Publications by authors named "Hyun Ae Woo"

49 Publications

Redox Regulation of PTEN by Peroxiredoxins.

Antioxidants (Basel) 2021 Feb 16;10(2). Epub 2021 Feb 16.

Department of Biochemistry, Research Center for Aging and Geriatrics, Research Institute of Medical Sciences, Chonnam National University Medical School, Gwangju 501-190, Korea.

Phosphatase and tensin homolog deleted on chromosome 10 () is known as a tumor suppressor gene that is frequently mutated in numerous human cancers and inherited syndromes. PTEN functions as a negative regulator of PI3K/Akt signaling pathway by dephosphorylating phosphatidylinositol (3, 4, 5)-trisphosphate (PIP3) to phosphatidylinositol (4, 5)-bisphosphate (PIP2), which leads to the inhibition of cell growth, proliferation, cell survival, and protein synthesis. PTEN contains a cysteine residue in the active site that can be oxidized by peroxides, forming an intramolecular disulfide bond between Cys and Cys. Redox regulation of PTEN by reactive oxygen species (ROS) plays a crucial role in cellular signaling. Peroxiredoxins (Prxs) are a superfamily of peroxidase that catalyzes reduction of peroxides and maintains redox homeostasis. Mammalian Prxs have 6 isoforms (I-VI) and can scavenge cellular peroxides. It has been demonstrated that Prx I can preserve and promote the tumor-suppressive function of PTEN by preventing oxidation of PTEN under benign oxidative stress via direct interaction. Also, Prx II-deficient cells increased PTEN oxidation and insulin sensitivity. Furthermore, Prx III has been shown to protect PTEN from oxidation induced by 15s-HpETE and 12s-HpETE, these are potent inflammatory and pro-oxidant mediators. Understanding the tight connection between PTEN and Prxs is important for providing novel therapies. Herein, we summarized recent studies focusing on the relationship of Prxs and the redox regulation of PTEN.
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http://dx.doi.org/10.3390/antiox10020302DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7920247PMC
February 2021

Maturation of Mitochondrially Targeted Prx V Involves a Second Cleavage by Mitochondrial Intermediate Peptidase That Is Sensitive to Inhibition by HO.

Antioxidants (Basel) 2021 Feb 25;10(3). Epub 2021 Feb 25.

Yonsei Biomedical Research Institute, Yonsei University College of Medicine, Seoul 120-752, Korea.

Prx V mRNA contains two in-frame AUG codons, producing a long (L-Prx V) and short form of Prx V (S-Prx V), and mouse L-Prx V is expressed as a precursor protein containing a 49-amino acid N-terminal mitochondria targeting sequence. Here, we show that the N-terminal 41-residue sequence of L-Prx V is cleaved by mitochondrial processing peptidase (MPP) in the mitochondrial matrix to produce an intermediate Prx V (I-Prx V) with a destabilizing phenylalanine at its N-terminus, and further, that the next 8-residue sequence is cleaved by mitochondrial intermediate peptidase (MIP) to convert I-Prx V to a stabilized mature form that is identical to S-Prx V. Further, we show that when mitochondrial HO levels are increased in HeLa cells using rotenone, in several mouse tissues by deleting Prx III, and in the adrenal gland by deleting Srx or by exposing mice to immobilized stress, I-Prx V accumulates transiently and mature S-Prx V levels decrease in mitochondria over time. These findings support the view that MIP is inhibited by HO, resulting in the accumulation and subsequent degradation of I-Prx V, identifying a role for redox mediated regulation of Prx V proteolytic maturation and expression in mitochondria.
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http://dx.doi.org/10.3390/antiox10030346DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7996597PMC
February 2021

The critical role of redox regulation of PTEN and peroxiredoxin III in alcoholic fatty liver.

Free Radic Biol Med 2021 Jan 26;162:141-148. Epub 2020 Nov 26.

Department of Biochemistry, Department of Biomedical Sciences, Research Center for Aging and Geriatrics, Research Institute of Medical Sciences, Chonnam National University Medical School, Gwangju, 501-190, South Korea. Electronic address:

Hepatic steatosis and subsequent fatty liver disease are developed in response to alcohol consumption. Reactive oxygen species (ROS) are thought to play an important role in the alcoholic fatty liver disease (AFLD). However, the molecular targets of ROS and the underlying cellular mechanisms are unknown. Here, we investigate roles of peroxiredoxin III and redox regulation of phosphatase and tension homolog deleted on chromosome 10 (PTEN) in the alcoholic fatty liver. Alcohol-induced mitochondrial oxidative stress was found to contribute to reversible oxidation of PTEN, which results in Akt and MAPK hyperactivation with elevated levels of the lipogenesis regulators SREBP1c and PPARγ. Moreover, mitochondrial peroxiredoxin III was found to have antagonistic effects on lipogenesis via the redox regulation of PTEN by removing ROS, upon alcohol exposure. This study demonstrated that redox regulation of PTEN and peroxiredoxin III play crucial roles in the development of AFLD.
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http://dx.doi.org/10.1016/j.freeradbiomed.2020.11.022DOI Listing
January 2021

Peroxiredoxin 3 Has Important Roles on Arsenic Trioxide Induced Apoptosis in Human Acute Promyelocytic Leukemia Cell Line via Hyperoxidation of Mitochondrial Specific Reactive Oxygen Species.

Mol Cells 2020 Sep;43(9):813-820

Department of Hematology and Oncology, Ewha Womans University College of Medicine, Seoul 07985, Korea.

NB4 cell, the human acute promyelocytic leukemia (APL) cell line, was treated with various concentrations of arsenic trioxide (ATO) to induce apoptosis, measured by staining with 7-amino-actinomycin D (7-AAD) by flow cytometry. 2', 7'-dichlorodihydro-fluorescein-diacetate (DCF-DA) and MitoSOX Red mitochondrial superoxide indicator were used to detect intracellular and mitochondrial reactive oxygen species (ROS). The steady-state level of SO (Cysteine sulfinic acid, Cys-SOH) form for peroxiredoxin 3 (PRX3) was measured by a western blot. To evaluate the effect of sulfiredoxin 1 depletion, NB4 cells were transfected with small interfering RNA and analyzed for their influence on ROS, redox enzymes, and apoptosis. The mitochondrial ROS of NB4 cells significantly increased after ATO treatment. NB4 cell apoptosis after ATO treatment increased in a time-dependent manner. Increased SO form and dimeric PRX3 were observed as a hyperoxidation reaction in NB4 cells post-ATO treatment, in concordance with mitochondrial ROS accumulation. Sulfiredoxin 1 expression is downregulated by small interfering RNA transfection, which potentiated mitochondrial ROS generation and cell growth arrest in ATO-treated NB4 cells. Our results indicate that ATO-induced ROS generation in APL cell mitochondria is attributable to PRX3 hyperoxidation as well as dimerized PRX3 accumulation, subsequently triggering apoptosis. The downregulation of sulfiredoxin 1 could amplify apoptosis in ATO-treated APL cells.
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http://dx.doi.org/10.14348/molcells.2020.2234DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7528683PMC
September 2020

Ablation of Peroxiredoxin V Exacerbates Ischemia/Reperfusion-Induced Kidney Injury in Mice.

Antioxidants (Basel) 2020 Aug 18;9(8). Epub 2020 Aug 18.

College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 120-750, Korea.

Ischemia/reperfusion (I/R) is one of the major causes of acute kidney injury (AKI) and associated with increased mortality and progression to chronic kidney injury (CKI). Molecular mechanisms underlying I/R injury involve the production and excessive accumulation of reactive oxygen species (ROS). Peroxiredoxin (Prx) V, a cysteine-dependent peroxidase, is located in the cytosol, mitochondria, and peroxisome and has an intensive ROS scavenging activity. Therefore, we focused on the role of Prx V during I/R-induced AKI using Prx V knockout (KO) mice. Ablation of Prx V augmented tubular damage, apoptosis, and declined renal function. Prx V deletion also showed higher susceptibility to I/R injury with increased markers for oxidative stress, ER stress, and inflammation in the kidney. Overall, these results demonstrate that Prx V protects the kidneys against I/R-induced injury.
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http://dx.doi.org/10.3390/antiox9080769DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7464645PMC
August 2020

Redox regulation of tumor suppressor PTEN in cell signaling.

Redox Biol 2020 07 3;34:101553. Epub 2020 May 3.

Department of Biochemistry, Department of Biomedical Sciences, Research Center for Aging and Geriatrics, Research Institute of Medical Sciences, Chonnam National University Medical School, Gwangju, 501-190, Republic of Korea. Electronic address:

Phosphatase and tensin homologs deleted on chromosome 10 (PTEN) is a potent tumor suppressor and often dysregulated in cancers. Cellular PTEN activity is restrained by the oxidation of active-site cysteine by reactive oxygen species (ROS). Recovery of its enzymatic activity predominantly depends on the availability of cellular thioredoxin (Trx) and peroxiredoxins (Prx), both are important players in cell signaling. Trx and Prx undergo redox-dependent conformational changes through the oxidation of cysteine residues at their active sites. Their dynamics are essential for protein functionality and regulation. In this review, we summarized the recent advances regarding the redox regulation of PTEN, with a specific focus on our current state-of-the-art understanding of the redox regulation of PTEN. We also proposed a tight association of the redox regulation of PTEN with Trx dimerization and Prx hyperoxidation, providing guidance for the identification of novel therapeutic targets.
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http://dx.doi.org/10.1016/j.redox.2020.101553DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7226887PMC
July 2020

Multiple functions of 2-Cys peroxiredoxins, I and II, and their regulations via post-translational modifications.

Free Radic Biol Med 2020 05 7;152:107-115. Epub 2020 Mar 7.

College of Pharmacy and College of Natural Sciences, Ewha Womans University, Seoul, 120-750, South Korea.

Peroxiredoxins (Prxs) are an unusual family of thiol-specific peroxidases that possess a binding site for HO and rely on a conserved cysteine residue for rapid reaction with HO. Among 6 mammalian isoforms (Prx I to VI), Prx I and Prx II are mainly found in the cytosol and nucleus. Prx I and Prx II function as antioxidant enzymes and protein chaperone under oxidative distress conditions. Under oxidative eustress conditions, Prx I and Prx II regulate the levels of HO at specific area of the cells as well as sense and transduce HO signaling to target proteins. Prx I and Prx II are known to be covalently modified on multiple sites: Prx I is hyperoxidized on Cys; phosphorylated on Ser, Thr, and Tyr; acetylated on Lys, Lys, Lys, Lys, and Lys; glutathionylated on Cys, Cys, and Cys; and nitrosylated on Cys and Cys, whereas Prx II is hyperoxidized on Cys; phosphorylated on Thr, Ser, and Thr; acetylated on Ala and Lys; glutathionylated on Cys and Cys; and nitrosylated on Cys and Cys. In this review, we describe how these post-translational modifications affect various functions of Prx I and Prx II.
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http://dx.doi.org/10.1016/j.freeradbiomed.2020.02.028DOI Listing
May 2020

enterotoxin upregulates heme oxygenase-1 in dendritic cells reactive oxygen species-, mitogen-activated protein kinase-, and Nrf2-dependent pathway.

World J Gastroenterol 2020 Jan;26(3):291-306

Department of Microbiology and Department of Biomedical Science, Hanyang University College of Medicine and Graduate School of Biomedical Science and Engineering, Seoul 04763, South Korea.

Background: Enterotoxigenic (ETBF) causes colitis and diarrhea, and is considered a candidate pathogen in inflammatory bowel diseases as well as colorectal cancers. These diseases are dependent on ETBF-secreted toxin (BFT). Dendritic cells (DCs) play an important role in directing the nature of adaptive immune responses to bacterial infection and heme oxygenase-1 (HO-1) is involved in the regulation of DC function.

Aim: To investigate the role of BFT in HO-1 expression in DCs.

Methods: Murine DCs were generated from specific pathogen-free C57BL/6 and Nrf2 knockout mice. DCs were exposed to BFT, after which HO-1 expression and the related signaling factor activation were measured by quantitative RT-PCR, EMSA, fluorescent microscopy, immunoblot, and ELISA.

Results: HO-1 expression was upregulated in DCs stimulated with BFT. Although BFT activated transcription factors such as NF-κB, AP-1, and Nrf2, activation of NF-κB and AP-1 was not involved in the induction of HO-1 expression in BFT-exposed DCs. Instead, upregulation of HO-1 expression was dependent on Nrf2 activation in DCs. Moreover, HO-1 expression via Nrf2 in DCs was regulated by mitogen-activated protein kinases such as ERK and p38. Furthermore, BFT enhanced the production of reactive oxygen species (ROS) and inhibition of ROS production resulted in a significant decrease of phospho-ERK, phospho-p38, Nrf2, and HO-1 expression.

Conclusion: These results suggest that signaling pathways involving ROS-mediated ERK and p38 mitogen-activated protein kinases-Nrf2 activation in DCs are required for HO-1 induction during exposure to ETBF-produced BFT.
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http://dx.doi.org/10.3748/wjg.v26.i3.291DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6969884PMC
January 2020

Regulation of Autophagy Is a Novel Tumorigenesis-Related Activity of Multifunctional Translationally Controlled Tumor Protein.

Cells 2020 01 20;9(1). Epub 2020 Jan 20.

Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul 03760, Korea.

Translationally controlled tumor protein (TCTP) is highly conserved in eukaryotic organisms and plays multiple roles regulating cellular growth and homeostasis. Because of its anti-apoptotic activity and its role in the regulation of cancer metastasis, TCTP has become a promising target for cancer therapy. Moreover, growing evidence points to its clinical role in cancer prognosis. How TCTP regulates cellular growth in cancer has been widely studied, but how it regulates cellular homeostasis has received relatively little attention. This review discusses how TCTP is related to cancer and its potential as a target in cancer therapeutics, including its novel role in the regulation of autophagy. Regulation of autophagy is essential for cell recycling and scavenging cellular materials to sustain cell survival under the metabolic stress that cancer cells undergo during their aggressive proliferation.
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http://dx.doi.org/10.3390/cells9010257DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7017196PMC
January 2020

Peroxiredoxin III Protects Tumor Suppressor PTEN from Oxidation by 15-Hydroperoxy-eicosatetraenoic Acid.

Oxid Med Cell Longev 2019 15;2019:2828493. Epub 2019 Sep 15.

Department of Biochemistry, Department of Biomedical Sciences, Research Center for Aging and Geriatrics, Research Institute of Medical Sciences, Chonnam National University Medical School, Gwangju 501-190, Republic of Korea.

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a lipid and protein phosphatase that coordinates various cellular processes. Its activity is regulated by the reversible oxidation of an active-site cysteine residue by HO and thioredoxin. However, the potential role of lipid peroxides in the redox regulation of PTEN remains obscure. To evaluate this, 15-hydroperoxy-eicosatetraenoic acid (15s-HpETE), a lipid peroxide, was employed to investigate its effect on PTEN using molecular and cellular-based assays. Exposure to 15s-HpETE resulted in the oxidation of recombinant PTEN. Reversible oxidation of PTEN was also observed in mouse embryonic fibroblast (MEF) cells treated with a 15s-HpETE and Lipofectamine mixture. The oxidative dimerization of thioredoxin was found simultaneously. In addition, the absence of peroxiredoxin III aggravated 15s-HpETE-induced PTEN oxidation in MEF cells. Our study provides novel insight into the mechanism linking lipid peroxidation to the etiology of tumorigenesis.
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http://dx.doi.org/10.1155/2019/2828493DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6766106PMC
April 2020

Constituents of the leaves and twigs of Elaeagnus umbellata and their proliferative effects on human keratinocyte HaCaT cells.

Fitoterapia 2019 Nov 17;139:104374. Epub 2019 Oct 17.

College of Pharmacy, Yeungnam University, Gyeongsan-si, Gyeongsangbukdo, 38541, Republic of Korea. Electronic address:

Bioassay-guided fractionation of an extract of leaves and twigs of Elaeagnus umbellata led to the isolation of a serotonin derivative, N-[2-(5-hydroxyl-1H-indol-3-yl)ethyl]-butanamide (1), along with six flavonoid glycosides, kaempferol-3-O-β-d-xylopyranosyl(1 → 2)-β-d-galactopyranoside-7-O-α-l-rhamnopyranoside (2), kaempferol-3-O-β-d-galactopyranoside-7-O-α-l-rhamnopyranoside (3), kaempferol-3-O-α-l-rhamnopyranosyl(1 → 6)-β-d-galactopyranoside-7-O-α-l-rhamnopyranoside (4), kaempferol-3-O-β-d-xylopyranosyl(1 → 2)-β-d-galactopyranoside (5), kaempferol-3-O-rutinoside (6), and kaempferol-3-O-β-d-glucopyranosyl(1 → 2)-β-d-galactopyranoside-7-O-α-l-rhamnopyranoside (7). Their structures were elucidated using 1D/2D nuclear magnetic resonance spectroscopy and mass spectrometry. Compounds 1-6 were evaluated for their proliferative effects on HaCaT keratinocytes; 1-5 promoted keratinocyte proliferation dose dependently. Compounds 3 and 4 showed potent activities. These results suggest that the leaves and twigs of E. umbellata have wound healing and skin cell regeneration potentials.
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http://dx.doi.org/10.1016/j.fitote.2019.104374DOI Listing
November 2019

Peroxiredoxin5 Controls Vertebrate Ciliogenesis by Modulating Mitochondrial Reactive Oxygen Species.

Antioxid Redox Signal 2019 05 30;30(14):1731-1745. Epub 2018 Oct 30.

1 KNU-Center for Nonlinear Dynamics, CMRI, School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, College of Natural Sciences, Kyungpook National University , Daegu, South Korea .

Aims: Peroxiredoxin5 (Prdx5), a thioredoxin peroxidase, is an antioxidant enzyme that is widely studied for its antioxidant properties and protective roles in neurological and cardiovascular disorders. This study is aimed at investigating the functional significance of Prdx5 in mitochondria and at analyzing its roles in ciliogenesis during the process of vertebrate development.

Results: We found that several Prdx genes were strongly expressed in multiciliated cells in developing Xenopus embryos, and their peroxidatic functions were crucial for normal cilia development. Depletion of Prdx5 increased levels of cellular reactive oxygen species (ROS), consequently leading to mitochondrial dysfunction and abnormal cilia formation. Proteomic and transcriptomic approaches revealed that excessive ROS accumulation on Prdx5 depletion subsequently reduced the expression level of pyruvate kinase (PK), a key metabolic enzyme in energy production. We further confirmed that the promotor activity of PK was significantly reduced on Prdx5 depletion and that the reduction in PK expression and its promoter activity led to ciliary defects observed in Prdx5-depleted cells.

Innovation: Our data revealed the novel relationship between ROS and Prdx5 and the consequent effects of this interaction on vertebrate ciliogenesis. The normal process of ciliogenesis is interrupted by the Prdx5 depletion, resulting in excessive ROS levels and suggesting cilia as vulnerable targets of ROS.

Conclusion: Prdx5 plays protective roles in mitochondria and is critical for normal cilia development by regulating the levels of ROS. The loss of Prdx5 is associated with excessive production of ROS, resulting in mitochondrial dysfunction and aberrant ciliogenesis.
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http://dx.doi.org/10.1089/ars.2018.7507DOI Listing
May 2019

Some Biological Consequences of the Inhibition of Na,K-ATPase by Translationally Controlled Tumor Protein (TCTP).

Int J Mol Sci 2018 Jun 4;19(6). Epub 2018 Jun 4.

Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul 120-750, Korea.

Na,K-ATPase is an ionic pump that regulates the osmotic equilibrium and membrane potential of cells and also functions as a signal transducer. The interaction of Na,K-ATPase with translationally controlled tumor protein (TCTP) results, among others, in the inhibition of the former's pump activity and in the initiation of manifold biological and pathological phenomena. These phenomena include hypertension and cataract development in TCTP-overexpressing transgenic mice, as well as the induction of tumorigenesis signaling pathways and the activation of Src that ultimately leads to cell proliferation and migration. This review attempts to collate the biological effects of Na,K-ATPase and TCTP interaction and suggests that this interaction has the potential to serve as a possible therapeutic target for selected diseases.
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http://dx.doi.org/10.3390/ijms19061657DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6032315PMC
June 2018

Peroxiredoxin 5 regulates adipogenesis-attenuating oxidative stress in obese mouse models induced by a high-fat diet.

Free Radic Biol Med 2018 08 16;123:27-38. Epub 2018 May 16.

School of Life science, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, Republic of Korea; College of Natural Sciences, Kyungpook National University, Daegu 41566, Republic of Korea. Electronic address:

Elevated levels of reactive oxygen species (ROS) are a hallmark of obesity. Peroxiredoxin 5 (Prx5), which is a cysteine-dependent peroxidase enzyme, has an intensive ROS scavenging activity because it is located in the cytosol and mitochondria. Therefore, we focused on the role of Prx5 in regulating mitochondrial ROS and adipogenesis. We demonstrated that Prx5 expression was upregulated during adipogenesis and Prx5 overexpression suppressed adipogenesis by regulating cytosolic and mitochondrial ROS generation. Silencing Prx5 promoted preadipocytes to differentiate into adipocytes accumulating lipids by activating adipogenic protein expression. Prx5-deletion mice fed on a high-fat diet (HFD) exhibited significant increase in body weight, enormous fat pads, and adipocyte hypertrophy in comparison to wild type mice. Prx5 deletion also remarkably induced adipogenesis-related gene expression in white adipose tissue. These phenotypic changes in Prx5-deletion mice were accompanied with lipid metabolic disorders, such as excessive lipid accumulation in the liver, severe hepatic steatosis, and high levels of triglyceride in the serum. These results demonstrated that Prx5 deletion increased the susceptibility to HFD-induced obesity and several of its associated metabolic disorders. In conclusion, we suggest that Prx5 inhibits adipogenesis by modulating ROS generation and adipogenic gene expression, implying that Prx5 may serve as a potential strategy to prevent and treat obesity.
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http://dx.doi.org/10.1016/j.freeradbiomed.2018.05.061DOI Listing
August 2018

PI3K-mTOR-S6K Signaling Mediates Neuronal Viability via Collapsin Response Mediator Protein-2 Expression.

Front Mol Neurosci 2017 15;10:288. Epub 2017 Sep 15.

College of Pharmacy, Research Institute of Pharmaceutical Sciences, Ewha Womans UniversitySeoul, South Korea.

Collapsin response mediator protein (CRMP)-2 and the mammalian target of rapamycin complex 1 (mTORC1) signaling pathway are associated with common physiological functions such as neuronal polarity, axonal outgrowth and synaptic strength, as well as various brain disorders including epilepsy. But, their regulatory and functional links are unclear. Alterations in CRMP-2 expression that lead to its functional changes are implicated in brain disorders such as epilepsy. Here, we investigate whether changes in CRMP-2 expression, possibly regulated by mTOR-related signaling, correlates with neuronal growth and viability. Inhibition of mTOR and/or phosphoinositol-3-kinase (PI3K) led to deceased p-S6K, and p-S6 signals also reduced CRMP-2 expression. These changes corresponded to inhibition of neuronal viability and proliferation in cultured hippocampal HT-22 cells under both basal serum-free and serum- or insulin-induced mTOR pathway-activated conditions. CRMP-2 expression tended to be increased by mTOR activation, indicated by an increase in p-S6/S6 level, in pentylentetrazole (PTZ)-induced epileptic rat hippocampal tissues was also significantly reduced by mTOR inhibition. Knockdown of CRMP-2 by si-RNA reduced the neuronal viability without changes in mTOR signaling, and overexpression of CRMP-2 recovered the glutamate-induced neurotoxicity and decrease of mTOR signaling in HT-22 cells. In conclusion, CRMP-2 protein expression controlled by the PI3K-mTOR-S6K signaling axis exerts its important functional roles in neuronal growth and survival.
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http://dx.doi.org/10.3389/fnmol.2017.00288DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5605571PMC
September 2017

Redox regulation of the tumor suppressor PTEN by the thioredoxin system and cumene hydroperoxide.

Free Radic Biol Med 2017 11 1;112:277-286. Epub 2017 Aug 1.

Department of Biochemistry, Department of Biomedical Sciences, Research Center for Aging and Geriatrics, Research Institute of Medical Sciences, Chonnam National University Medical School, Gwangju 501-190, Republic of Korea. Electronic address:

Intracellular redox status influences the oxidation and enzyme activity of the tumor suppressor phosphatase and tensin homolog on chromosome 10 (PTEN). Cumene hydroperoxide (CuHP), an organic hydroperoxide, is a known tumor promoter. However, molecular targets and action mechanism of CuHP in tumor promotion have not been well characterized. In this study, we investigated the effect of CuHP on the redox state of PTEN in HeLa cells. In addition, the intracellular reducing system of oxidized PTEN was analyzed using a biochemical approach and the effect of CuHP on this reducing system was also analyzed. While PTEN oxidized by hydrogen peroxide is progressively converted to its reduced form, PTEN was irreversibly oxidized by exposure to CuHP in HeLa cells. A combination of protein fractionation and mass analysis showed that the reducing system of PTEN was comprised of NADPH, thioredoxin reductase (TrxR), and thioredoxin (Trx). Although CuHP-mediated PTEN oxidation was not reversible in cells, CuHP-oxidized PTEN was reactivated by the exogenous Trx system, indicating that the cellular Trx redox system for PTEN is inactivated by CuHP. We present evidence that PTEN oxidation and the concomitant inhibition of thioredoxin by CuHP results in irreversible oxidation of PTEN in HeLa cells. In addition, ablation of peroxiredoxin (Prdx) enhanced CuHP-induced PTEN oxidation in cells. These results provide a new line of evidence that PTEN might be a crucial determinant of cell fate in response to cellular oxidative stress induced by organic hydroperoxides.
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http://dx.doi.org/10.1016/j.freeradbiomed.2017.07.029DOI Listing
November 2017

The Role of Peroxiredoxins in the Transduction of HO Signals.

Antioxid Redox Signal 2018 03 10;28(7):537-557. Epub 2017 Jul 10.

3 Department of Life Science, Ewha Womans University , Seoul, Korea.

Significance: Hydrogen peroxide (HO) is produced on stimulation of many cell surface receptors and serves as an intracellular messenger in the regulation of diverse physiological events, mostly by oxidizing cysteine residues of effector proteins. Mammalian cells express multiple HO-eliminating enzymes, including catalase, glutathione peroxidase (GPx), and peroxiredoxin (Prx). A conserved cysteine in Prx family members is the site of oxidation by HO. Peroxiredoxins possess a high-affinity binding site for HO that is lacking in catalase and GPx and which renders the catalytic cysteine highly susceptible to oxidation, with a rate constant several orders of magnitude greater than that for oxidation of cysteine in most HO effector proteins. Moreover, Prxs are abundant and present in all subcellular compartments. The cysteines of most HO effectors are therefore at a competitive disadvantage for reaction with HO. Recent Advances: Here we review intracellular sources of HO as well as HO target proteins classified according to biochemical and cellular function. We then highlight two strategies implemented by cells to overcome the kinetic disadvantage of most target proteins with regard to HO-mediated oxidation: transient inactivation of local Prx molecules via phosphorylation, and indirect oxidation of target cysteines via oxidized Prx. Critical Issues and Future Directions: Recent studies suggest that only a small fraction of the total pools of Prxs and HO effector proteins localized in specific subcellular compartments participates in HO signaling. Development of sensitive tools to selectively detect phosphorylated Prxs and oxidized effector proteins is needed to provide further insight into HO signaling. Antioxid. Redox Signal. 28, 537-557.
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http://dx.doi.org/10.1089/ars.2017.7167DOI Listing
March 2018

Minor phenolics from Angelica keiskei and their proliferative effects on Hep3B cells.

Bioorg Med Chem Lett 2017 07 18;27(14):3065-3070. Epub 2017 May 18.

College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 120-750, Republic of Korea. Electronic address:

A new coumarin, (-)-cis-(3'R,4'R)-4'-O-angeloylkhellactone-3'-O-β-d-glucopyranoside (1) and two new chalcones, 3'-[(2E)-5-carboxy-3-methyl-2-pentenyl]-4,2',4'-trihydroxychalcone (4) and (±)-4,2',4'-trihydroxy-3'-{2-hydroxy-2-[tetrahydro-2-methyl-5-(1-methylethenyl)-2-furanyl]ethyl}chalcone (5) were isolated from the aerial parts of Angelica keiskei (Umbelliferae), together with six known compounds: (R)-O-isobutyroyllomatin (2), 3'-O-methylvaginol (3), (-)-jejuchalcone F (6), isoliquiritigenin (7), davidigenin (8), and (±)-liquiritigenin (9). The structures of the new compounds were determined by interpretation of their spectroscopic data including 1D and 2D NMR data. All known compounds (2, 3, and 6-9) were isolated as constituents of A. keiskei for the first time. To identify novel hepatocyte proliferation inducer for liver regeneration, 1-9 were evaluated for their cell proliferative effects using a Hep3B human hepatoma cell line. All isolates exhibited cell proliferative effects compared to untreated control (DMSO). Cytoprotective effects against oxidative stress induced by glucose oxidase were also examined on Hep3B cells and mouse fibroblast NIH3T3 cells and all compounds showed significant dose-dependent protection against oxidative stress.
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http://dx.doi.org/10.1016/j.bmcl.2017.05.054DOI Listing
July 2017

TPT1 (tumor protein, translationally-controlled 1) negatively regulates autophagy through the BECN1 interactome and an MTORC1-mediated pathway.

Autophagy 2017 May 15;13(5):820-833. Epub 2017 Feb 15.

a Graduate School of Pharmaceutical Sciences , College of Pharmacy, Ewha Womans University , Seoul , Korea.

TPT1/TCTP (tumor protein, translationally-controlled 1) is highly expressed in tumor cells, known to participate in various cellular activities including protein synthesis, growth and cell survival. In addition, TPT1 was identified as a direct target of the tumor suppressor TP53/p53 although little is known about the mechanism underlying the anti-survival function of TPT1. Here, we describe a role of TPT1 in the regulation of the MTORC1 pathway through modulating the molecular machinery of macroautophagy/autophagy. TPT1 inhibition induced cellular autophagy via the MTORC1 and AMPK pathways, which are inhibited and activated, respectively, during treatment with the MTOR inhibitor rapamycin. We also found that the depletion of TPT1 potentiated rapamycin-induced autophagy by synergizing with MTORC1 inhibition. We further demonstrated that TPT1 knockdown altered the BECN1 interactome, a representative MTOR-independent pathway, to stimulate autophagosome formation, via downregulating BCL2 expression through activating MAPK8/JNK1, and thereby enhancing BECN1-phosphatidylinositol 3-kinase (PtdIns3K)-UVRAG complex formation. Furthermore, reduced TPT1 promoted autophagic flux by modulating not only early steps of autophagy but also autophagosome maturation. Consistent with in vitro findings, in vivo organ analysis using Tpt1 heterozygote knockout mice showed that autophagy is enhanced because of haploinsufficient TPT1 expression. Overall, our study demonstrated the novel role of TPT1 as a negative regulator of autophagy that may have potential use in manipulating various diseases associated with autophagic dysfunction.
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http://dx.doi.org/10.1080/15548627.2017.1287650DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5446065PMC
May 2017

Protective Role of Mitochondrial Peroxiredoxin III against UVB-Induced Apoptosis of Epidermal Keratinocytes.

J Invest Dermatol 2017 06 12;137(6):1333-1342. Epub 2017 Feb 12.

Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul, Republic of Korea; College of Pharmacy, Ewha Womans University, Seoul, Republic of Korea. Electronic address:

UVB light induces generation of reactive oxygen species, ultimately leading to skin cell damage. Mitochondria are a major source of reactive oxygen species in UVB-irradiated skin cells, with increased levels of mitochondrial reactive oxygen species having been implicated in keratinocyte apoptosis. Peroxiredoxin III (PrxIII) is the most abundant and potent HO-removing enzyme in the mitochondria of most cell types. Here, the protective role of PrxIII against UVB-induced apoptosis of epidermal keratinocytes was investigated. Mitochondrial HO levels were differentiated from other types of ROS using mitochondria-specific fluorescent HO indicators. Upon UVB irradiation, PrxIII-knockdown HaCaT human keratinocytes and PrxIII-deficient (PrxIII) mouse primary keratinocytes exhibited enhanced accumulation of mitochondrial HO compared with PrxIII-expressing controls. Keratinocytes lacking PrxIII were subsequently sensitized to apoptosis through mitochondrial membrane potential loss, cardiolipin oxidation, cytochrome c release, and caspase activation. Increased UVB-induced epidermal tissue damage in PrxIII mice was attributable to increased caspase-dependent keratinocyte apoptosis. Our findings show that mitochondrial HO is a key mediator in UVB-induced apoptosis of keratinocytes and that PrxIII plays a critical role in protecting epidermal keratinocytes against UVB-induced apoptosis through eliminating mitochondrial HO. These findings support the concept that reinforcing mitochondrial PrxIII defenses may help prevent UVB-induced skin damage such as inflammation, sunburn, and photoaging.
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http://dx.doi.org/10.1016/j.jid.2017.01.027DOI Listing
June 2017

Bacteroides fragilis Enterotoxin Upregulates Heme Oxygenase-1 in Intestinal Epithelial Cells via a Mitogen-Activated Protein Kinase- and NF-κB-Dependent Pathway, Leading to Modulation of Apoptosis.

Infect Immun 2016 09 19;84(9):2541-54. Epub 2016 Aug 19.

Department of Microbiology and Department of Biomedical Science, Hanyang University College of Medicine and Graduate School of Biomedical Science and Engineering, Seoul, South Korea

The Bacteroides fragilis enterotoxin (BFT), a virulence factor of enterotoxigenic B. fragilis (ETBF), interacts with intestinal epithelial cells and can provoke signals that induce mucosal inflammation. Although expression of heme oxygenase-1 (HO-1) is associated with regulation of inflammatory responses, little is known about HO-1 induction in ETBF infection. This study was conducted to investigate the effect of BFT on HO-1 expression in intestinal epithelial cells. Stimulation of intestinal epithelial cells with BFT resulted in upregulated expression of HO-1. BFT activated transcription factors such as NF-κB, AP-1, and Nrf2 in intestinal epithelial cells. Upregulation of HO-1 in intestinal epithelial cells was dependent on activated IκB kinase (IKK)-NF-κB signals. However, suppression of Nrf2 or AP-1 signals in intestinal epithelial cells did not result in significant attenuation of BFT-induced HO-1 expression. HO-1 induction via IKK-NF-κB in intestinal epithelial cells was regulated by p38 mitogen-activated protein kinases (MAPKs). Furthermore, suppression of HO-1 activity led to increased apoptosis in BFT-stimulated epithelial cells. These results suggest that a signaling pathway involving p38 MAPK-IKK-NF-κB in intestinal epithelial cells is required for HO-1 induction during exposure to BFT. Following this induction, increased HO-1 expression may regulate the apoptotic process in responses to BFT stimulation.
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http://dx.doi.org/10.1128/IAI.00191-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4995915PMC
September 2016

Crude Preparations of Helicobacter pylori Outer Membrane Vesicles Induce Upregulation of Heme Oxygenase-1 via Activating Akt-Nrf2 and mTOR-IκB Kinase-NF-κB Pathways in Dendritic Cells.

Infect Immun 2016 08 21;84(8):2162-2174. Epub 2016 Jul 21.

Department of Microbiology and Department of Biomedical Science, Hanyang University College of Medicine and Graduate School of Biomedical Science and Engineering, Seoul, South Korea

Helicobacter pylori sheds outer membrane vesicles (OMVs) that contain many surface elements of bacteria. Dendritic cells (DCs) play a major role in directing the nature of adaptive immune responses against H. pylori, and heme oxygenase-1 (HO-1) has been implicated in regulating function of DCs. In addition, HO-1 is important for adaptive immunity and the stress response. Although H. pylori-derived OMVs may contribute to the pathogenesis of H. pylori infection, responses of DCs to OMVs have not been elucidated. In the present study, we investigated the role of H. pylori-derived crude OMVs in modulating the expression of HO-1 in DCs. Exposure of DCs to crude H. pylori OMVs upregulated HO-1 expression. Crude OMVs obtained from a cagA-negative isogenic mutant strain induced less HO-1 expression than OMVs obtained from a wild-type strain. Crude H. pylori OMVs activated signals of transcription factors such as NF-κB, AP-1, and Nrf2. Suppression of NF-κB or Nrf2 resulted in significant attenuation of crude OMV-induced HO-1 expression. Crude OMVs increased the phosphorylation of Akt and downstream target molecules of mammalian target of rapamycin (mTOR), such as S6 kinase 1 (S6K1). Suppression of Akt resulted in inhibition of crude OMV-induced Nrf2-dependent HO-1 expression. Furthermore, suppression of mTOR was associated with inhibition of IκB kinase (IKK), NF-κB, and HO-1 expression in crude OMV-exposed DCs. These results suggest that H. pylori-derived OMVs regulate HO-1 expression through two different pathways in DCs, Akt-Nrf2 and mTOR-IKK-NF-κB signaling. Following this induction, increased HO-1 expression in DCs may modulate inflammatory responses in H. pylori infection.
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http://dx.doi.org/10.1128/IAI.00190-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4962631PMC
August 2016

Identification of cytoprotective constituents of the flower buds of Tussilago farfara against glucose oxidase-induced oxidative stress in mouse fibroblast NIH3T3 cells and human keratinocyte HaCaT cells.

Arch Pharm Res 2016 Apr 16;39(4):474-480. Epub 2016 Mar 16.

College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul, 03760, Korea.

A new cytoprotective compound, 1-[(4S)-3,4-dihydro-4-hydroxy-2,2-dimethyl-2H-1-benzopyran-6-yl]-ethanone (1) was isolated from the flower buds of Tussilago farfara L. (Compositae), together with eight known compounds, 3,4-dicaffeoyl isoquinic acid (2), trans-cinnamic acid (3), 4-hydroxyacetophenone (4), 4,5-dicaffeoylquinic acid methyl ester (5), 3,5-dicaffeoylquinic acid methyl ester (6), 4-hydroxybenzoic acid (7), isoquercetrin (8), and ligucyperonol (9). Compounds 2-4 were found in this plant for the first time. The isolates 1-9, were tested for their cytoprotective activities against glucose oxidase-induced oxidative stress in mouse fibroblast NIH3T3 cells and human keratinocyte HaCaT cells. Among them, 1 and 3 showed significant cytoprotective activities as determined by MTT assay and lactate dehydrogenase leakage, indicating their possibility as the potent cytoprotective agents. The structure of 1 was determined by spectroscopic data analysis including 1D- and 2D-NMR experiments, and its absolute configuration was elucidated by a circular dichroism.
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http://dx.doi.org/10.1007/s12272-016-0730-zDOI Listing
April 2016

Control of the pericentrosomal H2O2 level by peroxiredoxin I is critical for mitotic progression.

J Cell Biol 2015 Jul;210(1):23-33

Yonsei Biomedical Research Institute, Yonsei University, Seoul 120-749, South Korea

Proteins associated with the centrosome play key roles in mitotic progression in mammalian cells. The activity of Cdk1-opposing phosphatases at the centrosome must be inhibited during early mitosis to prevent premature dephosphorylation of Cdh1-an activator of the ubiquitin ligase anaphase-promoting complex/cyclosome-and the consequent premature degradation of mitotic activators. In this paper, we show that reversible oxidative inactivation of centrosome-bound protein phosphatases such as Cdc14B by H2O2 is likely responsible for this inhibition. The intracellular concentration of H2O2 increases as the cell cycle progresses. Whereas the centrosome is shielded from H2O2 through its association with the H2O2-eliminating enzyme peroxiredoxin I (PrxI) during interphase, the centrosome-associated PrxI is selectively inactivated through phosphorylation by Cdk1 during early mitosis, thereby exposing the centrosome to H2O2 and facilitating inactivation of centrosome-bound phosphatases. Dephosphorylation of PrxI by okadaic acid-sensitive phosphatases during late mitosis again shields the centrosome from H2O2 and thereby allows the reactivation of Cdk1-opposing phosphatases at the organelle.
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http://dx.doi.org/10.1083/jcb.201412068DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4493999PMC
July 2015

A new 9,10-dihydrophenanthrene and cell proliferative 3,4-δ-dehydrotocopherols from Stemona tuberosa.

Molecules 2015 Apr 3;20(4):5965-74. Epub 2015 Apr 3.

College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 120-750, Korea.

A new compound, 9,10-dihydro-5-methoxy-8-methyl-2,7-phenanthrenediol (1), was isolated from the roots of Stemona tuberosa Lour. (Stemonaceae) together with two new optically active compounds, (2S,4'R,8'R)-3,4-δ-dehydrotocopherol (2) and (2R,4'R,8'R)-3,4-δ-dehydrotocopherol (3). The structures of compounds 1-3 were determined on the basis of spectroscopic data analysis. Compounds 2 and 3 were each purified from a stereoisomeric mixture of 2 and 3 by preparative HPLC using a chiral column for the first time. The absolute configurations at C-2 of 2 and 3 were determined by Circular Dichroism (CD) experiments. As a part of the research to find natural wound healing agents, all isolates and the mixture of 2 and 3 were evaluated for their cell proliferative effects using a mouse fibroblast NIH3T3 and a HeLa human cervical cancer cell line. As a result, 1, 2, 3, or the mixture of 2 and 3 showed 41.6%, 78.4%, 118.6%, 38.2% increases of cell proliferation in the mouse fibroblast NIH3T3 respectively, compared to 28.4% increase of δ-tocopherol. Moreover, none of them induced cancer cell proliferation. Therefore, 3,4-δ-dehydrotocopherols, especially pure isomers 2 and 3 can be suggested as potential wound healing agents.
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http://dx.doi.org/10.3390/molecules20045965DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6272770PMC
April 2015

EW-7197 inhibits hepatic, renal, and pulmonary fibrosis by blocking TGF-β/Smad and ROS signaling.

Cell Mol Life Sci 2015 May 9;72(10):2023-39. Epub 2014 Dec 9.

College of Pharmacy, Ewha Womans University, Seodaemun-gu, Seoul, 120-750, South Korea.

Fibrosis is an inherent response to chronic damage upon immense apoptosis or necrosis. Transforming growth factor-beta1 (TGF-β1) signaling plays a key role in the fibrotic response to chronic liver injury. To develop anti-fibrotic therapeutics, we synthesized a novel small-molecule inhibitor of the TGF-β type I receptor kinase (ALK5), EW-7197, and evaluated its therapeutic potential in carbon tetrachloride (CCl4) mouse, bile duct ligation (BDL) rat, bleomycin (BLM) mouse, and unilateral ureteral obstruction (UUO) mouse models. Western blot, immunofluorescence, siRNA, and ChIP analysis were carried out to characterize EW-7197 as a TGF-β/Smad signaling inhibitor in LX-2, Hepa1c1c7, NRK52E, and MRC5 cells. In vivo anti-fibrotic activities of EW-7197 were examined by microarray, immunohistochemistry, western blotting, and a survival study in the animal models. EW-7197 decreased the expression of collagen, α-smooth muscle actin (α-SMA), fibronectin, 4-hydroxy-2, 3-nonenal, and integrins in the livers of CCl4 mice and BDL rats, in the lungs of BLM mice, and in the kidneys of UUO mice. Furthermore, EW-7197 extended the lifespan of CCl4 mice, BDL rats, and BLM mice. EW-7197 blocked the TGF-β1-stimulated production of reactive oxygen species (ROS), collagen, and α-SMA in LX-2 cells and hepatic stellate cells (HSCs) isolated from mice. Moreover, EW-7197 attenuated TGF-β- and ROS-induced HSCs activation to myofibroblasts as well as extracellular matrix accumulation. The mechanism of EW-7197 appeared to be blockade of both TGF-β1/Smad2/3 and ROS signaling to exert an anti-fibrotic activity. This study shows that EW-7197 has a strong potential as an anti-fibrosis therapeutic agent via inhibition of TGF-β-/Smad2/3 and ROS signaling.
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http://dx.doi.org/10.1007/s00018-014-1798-6DOI Listing
May 2015

Peroxiredoxin 3 has a crucial role in the contractile function of skeletal muscle by regulating mitochondrial homeostasis.

Free Radic Biol Med 2014 Dec 16;77:298-306. Epub 2014 Sep 16.

Aging Research Institute, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-806, Republic of Korea; Department of Functional Genomics, Korea University of Science and Technology, Daejeon 305-333, Republic of Korea. Electronic address:

Antioxidant systems against reactive oxygen species (ROS) are important factors in regulating homeostasis in various cells, tissues, and organs. Although ROS are known to cause to muscular disorders, the effects of mitochondrial ROS in muscle physiology have not been fully understood. Here, we investigated the effects of ROS on muscle mass and function using mice deficient in peroxiredoxin 3 (Prx3), which is a mitochondrial antioxidant protein. Ablation of Prx3 deregulated the mitochondrial network and membrane potential of myotubes, in which ROS levels were increased. We showed that the DNA content of mitochondria and ATP production were also reduced in Prx3-KO muscle. Of note, the mitofusin 1 and 2 protein levels decreased in Prx3-KO muscle, a biochemical evidence of impaired mitochondrial fusion. Contractile dysfunction was examined by measuring isometric forces of isolated extensor digitorum longus (EDL) and soleus muscles. Maximum absolute forces in both the EDL and the soleus muscles were not significantly affected in Prx3-KO mice. However, fatigue trials revealed that the decrease in relative force was greater and more rapid in soleus from Prx3-KO compared to wild-type mice. Taken together, these results suggest that Prx3 plays a crucial role in mitochondrial homeostasis and thereby controls the contractile functions of skeletal muscle.
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http://dx.doi.org/10.1016/j.freeradbiomed.2014.09.010DOI Listing
December 2014

Circadian rhythm of hyperoxidized peroxiredoxin II is determined by hemoglobin autoxidation and the 20S proteasome in red blood cells.

Proc Natl Acad Sci U S A 2014 Aug 4;111(33):12043-8. Epub 2014 Aug 4.

Yonsei Biomedical Research Institute, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752, Korea

The catalytic cysteine of the typical 2-Cys Prx subfamily of peroxiredoxins is occasionally hyperoxidized to cysteine sulfinic acid during the peroxidase catalytic cycle. Sulfinic Prx (Prx-SO2H) is reduced back to the active form of the enzyme by sulfiredoxin. The abundance of Prx-SO2H was recently shown to oscillate with a period of ∼24 h in human red blood cells (RBCs). We have now investigated the molecular mechanism and physiological relevance of such oscillation in mouse RBCs. Poisoning of RBCs with CO abolished Prx-SO2H formation, implicating H2O2 produced from hemoglobin autoxidation in Prx hyperoxidation. RBCs express the closely related PrxI and PrxII isoforms, and analysis of RBCs deficient in either isoform identified PrxII as the hyperoxidized Prx in these cells. Unexpectedly, RBCs from sulfiredoxin-deficient mice also exhibited circadian oscillation of Prx-SO2H. Analysis of the effects of protease inhibitors together with the observation that the purified 20S proteasome degraded PrxII-SO2H selectively over nonhyperoxidized PrxII suggested that the 20S proteasome is responsible for the decay phase of PrxII-SO2H oscillation. About 1% of total PrxII undergoes daily oscillation, resulting in a gradual loss of PrxII during the life span of RBCs. PrxII-SO2H was detected in cytosolic and ghost membrane fractions of RBCs, and the amount of membrane-bound PrxII-SO2H oscillated in a phase opposite to that of total PrxII-SO2H. Our results suggest that membrane association of PrxII-SO2H is a tightly controlled process and might play a role in the tuning of RBC function to environmental changes.
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http://dx.doi.org/10.1073/pnas.1401100111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4142998PMC
August 2014

Selective inhibition of the function of tyrosine-phosphorylated STAT3 with a phosphorylation site-specific intrabody.

Proc Natl Acad Sci U S A 2014 Apr 14;111(17):6269-74. Epub 2014 Apr 14.

Division of Life and Pharmaceutical Sciences, Graduate School of Pharmaceutical Sciences, and Global Top 5 Research Program, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 120-750, Korea.

Signal transducer and activator of transcription 3 (STAT3) is a multifunctional protein that participates in signaling pathways initiated by various growth factors and cytokines. It exists in multiple forms including those phosphorylated on Tyr(705) (pYSTAT3) or Ser(727) (pSSTAT3) as well as the unphosphorylated protein (USTAT3). In addition to the canonical transcriptional regulatory role of pYSTAT3, both USTAT3 and pSSTAT3 function as transcriptional regulators by binding to distinct promoter sites and play signaling roles in the cytosol or mitochondria. The roles of each STAT3 species in different biological processes have not been readily amenable to investigation, however. We have now prepared an intrabody that binds specifically and with high affinity to the tyrosine-phosphorylated site of pYSTAT3. Adenovirus-mediated expression of the intrabody in HepG2 cells as well as mouse liver blocked both the accumulation of pYSTAT3 in the nucleus and the production of acute phase response proteins induced by interleukin-6. Intrabody expression did not affect the overall accumulation of pSSTAT3 induced by interleukin-6 or phorbol 12-myristate 13-acetate (PMA), the PMA-induced expression of the c-Fos gene, or the PMA-induced accumulation of pSSTAT3 specifically in mitochondria. In addition, it had no effect on interleukin-6-induced expression of the gene for IFN regulatory factor 1, a downstream target of STAT1. Our results suggest that the engineered intrabody is able to block specifically the downstream effects of pYSTAT3 without influencing those of pSSTAT3, demonstrating the potential of intrabodies as tools to dissect the cellular functions of specific modified forms of proteins that exist as multiple species.
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http://dx.doi.org/10.1073/pnas.1316815111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4035943PMC
April 2014

Ablation of peroxiredoxin II attenuates experimental colitis by increasing FoxO1-induced Foxp3+ regulatory T cells.

J Immunol 2013 Oct 18;191(8):4029-37. Epub 2013 Sep 18.

College of Pharmacy and Global Top 5 Research Program, Ewha Womans University, Seoul 120-750, Korea.

Peroxiredoxin (Prx) II is an intracellular antioxidant molecule that eliminates hydrogen peroxide, employing a high substrate-binding affinity. PrxII deficiency increases the levels of intracellular reactive oxygen species in many types of cells, which may increase reactive oxygen species-mediated inflammation. In this study, we investigated the susceptibility of PrxII knockout (KO) mice to experimentally induced colitis and the effects of PrxII on the immune system. Wild-type mice displayed pronounced weight loss, high mortality, and colon shortening after dextran sulfate sodium administration, whereas colonic inflammation was significantly attenuated in PrxII KO mice. Although macrophages were hyperactivated in PrxII KO mice, the amount of IFN-γ and IL-17 produced by CD4(+) T cells was substantially reduced. Foxp3(+) regulatory T (Treg) cells were elevated, and Foxp3 protein expression was increased in the absence of PrxII in vitro and in vivo. Restoration of PrxII into KO cells suppressed the increased Foxp3 expression. Interestingly, endogenous PrxII was inactivated through hyperoxidation during Treg cell development. Furthermore, PrxII deficiency stabilized FoxO1 expression by reducing mouse double minute 2 homolog expression and subsequently activated FoxO1-mediated Foxp3 gene transcription. PrxII overexpression, in contrast, reduced FoxO1 and Foxp3 expression. More interestingly, adoptive transfer of naive CD4(+) T cells from PrxII KO mice into immune-deficient mice attenuated T cell-induced colitis, with a reduction in mouse double minute 2 homolog expression and an increase in FoxO1 and Foxp3 expression. These results suggest that inactivation of PrxII is important for the stability of FoxO1 protein, which subsequently mediates Foxp3(+) Treg cell development, thereby attenuating colonic inflammation.
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http://dx.doi.org/10.4049/jimmunol.1203247DOI Listing
October 2013