor and investigated its mechanism of action on Ca2+-dependent endothelial nitric oxide synthase (eNOS) activation. RPT was uncompetitively inhibited for both arginases I and II prepared from mouse liver and kidney. It also inhibited arginase activity in both aorta and human umbilical vein endothelial cells (HUVECs). Using both microscope and FACS analyses, RPT treatments induced increases in cytosolic Ca2+ levels using Fluo-4 AM as a calcium indicator. Increased cytosolic Ca2+ elicited the phosphorylations of both CaMKII and eNOS Ser1177 in a time-dependent manner. RPT incubations also increased intracellular L-arginine (L-Arg) levels and activated the CaMKII/AMPK/Akt/eNOS signaling cascade in HUVECs. Treatment of L-Arg and ABH, arginase inhibitor, increased intracellular Ca2+ concentrations and activated CaMKII-dependent eNOS activation in ECs of WT mice, but, the effects were not observed in ECs of inositol triphosphate receptor type 1 knockout (IP3R1-/-) mice. In the aortic endothelium of WT mice, RPT also augmented nitric oxide (NO) production and attenuated reactive oxygen species (ROS) generation. In a vascular tension assay using RPT-treated aortic tissue, cumulative vasorelaxant responses to acetylcholine (Ach) were enhanced, and phenylephrine (PE)-dependent vasoconstrictive responses were retarded, although sodium nitroprusside and KCl responses were not different. In this study, we present a novel mechanism for RPT, as an arginase inhibitor, to increase cytosolic Ca2+ concentration in a L-Arg-dependent manner and enhance endothelial function through eNOS activation.
View Article and Find Full Text PDF

Download full-text PDF

Source
June 2021

Arginase II protein regulates Parkin-dependent p32 degradation that contributes to Ca2+-dependent eNOS activation in endothelial cells.

Cardiovasc Res 2021 May 8. Epub 2021 May 8.

Department of Biological Sciences.

Aims: Arginase II (ArgII) plays a key role in the regulation of Ca2+ between the cytosol and mitochondria in a p32-dependent manner. p32 contributes to endothelial nitric oxide synthase (eNOS) activation through the Ca2+/CaMKII/AMPK/p38MAPK/Akt signaling cascade. Therefore, we investigated a novel function of ArgII in the regulation of p32 stability.

Methods And Results: mRNA levels were measured by qRT-PCR, and protein levels and activation were confirmed by western blot analysis. Ca2+ concentrations were measured by FACS analysis and a vascular tension assay was performed. ArgII bound to p32, and ArgII protein knockdown using siArgII facilitated the ubiquitin-dependent proteasomal degradation of p32. β-lactone, a proteasome inhibitor, inhibited the p32 degradation associated with endothelial dysfunction in a Ca2+-dependent manner. The amino acids Lys154, Lys 180, and Lys220 of the p32 protein were identified as putative ubiquitination sites. When these sites were mutated, p32 was resistant to degradation in the presence of siArgII, and endothelial function was impaired. Knockdown of Pink/Parkin as an E3-ubiquitin ligase with siRNAs resulted in increased p32, decreased [Ca2+]c, and attenuated CaMKII-dependent eNOS activation by siArgII. SiArgII-dependent Parkin activation was attenuated by KN93, a CaMKII inhibitor. Knockdown of ArgII mRNA and its gene, but not inhibition of its activity, accelerated the interaction between p32 and Parkin and reduced p32 levels. In aortas of ArgII-/- mice, p32 levels were reduced by activated Parkin and inhibition of CaMKII attenuated Parkin-dependent p32 lysis. SiParkin blunted the phosphorylation of the activated CaMKII/AMPK/p38MAPK/Akt/eNOS signaling cascade. However, ApoE-/- mice fed a high-cholesterol diet had greater ArgII activity, significantly attenuated phosphorylation of Parkin, and increased p32 levels. Incubation with siArgII augmented p32 ubiquitination through Parkin activation, and induced signaling cascade activation.

Conclusion: The results suggest a novel function for ArgII protein in Parkin-dependent ubiquitination of p32 that is associated with Ca2+-mediated eNOS activation in endothelial cells.

Translational Perspective: In many vascular disorders, the downregulation of ArgII has been shown to be beneficial. This enzyme plays a crucial role in the regulation Ca2+ concentrations in a p32-dependent manner and activates the eNOS activation signaling cascade. In this study, we discovered that ArgII downregulation, inhibition of its activity, and gene knockout/down, induced the activation of Parkin (an E3-ubiquitin ligase) through a CaMKII-dependent mechanism. ArgII protein, as a p32 binding partner, prevented Parkin-dependent p32 ubiquitination, but inhibition of ArgII activity had no effect on ubiquitination. These novel findings have the potential to be translated into future therapeutic strategies to treat vascular diseases.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/cvr/cvab163DOI Listing
May 2021

Circulating miRNAs Associated with Dysregulated Vascular and Trophoblast Function as Target-Based Diagnostic Biomarkers for Preeclampsia.

Cells 2020 08 31;9(9). Epub 2020 Aug 31.

Departments of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do 24341, Korea.

Preeclampsia (PE) is a pregnancy-specific disorder associated with hypertension and proteinuria. Since there is no proven method to treat PE, early prediction and accurate diagnosis are essential for appropriate management of the disease. Thus, reliable biomarkers for diagnosing PE need to be identified and evaluated. We analyzed serum-soluble factors and miRNAs in 92 patients with PE and an equal number of healthy controls to identify new useful biomarkers for PE. Serum miR-31-5p, miR-155-5p, and miR-214-3p levels were significantly elevated in these patients and highly correlated with clinical symptoms of hypertension and proteinuria, whereas the miR-1290-3p level was decreased. The increased miRNAs were upregulated in an NF-κB-dependent manner and suppressed endothelial nitric oxide synthase (eNOS) and placental growth factor (PlGF) expression. The level of each miRNA had greater than 90% diagnostic accuracy, which was further increased by analyzing its ratio relative to that of miR-1290-3p. Taken together, the ratios of miR-31-5p, miR-155-5p, or miR-214-3p to miR-1290-3p may serve as reliable diagnostic or prognostic tools for PE, thereby providing evidence that these miRNAs are promising mechanism-based targets for designing therapeutic and preventive strategies for the clinical management of PE.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/cells9092003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7565195PMC
August 2020

Pycnogenol Supplementation Attenuates Memory Deficits and Protects Hippocampal CA1 Pyramidal Neurons via Antioxidative Role in a Gerbil Model of Transient Forebrain Ischemia.

Nutrients 2020 Aug 17;12(8). Epub 2020 Aug 17.

Department of Anatomy, College of Korean Medicine, Dongguk University, Gyeongju, Gyeongbuk 38066, Korea.

Pycnogenol (an extract of the bark of French maritime pine tree) is used for dietary supplement and known to have excellent antioxidative efficacy. However, there are few reports on neuroprotective effect of Pycnogenol supplementation and its mechanisms against ischemic injury following transient forebrain ischemia (TFI) in gerbils. Now, we examined neuroprotective effect and its mechanisms of Pycnogenol in the gerbils with 5-min TFI, which evokes a significant death (loss) of pyramidal cells located in the cornu ammonis (CA1) region of gerbil hippocampus from 4-5 days post-TFI. Gerbils were pretreated with 30, 40, and 50 mg/kg of Pycnogenol once a day for 7 days before TFI surgery. Treatment with 50 mg/kg, not 30 or 40 mg/kg, of Pycnogenol potently protected learning and memory, as well as CA1 pyramidal cells, from ischemic injury. Treatment with 50 mg/kg Pycnogenol significantly enhanced immunoreactivity of antioxidant enzymes (superoxide dismutases and catalase) in the pyramidal cells before and after TFI induction. Furthermore, the treatment significantly reduced the generation of superoxide anion, ribonucleic acid oxidation and lipid peroxidation in the pyramidal cells. Moreover, interestingly, its neuroprotective effect was abolished by administration of sodium azide (a potent inhibitor of SODs and catalase activities). Taken together, current results clearly indicate that Pycnogenol supplementation can prevent neurons from ischemic stroke through its potent antioxidative role.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/nu12082477DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7468866PMC
August 2020

Experimental Pretreatment with Chlorogenic Acid Prevents Transient Ischemia-Induced Cognitive Decline and Neuronal Damage in the Hippocampus through Anti-Oxidative and Anti-Inflammatory Effects.

Molecules 2020 Aug 6;25(16). Epub 2020 Aug 6.

Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, Gangwon 24341, Korea.

Chlorogenic acid (CGA), an ester of caffeic acid and quinic acid, is among the phenolic acid compounds which can be naturally found in green coffee extract and tea. CGA has been studied since it displays significant pharmacological properties. The aim of this study was to investigate the effects of CGA on cognitive function and neuroprotection including its mechanisms in the hippocampus following transient forebrain ischemia in gerbils. Memory and learning following the ischemia was investigated by eight-arm radial maze and passive avoidance tests. Neuroprotection was examined by immunohistochemistry for neuronal nuclei-specific protein and Fluoro-Jade B histofluorescence staining. For mechanisms of the neuroprotection, alterations in copper, zinc-superoxide dismutase (SOD1), SOD2 as antioxidant enzymes, dihydroethidium and 4-hydroxy-2-nonenal as indicators for oxidative stress, and anti-inflammatory cytokines (interleukin (IL)-4 and IL-13) and pro-inflammatory cytokines (tumor necrosis factor α (TNF-α) and IL-2) were examined by Western blotting and/or immunohistochemistry. As a result, pretreatment with 30 mg/kg CGA attenuated cognitive impairment and displayed a neuroprotective effect against transient forebrain ischemia (TFI). In Western blotting, the expression levels of SOD2 and IL-4 were increased due to pretreatment with CGA and, furthermore, 4-HNE production and IL-4 expressions were inhibited by CGA pretreatment. Additionally, pretreated CGA enhanced antioxidant enzymes and anti-inflammatory cytokines and, in contrast, attenuated oxidative stress and pro-inflammatory cytokine expression. Based on these results, we suggest that CGA can be a useful neuroprotective material against ischemia-reperfusion injury due to its antioxidant and anti-inflammatory efficacies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/molecules25163578DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7463954PMC
August 2020

NF-κB-dependent miR-31/155 biogenesis is essential for TNF-α-induced impairment of endothelial progenitor cell function.

Exp Mol Med 2020 08 7;52(8):1298-1309. Epub 2020 Aug 7.

Department of Molecular and Cellular Biochemistry, Kangwon National University School of Medicine, Chuncheon, Gangwon-do, 24341, South Korea.

Endothelial progenitor cell (EPC) dysfunction impairs vascular function and remodeling in inflammation-associated diseases, including preeclampsia. However, the underlying mechanism of this inflammation-induced dysfunction remains unclear. In the present study, we found increases in TNF-α and miR-31/155 levels and reduced numbers of circulating EPCs in patients with preeclampsia. Patient-derived mononuclear cells (MNCs) cultured in autologous serum had decreased endothelial nitric oxide synthase (eNOS) expression, nitric oxide production, and differentiation into EPCs with angiogenic potential, and these effects were inhibited by a TNF-α-neutralizing antibody and miR-31/155 inhibitors. Moreover, TNF-α treatment of normal MNCs increased miR-31/155 biogenesis, decreased eNOS expression, reduced EPC differentiation, and impaired angiogenic potential. The TNF-α-induced impairment of EPC differentiation and function was rescued by NF-κB p65 knockdown or miR-31/155 inhibitors. In addition, treatment of MNCs with synthetic miR-31/155 or an eNOS inhibitor mimicked the inhibitory effects of TNF-α on eNOS expression and EPC functions. Moreover, transplantation of EPCs that had been differentiated from TNF-α-treated MNCs decreased neovascularization and blood perfusion in ischemic mouse hindlimbs compared with those of normally differentiated EPCs. These findings suggest that NF-κB activation is required for TNF-α-induced impairment of EPC mobilization, differentiation, and function via miR-31/155 biogenesis and eNOS downregulation. Our data provide a new role for NF-κB-dependent miR-31/155 in EPC dysfunction under the pathogenic conditions of inflammation-associated vascular diseases, including preeclampsia.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s12276-020-0478-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8080610PMC
August 2020

Overexpressed p32 localized in the endoplasmic reticulum and mitochondria negatively regulates calcium‑dependent endothelial nitric oxide synthase activit.

Mol Med Rep 2020 Sep 6;22(3):2395-2403. Epub 2020 Jul 6.

Department of Biological Sciences, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea.

The p32 protein plays a crucial role in the regulation of cytosolic Ca2+ concentrations ([Ca2+]c) that contributes to the Ca2+‑dependent signaling cascade. Using an adenovirus and plasmid p32‑overexpression system, the aim of the study was to evaluate the role of p32 in the regulation of [Ca2+] and its potential associated with Ca2+‑dependent endothelial nitric oxide synthase (eNOS) activation in endothelial cells. Using electron and confocal microscopic analysis, p32 overexpression was observed to be localized to mitochondria and the endoplasmic reticulum and played an important role in Ca2+ translocation, resulting in increased [Ca2+] in these organelles and reducing cytosolic [Ca2+] ([Ca2+]c). This decreased [Ca2+]c following p32 overexpression attenuated the Ca2+‑dependent signaling cascade of calcium/calmodulin dependent protein kinase II (CaMKII)/AKT/eNOS phosphorylation. Moreover, in aortic endothelia of wild‑type mice intravenously administered adenovirus encoding the p32 gene, increased p32 levels reduced NO production and accelerated reactive oxygen species (ROS) generation. In a vascular tension assay, p32 overexpression decreased acetylcholine (Ach)‑induced vasorelaxation and augmented phenylephrine (PE)‑dependent vasoconstriction. Notably, decreased levels of arginase II (ArgII) protein using siArgII were associated with downregulation of overexpressed p32 protein, which contributed to CaMKII‑dependent eNOS phosphorylation at Ser1177. These results indicated that increased protein levels of p32 caused endothelial dysfunction through attenuation of the Ca2+‑dependent signaling cascade and that ArgII protein participated in the stability of p32. Therefore, p32 may be a novel target for the treatment of vascular diseases associated with endothelial disorders.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3892/mmr.2020.11307DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7411372PMC
September 2020

p32-Dependent p38 MAPK Activation by Arginase II Downregulation Contributes to Endothelial Nitric Oxide Synthase Activation in HUVECs.

Cells 2020 02 8;9(2). Epub 2020 Feb 8.

Department of Biological Sciences, Kangwon National University, Chuncheon, Gangwon 24341, Korea.

Arginase II reciprocally regulates endothelial nitric oxide synthase (eNOS) through a p32-dependent Ca control. We investigated the signaling pathway of arginase II-dependent eNOS phosphorylation. Western blot analysis was applied for examining protein activation and [Ca]c was analyzed by microscopic and FACS analyses. Nitric oxide (NO) and reactive oxygen species (ROS) productions were measured using specific fluorescent dyes under microscopy. NO signaling pathway was tested by measuring vascular tension. Following arginase II downregulation by chemical inhibition or gene knockout (KO, ArgII), increased eNOS phosphorylation at Ser1177 and decreased phosphorylation at Thr495 was depend on p38 MAPK activation, which induced by CaMKII activation through p32-dependent increase in [Ca]c. The protein amount of p32 negatively regulated p38 MAPK activation. p38 MAPK contributed to Akt-induced eNOS phosphorylation at Ser1177 that resulted in accelerated NO production and reduced reactive oxygen species production in aortic endothelia. In vascular tension assay, p38 MAPK inhibitor decreased acetylcholine-induced vasorelaxation responses and increased phenylephrine-dependent vasoconstrictive responses. In ApoE mice fed a high cholesterol diet, arginase II inhibition restored p32/CaMKII/p38 MAPK/Akt/eNOS signaling cascade that was attenuated by p38 MAPK inhibition. Here, we demonstrated a novel signaling pathway contributing to understanding of the relationship between arginase II, endothelial dysfunction, and atherogenesis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/cells9020392DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7072651PMC
February 2020

Post-treatment with oxcarbazepine confers potent neuroprotection against transient global cerebral ischemic injury by activating Nrf2 defense pathway.

Biomed Pharmacother 2020 Apr 22;124:109850. Epub 2020 Jan 22.

Department of Anatomy, College of Korean Medicine, Dongguk University, Gyeongju, Gyeongbuk 38066, Republic of Korea. Electronic address:

Oxcarbazepine (OXC), a voltage-gated sodium channel blocker, is an antiepileptic medication and used for the bipolar disorders treatment. Some voltage-gated sodium channel blockers have been demonstrated to display strong neuroprotective properties in models of cerebral ischemia. However, neuroprotective effects and mechanisms of OXC have not yet been reported. Here, we investigated the protective effect of OXC and its mechanisms in the cornu ammonis 1 subfield (CA1) of gerbils subjected to 5 min of transient global cerebral ischemia (tGCI). tGCI led to death of most pyramidal neurons in CA1 at 5 days after ischemia. OXC (100 and 200 mg/kg) was intraperitoneally administered once at 30 min after tGCI. Treatment with 200 mg/kg, not 100 mg/kg OXC, significantly protected CA1 pyramidal neurons from tGCI-induced injury. OXC treatment significantly decreased superoxide anion production, 4-hydroxy-2-nonenal and 8-hydroxyguanine levels in ischemic CA1 pyramidal neurons. In addition, the treatment restored levels of superoxide dismutases, catalase, and glutathione peroxidase. Furthermore, the treatment distinctly inhibited tGCI-induced microglia activation and significantly reduced levels of pro-inflammatory cytokines (interleukin-1β and tumor necrosis factor-α). In particular, OXC treatment significantly enhanced expressions of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream protein heme oxygenase-1 in ischemic CA1. The neuroprotective effects of OXC were abolished by brusatol (an inhibitor of Nrf2). Taken together, these results indicate that post-treatment of OXC can display neuroprotection against brain injuries following ischemic insults. This neuroprotection may be displayed by attenuation of oxidative stress and neuroinflammation, which can be mediated by activation of Nrf2 pathway.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.biopha.2020.109850DOI Listing
April 2020

A 2-Min Transient Ischemia Confers Cerebral Ischemic Tolerance in Non-Obese Gerbils, but Results in Neuronal Death in Obese Gerbils by Increasing Abnormal mTOR Activation-Mediated Oxidative Stress and Neuroinflammation.

Cells 2019 09 22;8(10). Epub 2019 Sep 22.

Department of Biomedical Science and Research Institute for Bioscience and Biotechnology, Hallym University, Chuncheon, Gangwon 24252, Korea.

A brief episode of transient ischemia (TI) can confer cerebral ischemic tolerance against a subsequent severer TI under standard condition. The brain under obesity's conditions is more sensitive to ischemic injury. However, the impact of a brief episode of TI under obesity's conditions has not been fully addressed yet. Thus, the objective of this study was to determine the effect of a brief TI in the hippocampus of high-fat diet (HFD)-induced obese gerbils and related mechanisms. Gerbils were maintained on HFD or normal diet (ND) for 12 weeks and subjected to 2 min TI. HFD gerbils were heavier, with higher blood glucose, serum total cholesterol, triglycerides, and leptin levels. Massive loss of pyramidal neurons occurred in the hippocampal cornu ammonis 1 (CA1) field of HFD animals at 5 days after 2 min of TI, but 2 min of TI did not elicit death of pyramidal neurons in ND gerbils. The HFD group showed significantly increased levels of oxidative stress indicators (dihydroethidium and 4-hydroxynonenal) and proinflammatory cytokines (tumor necrosis factor-α and interleukin-1β) and microglial activation in pre- and/or post-ischemic phases compared to the ND group. Levels of mammalian target of rapamycin (mTOR) and phosphorylated-mTOR in the CA1 field of the HFD group were also significantly higher than the ND group. On the other hand, inhibition of mTOR activation by rapamycin (an allosteric mTOR inhibitor) significantly attenuated neuronal death induced by HFD, showing reduction of HFD-induced increases of oxidative stress indicators and proinflammatory cytokines, and microglia activation. Taken together, a brief episode of TI can evoke neuronal death under obesity's conditions. It might be closely associated with an abnormal increase of mTOR activation-mediated, severe oxidative stress and neuroinflammation in pre- and/or post-ischemic phases.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/cells8101126DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6830098PMC
September 2019

Risperidone Treatment after Transient Ischemia Induces Hypothermia and Provides Neuroprotection in the Gerbil Hippocampus by Decreasing Oxidative Stress.

Int J Mol Sci 2019 Sep 18;20(18). Epub 2019 Sep 18.

Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, Gangwon 24341, Korea.

Compelling evidence from preclinical and clinical studies has shown that mild hypothermia is neuroprotective against ischemic stroke. We investigated the neuroprotective effect of post-risperidone (RIS) treatment against transient ischemic injury and its mechanisms in the gerbil brain. Transient ischemia (TI) was induced in the telencephalon by bilateral common carotid artery occlusion (BCCAO) for 5 min under normothermic condition (37 ± 0.2 °C). Treatment of RIS induced hypothermia until 12 h after TI in the TI-induced animals under uncontrolled body temperature (UBT) compared to that under controlled body temperature (CBT) (about 37 °C). Neuroprotective effect was statistically significant when we used 5 and 10 mg/kg doses ( < 0.05, respectively). In the RIS-treated TI group, many CA1 pyramidal neurons of the hippocampus survived under UBT compared to those under CBT. In this group under UBT, post-treatment with RIS to TI-induced animals markedly attenuated the activation of glial cells, an increase of oxidative stress markers [dihydroethidium, 8-hydroxy-2' -deoxyguanosine (8-OHdG), and 4-Hydroxynonenal (4-HNE)], and a decrease of superoxide dismutase 2 (SOD2) in their CA1 pyramidal neurons. Furthermore, RIS-induced hypothermia was significantly interrupted by NBOH-2C-CN hydrochloride (a selective 5-HT receptor agonist), but not bromocriptine mesylate (a D receptor agonist). Our findings indicate that RIS-induced hypothermia can effectively protect neuronal cell death from TI injury through attenuation of glial activation and maintenance of antioxidants, showing that 5-HT receptor is involved in RIS-induced hypothermia. Therefore, RIS could be introduced to reduce body temperature rapidly and might be applied to patients for hypothermic therapy following ischemic stroke.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/ijms20184621DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6770640PMC
September 2019

Down-regulation of cyclin-dependent kinase 5 attenuates p53-dependent apoptosis of hippocampal CA1 pyramidal neurons following transient cerebral ischemia.

Sci Rep 2019 09 10;9(1):13032. Epub 2019 Sep 10.

Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, Gangwon, 24341, Republic of Korea.

Abnormal activation of cyclin-dependent kinase 5 (Cdk5) is associated with pathophysiological conditions. Ischemic preconditioning (IPC) can provide neuroprotective effects against subsequent lethal ischemic insult. The objective of this study was to determine how Cdk5 and related molecules could affect neuroprotection in the hippocampus of gerbils after with IPC [a 2-min transient cerebral ischemia (TCI)] followed by 5-min subsequent TCI. Hippocampal CA1 pyramidal neurons were dead at 5 days post-TCI. However, treatment with roscovitine (a potent inhibitor of Cdk5) and IPC protected CA1 pyramidal neurons from TCI. Expression levels of Cdk5, p25, phospho (p)-Rb and p-p53 were increased in nuclei of CA1 pyramidal neurons at 1 and 2 days after TCI. However, these expressions were attenuated by roscovitine treatment and IPC. In particular, Cdk5, p-Rb and p-p53 immunoreactivities in their nuclei were decreased. Furthermore, TUNEL-positive CA1 pyramidal neurons were found at 5 days after TCI with increased expression levels of Bax, PUMA, and activated caspase-3. These TUNEL-positive cells and increased molecules were decreased by roscovitine treatment and IPC. Thus, roscovitine treatment and IPC could protect CA1 pyramidal neurons from TCI through down-regulating Cdk5, p25, and p-p53 in their nuclei. These findings indicate that down-regulating Cdk5 might be a key strategy to attenuate p53-dependent apoptosis of CA1 pyramidal neurons following TCI.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-019-49623-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6737192PMC
September 2019

Melatonin alleviates asphyxial cardiac arrest-induced cerebellar Purkinje cell death by attenuation of oxidative stress.

Exp Neurol 2019 10 26;320:112983. Epub 2019 Jun 26.

Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon 24341, Republic of Korea. Electronic address:

Although multiple reports using animal models have confirmed that melatonin appears to promote neuroprotective effects following ischemia/reperfusion-induced brain injury, the relationship between its protective effects and activation of autophagy in Purkinje cells following asphyxial cardiac arrest and cardiopulmonary resuscitation (CA/CPR) remains unclear. Rats used in this study were randomly assigned to 6 groups as follows; vehicle-treated sham operated group, vehicle-treated asphyxial CA/CPR operated group, melatonin-treated sham operated group, melatonin-treated asphyxial CA/CPR operated group, PDOT (a MT2 melatonin receptor antagonist) plus (+) melatonin-treated sham operated group and PDOT+melatonin-treated asphyxial CA/CPR operated group. Melatonin (20 mg/kg, i.p., 4 times before CA and 3 times after CA) treatment significantly improved survival rate and neurological deficit compared with the vehicle-treated asphyxial CA/CPR rats (survival rates ≥40% vs 10%), showing that melatonin treatment exhibited protective effect against asphyxial CA/CPR-induced Purkinje cell death. The protective effect of melatonin against CA/CPR-induced Purkinje cell death paralleled a remarkable attenuation of autophagy-like processes (Beclin-1, Atg7 and LC3), as well as a dramatic reduction in superoxide anion radical (O·-), intense enhancements of CuZn superoxide dismutase (SOD1) and MnSOD (SOD2) expressions. Furthermore, the protective effect was notably reversed by treatment with PDOT, which is a selective MT2 antagonist. In brief, melatonin conferred neuroprotection against asphyxial CA/CPR-induced Purkinje cell death via inhibiting autophagic activation by reducing expressions of O·- and increasing expressions of antioxidant enzymes, and suggests that MT2 is involved in neuroprotective effect of melatonin against Purkinje cell death caused by asphyxial CA/CPR.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.expneurol.2019.112983DOI Listing
October 2019

Arginase II activity regulates cytosolic Ca level in a p32-dependent manner that contributes to Ca-dependent vasoconstriction in native low-density lipoprotein-stimulated vascular smooth muscle cells.

Exp Mol Med 2019 06 3;51(6):1-12. Epub 2019 Jun 3.

Department of Biology, School of Medicine, Kangwon National University, Chuncheon, 24341, South Korea.

Although arginase II (ArgII) is abundant in mitochondria, Ca-accumulating organelles, the relationship between ArgII activity and Ca translocation into mitochondria and the regulation of cytosolic Ca signaling are completely unknown. We investigated the effects of ArgII activity on mitochondrial Ca uptake through mitochondrial p32 protein (p32m) and on CaMKII-dependent vascular smooth muscle cell (VSMC) contraction. Native low-density lipoprotein stimulation induced an increase in [Ca]m as measured by CoCl-quenched calcein-AM fluorescence, which was prevented by Arg inhibition in hAoSMCs and reduced in mAoSMCs from ArgII mice. Conversely, [Ca]c analyzed with Fluo-4 AM was increased by Arg inhibition and ArgII gene knockout. The increased [Ca]c resulted in CaMKII and MLC 20 phosphorylation, which was associated with enhanced vasoconstriction activity to phenylephrine (PE) in the vascular tension assay. Cy5-tagged siRNA against mitochondrial p32 mRNA (sip32m) abolished mitochondrial Ca uptake and induced activation of CaMKII. Spermine, a polyamine, induced mitochondrial Ca uptake and dephosphorylation of CaMKII and was completely inhibited by sip32m incubation. In mAoSMCs from ApoE-null mice fed a high-cholesterol diet (ApoE +HCD), Arg activity was increased, and spermine concentration was higher than that of wild-type mice. Furthermore, [Ca]m and p32m levels were elevated, and CaMKII phosphorylation was reduced in mAoSMCs from ApoE +HCD. In vascular tension experiments, an attenuated response to vasoconstrictors in de-endothelialized aorta from ApoE +HCD was recovered by incubation of sip32m. ArgII activity-dependent production of spermine augments Ca transition from the cytosol to the mitochondria in a p32m-dependent manner and regulates CaMKII-dependent constriction in VSMCs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s12276-019-0262-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6545325PMC
June 2019

Resveratrol is an arginase inhibitor contributing to vascular smooth muscle cell vasoconstriction via increasing cytosolic calcium.

Mol Med Rep 2019 May 14;19(5):3767-3774. Epub 2019 Mar 14.

Department of Biology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea.

The contractility of vascular smooth muscle cells (VSMCs) controls the lumen diameter of vessels, thus serving a role in regulating blood pressure and organ blood flow. Although arginases are known to have numerous effects in the biological activities of VSMCs, the effects of arginase II on the constriction of VSMCs has not yet been investigated. When conducting a natural products screen for an inhibitor against arginase, the present study identified that a relatively high concentration of resveratrol (RSV) exhibited arginase inhibitory activity. Therefore, the present study investigated whether RSV could regulate VSMCs contractions and the underlying mechanism. Arginase inhibition by RSV led to an increase in the concentration of the substrate L‑Arg and an accompanying increase in the cytosol Ca2+ concentration [(Ca2+)c] in VSMCs. The increased [Ca2+]c induced by RSV and L‑Arg treatments resulted in CaMKII‑dependent MLC20 phosphorylation. The effects of RSV on VSMCs were maintained even when VSMCs were pre‑treated with sirtinol, an inhibitor of Sirt proteins. In a vascular tension assay with de‑endothelialized aortic vessels, vasoconstrictor responses, which were measured using phenylephrine (PE), were significantly enhanced in the RSV‑ and L‑Arg‑treated vessels. Therefore, although arginase inhibition has exhibited beneficial effects in various diseases, care is required when considering administration of an arginase inhibitor to patients with vessels endothelial dysfunction as RSV can induce vessel contraction.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3892/mmr.2019.10035DOI Listing
May 2019

Fate of Astrocytes in The Gerbil Hippocampus After Transient Global Cerebral Ischemia.

Int J Mol Sci 2019 Feb 15;20(4). Epub 2019 Feb 15.

Department of Biomedical Science and Research Institute for Bioscience and Biotechnology, Hallym University, Chuncheon, Gangwon 24252, Korea.

Neuronal death and reactive gliosis are major features of brain tissue damage following transient global cerebral ischemia (tgCI). This study investigated long-term changes in neuronal death and astrogliosis in the gerbil hippocampus for 180 days after 5 min of tgCI. A massive loss of pyramidal neurons was found in the hippocampal CA1 area (CA1) area between 5 and 30 days after tgCI by Fluoro-Jade B (FJB, a marker for neuronal degeneration) histofluorescence staining, but pyramidal neurons in the CA2/3 area did not die. The reaction of astrocytes (astrogliosis) was examined by glial fibrillary acidic protein (GFAP) immunohistochemistry. Morphological change or degeneration (death) of the astrocytes was found in the CA1 area after tgCI, but, in the CA2/3 area, astrogliosis was hardly shown. GFAP immunoreactive astrocytes in the CA1 area was significantly increased in number with time and peaked at 30 days after tgCI, and they began to be degenerated or dead from 40 days after tgCI. The effect was examined by double immunofluorescence staining for FJB and GFAP. The number of FJB/GFAP⁺ cells (degenerating astrocytes) was gradually increased with time after tgCI. At 180 days after tgCI, FJB/GFAP⁺ cells were significantly decreased, but FJB⁺ cells (dead astrocytes) were significantly increased. In brief, 5 min of tgCI induced a progressive degeneration of CA1 pyramidal neurons from 5 until 30 days with an increase of reactive astrocytes, and, thereafter, astrocytes were degenerated with time and dead at later times. This phenomenon might be shown due to the death of neurons.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/ijms20040845DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6412566PMC
February 2019

NF-κB-responsive miR-155 induces functional impairment of vascular smooth muscle cells by downregulating soluble guanylyl cyclase.

Exp Mol Med 2019 02 15;51(2):1-12. Epub 2019 Feb 15.

Departments of Molecular and Cellular Biochemistry, Kangwon National University School of Medicine, Chuncheon, Gangwon-do, 24341, South Korea.

Vascular smooth muscle cells (VSMCs) play an important role in maintaining vascular function. Inflammation-mediated VSMC dysfunction leads to atherosclerotic intimal hyperplasia and preeclamptic hypertension; however, the underlying mechanisms are not clearly understood. We analyzed the expression levels of microRNA-155 (miR-155) in cultured VSMCs, mouse vessels, and clinical specimens and then assessed its role in VSMC function. Treatment with tumor necrosis factor-α (TNF-α) elevated miR-155 biogenesis in cultured VSMCs and vessel segments, which was prevented by NF-κB inhibition. MiR-155 expression was also increased in high-fat diet-fed ApoE mice and in patients with atherosclerosis and preeclampsia. The miR-155 levels were inversely correlated with soluble guanylyl cyclase β1 (sGCβ1) expression and nitric oxide (NO)-dependent cGMP production through targeting the sGCβ1 transcript. TNF-α-induced miR-155 caused VSMC phenotypic switching, which was confirmed by the downregulation of VSMC-specific marker genes, suppression of cell proliferation and migration, alterations in cell morphology, and NO-induced vasorelaxation. These events were mitigated by miR-155 inhibition. Moreover, TNF-α did not cause VSMC phenotypic modulation and limit NO-induced vasodilation in aortic vessels of miR-155 mice. These findings suggest that NF-κB-induced miR-155 impairs the VSMC contractile phenotype and NO-mediated vasorelaxation by downregulating sGCβ1 expression. These data suggest that NF-κB-responsive miR-155 is a novel negative regulator of VSMC functions by impairing the sGC/cGMP pathway, which is essential for maintaining the VSMC contractile phenotype and vasorelaxation, offering a new therapeutic target for the treatment of atherosclerosis and preeclampsia.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s12276-019-0212-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6376011PMC
February 2019

Arginase II Contributes to the Ca/CaMKII/eNOS Axis by Regulating Ca Concentration Between the Cytosol and Mitochondria in a p32-Dependent Manner.

J Am Heart Assoc 2018 09;7(18):e009579

1 Department of Biology School of medicine Kangwon National University Chuncheon Korea.

Background Arginase II activity contributes to reciprocal regulation of endothelial nitric oxide synthase ( eNOS ). We tested the hypotheses that arginase II activity participates in the regulation of Ca/Ca/calmodulin-dependent kinase II / eNOS activation, and this process is dependent on mitochondrial p32. Methods and Results Downregulation of arginase II increased the concentration of cytosolic Ca ([Ca]c) and decreased mitochondrial Ca ([Ca]m) in microscopic and fluorescence-activated cell sorting analyses, resulting in augmented eNOS Ser1177 phosphorylation and decreased eNOS Thr495 phosphorylation through Ca/Ca/calmodulin-dependent kinase II . These changes were observed in human umbilical vein endothelial cells treated with small interfering RNA against p32 (sip32). Using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, fluorescence immunoassay, and ion chromatography, inhibition of arginase II reduced the amount of spermine, a binding molecule, and the release of Ca from p32. In addition, arginase II gene knockdown using small interfering RNA and knockout arginase II -null mice resulted in reduced p32 protein level. In the aortas of wild-type mice, small interfering RNA against p32 induced eNOS Ser1177 phosphorylation and enhanced NO -dependent vasorelaxation. Arginase activity, p32 protein expression, spermine amount, and [Ca]m were increased in the aortas from apolipoprotein E (ApoE) mice fed a high-cholesterol diet, and intravenous administration of small interfering RNA against p32 restored Ca/Ca/calmodulin-dependent kinase II -dependent eNOS Ser1177 phosphorylation and improved endothelial dysfunction. The effects of arginase II downregulation were not associated with elevated NO production when tested in aortic endothelia from eNOS knockout mice. Conclusions These data demonstrate a novel function of arginase II in regulation of Ca-dependent eNOS phosphorylation. This novel mechanism drives arginase activation, mitochondrial dysfunction, endothelial dysfunction, and atherogenesis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1161/JAHA.118.009579DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6222941PMC
September 2018

NF-κB-responsive miRNA-31-5p elicits endothelial dysfunction associated with preeclampsia via down-regulation of endothelial nitric-oxide synthase.

J Biol Chem 2018 12 2;293(49):18989-19000. Epub 2018 Oct 2.

From the Departments of Molecular and Cellular Biochemistry,

Inflammatory cytokines, including tumor necrosis factor-α (TNFα), were elevated in patients with cardiovascular diseases and are also considered as crucial factors in the pathogenesis of preeclampsia; however, the underlying pathogenic mechanism has not been clearly elucidated. This study provides novel evidence that TNFα leads to endothelial dysfunction associated with hypertension and vascular remodeling in preeclampsia through down-regulation of endothelial nitric-oxide synthase (eNOS) by NF-κB-dependent biogenesis of microRNA (miR)-31-5p, which targets eNOS mRNA. In this study, we found that miR-31-5p was up-regulated in sera from patients with preeclampsia and in human endothelial cells treated with TNFα. TNFα-mediated induction of miR-31-5p was blocked by an NF-κB inhibitor and NF-κB p65 knockdown but not by mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase inhibitors, indicating that NF-κB is essential for biogenesis of miR-31-5p. The treatment of human endothelial cells with TNFα or miR-31-5p mimics decreased endothelial nitric-oxide synthase (eNOS) mRNA stability without affecting promoter activity, resulting in inhibition of eNOS expression and NO/cGMP production through blocking of the functional activity of the eNOS mRNA 3'-UTR. Moreover, TNFα and miR-31-5p mimic evoked endothelial dysfunction associated with defects in angiogenesis, trophoblastic invasion, and vasorelaxation in an cultured model of human placental arterial vessels, which are typical features of preeclampsia. These results suggest that NF-κB-responsive miR-31-5p elicits endothelial dysfunction, hypertension, and vascular remodeling via post-transcriptional down-regulation of eNOS and is a molecular risk factor in the pathogenesis and development of preeclampsia.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1074/jbc.RA118.005197DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6295733PMC
December 2018

TNF-α elicits phenotypic and functional alterations of vascular smooth muscle cells by miR-155-5p-dependent down-regulation of cGMP-dependent kinase 1.

J Biol Chem 2018 09 13;293(38):14812-14822. Epub 2018 Aug 13.

From the Departments of Molecular and Cellular Biochemistry,

cGMP-dependent protein kinase 1 (PKG1) plays an important role in nitric oxide (NO)/cGMP-mediated maintenance of vascular smooth muscle cell (VSMC) phenotype and vasorelaxation. Inflammatory cytokines, including tumor necrosis factor-α (TNFα), have long been understood to mediate several inflammatory vascular diseases. However, the underlying mechanism of TNFα-dependent inflammatory vascular disease is unclear. Here, we found that TNFα treatment decreased PKG1 expression in cultured VSMCs, which correlated with NF-κB-dependent biogenesis of miR-155-5p that targeted the 3'-UTR of PKG1 mRNA. TNFα induced VSMC phenotypic switching from a contractile to a synthetic state through the down-regulation of VSMC marker genes, suppression of actin polymerization, alteration of cell morphology, and elevation of cell proliferation and migration. All of these events were blocked by treatment with an inhibitor of miR-155-5p or PKG1, whereas transfection with miR-155-5p mimic or PKG1 siRNA promoted phenotypic modulation, similar to the response to TNFα. In addition, TNFα-induced miR-155-5p inhibited the vasorelaxant response of de-endothelialized mouse aortic vessels to 8-Br-cGMP by suppressing phosphorylation of myosin phosphatase and myosin light chain, both of which are downstream signal modulators of PKG1. Moreover, TNFα-induced VSMC phenotypic alteration and vasodilatory dysfunction were blocked by NF-κB inhibition. These results suggest that TNFα impairs NO/cGMP-mediated maintenance of the VSMC contractile phenotype and vascular relaxation by down-regulating PKG1 through NF-κB-dependent biogenesis of miR-155-5p. Thus, the NF-κB/miR-155-5p/PKG1 axis may be crucial in the pathogenesis of inflammatory vascular diseases, such as atherosclerotic intimal hyperplasia and preeclamptic hypertension.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1074/jbc.RA118.004220DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6153283PMC
September 2018

Early IV-injected human dermis-derived mesenchymal stem cells after transient global cerebral ischemia do not pass through damaged blood-brain barrier.

J Tissue Eng Regen Med 2018 07 3;12(7):1646-1657. Epub 2018 Jun 3.

Department of Neurobiology, and Institute of Medical Sciences, School of Medicine, Kangwon National University, Chuncheon, Gangwon, Republic of Korea.

There is lack of researches on effects of intravenously injected mesenchymal stem cells (MSCs) against transient cerebral ischemia (TCI). We investigated the disruption of the neurovascular unit (NVU), which comprises the blood-brain barrier and examined entry of human dermis-derived MSCs (hDMSCs) into the damaged hippocampal CA1 area in a gerbil model of TCI and their subsequent effects on neuroprotection and cognitive function. Impairments of neurons and blood-brain barrier were examined by immunohistochemistry, electron microscopy, and Evans blue and immunoglobulin G leakage. Neuronal death was observed in pyramidal neurons 5-day postischemia. NVU were structurally damaged; in particular, astrocyte end-feet were severely damaged from 2-day post-TCI and immunoglobulin G leaked out of the CA1 area 2 days after 5 min of TCI; however, Evans blue extravasation was not observed. On the basis of the results of NVU damages, ischemic gerbils received PKH2-transfected hDMSCs 3 times at early times (3 hr, 2, and 5 days) after TCI, and fluorescence imaging was used to detect hDMSCs in the tissue. PKH2-transfected hDMSCs were not found in the CA1 from immediate time to 8 days after injection, although they were detected in the liver. Furthermore, hDMSCs transplantation did not protect CA1 pyramidal neurons and did not improve cognitive impairment. Intravenously transplanted hDMSCs did not migrate to the damaged CA1 area induced by TCI. These findings suggest no neuroprotection and cognitive improvement by intravenous hDMSCs transplantation after 5 min of TCI.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/term.2692DOI Listing
July 2018

Arginase Inhibition Suppresses Native Low-Density Lipoprotein-Stimulated Vascular Smooth Muscle Cell Proliferation by NADPH Oxidase Inactivation.

Yonsei Med J 2018 May;59(3):366-375

Department of Biological Sciences, Kangwon National University, Chuncheon, Korea.

Purpose: Vascular smooth muscle cell (VSMC) proliferation induced by native low-density lipoprotein (nLDL) stimulation is dependent on superoxide production from activated NADPH oxidase. The present study aimed to investigate whether the novel arginase inhibitor limonin could suppress nLDL-induced VSMC proliferation and to examine related mechanisms.

Materials And Methods: Isolated VSMCs from rat aortas were treated with nLDL, and cell proliferation was measured by WST-1 and BrdU assays. NADPH oxidase activation was evaluated by lucigenin-induced chemiluminescence, and phosphorylation of protein kinase C (PKC) βII and extracellular signal-regulated kinase (ERK) 1/2 was determined by western blot analysis. Mitochondrial reactive oxygen species (ROS) generation was assessed using MitoSOX-red, and intracellular L-arginine concentrations were determined by high-performance liquid chromatography (HPLC) in the presence or absence of limonin.

Results: Limonin inhibited arginase I and II activity in the uncompetitive mode, and prevented nLDL-induced VSMC proliferation in a p21Waf1/Cip1-dependent manner without affecting arginase protein levels. Limonin blocked PKCβII phosphorylation, but not ERK1/2 phosphorylation, and translocation of p47phox to the membrane was decreased, as was superoxide production in nLDL-stimulated VSMCs. Moreover, mitochondrial ROS generation was increased by nLDL stimulation and blocked by preincubation with limonin. Mitochondrial ROS production was responsible for the phosphorylation of PKCβII. HPLC analysis showed that arginase inhibition with limonin increases intracellular L-arginine concentrations, but decreases polyamine concentrations. L-Arginine treatment prevented PKCβII phosphorylation without affecting ERK1/2 phosphorylation.

Conclusion: Increased L-arginine levels following limonin-dependent arginase inhibition prohibited NADPH oxidase activation in a PKCβII-dependent manner, and blocked nLDL-stimulated VSMC proliferation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3349/ymj.2018.59.3.366DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5889988PMC
May 2018

Arginase II inhibition prevents interleukin-8 production through regulation of p38 MAPK phosphorylation activated by loss of mitochondrial membrane potential in nLDL-stimulated hAoSMCs.

Exp Mol Med 2018 02 2;50(2):e438. Epub 2018 Feb 2.

Department of Biological Sciences, Kangwon National University, Chuncheon, Republic of Korea.

Arginase inhibition exhibits beneficial effects in vascular endothelial and smooth muscle cells. In human aortic smooth muscle cells (hAoSMCs), native low-density lipoprotein (nLDL) induced the production of interleukin-8 (IL-8) that is involved in the pathogenesis of cardiovascular diseases. Therefore, we examined the effect of arginase inhibition on IL-8 production and the underlying mechanism. In hAoSMCs, reverse transcription-PCR, western blotting and immunocytochemistry with MitoTracker confirmed that arginase II was confined predominantly to mitochondria. The mitochondrial membrane potential (MMP) was assessed using tetramethylrhodamine ethyl ester. The MMP decreased upon nLDL stimulation but was restored upon arginase inhibition. MMP loss caused by nLDL was prevented by treatment with the intracellular Ca chelator BAPTA-AM. In mitochondrial Ca measurements using Rhod-2 AM, increased mitochondrial Ca levels by nLDL were inhibited upon preincubation with an arginase inhibitor. Among the polyamines, spermine, an arginase activity-dependent product, caused mitochondrial Ca movement. The nLDL-induced MMP change resulted in p38 mitogen-activated protein kinase (MAPK) phosphorylation and IL-8 production and was prevented by the arginase inhibitors BAPTA and ruthenium 360. In isolated AoSMCs from ApoE mice fed a high-cholesterol diet, arginase activity, p38 MAPK phosphorylation, spermine and mitochondrial Ca levels and keratinocyte-derived chemokine (KC) production were increased compared with wild-type (WT) mice. However, in AoSMCs isolated from arginase II-null mice, increases in MMP and decreases in mitochondrial Ca levels were noted compared with WT and were associated with p38 MAPK activation and IL-8 production. These data suggest that arginase activity regulates the change in MMP through Ca uptake that is essential for p38 MAPK phosphorylation and IL-8 production.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/emm.2017.254DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5903817PMC
February 2018

Carbon monoxide prevents TNF-α-induced eNOS downregulation by inhibiting NF-κB-responsive miR-155-5p biogenesis.

Exp Mol Med 2017 11 24;49(11):e403. Epub 2017 Nov 24.

Departments of Molecular and Cellular Biochemistry, Kangwon National University School of Medicine, Chuncheon, Gangwon-do, South Korea.

Heme oxygenase-1-derived carbon monoxide prevents inflammatory vascular disorders. To date, there is no clear evidence that HO-1/CO prevents endothelial dysfunction associated with the downregulation of endothelial NO synthesis in human endothelial cells stimulated with TNF-α. Here, we found that the CO-releasing compound CORM-2 prevented TNF-α-mediated decreases in eNOS expression and NO/cGMP production, without affecting eNOS promoter activity, by maintaining the functional activity of the eNOS mRNA 3'-untranslated region. By contrast, CORM-2 inhibited MIR155HG expression and miR-155-5p biogenesis in TNF-α-stimulated endothelial cells, resulting in recovery of the 3'-UTR activity of eNOS mRNA, a target of miR-155-5p. The beneficial effect of CORM-2 was blocked by an NF-κB inhibitor, a miR-155-5p mimic, a HO-1 inhibitor and siRNA against HO-1, indicating that CO rescues TNF-α-induced eNOS downregulation through NF-κB-responsive miR-155-5p expression via HO-1 induction; similar protective effects of ectopic HO-1 expression and bilirubin were observed in endothelial cells treated with TNF-α. Moreover, heme degradation products, except iron and N-acetylcysteine prevented HO-mediated miR-155-5p biogenesis and eNOS downregulation. These data demonstrate that CO prevents TNF-α-mediated eNOS downregulation by inhibiting redox-sensitive miR-155-5p biogenesis through a positive forward circuit between CO and HO-1 induction. This circuit may play an important preventive role in inflammatory endothelial dysfunction associated with human vascular diseases.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/emm.2017.193DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5704195PMC
November 2017

Aspirin prevents TNF-α-induced endothelial cell dysfunction by regulating the NF-κB-dependent miR-155/eNOS pathway: Role of a miR-155/eNOS axis in preeclampsia.

Free Radic Biol Med 2017 03 11;104:185-198. Epub 2017 Jan 11.

Departments of Molecular and Cellular Biochemistry, Kangwon National University School of Medicine, Chuncheon, Gangwon-do 24341, South Korea. Electronic address:

Preeclampsia is an inflammatory disease with endothelial cell dysfunction that occurs via decreased endothelial nitric oxide synthase/nitric oxide (eNOS/NO) activity. Aspirin reduces the incidence of hypertensive pregnancy complications. However, the underlying mechanism has not been clearly explained. Here, we found that tumor necrosis factor (TNF)-α, microRNA (miR)-155, and eNOS levels as well as endothelial redox phenotype were differentially regulated in preeclamptic patients, implying the involvement of TNF-α- and redox signal-mediated miR-155 biogenesis and eNOS downregulation in the pathogenesis of preeclampsia. Aspirin prevented the TNF-α-mediated increase in miR-155 biogenesis and decreases in eNOS expression and NO/cGMP production in cultured human umbilical vein endothelial cells (HUVECs). Similar effects of aspirin were also observed in HUVECs treated with HO. The preventive effects of aspirin was associated with the inhibition of nuclear factor-κB (NF-κB)-dependent MIR155HG (miR-155 host gene) expression. Aspirin recovered the TNF-α-mediated decrease in wild-type, but not mutant, eNOS 3'-untranslated region reporter activity, whose effect was blocked by miR-155 mimic. Moreover, aspirin prevented TNF-α-mediated endothelial cell dysfunction associated with impaired vasorelaxation, angiogenesis, and trophoblast invasion, and the preventive effects were blocked by miR-155 mimic or an eNOS inhibitor. Aspirin rescued TNF-α-mediated eNOS downregulation coupled with endothelial dysfunction by inhibiting NF-κB-dependent transcriptional miR-155 biogenesis. Thus, the redox-sensitive NF-κB/miR-155/eNOS axis may be crucial in the pathogenesis of vascular disorders including preeclampsia.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.freeradbiomed.2017.01.010DOI Listing
March 2017

In vitro photodynamic effects of scavenger receptor targeted-photoactivatable nanoagents on activated macrophages.

Int J Biol Macromol 2017 Apr 9;97:181-189. Epub 2017 Jan 9.

Korea Basic Science Institute Chuncheon Center, Chuncheon, Gangwon 200-701, Republic of Korea. Electronic address:

Scavenger receptors (SRs) expressed on the activated macrophages in inflammation sites have been considered as the most interesting and important target biomarker for targeted drug delivery, imaging and therapy. In the present study, we fabricated the scavenger receptor-A (SR-A) targeted-photoactivatable nanoagents (termed as Ce6/DS-DOCA) by entrapping chlorin e6 (Ce6) into the amphiphilic dextran sulfate-deoxycholic acid (DS-DOCA) conjugates via physically hydrophobic interactions. Insoluble Ce6 was easily encapsulated into DS-DOCA nanoparticles by a dialysis method and the loading efficiency was approximately 51.7%. The Ce6/DS-DOCA formed nano-sized self-assembled aggregates (28.8±5.6nm in diameter), confirmed by transmission electron microscope, UV/Vis and fluorescence spectrophotometer. The Ce6/DS-DOCA nanoagents could generate highly reactive singlet oxygen under laser irradiation. Also, in vitro studies showed that they were more specifically taken up by lipopolysaccharide (LPS)-induced activated macrophages (RAW 264.7) via a SR-A-mediated endocytosis, relative to by non-activated macrophages, and notably induced cell death of activated macrophages under laser irradiation. Therefore, SR-A targetable and photoactivatable Ce6/DS-DOCA nanoagents with more selective targeting to the activated macrophages will have great potential for treatment of inflammatory diseases.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ijbiomac.2017.01.037DOI Listing
April 2017

Intravenous administration of piceatannol, an arginase inhibitor, improves endothelial dysfunction in aged mice.

Korean J Physiol Pharmacol 2017 Jan 21;21(1):83-90. Epub 2016 Dec 21.

Department of Biology, College of Natural Sciences, Kangwon National University, Chuncheon 24341, Korea.

Advanced age is one of the risk factors for vascular diseases that are mainly caused by impaired nitric oxide (NO) production. It has been demonstrated that endothelial arginase constrains the activity of endothelial nitric oxide synthase (eNOS) and limits NO generation. Hence, arginase inhibition is suggested to be vasoprotective in aging. In this study, we examined the effects of intravenous injection of Piceatannol, an arginase inhibitor, on aged mice. Our results show that Piceatannol administration reduced the blood pressure in aged mice by inhibiting arginase activity, which was associated with NO production and reactive oxygen species generation. In addition, Piceatannol administration recovered Ca/calmodulin-dependent protein kinase II phosphorylation, eNOS phosphorylation and eNOS dimer stability in the aged mice. The improved NO signaling was shown to be effective in attenuating the phenylephrine-dependent contractile response and in enhancing the acetylcholine-dependent vasorelaxation response in aortic rings from the aged mice. These data suggest Piceatannol as a potential treatment for vascular disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4196/kjpp.2017.21.1.83DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5214914PMC
January 2017

Arginase Inhibition Restores Peroxynitrite-Induced Endothelial Dysfunction via L-Arginine-Dependent Endothelial Nitric Oxide Synthase Phosphorylation.

Yonsei Med J 2016 Nov;57(6):1329-38

Department of Biology, College of Natural Sciences, School of Medicine, Kangwon National University, Chuncheon, Korea.

Purpose: Peroxynitrite plays a critical role in vascular pathophysiology by increasing arginase activity and decreasing endothelial nitric oxide synthase (eNOS) activity. Therefore, the aims of this study were to investigate whether arginase inhibition and L-arginine supplement could restore peroxynitrite-induced endothelial dysfunction and determine the involved mechanism.

Materials And Methods: Human umbilical vein endothelial cells (HUVECs) were treated with SIN-1, a peroxynitrite generator, and arginase activity, nitrite/nitrate production, and expression levels of proteins were measured. eNOS activation was evaluated via Western blot and dimer blot analysis. We also tested nitric oxide (NO) and reactive oxygen species (ROS) production and performed a vascular tension assay.

Results: SIN-1 treatment increased arginase activity in a time- and dose-dependent manner and reciprocally decreased nitrite/nitrate production that was prevented by peroxynitrite scavenger in HUVECs. Furthermore, SIN-1 induced an increase in the expression level of arginase I and II, though not in eNOS protein. The decreased eNOS phosphorylation at Ser1177 and the increased at Thr495 by SIN-1 were restored with arginase inhibitor and L-arginine. The changed eNOS phosphorylation was consistent in the stability of eNOS dimers. SIN-1 decreased NO production and increased ROS generation in the aortic endothelium, all of which was reversed by arginase inhibitor or L-arginine. N(G)-Nitro-L-arginine methyl ester (L-NAME) prevented SIN-1-induced ROS generation. In the vascular tension assay, SIN-1 enhanced vasoconstrictor responses to U46619 and attenuated vasorelaxant responses to acetylcholine that were reversed by arginase inhibition.

Conclusion: These findings may explain the beneficial effect of arginase inhibition and L-arginine supplement on endothelial dysfunction under redox imbalance-dependent pathophysiological conditions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3349/ymj.2016.57.6.1329DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5011263PMC
November 2016

Hydroquinone Strongly Alleviates Focal Ischemic Brain Injury via Blockage of Blood-Brain Barrier Disruption in Rats.

Toxicol Sci 2016 12 31;154(2):430-441. Epub 2016 Aug 31.

Department of Food Science and Nutrition, Hallym University, Chuncheon, 24252, South Korea.

Hydroquinone (HQ), a major benzene metabolite, occurs naturally in various plants and is manufactured for commercial use. Although HQ displays various biological effects, its neuroprotective effects following ischemic insults have not been investigated. In this study, we first examined neuroprotective effects of HQ in a rat model of transient focal cerebral ischemia. Animals were subjected to transient middle cerebral artery occlusion for 120 min. HQ (50 or 100 mg/kg) or vehicle was intraperitoneally administered once at 30 min after ischemia-reperfusion. Neuroprotection by treatment with 100 mg/kg of HQ was shown using evaluation of neurological deficits, positron-emission tomography (PET) and 2,3,5-triphenyltetrazoliumchloride (TTC) staining. In addition, HQ treatment significantly attenuated ischemia-induced Evans blue dye extravasation from blood vessels and significantly increased immunoreactivities of SMI-71 (an endothelial BBB marker) and glucose transporter-1 (GLUT-1, an endothelial cell marker) in ischemic cortex compared to the vehicle-treated ischemia-operated group. Confocal microscopy and western blot analysis also showed that HQ treatment maintained expressions of tight junction proteins (zonula occludens-1 and occludin) in the ischemic cortex. Post-treatment with HQ protected neurons from transient focal cerebral ischemic injury and the neuroprotective effect of HQ might be closely associated with prevention of BBB disruption via maintaining SMI-71 and GLUT-1 expressions as well as prevention of the degradation of zonula occludens-1 and occludin proteins.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/toxsci/kfw167DOI Listing
December 2016

Arginase Inhibitor 2,3,5,4'-Tetrahydroxystilbene-2-O-β-D-Glucoside Activates Endothelial Nitric Oxide Synthase and Improves Vascular Function.

Planta Med 2017 Feb 8;83(3-04):210-216. Epub 2016 Jul 8.

Department of Biological Sciences, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, South Korea.

Endothelial arginase constrains the activity of endothelial nitric oxide synthase by reducing nitric oxide bioavailability, which contributes to vascular diseases. During screening, we identified a novel compound from the rhizome of (Polygonaceae), 2,3,5,4'-tetrahydroxystilbene-2---D-glucoside (THSG), which inhibited arginase activity. THSG exhibited noncompetitive inhibition of arginase II and inhibited both arginases I and II in a dose-dependent manner. THSG-dependent arginase inhibition reciprocally increased nitric oxide production and decreased reactive oxygen species generation in aortic endothelia. These effects were associated with increased dimerization of endothelial nitric oxide synthase without changes in the protein expression levels of arginase I, arginase II, or endothelial nitric oxide synthase. In vascular tension assays, when aortic vessels from wild-type mice are incubated with THSG, responses to the nitric oxide-dependent vasorelaxant acetylcholine were augmented, but responses to an nitric oxide donor, sodium nitroprusside, were not affected. On the other hand, phenylephrine-dependent vasoconstriction was significantly retarded in THSG-treated vessels. In a high-cholesterol diet-fed atherogenic model mice (ApoE), THSG improved endothelial function by enhancement of the nitric oxide-cGMP pathway. Taken together, these results suggest that THSG may exert vasoprotective effects through augmentation of nitric oxide signaling by inhibiting arginase. Therefore, THSG may be useful in the treatment of vascular diseases that are derived from endothelial dysfunction, such as atherosclerosis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1055/s-0042-111014DOI Listing
February 2017