Publications by authors named "Sue Goo Rhee"

114 Publications

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

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

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

Peroxiredoxin-mediated disulfide bond formation is required for nucleocytoplasmic translocation and secretion of HMGB1 in response to inflammatory stimuli.

Redox Biol 2019 06 15;24:101203. Epub 2019 Apr 15.

Department of Microbiology, Yonsei University College of Medicine, Seoul 03722, South Korea; Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul 03722, South Korea; Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, Seoul 03722, South Korea; Center for Nanomedicine, Institute for Basic Science (IBS), Seoul 03722, South Korea. Electronic address:

The nuclear protein HMGB1 (high mobility group box 1) is secreted by monocytes-macrophages in response to inflammatory stimuli and serves as a danger-associated molecular pattern. Acetylation and phosphorylation of HMGB1 are implicated in the regulation of its nucleocytoplasmic translocation for secretion, although inflammatory stimuli are known to induce HO production. Here we show that HO-induced oxidation of HMGB1, which results in the formation of an intramolecular disulfide bond between Cys and Cys, is necessary and sufficient for its nucleocytoplasmic translocation and secretion. The oxidation is catalyzed by peroxiredoxin I (PrxI) and PrxII, which are first oxidized by HO and then transfer their disulfide oxidation state to HMGB1. The disulfide form of HMGB1 showed higher affinity for nuclear exportin CRM1 compared with the reduced form. Lipopolysaccharide (LPS)-induced HMGB1 secretion was greatly attenuated in macrophages derived from PrxI or PrxII knockout mice, as was the LPS-induced increase in serum HMGB1 levels.
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http://dx.doi.org/10.1016/j.redox.2019.101203DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6482348PMC
June 2019

A catalytic career: Studies spanning glutamine synthetase, phospholipase C, peroxiredoxin, and the intracellular messenger role of hydrogen peroxide.

Authors:
Sue Goo Rhee

J Biol Chem 2019 03;294(13):5169-5180

From the Yonsei Biomedical Research Institute, Yonsei University College of Medicine, Seoul 120-752, Korea and the Biochemistry and Biophysics Center, NHLBI, National Institutes of Health, Bethesda, Maryland 20892.

I learned biochemistry from P. Boon Chock and Earl Stadtman while working on the regulation of glutamine synthetase as a postdoctoral fellow at the National Institutes of Health. After becoming a tenured scientist at the same institute, my group discovered, purified, and cloned the first three prototypical members of the phospholipase C family and uncovered the mechanisms by which various cell-surface receptors activate these enzymes to generate diacylglycerol and inositol 1,4,5-trisphosphate. We also discovered the family of peroxiredoxin (Prx) enzymes that catalyze the reduction of HO, and we established that mammalian cells express six Prx isoforms that not only protect against oxidative damage but also mediate cell signaling by modulating intracellular HO levels. To validate the signaling role of HO, we showed that epidermal growth factor induces a transient increase in intracellular HO levels, and the essential cysteine residue of protein-tyrosine phosphatases is a target for specific and reversible oxidation by the HO produced in such cells. These observations led to a new paradigm in receptor signaling, in which protein tyrosine phosphorylation is achieved not via activation of receptor tyrosine kinases alone but also through concurrent inhibition of protein-tyrosine phosphatases by HO Our studies revealed that Prx isozymes are extensively regulated via phosphorylation as well as by hyperoxidation of the active-site cysteine to cysteine sulfinic acid, with the reverse reaction being catalyzed by sulfiredoxin. This reversible hyperoxidation of Prx was further shown to constitute a universal marker for circadian rhythms in all domains of life.
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http://dx.doi.org/10.1074/jbc.X119.007975DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6442055PMC
March 2019

Inactivation of the PtdIns(4)P phosphatase Sac1 at the Golgi by HO produced via Ca-dependent Duox in EGF-stimulated cells.

Free Radic Biol Med 2019 02 23;131:40-49. Epub 2018 Nov 23.

Department of Life Science, Ewha Womans University, Seoul 03760, Republic of Korea. Electronic address:

Binding of epidermal growth factor (EGF) to its cell surface receptor induces production of HO, which serves as an intracellular messenger. We have shown that exogenous HO reversibly inactivates the phosphatidylinositol 4-phosphate [PtdIns(4)P] phosphatase Sac1 (suppressor of actin 1) at the Golgi complex of mammalian cells by oxidizing its catalytic cysteine residue and thereby increases both the amount of Golgi PtdIns(4)P and the rate of protein secretion. Here we investigated the effects of EGF on Sac1 oxidation and PtdIns(4)P abundance at the Golgi in A431 cells. EGF induced a transient increase in Golgi PtdIns(4)P as well as a transient oxidation of Sac1 in a manner dependent on elevation of the intracellular Ca concentration and on HO. Oxidation of Sac1 occurred at the Golgi, as revealed with the use of the Golgi-confined Sac1-K2A mutant. Knockdown of Duox enzymes implicated these Ca-dependent members of the NADPH oxidase family as the major source of HO for Sac1 oxidation. Expression of a Golgi-targeted HO probe revealed transient EGF-induced HO production at this organelle. Our findings have thus uncovered a previously unrecognized EGF signaling pathway that links intracellular Ca mobilization to events at the Golgi including Duox activation, HO production, Sac1 oxidation, and PtdIns(4)P accumulation.
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http://dx.doi.org/10.1016/j.freeradbiomed.2018.11.021DOI Listing
February 2019

Accumulation of PtdIns(4)P at the Golgi mediated by reversible oxidation of the PtdIns(4)P phosphatase Sac1 by HO.

Free Radic Biol Med 2019 01 16;130:426-435. Epub 2018 Nov 16.

Yonsei Biomedical Research Institute, Yonsei University, Seoul 03722, Republic of Korea. Electronic address:

Phosphatidylinositol 4-phosphate [PtdIns(4)P] plays a key role in the biogenesis of transport vesicles at the Golgi complex by recruiting coat proteins and their accessory factors. The PtdIns(4)P content of the Golgi is determined by the concerted action of PtdIns 4-kinase (PI4K) and PtdIns(4)P phosphatase enzymes. Sac1 (suppressor of actin 1) is the major PtdIns(4)P phosphatase and is localized to the Golgi and endoplasmic reticulum. The targeting of both PI4Ks and Sac1 to the Golgi membrane is extensively regulated, as is the catalytic activity of PI4Ks at the Golgi. However, regulation of the catalytic activity of Sac1 has been largely unexplored. Here we show that Sac1undergoes reversible inactivation in mammalian cells when its catalytic Cys residue is oxidized by exogenous HO to form an intramolecular disulfide with Cys. The oxidative inactivation of Sac1 results in the accumulation of PtdIns(4)P at the Golgi, with this effect also being supported by the HO-induced activation of p38 mitogen-activated protein kinase (MAPK), which was previously shown to promote the translocation of Sac1 from the Golgi to the endoplasmic reticulum. The increase in Golgi PtdIns(4)P due to Sac1 inactivation, however, is faster than that due to Sac1 translocation. Exposure of cells to HO also increased membrane protein trafficking from the Golgi to the plasma membrane as well as protein secretion.
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http://dx.doi.org/10.1016/j.freeradbiomed.2018.11.008DOI Listing
January 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

Cellular Timekeeping: It's Redox o'Clock.

Cold Spring Harb Perspect Biol 2018 05 1;10(5). Epub 2018 May 1.

The Francis Crick Institute, London NW1 1AT, United Kingdom.

Mounting evidence in recent years supports the extensive interaction between the circadian and redox systems. The existence of such a relationship is not surprising because most organisms, be they diurnal or nocturnal, display daily oscillations in energy intake, locomotor activity, and exposure to exogenous and internally generated oxidants. The transcriptional clock controls the levels of many antioxidant proteins and redox-active cofactors, and, conversely, the cellular redox poise has been shown to feed back to the transcriptional oscillator via redox-sensitive transcription factors and enzymes. However, the circadian cycles in the -sulfinylation of the peroxiredoxin (PRDX) proteins constituted the first example of an autonomous circadian redox oscillation, which occurred independently of the transcriptional clock. Importantly, the high phylogenetic conservation of these rhythms suggests that they might predate the evolution of the transcriptional oscillator, and therefore could be a part of a primordial circadian redox/metabolic oscillator. This discovery forced the reappraisal of the dogmatic transcription-centered view of the clockwork and opened a new avenue of research. Indeed, the investigation into the links between the circadian and redox systems is still in its infancy, and many important questions remain to be addressed.
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http://dx.doi.org/10.1101/cshperspect.a027698DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5932581PMC
May 2018

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

Mitochondrial HO signaling is controlled by the concerted action of peroxiredoxin III and sulfiredoxin: Linking mitochondrial function to circadian rhythm.

Free Radic Biol Med 2016 11 27;100:73-80. Epub 2016 Oct 27.

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

Mitochondria produce hydrogen peroxide (HO) during energy metabolism in most mammalian cells as well as during the oxidation of cholesterol associated with the synthesis of steroid hormones in steroidogenic cells. Some of the HO produced in mitochondria is released into the cytosol, where it serves as a key regulator of various signaling pathways. Given that mitochondria are equipped with several HO-eliminating enzymes, however, it had not been clear how mitochondrial HO can escape destruction by these enzymes for such release. Peroxiredoxin III (PrxIII) is the most abundant and efficient HO-eliminating enzyme in mitochondria of most cell types. We found that PrxIII undergoes reversible inactivation through hyperoxidation of its catalytic cysteine residue to cysteine sulfinic acid, and that release of mitochondrial HO likely occurs as a result of such PrxIII inactivation. The hyperoxidized form of PrxIII (PrxIII-SOH) is reduced and reactivated by sulfiredoxin (Srx). We also found that the amounts of PrxIII-SOH and Srx undergo antiphasic circadian oscillation in mitochondria of the adrenal gland, heart, and brown adipose tissue of mice maintained under normal conditions. Cytosolic Srx was found to be imported into mitochondria via a mechanism that requires formation of a disulfide-linked complex with heat shock protein 90, which is likely promoted by HO released from mitochondria. The imported Srx was found to be degraded by Lon protease in a manner dependent on PrxIII hyperoxidation state. The coordinated import and degradation of Srx underlie Srx oscillation and consequent PrxIII-SOH oscillation in mitochondria. The rhythmic change in the amount of PrxIII-SOH suggests that mitochondrial release of HO is also likely a circadian event that conveys temporal information on steroidogenesis in the adrenal gland and on energy metabolism in heart and brown adipose tissue to cytosolic signaling pathways.
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http://dx.doi.org/10.1016/j.freeradbiomed.2016.10.011DOI Listing
November 2016

Multiple Functions and Regulation of Mammalian Peroxiredoxins.

Annu Rev Biochem 2017 06 2;86:749-775. Epub 2017 Feb 2.

Yonsei Biomedical Research Institute, Yonsei University College of Medicine, Seoul 120-752, Korea; email:

Peroxiredoxins (Prxs) constitute a major family of peroxidases, with mammalian cells expressing six Prx isoforms (PrxI to PrxVI). Cells produce hydrogen peroxide (HO) at various intracellular locations where it can serve as a signaling molecule. Given that Prxs are abundant and possess a structure that renders the cysteine (Cys) residue at the active site highly sensitive to oxidation by HO, the signaling function of this oxidant requires extensive and highly localized regulation. Recent findings on the reversible regulation of PrxI through phosphorylation at the centrosome and on the hyperoxidation of the Cys at the active site of PrxIII in mitochondria are described in this review as examples of such local regulation of HO signaling. Moreover, their high affinity for and sensitivity to oxidation by HO confer on Prxs the ability to serve as sensors and transducers of HO signaling through transfer of their oxidation state to bound effector proteins.
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http://dx.doi.org/10.1146/annurev-biochem-060815-014431DOI Listing
June 2017

p62/SQSTM1 is required for the protection against endoplasmic reticulum stress-induced apoptotic cell death.

Free Radic Res 2016 Dec 23;50(12):1408-1421. Epub 2016 Nov 23.

a Severance Biomedical Science Institute , Yonsei Biomedical Research Institute, Yonsei University College of Medicine , Seoul , Republic of Korea.

Endoplasmic reticulum (ER) stress is triggered by various cellular stresses that disturb protein folding or calcium homeostasis in the ER. To cope with these stresses, ER stress activates the unfolded protein response (UPR) pathway, but unresolved ER stress induces reactive oxygen species (ROS) accumulation leading to apoptotic cell death. However, the mechanisms that underlie protection from ER stress-induced cell death are not clearly defined. The nuclear factor erythroid 2-related factor 2 (Nrf2)-Kelch-like ECH-associated protein 1 (Keap1) pathway plays a crucial role in the protection of cells against ROS-mediated oxidative damage. Keap1 acts as a negative regulator of Nrf2 activation. In this study, we investigated the role of the Nrf2-Keap1 pathway in protection from ER stress-induced cell death using tunicamycin (TM) as an ER stress inducer. We found that Nrf2 is an essential protein for the prevention from TM-induced apoptotic cell death and its activation is driven by autophagic Keap1 degradation. Furthermore, ablation of p62, an adapter protein in the autophagy process, attenuates the Keap1 degradation and Nrf2 activation that was induced by TM treatment, and thereby increases susceptibility to apoptotic cell death. Conversely, reinforcement of p62 alleviated TM-induced cell death in p62-deficient cells. Taken together, these results demonstrate that p62 plays an important role in protecting cells from TM-induced cell death through Nrf2 activation.
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http://dx.doi.org/10.1080/10715762.2016.1253073DOI Listing
December 2016

Mitochondrial HO signaling is controlled by the concerted action of peroxiredoxin III and sulfiredoxin: Linking mitochondrial function to circadian rhythm.

Free Radic Biol Med 2016 10 4;99:120-127. Epub 2016 Aug 4.

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

Mitochondria produce hydrogen peroxide (HO) during energy metabolism in most mammalian cells as well as during the oxidation of cholesterol associated with the synthesis of steroid hormones in steroidogenic cells. Some of the HO produced in mitochondria is released into the cytosol, where it serves as a key regulator of various signaling pathways. Given that mitochondria are equipped with several HO-eliminating enzymes, however, it had not been clear how mitochondrial HO can escape destruction by these enzymes for such release. Peroxiredoxin III (PrxIII) is the most abundant and efficient HO-eliminating enzyme in mitochondria of most cell types. We found that PrxIII undergoes reversible inactivation through hyperoxidation of its catalytic cysteine residue to cysteine sulfinic acid, and that release of mitochondrial HO likely occurs as a result of such PrxIII inactivation. The hyperoxidized form of PrxIII (PrxIII-SOH) is reduced and reactivated by sulfiredoxin (Srx). We also found that the amounts of PrxIII-SOH and Srx undergo antiphasic circadian oscillation in mitochondria of the adrenal gland, heart, and brown adipose tissue of mice maintained under normal conditions. Cytosolic Srx was found to be imported into mitochondria via a mechanism that requires formation of a disulfide-linked complex with heat shock protein 90, which is likely promoted by HO released from mitochondria. The imported Srx was found to be degraded by Lon protease in a manner dependent on PrxIII hyperoxidation state. The coordinated import and degradation of Srx underlie Srx oscillation and consequent PrxIII-SOH oscillation in mitochondria. The rhythmic change in the amount of PrxIII-SOH suggests that mitochondrial release of HO is also likely a circadian event that conveys temporal information on steroidogenesis in the adrenal gland and on energy metabolism in heart and brown adipose tissue to cytosolic signaling pathways.
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http://dx.doi.org/10.1016/j.freeradbiomed.2016.07.029DOI Listing
October 2016

SESN2/sestrin2 suppresses sepsis by inducing mitophagy and inhibiting NLRP3 activation in macrophages.

Autophagy 2016 08 23;12(8):1272-91. Epub 2016 Jun 23.

a Research Center for Natural Human Defense System , Yonsei University College of Medicine , Seoul , Korea.

Proper regulation of mitophagy for mitochondrial homeostasis is important in various inflammatory diseases. However, the precise mechanisms by which mitophagy is activated to regulate inflammatory responses remain largely unknown. The NLRP3 (NLR family, pyrin domain containing 3) inflammasome serves as a platform that triggers the activation of CASP1 (caspase 1) and secretion of proinflammatory cytokines. Here, we demonstrate that SESN2 (sestrin 2), known as stress-inducible protein, suppresses prolonged NLRP3 inflammasome activation by clearance of damaged mitochondria through inducing mitophagy in macrophages. SESN2 plays a dual role in inducing mitophagy in response to inflammasome activation. First, SESN2 induces "mitochondrial priming" by marking mitochondria for recognition by the autophagic machinery. For mitochondrial preparing, SESN2 facilitates the perinuclear-clustering of mitochondria by mediating aggregation of SQSTM1 (sequestosome 1) and its binding to lysine 63 (Lys63)-linked ubiquitins on the mitochondrial surface. Second, SESN2 activates the specific autophagic machinery for degradation of primed mitochondria via an increase of ULK1 (unc-51 like kinase 1) protein levels. Moreover, increased SESN2 expression by extended LPS (lipopolysaccharide) stimulation is mediated by NOS2 (nitric oxide synthase 2, inducible)-mediated NO (nitric oxide) in macrophages. Thus, Sesn2-deficient mice displayed defective mitophagy, which resulted in hyperactivation of inflammasomes and increased mortality in 2 different sepsis models. Our findings define a unique regulatory mechanism of mitophagy activation for immunological homeostasis that protects the host from sepsis.
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http://dx.doi.org/10.1080/15548627.2016.1183081DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4968237PMC
August 2016

Overview on Peroxiredoxin.

Authors:
Sue Goo Rhee

Mol Cells 2016 Jan;39(1):1-5

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

Peroxiredoxins (Prxs) are a very large and highly conserved family of peroxidases that reduce peroxides, with a conserved cysteine residue, designated the "peroxidatic" Cys (CP) serving as the site of oxidation by peroxides (Hall et al., 2011; Rhee et al., 2012). Peroxides oxidize the CP-SH to cysteine sulfenic acid (CP-SOH), which then reacts with another cysteine residue, named the "resolving" Cys (CR) to form a disulfide that is subsequently reduced by an appropriate electron donor to complete a catalytic cycle. This overview summarizes the status of studies on Prxs and relates the following 10 minireviews.
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http://dx.doi.org/10.14348/molcells.2016.2368DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4749868PMC
January 2016

Sulfiredoxin inhibitor induces preferential death of cancer cells through reactive oxygen species-mediated mitochondrial damage.

Free Radic Biol Med 2016 Feb 23;91:264-74. Epub 2015 Dec 23.

Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, South Korea. Electronic address:

Recent studies have shown that many types of cancer cells have increased levels of reactive oxygen species (ROS) and enhance antioxidant capacity as an adaptation to intrinsic oxidative stress, suggesting that cancer cells are more vulnerable to oxidative insults and are more dependent on antioxidant systems compared with normal cells. Thus, disruption of redox homeostasis caused by a decline in antioxidant capacity may provide a method for the selective death of cancer cells. Here we show that ROS-mediated selective death of tumor cells can be caused by inhibiting sulfiredoxin (Srx), which reduces hyperoxidized peroxiredoxins, leading to their reactivation. Srx inhibitor increased the accumulation of sulfinic peroxiredoxins and ROS, which led to oxidative mitochondrial damage and caspase activation, resulting in the death of A549 human lung adenocarcinoma cells. Srx depletion also inhibited the growth of A549 cells like Srx inhibition, and the cytotoxic effects of Srx inhibitor were considerably reversed by Srx overexpression or antioxidants such as N-acetyl cysteine and butylated hydroxyanisol. Moreover, Srx inhibitor rendered tumorigenic ovarian cells more susceptible to ROS-mediated death compared with nontumorigenic cells and significantly suppressed the growth of A549 xenografts without acute toxicity. Our results suggest that Srx might serve as a novel therapeutic target for cancer treatment based on ROS-mediated cell death.
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http://dx.doi.org/10.1016/j.freeradbiomed.2015.12.023DOI Listing
February 2016

Effective Killing of Cancer Cells Through ROS-Mediated Mechanisms by AMRI-59 Targeting Peroxiredoxin I.

Antioxid Redox Signal 2016 Mar 18;24(8):453-69. Epub 2015 Dec 18.

1 Graduate School of Pharmaceutical Sciences, Ewha Womans University , Seoul, Republic of Korea.

Aims: The intrinsic increase of reactive oxygen species (ROS) production in cancer cells after malignant transformation frequently induces redox adaptation, leading to enhanced antioxidant capacity. Peroxiredoxin I (PrxI), an enzyme responsible for eliminating hydrogen peroxide, has been found to be elevated in many types of cancer cells. Since overexpression of PrxI promoted cancer cells' survival and resistance to chemotherapy and radiotherapy, PrxI has been proposed as a therapeutic target for anticancer drugs. In this study, we aimed to investigate the anticancer efficacy of a small molecule inhibitor of PrxI.

Results: By a high-throughput screening approach, we identified AMRI-59 as a potent inhibitor of PrxI. AMRI-59 increased cellular ROS, leading to the activation of both mitochondria- and apoptosis signal-regulated kinase-1-mediated signaling pathways, resulting in apoptosis of A549 human lung adenocarcinoma. AMRI-59 caused no significant changes in ROS level, proliferation, and apoptosis of PrxI-knockdown A549 cells by RNA interference. PrxI overexpression or N-acetylcysteine pretreatment abrogated AMRI-59-induced cytotoxicity in A549 cells. AMRI-59 rendered tumorigenic ovarian cells more susceptible to ROS-mediated death compared with nontumorigenic cells. Moreover, significant antitumor activity of AMRI-59 was observed in mouse tumor xenograft model implanted with A549 cells with no apparent acute toxicity.

Innovation: This study offers preclinical proof-of-concept for AMRI-59, a lead small molecule inhibitor of PrxI, as an anticancer agent.

Conclusions: Our results highlight a promising strategy for cancer therapy that preferentially eradicates cancer cells by targeting the PrxI-mediated redox-dependent survival pathways.
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http://dx.doi.org/10.1089/ars.2014.6187DOI Listing
March 2016

Circadian Oscillation of Sulfiredoxin in the Mitochondria.

Mol Cell 2015 Aug 30;59(4):651-63. Epub 2015 Jul 30.

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

Hydrogen peroxide (H2O2) released from mitochondria regulates various cell signaling pathways. Given that H2O2-eliminating enzymes such as peroxiredoxin III (PrxIII) are abundant in mitochondria, however, it has remained unknown how such release can occur. Active PrxIII-SH undergoes reversible inactivation via hyperoxidation to PrxIII-SO2, which is then reduced by sulfiredoxin. We now show that the amounts of PrxIII-SO2 and sulfiredoxin undergo antiphasic circadian oscillation in the mitochondria of specific tissues of mice maintained under normal conditions. Cytosolic sulfiredoxin was found to be imported into the mitochondria via a mechanism that requires formation of a disulfide-linked complex with heat shock protein 90, which is promoted by H2O2 released from mitochondria. The imported sulfiredoxin is degraded by Lon in a manner dependent on PrxIII hyperoxidation state. The coordinated import and degradation of sulfiredoxin provide the basis for sulfiredoxin oscillation and consequent PrxIII-SO2 oscillation in mitochondria and likely result in an oscillatory H2O2 release.
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http://dx.doi.org/10.1016/j.molcel.2015.06.031DOI Listing
August 2015

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

The antioxidant function of sestrins is mediated by promotion of autophagic degradation of Keap1 and Nrf2 activation and by inhibition of mTORC1.

Free Radic Biol Med 2015 Nov 25;88(Pt B):205-211. Epub 2015 Jun 25.

Severance Biomedical Science Institute and Yonsei Biomedical Research Institute, Yonsei University College of Medicine, Seoul 120-752, Republic of Korea. Electronic address:

Sestrins 1 to 3 constitute a family of proteins that are induced in mammalian cells in response to environmental stressors. Despite their apparent lack of intrinsic catalytic antioxidant activity, Sestrins protect cells from oxidative stress by lowering intracellular levels of H2O2. Here we review the mechanisms by which various types of cellular stress induce Sestrin gene transcription as well as those underlying the antioxidant function of these proteins. Several transcriptional factors, including p53, HIF-1, FoxO, C/EBP-β, ATF4, Nrf2, and PGC-1α, contribute directly to the transcriptional activation of Sestrin genes in response to various types of stress. The antioxidant function of Sestrins is mediated by two main pathways. In one pathway, Sestrins promote the p62-dependent autophagic degradation of Keap1 and thereby upregulate Nrf2 signaling and the consequent expression of genes for antioxidant enzymes. In the second pathway, Sestrins block mTORC1 activation and thereby attenuate reactive oxygen species accumulation. This inhibition of mTORC1 activity is achieved either via the AMPK-dependent phosphorylation and activation of TSC2 and consequent inhibition of the GTPase Rheb or via inhibition of the GTPase Rag and consequent prevention of the lysosomal localization of mTORC1 triggered by amino acids. Elucidation of how these pathways operate individually or cooperatively under different stress conditions awaits further study.
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http://dx.doi.org/10.1016/j.freeradbiomed.2015.06.007DOI Listing
November 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

TRP14 inhibits osteoclast differentiation via its catalytic activity.

Mol Cell Biol 2014 Sep 7;34(18):3515-24. Epub 2014 Jul 7.

Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, Republic of Korea

We previously reported the inhibitory role of thioredoxin-related protein of 14 kDa (TRP14), a novel disulfide reductase, in nuclear factor-κB (NF-κB) activation, but its biological function has remained to be explored. Here, we evaluated the role of TRP14 in the differentiation and function of osteoclasts (OCs), for which NF-κB and cellular redox regulation have been known to be crucial, using RAW 264.7 macrophage cells expressing wild-type TRP14 or a catalytically inactive mutant, as well as its small interfering RNA. TRP14 depletion enhanced OC differentiation, actin ring formation, and bone resorption, as well as the accumulation of reactive oxygen species (ROS). TRP14 depletion promoted the activation of NF-κB, c-Jun NH2-terminal kinase, and p38, the expression of c-Fos, and the consequent induction of nuclear factor of activated T cell, cytoplasmic 1 (NFATc1), a key determinant of osteoclastogenesis. However, pretreatment with N-acetylcysteine or diphenylene iodonium significantly reduced the OC differentiation, as well as the ROS accumulation and NF-κB activation, that were enhanced by TRP14 depletion. Furthermore, receptor activator of NF-κB ligand (RANKL)-induced ROS accumulation, NF-κB activation, and OC differentiation were inhibited by the ectopic expression of wild-type TRP14 but not by its catalytically inactive mutant. These results suggest that TRP14 regulates OC differentiation and bone resorption through its catalytic activity and that enhancing TRP14 may present a new strategy for preventing bone resorption diseases.
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http://dx.doi.org/10.1128/MCB.00293-14DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4135626PMC
September 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

Dominant role of peroxiredoxin/JNK axis in stemness regulation during neurogenesis from embryonic stem cells.

Stem Cells 2014 Apr;32(4):998-1011

Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea; Department of Functional Genomics, University of Science and Technology (UST), Daejeon, Republic of Korea; National Primate Research Center, KRIBB, Chungcheongbuk-do, Republic of Korea; Division of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea.

Redox balance has been suggested as an important determinant of "stemness" in embryonic stem cells (ESCs). In this study, we demonstrate that peroxiredoxin (Prx) plays a pivotal role in maintenance of ESC stemness during neurogenesis through suppression of reactive oxygen species (ROS)-sensitive signaling. During neurogenesis, Prx I and Oct4 are expressed in a mutually dependent manner and their expression is abruptly downregulated by an excess of ROS. Thus, in Prx I(-/-) or Prx II(-/-) ESCs, rapid loss of stemness can occur due to spontaneous ROS overload, leading to their active commitment into neurons; however, stemness is restored by the addition of an antioxidant or an inhibitor of c-Jun N-terminal kinase (JNK). In addition, Prx I and Prx II appear to have a tight association with the mechanism underlying the protection of ESC stemness in developing teratomas. These results suggest that Prx functions as a protector of ESC stemness by opposing ROS/JNK cascades during neurogenesis. Therefore, our findings have important implications for understanding of maintenance of ESC stemness through involvement of antioxidant enzymes and may lead to development of an alternative stem cell-based therapeutic strategy for production of high-quality neurons in large quantity.
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http://dx.doi.org/10.1002/stem.1593DOI Listing
April 2014

Reflections on the days of phospholipase C.

Authors:
Sue Goo Rhee

Adv Biol Regul 2013 Sep 3;53(3):223-31. Epub 2013 Sep 3.

Yonsei Biomedical Research Institute, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752, South Korea. Electronic address:

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http://dx.doi.org/10.1016/j.jbior.2013.08.004DOI Listing
September 2013

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

Study of the signaling function of sulfiredoxin and peroxiredoxin III in isolated adrenal gland: unsuitability of clonal and primary adrenocortical cells.

Methods Enzymol 2013 ;527:169-81

Yonsei Biomedical Research Institute, Yonsei University College of Medicine, Seodaemun-gu, Seoul, South Korea.

Members of the peroxiredoxin (Prx) family of antioxidant enzymes are inactivated via hyperoxidation of the active site cysteine by the substrate H2O2 and are reactivated via an ATP-consuming process catalyzed by sulfiredoxin (Srx). PrxIII is reversibly inactivated by H2O2 produced by cytochrome P450 11B1 (CYP11B1) in mitochondria during corticosterone synthesis in the adrenal gland of mice injected with adrenocorticotropic hormone (ACTH). Inactivation of PrxIII triggers a sequence of events including accumulation of H2O2, activation of p38 mitogen-activated kinase (MAPK), inhibition of cholesterol transfer, and suppression of corticosterone synthesis. Srx expression is significantly induced by ACTH injection. The coupling of CYP11B1 activity to PrxIII inactivation and Srx induction provides a feedback regulatory mechanism for steroidogenesis that functions independently of the hypothalamic-pituitary-adrenal axis. Furthermore, the PrxIII-Srx regulatory pathway is critical for the circadian rhythm of corticosterone production. Although adrenocortical tumor cell lines such as Y-1 and H295R have been used extensively for studying the mechanism of steroidogenesis, those clonal cells were found to be unsuitable as an in vitro model for redox signaling because the amount of Srx in the cell lines is much higher than that in mouse adrenal gland and not affected by ACTH stimulation. Furthermore, the levels of PrxIII in the clonal cells are greatly reduced compared to that in the adrenal gland, and ACTH does not induce PrxIII hyperoxidation in the clonal cells. Primary adrenocortical cells isolated from the mouse adrenal gland were also found to be an invalid model because Srx levels are increased, along with decreased levels of hyperoxidized PrxIII, soon after isolation of these cells. Organ culture system is, however, appropriate for studying the PrxIII-Srx regulatory function as the levels of hyperoxidized PrxIII and Srx in the adrenal glands maintained overnight in culture medium are not changed.
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http://dx.doi.org/10.1016/B978-0-12-405882-8.00009-XDOI Listing
January 2014