Publications by authors named "Kyuho Jeong"

29 Publications

  • Page 1 of 1

P2Y2R Deficiency Ameliorates Hepatic Steatosis by Reducing Lipogenesis and Enhancing Fatty Acid β-Oxidation through AMPK and PGC-1α Induction in High-Fat Diet-Fed Mice.

Int J Mol Sci 2021 May 24;22(11). Epub 2021 May 24.

Department of Pharmacology, Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju 52727, Korea.

Non-alcoholic fatty liver disease (NAFLD) is a chronic metabolic liver disease associated with obesity and insulin resistance. Activation of the purinergic receptor P2Y2R has been reported to promote adipogenesis, inflammation and dyslipidemia in adipose tissues in obese mice. However, the role of P2Y2R and its mechanisms in NAFLD remain unknown. We hypothesized that P2Y2R deficiency may play a protective role in NAFLD by modulating lipid metabolism in the liver. In this study, we fed wild type and P2Y2R knockout mice with a high-fat diet (HFD) for 12 weeks and analyzed metabolic phenotypes. First, P2Y2R deficiency effectively improved insulin resistance with a reduction in body weight and plasma insulin. Second, P2Y2R deficiency attenuated hepatic lipid accumulation and injury with reduced alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. Third, P2Y2R deficiency decreased the expression of fatty acid synthesis mediators (cluster of differentiation (CD36), fatty acid synthase (FAS), and stearoyl-CoA desaturase 1 (SCD1)); and increased the expression of adipose triglyceride lipase (ATGL), a lipolytic enzyme. Mechanistically, P2Y2R deficiency increased the AMP-activated protein kinase (AMPK) activity to improve mitochondrial fatty acid β-oxidation (FAO) by regulating acetyl-CoA carboxylase (ACC) and carnitine palmitoyltransferase 1A (CPT1A)-mediated FAO pathway. In addition, P2Y2R deficiency increased peroxisome proliferator-activated gamma co-activator-1α (PGC-1α)-mediated mitochondrial biogenesis. Conclusively, P2Y2R deficiency ameliorated HFD-induced hepatic steatosis by enhancing FAO through AMPK signaling and PGC-1α pathway, suggesting P2Y2R as a promising therapeutic target for NAFLD.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/ijms22115528DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8197197PMC
May 2021

FAK in the nucleus prevents VSMC proliferation by promoting p27 and p21 expression via Skp2 degradation.

Cardiovasc Res 2021 Apr 11. Epub 2021 Apr 11.

Department of Biochemistry and Molecular Biology, College of Medicine, University of South Alabama, Mobile, AL 36688.

Aim: Vascular smooth muscle cells (VSMCs) normally exhibit a very low proliferative rate. Vessel injury triggers VSMC proliferation, in part, through focal adhesion kinase (FAK) activation, which increases transcription of cyclin D1, a key activator for cell cycle-dependent kinases (CDKs). At the same time, we also observe that FAK regulates the expression of the CDK inhibitors (CDKIs) p27 and p21. However, the mechanism of how FAK controls CDKIs in cell cycle progression is not fully understood.

Methods And Results: We found that pharmacological and genetic FAK inhibition increased p27 and p21 by reducing stability of S-phase kinase-associated protein 2 (Skp2), which targets the CDKIs for degradation. FAK N-terminal domain interacts with Skp2 and an APC/C E3 ligase activator, fizzy-related 1 (Fzr1) in the nucleus, which promotes ubiquitination and degradation of both Skp2 and Fzr1. Notably, overexpression of cyclin D1 alone failed to promote proliferation of genetic FAK kinase-dead (KD) VSMCs, suggesting that the FAK-Skp2-CDKI signaling axis is distinct from the FAK-cyclin D1 pathway. However, overexpression of both cyclin D1 and Skp2 enables proliferation of FAK-KD VSMCs, implicating that FAK ought to control both activating and inhibitory switches for CDKs. In vivo, wire injury activates FAK in the cytosol and increased Skp2 and decreased p27 and p21 levels.

Conclusions: Both pharmacological FAK and genetic FAK inhibition reduced Skp2 expression in VSMCs upon injury, which significantly reduced intimal hyperplasia through elevated expression of p27 and p21. This study revealed that nuclear FAK-Skp2-CDKI signaling negatively regulates CDK activity in VSMC proliferation.

Translational Perspective: Increased VSMC proliferation contributes to pathological vessel narrowing in atherosclerosisand following vascular interventions. Blocking VSMC proliferation will reduce atherosclerosisprogression and increase patency of vascular interventions. We found that forced nuclear FAKlocalization by FAK inhibition reduced VSMC proliferation upon vessel injury. Nuclear FAKdecreased Skp2 protein expression by proteasomal degradation, thereby increasing theexpression of cell cycle inhibitors p27 and p21 and blocking cell cycle progression. This studyhas demonstrated the potential for FAK inhibitors in blocking VSMC proliferation to treat vessel narrowing diseases.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/cvr/cvab132DOI Listing
April 2021

Geniposide Improves Diabetic Nephropathy by Enhancing ULK1-Mediated Autophagy and Reducing Oxidative Stress through AMPK Activation.

Int J Mol Sci 2021 Feb 6;22(4). Epub 2021 Feb 6.

Department of Pharmacology, Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju 52727, Korea.

Diabetic nephropathy (DN) is a common pathological feature in patients with diabetes and the leading cause of end-stage renal disease. Although several pharmacological agents have been developed, the management of DN remains challenging. Geniposide, a natural compound has been reported for anti-inflammatory and anti-diabetic effects; however, its role in DN remains poorly understood. This study investigated the protective effects of geniposide on DN and its underlying mechanisms. We used a C57BL/6 mouse model of DN in combination with a high-fat diet and streptozotocin after unilateral nephrectomy and treated with geniposide by oral gavage for 5 weeks. Geniposide effectively improves DN-induced renal structural and functional abnormalities by reducing albuminuria, podocyte loss, glomerular and tubular injury, renal inflammation and interstitial fibrosis. These changes induced by geniposide were associated with an increase of AMPK activity to enhance ULK1-mediated autophagy response and a decrease of AKT activity to block oxidative stress, inflammation and fibrosis in diabetic kidney. In addition, geniposide increased the activities of PKA and GSK3β, possibly modulating AMPK and AKT pathways, efficiently improving renal dysfunction and ameliorating the progression of DN. Conclusively, geniposide enhances ULK1-mediated autophagy and reduces oxidative stress, inflammation and fibrosis, suggesting geniposide as a promising treatment for DN.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/ijms22041651DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7915505PMC
February 2021

Focal Adhesion Kinase Activity and Localization is Critical for TNF-α-Induced Nuclear Factor-κB Activation.

Inflammation 2021 Jun 2;44(3):1130-1144. Epub 2021 Feb 2.

Department of Biochemistry and Molecular Biology, University of South Alabama College of Medicine, 5851 N. USA Drive, Room 2366, Mobile, AL, 36688, USA.

While sustained nuclear factor-κB (NF-κB) activation is critical for proinflammatory molecule expression, regulators of NF-κB activity during chronic inflammation are not known. We investigated the role of focal adhesion kinase (FAK) on sustained NF-κB activation in tumor necrosis factor-α (TNF-α)-stimulated endothelial cells (ECs) both in vitro and in vivo. We found that FAK inhibition abolished TNF-α-mediated sustained NF-κB activity in ECs by disrupting formation of TNF-α receptor complex-I (TNFRC-I). Additionally, FAK inhibition diminished recruitment of receptor-interacting serine/threonine-protein kinase 1 (RIPK1) and the inhibitor of NF-κB (IκB) kinase (IKK) complex to TNFRC-I, resulting in elevated stability of IκBα protein. In mice given TNF-α, pharmacological and genetic FAK inhibition blocked TNF-α-induced IKK-NF-κB activation in aortic ECs. Mechanistically, TNF-α activated and redistributed FAK from the nucleus to the cytoplasm, causing elevated IKK-NF-κB activation. On the other hand, FAK inhibition trapped FAK in the nucleus of ECs even upon TNF-α stimulation, leading to reduced IKK-NF-κB activity. Together, these findings support a potential use for FAK inhibitors in treating chronic inflammatory diseases.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10753-020-01408-5DOI Listing
June 2021

Fermentation of Sprouted Ginseng () Increases Flavonoid and Phenolic Contents to Attenuate Alcoholic Hangover and Acute Liver Injury in Mice.

Am J Chin Med 2021 26;49(1):131-146. Epub 2020 Dec 26.

Department of Pharmacology, Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju 52727, Republic of Korea.

Alcoholic liver damage is caused by ethanol and its oxidized intermediates, and endotoxin-induced acute liver failure is mediated by apoptosis and inflammation. We investigated whether extracts of sprouts of (SG) attenuate alcohol or endotoxin-induced acute liver injury in mice. Whole SG contains eight times more ginsenosides than the root and, because it grows quickly ([Formula: see text]30 days) without using pesticides, the whole-plant can be harvested. The extracts were enriched in phenolics and flavonoids and showed high radical scavenging activities. Mice received oral administration of SG or fermented SG (FSG) extracts 1 h before an injection of either ethanol or lipopolysaccharide and D-galactosamine (LPS/GalN). The latency of righting reflex was monitored to examine the effect of extracts on relieving hangover symptoms. The results indicate that FSG significantly reduced the latency of righting reflex, SG and FSG increased the activity and expression of ethanol-metabolizing enzymes, and FSG decreased hepatic necrosis and plasma levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). During the ethanol metabolism, cytochrome P450 2E1 expression was increased, but 4-hydroxynonenal levels were decreased by the extracts due to their anti-oxidant activity. LPS/GalN-induced liver injury was reduced by SG and FSG; plasma ALT and AST levels, hepatic necrosis, and apoptotic and inflammatory markers were all decreased. In conclusion, SG extracts attenuated ethanol-induced hangover and endotoxin-induced acute liver injury, and fermentation enhanced the efficacy with regard to relieving hangover.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1142/S0192415X21500075DOI Listing
December 2020

P2Y2R contributes to the development of diabetic nephropathy by inhibiting autophagy response.

Mol Metab 2020 12 25;42:101089. Epub 2020 Sep 25.

Department of Pharmacology, Institute of Health Sciences, Gyeongsang National University School of Medicine, Jinju 52727, Republic of Korea; Department of Convergence Medical Sciences, Institute of Health Sciences, Gyeongsang National University Graduate School, Jinju 52727, Republic of Korea. Electronic address:

Objective: Diabetic nephropathy (DN) is one of the most common complications of diabetes and a critical risk factor for developing end-stage renal disease. Activation of purinergic receptors, including P2Y2R has been associated with the pathogenesis of renal diseases, such as polycystic kidney and glomerulonephritis. However, the role of P2Y2R and its precise mechanisms in DN remain unknown. We hypothesised that P2Y2R deficiency may play a protective role in DN by modulating the autophagy signalling pathway.

Methods: We used a mouse model of DN by combining a treatment of high-fat diet and streptozotocin after unilateral nephrectomy in wild-type or P2Y2R knockout mice. We measured renal functional parameter in plasma, examined renal histology, and analysed expression of autophagy regulatory proteins.

Results: Hyperglycaemia and ATP release were induced in wild type-DN mice and positively correlated with renal dysfunction. Conversely, P2Y2R knockout markedly attenuates albuminuria, podocyte loss, development of glomerulopathy, renal tubular injury, apoptosis and interstitial fibrosis induced by DN. These protective effects were associated with inhibition of AKT-mediated FOXO3a (forkhead box O3a) phosphorylation and induction of FOXO3a-induced autophagy gene transcription. Furthermore, inhibitory phosphorylation of ULK-1 was decreased, and the downstream Beclin-1 autophagy signalling was activated in P2Y2R deficiency. Increased SIRT-1 (sirtuin-1) and FOXO3a expression in P2Y2R deficiency also enhanced autophagy response, thereby ameliorating renal dysfunction in DN.

Conclusions: P2Y2R contributes to the pathogenesis of DN by impairing autophagy and serves as a therapeutic target for treating DN.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.molmet.2020.101089DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7568185PMC
December 2020

Honokiol Protects the Kidney from Renal Ischemia and Reperfusion Injury by Upregulating the Glutathione Biosynthetic Enzymes.

Biomedicines 2020 Sep 15;8(9). Epub 2020 Sep 15.

Department of Pharmacology, Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju 52727, Korea.

Glutathione (GSH) is an endogenous antioxidant found in plants, animals, fungi, and some microorganisms that protects cells by neutralizing hydrogen peroxide. Honokiol, an active ingredient of , is known for antioxidant, anti-inflammatory, and anti-bacterial properties. We investigated the protective mechanism of honokiol through regulating cellular GSH in renal proximal tubules against acute kidney injury (AKI). First, we measured cellular GSH levels and correlated them with the expression of GSH biosynthetic enzymes after honokiol treatment in human kidney-2 (HK-2) cells. Second, we used pharmacological inhibitors or siRNA-mediated gene silencing approach to determine the signaling pathway induced by honokiol. Third, the protective effect of honokiol via GSH biosynthesis was investigated in renal ischemia-reperfusion (IR) mice. Honokiol significantly increased cellular GSH levels by upregulating the subunits of glutamate-cysteine ligase (Gcl)-Gclc and Gclm. These increases were mediated by activation of nuclear factor erythroid 2-related factor 2, via PI3K/Akt and protein kinase C signaling. Consistently, honokiol treatment reduced the plasma creatinine, tubular cell death, neutrophil infiltration and lipid peroxidation in IR mice and the effect was correlated with upregulation of Gclc and Gclm. Conclusively, honokiol may benefit to patients with AKI by increasing antioxidant GSH via transcriptional activation of the biosynthetic enzymes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/biomedicines8090352DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7555803PMC
September 2020

Fermented Extracts Attenuate Endotoxin-Induced Acute Liver Injury in Mice.

Nutrients 2020 Sep 13;12(9). Epub 2020 Sep 13.

Department of Pharmacology, Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju 52727, Korea.

Endotoxin-induced acute liver injury is mediated by an excessive inflammatory response, hepatocellular oxidative stress, and apoptosis. Traditional medicinal plants have been used to treat various disorders. (PG) has been shown to be beneficial in relieving cough and asthma and to have anti-tumor, anti-inflammatory, anti-diabetic activities. The pharmacological action of PG is mainly due to saponins, flavonoids, phenolic, and other compounds. However, raw PG exhibits some side effects at high doses. Here, we extracted raw PG with varying fermentation methods and examined its anti-inflammatory effect and associated signaling kinases in Raw264.7 cells. Then, we investigated the effect of fermented black PG (FBPG) on endotoxin-induced liver injury. Mice were administered FBPG orally at 1 h before the lipopolysaccharide and D-galactosamine (LPS/GalN) injection and sacrificed after 5 h. Black PG (BPG) and FBPG showed a significant reduction in pro-inflammatory cytokines and extracellular nitric oxide (NO); p-38 and ERK signaling was involved in reducing inducible NO synthase in Raw264.7 cells. Consistently, FBPG attenuates LPS/GalN-induced liver injury; plasma ALT and AST, hepatic necrosis, pro-inflammatory cytokines, apoptosis, and lipid peroxidation were all reduced. In conclusion, PG extracts, particularly FBPG, play anti-inflammatory, antioxidant, and anti-apoptotic roles, alleviating endotoxin-induced acute liver injury. Processing raw PG into FBPG extract may be clinically useful by improving the pharmacologically active ingredients and reducing the required dosage.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/nu12092802DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7551015PMC
September 2020

Targeting focal adhesion kinase in cancer cells and the tumor microenvironment.

Exp Mol Med 2020 06 9;52(6):877-886. Epub 2020 Jun 9.

Department of Biochemistry and Molecular Biology, University of South Alabama, College of Medicine, Mobile, AL, 36688, USA.

Focal adhesion kinase (FAK) is an integrin-associated protein tyrosine kinase that is frequently overexpressed in advanced human cancers. Recent studies have demonstrated that aside from FAK's catalytic activity in cancer cells, its cellular localization is also critical for regulating the transcription of chemokines that promote a favorable tumor microenvironment (TME) by suppressing destructive host immunity. In addition to the protumor roles of FAK in cancer cells, FAK activity within cells of the TME may also support tumor growth and metastasis through various mechanisms, including increased angiogenesis and vascular permeability and effects related to fibrosis in the stroma. Small molecule FAK inhibitors have demonstrated efficacy in alleviating tumor growth and metastasis, and some are currently in clinical development phases. However, several preclinical trials have shown increased benefits from dual therapies using FAK inhibitors in combination with other chemotherapies or with immune cell activators. This review will discuss the role of nuclear FAK as a driver for tumor cell survival as well as potential therapeutic strategies to target FAK in both tumors and the TME.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s12276-020-0447-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7338452PMC
June 2020

FAK Family Kinases in Vascular Diseases.

Int J Mol Sci 2020 May 21;21(10). Epub 2020 May 21.

Department of Biochemistry and Molecular Biology, College of Medicine, University of South Alabama, Mobile, AL 36688, USA.

In various vascular diseases, extracellular matrix (ECM) and integrin expression are frequently altered, leading to focal adhesion kinase (FAK) or proline-rich tyrosine kinase 2 (Pyk2) activation. In addition to the major roles of FAK and Pyk2 in regulating adhesion dynamics via integrins, recent studies have shown a new role for nuclear FAK in gene regulation in various vascular cells. In particular, FAK primarily localizes within the nuclei of vascular smooth muscle cells (VSMCs) of healthy arteries. However, vessel injury increased FAK localization back to adhesions and elevated FAK activity, leading to VSMC hyperplasia. The study suggested that abnormal FAK or Pyk2 activation in vascular cells may cause pathology in vascular diseases. Here we will review several studies of FAK and Pyk2 associated with integrin signaling in vascular diseases including restenosis, atherosclerosis, heart failure, pulmonary arterial hypertension, aneurysm, and thrombosis. Despite the importance of FAK family kinases in vascular diseases, comprehensive reviews are scarce. Therefore, we summarized animal models involving FAK family kinases in vascular diseases.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/ijms21103630DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7279255PMC
May 2020

A Quantitative Method to Measure Low Levels of ROS in Nonphagocytic Cells by Using a Chemiluminescent Imaging System.

Oxid Med Cell Longev 2019 11;2019:1754593. Epub 2019 Jun 11.

Department of Biochemistry and Molecular Biology, College of Medicine, University of South Alabama, Mobile, AL 36688, USA.

Chemiluminescence (CL) is one of the most useful methods for detecting reactive oxygen species (ROS). Although fluorescence dyes or genetically encoded biosensors have been developed, CL is still used due to its high sensitivity, ease of use, and low cost. While initially established and used to measure high levels of ROS in phagocytic cells, CL assays are not ideal for measuring low levels of ROS. Here, we developed a newly modified CL assay using a chemiluminescent imaging system for measuring low concentrations of ROS in nonphagocytic cells. We found that dissolving luminol in NaOH, rather than DMSO, increased the HO-induced CL signal and that the addition of 4-iodophenylboronic acid (4IPBA) further increased CL intensity. Our new system also increased the rate and intensity of the CL signal in phorbol 12-myristate 13-acetate- (PMA-) treated HT-29 colon cancer cells compared to those in luminol only. We were able to quantify ROS levels from both cells and media in parallel using an HO standard. A significant benefit to our system is that we can easily measure stimulus-induced ROS formation in a real-time manner and also investigate intracellular signaling pathways from a single sample simultaneously. We found that PMA induced tyrosine phosphorylation of protein tyrosine kinases (PTKs), such as focal adhesion kinase (FAK), protein tyrosine kinase 2 (Pyk2), and Src, and increased actin stress fiber formation in a ROS-dependent manner. Interestingly, treatment with either N-acetyl-L-cysteine (NAC) or diphenyleneiodonium (DPI) reduced the PMA-stimulated phosphorylation of these PTKs, implicating a potential role in cellular ROS signaling. Thus, our newly optimized CL assay using 4IPBA and a chemiluminescent imaging method provides a simple, real-time, and low-cost method for the quantification of low levels of ROS.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1155/2019/1754593DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6594271PMC
January 2020

FAK and Pyk2 activity promote TNF-α and IL-1β-mediated pro-inflammatory gene expression and vascular inflammation.

Sci Rep 2019 05 20;9(1):7617. Epub 2019 May 20.

Department of Biochemistry and Molecular Biology, College of Medicine, University of South Alabama, Mobile, AL, 36688, USA.

Protein tyrosine kinase (PTK) activity has been implicated in pro-inflammatory gene expression following tumor necrosis factor-α (TNF-α) or interkeukin-1β (IL-1β) stimulation. However, the identity of responsible PTK(s) in cytokine signaling have not been elucidated. To evaluate which PTK is critical to promote the cytokine-induced inflammatory cell adhesion molecule (CAM) expression including VCAM-1, ICAM-1, and E-selectin in human aortic endothelial cells (HAoECs), we have tested pharmacological inhibitors of major PTKs: Src and the focal adhesion kinase (FAK) family kinases - FAK and proline-rich tyrosine kinase (Pyk2). We found that a dual inhibitor of FAK/Pyk2 (PF-271) most effectively reduced all three CAMs upon TNF-α or IL-1β stimulation compared to FAK or Src specific inhibitors (PF-228 or Dasatinib), which inhibited only VCAM-1 expression. In vitro inflammation assays showed PF-271 reduced monocyte attachment and transmigration on HAoECs. Furthermore, FAK/Pyk2 activity was not limited to CAM expression but was also required for expression of various pro-inflammatory molecules including MCP-1 and IP-10. Both TNF-α and IL-1β signaling requires FAK/Pyk2 activity to activate ERK and JNK MAPKs leading to inflammatory gene expression. Knockdown of either FAK or Pyk2 reduced TNF-α-stimulated ERK and JNK activation and CAM expression, suggesting that activation of ERK or JNK is specific through FAK and Pyk2. Finally, FAK/Pyk2 activity is required for VCAM-1 expression and macrophage recruitment to the vessel wall in a carotid ligation model in ApoE-/- mice. Our findings define critical roles of FAK/Pyk2 in mediating inflammatory cytokine signaling and implicate FAK/Pyk2 inhibitors as potential therapeutic agents to treat vascular inflammatory disease such as atherosclerosis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-019-44098-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6527705PMC
May 2019

Nuclear Focal Adhesion Kinase Controls Vascular Smooth Muscle Cell Proliferation and Neointimal Hyperplasia Through GATA4-Mediated Cyclin D1 Transcription.

Circ Res 2019 07 17;125(2):152-166. Epub 2019 May 17.

From the Department of Biochemistry and Molecular Biology (K.J., J.M.M., H.P., S.-J.K., Y.A.R.R., W.T.G., J.-S.K., E.-Y.E.A., S.-T.S.L.), University of South Alabama, College of Medicine, Mobile.

Rationale: Neointimal hyperplasia is characterized by excessive accumulation of vascular smooth muscle cells (SMCs) leading to occlusive disorders, such as atherosclerosis and stenosis. Blood vessel injury increases growth factor secretion and matrix synthesis, which promotes SMC proliferation and neointimal hyperplasia via FAK (focal adhesion kinase).

Objective: To understand the mechanism of FAK action in SMC proliferation and neointimal hyperplasia.

Methods And Results: Using combined pharmacological FAK catalytic inhibition (VS-4718) and SMC-specific FAK kinase-dead (Myh11-Cre-ER) mouse models, we report that FAK regulates SMC proliferation and neointimal hyperplasia in part by governing GATA4- (GATA-binding protein 4) cyclin D1 signaling. Inhibition of FAK catalytic activity facilitates FAK nuclear localization, which is required for proteasome-mediated GATA4 degradation in the cytoplasm. Chromatin immunoprecipitation identified GATA4 binding to the mouse cyclin D1 promoter, and loss of GATA4-mediated cyclin D1 transcription diminished SMC proliferation. Stimulation with platelet-derived growth factor or serum activated FAK and redistributed FAK from the nucleus to cytoplasm, leading to concomitant increase in GATA4 protein and cyclin D1 expression. In a femoral artery wire injury model, increased neointimal hyperplasia was observed in parallel with elevated FAK activity, GATA4 and cyclin D1 expression following injury in control mice, but not in VS-4718-treated and SMC-specific FAK kinase-dead mice. Finally, lentiviral shGATA4 knockdown in the wire injury significantly reduced cyclin D1 expression, SMC proliferation, and neointimal hyperplasia compared with control mice.

Conclusions: Nuclear enrichment of FAK by inhibition of FAK catalytic activity during vessel injury blocks SMC proliferation and neointimal hyperplasia through regulation of GATA4-mediated cyclin D1 transcription.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1161/CIRCRESAHA.118.314344DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6702425PMC
July 2019

FAK inhibition reduces metastasis of α4 integrin-expressing melanoma to lymph nodes by targeting lymphatic VCAM-1 expression.

Biochem Biophys Res Commun 2019 02 17;509(4):1034-1040. Epub 2019 Jan 17.

Department of Biochemistry and Molecular Biology, College of Medicine, University of South Alabama, Mobile, AL, 36688, United States. Electronic address:

Malignant melanoma typically metastasizes to lymph nodes (LNs) as a primary or in-transit lesion before secondary metastasis occurs, and LN biopsy is a common procedure to diagnose melanoma progression. Since cancer metastasis is a complex process where various interactions between tumor cells and the stroma play key roles in establishing metastatic lesions, the exact mechanisms underlying melanoma metastasis to LNs remains unknown. It has been known that focal adhesion kinase (FAK) activity promotes the expression of proinflammatory vascular cell adhesion molecule-1 (VCAM-1). As VCAM-1 is a major receptor for α4 integrin and plays a key role in leukocyte recruitment, we reasoned that inhibition of FAK activity may reduce VCAM-1 expression within LNs and thus reduce metastasis of α4 integrin-expressing melanoma to LNs. First, we found that a pharmacological FAK inhibitor, PF-271, blocked tumor necrosis factor-α (TNF-α)-mediated VCAM-1 expression on human dermal lymphatic endothelial cells (HDLECs). In vitro, PF-271 significantly decreased B16F10 melanoma adhesion to and transmigration through HDLECs compared to TNF-α treated cells. Furthermore, in vivo FAK inhibition by oral PF-271 administration reduced VCAM-1 expression in inguinal, cervical, and popliteal LNs compared to vehicle treated mice. Finally, in a footpad metastasis model, B16F10 melanoma cells were injected into the right footpad of C57BL/6 mice, and PF-271 (50 mg/kg, twice daily for 6 days) was orally administrated after 1 week of tumor transplantation. While untreated mice exhibited significant metastatic melanoma lesions in popliteal LNs, PF-271 treated mice showed only marginal melanoma metastasis. These results support the possibility that FAK inhibitors may be a novel preventative option in melanoma metastasis by blocking VCAM-1 expression in LNs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bbrc.2019.01.050DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6350924PMC
February 2019

Supplementation of Ameliorates Diabetic Nephropathy and Hepatic Steatosis by Activating Autophagy in Mice.

Nutrients 2018 Nov 7;10(11). Epub 2018 Nov 7.

Department of Pharmacology, Institute of Health Sciences, Gyeongsang National University School of Medicine, Jinju 52727, Korea.

Diabetic nephropathy (DN) is a diabetic complication marked by albuminuria and a decline of the glomerular filtration rate. Diabetic kidneys are defective in the autophagy process and mitochondrial function and their enhancement of activity alleviates the pathology. In this paper, we developed a mouse model of DN by a combined treatment of a high-fat diet and streptozotocin after unilateral nephrectomy and supplementation with flower or leaf extracts of (AM) were tested. The preventive effects of the extracts on DN pathology and changes on autophagy and mitochondrial proteins were investigated. DN mice showed a significant increase in fasting blood glucose, plasma creatinine, blood urea nitrogen, and urinary albumin levels. Periodic acid⁻Schiff and Sirius red staining of the diabetic kidney presented a significant change in glomerular and tubular structures that was associated with podocyte loss and fibrotic protein accumulation. These changes were attenuated by AM extract treatment in DN mice. In addition, hepatic injury, proinflammatory cytokines, and lipid accumulation were decreased by AM extracts in DN mice. As a protective mechanism, AM extracts significantly increased the expression of proteins by regulating autophagy and mitochondrial dynamics, which potentially prevented the kidney and liver from accumulating pathogenic proteins and dysfunctional mitochondria, which alleviated the progression of DN.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/nu10111703DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6266484PMC
November 2018

Perilla Oil Decreases Aortic and Hepatic Lipid Accumulation by Modulating Lipogenesis and Lipolysis in High-Fat Diet-Fed Mice.

J Med Food 2019 Jan 12;22(1):14-21. Epub 2018 Sep 12.

1 Department of Pharmacology, Institute of Health Sciences, Gyeongsang National University School of Medicine, Jinju, Korea.

Perilla oil has been shown to be beneficial for ameliorating metabolic disorders, but its protective effect is still controversial. We investigated the effect of perilla oil on obesity-induced hepatic and vascular changes in high-fat diet (HFD)-fed mice and provided underlying mechanisms for potential therapeutic applications. Tomato and paprika extract was added to prevent the oxidation during storage of perilla oil. HFD-fed mice were orally administered palm or perilla oil for 90 days. Food intake, body and liver weight, and serum cholesterol levels were measured. Arterial and hepatic lipid accumulation was determined by histological staining. Hepatic triglyceride levels and the expression of proteins regulating lipid metabolism were analyzed. Food intake and body weight were not different between palm oil-treated and perilla oil-treated mice. Serum cholesterol level was significantly lower in perilla oil-treated mice compared with palm oil-treated mice. HFD-induced lipid accumulation was also lower in thoracic aorta and liver by perilla oil compared with palm oil. Perilla oil also decreased hepatic triglyceride level without changing the liver weight. Perilla oil treatment increased the AMP-activated protein kinase and acetyl-CoA carboxylase phosphorylation and the lipolytic protein levels, whereas it decreased the lipogenic protein levels in the liver. In conclusion, perilla oil reduced serum cholesterol and arterial and hepatic lipid accumulation in HFD-fed mice. The data suggest that perilla oil improves the balance of lipogenic and lipolytic protein expression, and ameliorates obesity-induced metabolic disorders and cardiovascular diseases.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1089/jmf.2018.4226DOI Listing
January 2019

The proximal tubular α7 nicotinic acetylcholine receptor attenuates ischemic acute kidney injury through Akt/PKC signaling-mediated HO-1 induction.

Exp Mol Med 2018 04 20;50(4):1-17. Epub 2018 Apr 20.

Department of Pharmacology, Institute of Health Sciences, Gyeongsang National University School of Medicine, Jinju, Republic of Korea.

Activation of the α7 nicotinic acetylcholine receptor (α7nAChR) has been shown to attenuate excessive inflammation by inhibiting proinflammatory cytokines during ischemia-reperfusion (IR) injury; however, the underlying kidney-specific molecular mechanisms remain unclear. The protective action of α7nAChR against renal IR injury was investigated using a selective α7nAChR agonist and antagonist. α7nAChR activation reduced plasma creatinine levels and tubular cell damage, whereas α7nAChR inhibition aggravated the IR-induced phenotype. α7nAChR activation decreased neutrophil infiltration and proinflammatory cytokine expression, increased heme oxygenase-1 (HO-1) expression, and reduced proximal tubular apoptosis after IR as shown by terminal deoxynucleotidyl transferase dUTP nick-end labeling staining and caspase-3 cleavage. In this study, we first showed that α7nAChR activation in the proximal tubules induced HO-1 expression through the phosphoinositide 3-kinase (PI3K)/Akt and protein kinase C (PKC) signaling pathway in vivo in renal IR mice and in vitro in proximal tubular cells. Chemical inhibitors of PKC or PI3K/Akt and small interfering RNA-mediated PKC silencing confirmed the signal specificity of α7nAChR-mediated HO-1 induction in the proximal tubular cells. α7nAChR activation inhibited high-mobility group box 1 release by inducing HO-1 expression and reduced proinflammatory cytokine gene expression and apoptotic cell death in tumor necrosis factor α-stimulated proximal tubular cells. Taken together, we conclude that α7nAChR activation in proximal tubular cells directly protects cells against renal IR injury by inducing HO-1 expression through PI3K/Akt and PKC signaling.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s12276-018-0061-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5938048PMC
April 2018

Alternative translation initiation of Caveolin-2 desensitizes insulin signaling through dephosphorylation of insulin receptor by PTP1B and causes insulin resistance.

Biochim Biophys Acta Mol Basis Dis 2018 06 29;1864(6 Pt A):2169-2182. Epub 2018 Mar 29.

Division of Life Science, Graduate School of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju 52828, Republic of Korea. Electronic address:

Insulin resistance, defined as attenuated sensitivity responding to insulin, impairs insulin action. Direct causes and molecular mechanisms of insulin resistance have thus far remained elusive. Here we show that alternative translation initiation (ATI) of Caveolin-2 (Cav-2) regulates insulin sensitivity. Cav-2β isoform yielded by ATI desensitizes insulin receptor (IR) via dephosphorylation by protein-tyrosine phosphatase 1B (PTP1B), and subsequent endocytosis and lysosomal degradation of IR, causing insulin resistance. Blockage of Cav-2 ATI protects against insulin resistance by preventing Cav-2β-PTP1B-directed IR desensitization, thereby normalizing insulin sensitivity and glucose uptake. Our findings show that Cav-2β is a negative regulator of IR signaling, and identify a mechanism causing insulin resistance through control of insulin sensitivity via Cav-2 ATI.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bbadis.2018.03.022DOI Listing
June 2018

A-type lamin-dependent homo-oligomerization for pY19-Caveolin-2 to function as an insulin-response epigenetic regulator.

Biochim Biophys Acta 2016 11 21;1863(11):2681-2689. Epub 2016 Aug 21.

Division of Life Science, Graduate School of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju 660-701, Republic of Korea. Electronic address:

Association of Caveolin-2 in the inner nuclear membrane specifically with A-type lamin is crucial for the maintenance of its Tyr-19 phosphorylation to promote insulin-response epigenetic activation at the nuclear periphery. Here, we identify that pY19-Caveolin-2 in the inner nuclear membrane exists as homo-oligomeric forms and the A-type lamin is required for sustenance of its oligomeric status. Oligomerization-defective and hence pY19-dephosphorylated monomeric Caveolin-2 in the inner nuclear membrane is unable to carry out Caveolin-2-mediated epigenetic activation of Egr-1 and JunB genes and transactivation of Elk-1 and STAT3 in response to insulin. The homo-oligomeric pY19-Caveolin-2 localizes in and recruits epigenetic modifiers to the A-type lamin-enriched inner nuclear membrane microdomain for the epigenetic activation. Our data show that A-type lamin-dependent Caveolin-2 homo-oligomerization in the inner nuclear membrane microdomain is a precondition for pY19-Caveolin-2-mediated insulin-response epigenetic activation at the nuclear periphery.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bbamcr.2016.08.011DOI Listing
November 2016

Essential role of flotillin-1 palmitoylation in the intracellular localization and signaling function of IGF-1 receptor.

J Cell Sci 2015 Jun 23;128(11):2179-90. Epub 2015 Apr 23.

Division of Life Science, Graduate School of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju 660-701, Korea

Here, we explored flotillin-1-mediated regulation of insulin-like growth factor-1 (IGF-1) signaling. Flotillin-1-deficient cells exhibited a reduction in the activation of IGF-1 receptor (IGF-1R), ERK1/2 and Akt pathways, and the transcriptional activation of Elk-1 and the proliferation in response to IGF-1 were reduced in these cells. We found that IGF-1-independent flotillin-1 palmitoylation at Cys34 in the endoplasmic reticulum (ER) was required for the ER exit and the plasma membrane localization of flotillin-1 and IGF-1R. IGF-1-dependent depalmitoylation and repalmitoylation of flotillin-1 sustained tyrosine kinase activation of the plasma-membrane-targeted IGF-1R. Dysfunction and blocking the turnover of flotillin-1 palmitoylation abrogated cancer cell proliferation after IGF-1R signaling activation. Our data show that flotillin-1 palmitoylation is a new mechanism by which the intracellular localization and activation of IGF-1R are controlled.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1242/jcs.169409DOI Listing
June 2015

Insulin-response epigenetic activation of Egr-1 and JunB genes at the nuclear periphery by A-type lamin-associated pY19-Caveolin-2 in the inner nuclear membrane.

Nucleic Acids Res 2015 Mar 9;43(6):3114-27. Epub 2015 Mar 9.

Department of Biochemistry, Division of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju 660-701, Korea

Insulin controls transcription to sustain its physiologic effects for the organism to adapt to environmental changes added to genetic predisposition. Nevertheless, insulin-induced transcriptional regulation by epigenetic factors and in defined nuclear territory remains elusive. Here we show that inner nuclear membrane (INM)-integrated caveolin-2 (Cav-2) regulates insulin-response epigenetic activation of Egr-1 and JunB genes at the nuclear periphery. INM-targeted pY19-Cav-2 in response to insulin associates specifically with the A-type lamin, disengages the repressed Egr-1 and JunB promoters from lamin A/C through disassembly of H3K9me3, and facilitates assembly of H3K9ac, H3K18ac and H3K27ac by recruitment of GCN5 and p300 and the subsequent enrichment of RNA polymerase II (Pol II) on the promoters at the nuclear periphery. Our findings show that Cav-2 is an epigenetic regulator of histone H3 modifications, and provide novel mechanisms of insulin-response epigenetic activation at the nuclear periphery.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/nar/gkv181DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4381080PMC
March 2015

Fatty acylated caveolin-2 is a substrate of insulin receptor tyrosine kinase for insulin receptor substrate-1-directed signaling activation.

Biochim Biophys Acta 2015 May 7;1853(5):1022-34. Epub 2015 Feb 7.

Department of Biochemistry, Division of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju 660-701, Republic of Korea. Electronic address:

Here, we demonstrate that insulin receptor (IR) tyrosine kinase catalyzes Tyr-19 and Tyr-27 phosphorylation of caveolin-2 (cav-2), leading to stimulation of signaling proteins downstream of IR, and that the catalysis is dependent on fatty acylation status of cav-2, promoting its interaction with IR. Cav-2 is myristoylated at Gly-2 and palmitoylated at Cys-109, Cys-122, and Cys-145. The fatty acylation deficient mutants are unable to localize in the plasma membrane and not phosphorylated by IR tyrosine kinase. IR interacts with the C-terminal domain of cav-2 containing the cysteines for palmitoylation. IR mutants, Y999F and K1057A, but not W1220S, fail interaction with cav-2. Insulin receptor substrate-1 (IRS-1) is recruited to interact with the IR-catalyzed phospho-tyrosine cav-2, which facilitates IRS-1 association with and activation by IR to initiate IRS-1-mediated downstream signaling. Cav-2 fatty acylation and tyrosine phosphorylation are necessary for the IRS-1-dependent PI3K-Akt and ERK activations responsible for glucose uptake and cell survival and proliferation. In conclusion, fatty acylated cav-2 is a new substrate of IR tyrosine kinase, and the fatty acylation and phosphorylation of cav-2 present novel mechanisms by which insulin signaling is activated.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bbamcr.2015.02.002DOI Listing
May 2015

A novel actin cytoskeleton-dependent noncaveolar microdomain composed of homo-oligomeric caveolin-2 for activation of insulin signaling.

Biochim Biophys Acta 2013 Oct 9;1833(10):2176-89. Epub 2013 May 9.

Department of Biochemistry, Gyeongsang National University, Jinju, Republic of Korea.

The role of caveolin-2 (cav-2), independently of caveolin-1 (cav-1) and caveolae, has remained elusive. Our data show that cav-2 exists in the plasma membrane (PM) in cells lacking cav-1 and forms homo-oligomeric complexes. Cav-2 did not interact with cavin-1 and cavin-2 in the PM. Rab6-GTP was required for the microtubule-dependent exocytic transport of cav-2 from the Golgi to the PM independently of cav-1. The cav-2-oligomerized noncaveolar microdomain was unaffected by cholesterol depletion and protected from shearing of silica-coated PM. Activation of insulin receptor (IR) was processed in the microdomain. Actin depolymerization affected the formation and sustenance of cav-2-oligomerized noncaveolar microdomain and attenuated IR recruitment to the microdomain thereby inhibiting IR signaling activation. Cav-2 shRNA stable cells and the cells ectopically expressing an oligomerization domain truncation mutant, cav-2∆47-86 exhibited retardation of IR signaling activation via the noncaveolar microdomain. Elevation in status of cav-2 expression rendered the noncaveolar activation of IR signaling in cav-1 down-regulated or/and cholesterol-depleted cells. Our findings reveal a novel homo-oligomeric cav-2 microdomain responsible for regulating activation of IR signaling in the PM.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bbamcr.2013.05.003DOI Listing
October 2013

Rab6-mediated retrograde transport regulates inner nuclear membrane targeting of caveolin-2 in response to insulin.

Traffic 2012 Sep 11;13(9):1218-33. Epub 2012 Jun 11.

Department of Biochemistry, Division of Applied Life Science (BK21 Program), PMBBRC, Gyeongsang National University, Jinju 660-701, Korea.

Here, we have identified a retrograde transport pathway of caveolin-2 (cav-2) for its regulatory function in the nucleus. Confocal microscopy analysis, photoactivation experiments and subcellular fractionation revealed that cav-2 localized in the Golgi was transported to the inner nuclear membrane (INM) in response to insulin. Exogenous caveolin-1 (cav-1) and P132L-cav-1 expression did not affect the Golgi localization and insulin-induced INM targeting of cav-2. Cav-2(DKV) mutant in the endoplasmic reticulum (ER) was unable to translocate to the INM in response to insulin. The GTP-bound form of Rab6 promoted, but Rab6 siRNA and the GDP-bound form of Rab6 abrogated, retrograde trafficking of cav-2 from the Golgi to ER. Colchicine or nocodazole treatment abolished insulin-induced INM targeting of cav-2. Knock down of gp210 inhibited insulin-induced import of cav-2 from ER/outer nuclear membrane (ONM) to the INM. The INM-targeted cav-2 prevented heterochromatinization and promoted transcriptional activation of Elk-1 and signal transducer and activator of transcription 3 (STAT3). The results provide molecular mechanisms for insulin-induced INM translocation of cav-2 initiated (i) by Golgi-to-ER retrograde trafficking of cav-2 via microtubule-based Rab6-GTP-dependent transport and subsequently processed (ii) by gp210-mediated import of cav-2 from ER/ONM to INM.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/j.1600-0854.2012.01378.xDOI Listing
September 2012

Regulation of cancer cell proliferation by caveolin-2 down-regulation and re-expression.

Int J Oncol 2011 May 3;38(5):1395-402. Epub 2011 Mar 3.

Department of Biochemistry, Division of Applied Life Science (BK21), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Republic of Korea.

We investigated whether altering caveolin-2 (cav-2) expression affects the proliferation of cancer cells. Cav-2 was not detected in HepG2, SH-SY5Y and LN-CaP cells, and the loss of cav-2 expression was not restored by 5-aza-2'-deoxycytidine treatment. In contrast, C6, HeLa, A549, MCF7 and PC3M cells expressed cav-2. Effects of re-expression of exogenous cav-2 in HepG2, SH-SY5Y and LN-CaP cells, and siRNA-mediated down-regulation of endogenous cav-2 in C6, HeLa, A549, MCF7 and PC3M cells on cancer proliferation were examined by MTT assay, colony formation assay and flow cytometric analysis. Cav-2 transfection in HepG2 hepatocellular carcinoma cells and knockdown in C6 glioma cells caused reduction in cell proliferation and growth with retarded entry into the S phase. Cav-2 re-expression in SH-SY5Y neuroblastoma cells and depletion in HeLa epithelial cervical cancer and A549 lung adenocarcinoma cells promoted cancer cell proliferation. Luciferase reporter assay showed that transcriptional activation of Elk-1 and STAT3 was significantly decreased in cav-2-transfected HepG2 hepatocellular carcinoma and down-regulated C6 glioma cells. Our data suggest that cav-2 acts as a modulator of cancer progression.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3892/ijo.2011.958DOI Listing
May 2011

A novel domain of caveolin-2 that controls nuclear targeting: regulation of insulin-specific ERK activation and nuclear translocation by caveolin-2.

J Cell Mol Med 2011 Apr;15(4):888-908

Department of Biochemistry, Division of Applied Life Science, PMBBRC, Gyeongsang National University, Jinju, Korea.

Herein, we report that insulin-activated extracellular signal-regulated kinase (ERK) is translocated to the nuclear envelope by caveolin-2 (cav-2) and associates with lamin A/C in the inner nuclear membrane in response to insulin. We identified that the Ser¹⁵⁴ -Val¹⁵⁵ -Ser¹⁵⁶ domain on the C-terminal of cav-2 is essential for insulin-induced phosphorylation and nuclear targeting of ERK and cav-2. In human embryonic kidney 293T cells, ERK was not activated and translocated to the nucleus by insulin in comparison to insulin-like growth factor-1 (IGF-1). However, insulin-stimulated activation of ERK was induced by exogenous addition of cav-2. The activated ERK associated and translocated with the cav-2 to the nucleus. In turn, cav-2 promoted phospho-ERK interaction with lamin A/C in the inner nuclear membrane. In contrast, ERK, but not cav-2, was phosphorylated and translocated to the nucleus by IGF-1. The nuclear targeted phospho-ERK failed to localize in the nuclear envelope in response to IGF-1. Together, our data demonstrate that translocation of phospho-ERK to the nuclear envelope is mediated by Ser¹⁵⁴ -Val¹⁵⁵ -Ser¹⁵⁶ domain of cav-2 and this event is an insulin-specific action.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/j.1582-4934.2010.01079.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3922675PMC
April 2011

Identification of pY19-caveolin-2 as a positive regulator of insulin-stimulated actin cytoskeleton-dependent mitogenesis.

J Cell Mol Med 2009 Aug;13(8A):1549-64

Department of Biochemistry, Division of Applied Life Science (BK21), Environmental Biotechnology National Core Research Center, Gyeongsang National University, Jinju, Korea.

Mitogenic regulation by caveolin-2 in response to insulin was investigated. Insulin triggered phosphorylation of caveolin-2 on tyrosine 19. Insulin increased the interaction between pY19-caveolin-2 and phospho-ERK, and that interaction was inhibited by a MEK inhibitor U0126. Insulin-induced interaction of caveolin-2 with phospho-ERK was prevented when tyrosine 19 is mutated to alanine. Insulin relocalized phospho-ERK and pY19-caveolin-2 to the nucleus and their nuclear co-localization was impaired by U0126. Down-regulation of caveolin-2 by caveolin-2 siRNA arrested the insulin-induced nuclear localization of ERK with no change in the insulin-stimulated ERK activation. Of consequence, the caveolin-2 siRNA attenuated the ERK-mediated c-Jun and cyclinD1 expression and DNA synthesis by insulin. In addition, actin cytoskeleton influenced the nuclear translocation of caveolin-2-ERK complex. Collectively, our findings underscore the importance of pY19-caveolin-2 with the spatial coordination by insulin in ERK-mediated mitogenic regulation of insulin signalling and indicate that the phosphorylation of pY19-caveolin-2 is required for actin cytoskeleton-dependent ERK nuclear import.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/j.1582-4934.2009.00391.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3828866PMC
August 2009

Caveolin-2 regulation of STAT3 transcriptional activation in response to insulin.

Biochim Biophys Acta 2009 Jul 7;1793(7):1325-33. Epub 2009 May 7.

Department of Biochemistry, Gyeongsang National University, Jinju 660-701, Republic of Korea.

The regulatory function of caveolin-2 in signal transducer and activator of transcription 3 (STAT3) signaling by insulin was investigated. Insulin-induced increase in phosphorylation of STAT3 was reduced by caveolin-2 siRNA. Mutagenesis studies identified that phosphorylation of tyrosines 19 and 27 on caveolin-2 is required for the STAT3 activation. Caveolin-2 Y27A mutation decreased insulin-induced phosphorylation of STAT3 interacting with caveolin-2. pY27-Caveolin-2 was required for nuclear translocation of pY705-STAT3 in response to insulin. In contrast, caveolin-2 Y19A mutation influenced neither the phosphorylation of STAT3 nor nuclear translocation of pY705-STAT3. pY19-Caveolin-2, however, was essential for insulin-induced DNA binding of pS727-STAT3 and STAT3-targeted gene induction in the nucleus. Finally, insulin-induced transcriptional activation of STAT3 depended on phosphorylation of both 19 and 27 tyrosines. Together, our data reveal that phosphotyrosine-caveolin-2 is a novel regulator for transcriptional activation of STAT3 in response to insulin.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bbamcr.2009.04.015DOI Listing
July 2009

Modulation of the caveolin-3 localization to caveolae and STAT3 to mitochondria by catecholamine-induced cardiac hypertrophy in H9c2 cardiomyoblasts.

Exp Mol Med 2009 Apr;41(4):226-35

Department of Biochemistry, Gyeongsang National University, Jinju 660-701, Korea.

We investigated the effect of phenylephrine (PE)- and isoproterenol (ISO)-induced cardiac hypertrophy on subcellular localization and expression of caveolin-3 and STAT3 in H9c2 cardiomyoblast cells. Caveolin-3 localization to plasma membrane was attenuated and localization of caveolin-3 to caveolae in the plasma membrane was 24.3% reduced by the catecholamine- induced hypertrophy. STAT3 and phospho-STAT3 were up-regulated but verapamil and cyclosporin A synergistically decreased the STAT3 and phospho- STAT3 levels in PE- and ISO-induced hypertrophic cells. Both expression and activation of STAT3 were increased in the nucleus by the hypertrophy. Immunofluorescence analysis revealed that the catecholamine- induced hypertrophy promoted nuclear localization of pY705-STAT3. Of interest, phosphorylation of pS727- STAT3 in mitochondria was significantly reduced by catecholamine-induced hypertrophy. In addition, mitochondrial complexes II and III were greatly down- regulated in the hypertrophic cells. Our data suggest that the alterations in nuclear and mitochondrial activation of STAT3 and caveolae localization of caveolin-3 are related to the development of the catecholamine-induced cardiac hypertrophy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3858/emm.2009.41.4.025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2679235PMC
April 2009