Overexpression of SIRT3 Suppresses Oxidative Stress-induced Neurotoxicity and Mitochondrial Dysfunction in Dopaminergic Neuronal Cells

이신려,전유미,조명진,김형준 한국뇌신경과학회 2021 Experimental Neurobiology Vol.30 No.5

Sirtuin 3 (SIRT3), a well-known mitochondrial deacetylase, is involved in mitochondrial function and metabolism under various stress conditions. In this study, we found that the expression of SIRT3 was markedly increased by oxidative stress in dopaminergic neuronal cells. In addition, SIRT3 overexpression enhanced mitochondrial activity in differentiated SH-SY5Y cells. We also showed that SIRT3 overexpression attenuated rotenoneor H2O2-induced toxicity in differentiated SH-SY5Y cells (human dopaminergic cell line). We further found that knockdown of SIRT3 enhanced rotenone- or H2O2-induced toxicity in differentiated SH-SY5Y cells. Moreover, overexpression of SIRT3 mitigated cell death caused by LPS/IFN-γ stimulation in astrocytes. We also found that the rotenone treatment increases the level of SIRT3 in Drosophila brain. We observed that downregulation of sirt2 (Drosophila homologue of SIRT3) significantly accelerated the rotenone-induced toxicity in flies. Taken together, these findings suggest that the overexpression of SIRT3 mitigates oxidative stress-induced cell death and mitochondrial dysfunction in dopaminergic neurons and astrocytes.

Ginsenoside Rb3 ameliorates podocyte injury under hyperlipidemic conditions via PPARδ- or SIRT6-mediated suppression of inflammation and oxidative stress

Heeseung Oh,Wonjun Cho,Seung Yeon Park,A.M. Abd El-Aty,Ji Hoon Jeong,Tae Woo Jung The Korean Society of Ginseng 2023 Journal of Ginseng Research Vol.47 No.3

Background: Rb3 is a ginsenoside with anti-inflammatory properties in many cell types and has been reported to attenuate inflammation-related metabolic diseases such as insulin resistance, nonalcoholic fatty liver disease, and cardiovascular disease. However, the effect of Rb3 on podocyte apoptosis under hyperlipidemic conditions, which contributes to the development of obesity-mediated renal disease, remains unclear. In the current study, we aimed to investigate the effect of Rb3 on podocyte apoptosis in the presence of palmitate and explore its underlying molecular mechanisms. Methods: Human podocytes (CIHP-1 cells) were exposed to Rb3 in the presence of palmitate as a model of hyperlipidemia. Cell viability was assessed by MTT assay. The effects of Rb3 on the expression of various proteins were analyzed by Western blotting. Apoptosis levels were determined by MTT assay, caspase 3 activity assay, and cleaved caspase 3 expression. Results: We found that Rb3 treatment alleviated the impairment of cell viability and increased caspase 3 activity as well as inflammatory markers in palmitate-treated podocytes. Treatment with Rb3 dosedependently increased PPARδ and SIRT6 expression. Knockdown of PPARδ or SIRT6 reduced the effects of Rb3 on apoptosis as well as inflammation and oxidative stress in cultured podocytes. Conclusions: The current results suggest that Rb3 alleviates inflammation and oxidative stress via PPARδ-or SIRT6-mediated signaling, thereby attenuating apoptosis in podocytes in the presence of palmitate. The present study provides Rb3 as an effective strategy for treating obesity-mediated renal injury.

Expression of Sirt1 in mouse testes

Seungseok Ok,Young Seok Oh,Myung Chan Gye 한국발생생물학회 2014 한국발생생물학회 학술발표대회 Vol.2014 No.9

Sirt1 belongs to class III histone/protein deacetylase. Sirt1 KO mice have spermatogenic defects. In this study, expression of Sirt1 and acetylated histone 3k9 (H3k9ac) was examined in developing mouse testes. Among two splicing variants of sirt1 mRNA long form was dominant in developing testis. Testicular sirt1 mRNA levels were low at birth, increased until 14 days post partum (pp) and remained constant thereafter. Sirt1 immunoreactivity was weak to negligible in gonocytes, moderate in spermatogonia, absent in preleptotene spermatocytes, moderate in zygotene spermatocytes, strong in pachytene spermatocytes, and weak in diplotene spermatocytes. Round and elongating spermatids were negative for Sirt1. Acetylated histone 3k9 (H3k9ac) immunoreactivity was moderate in spermatogonia and weak to negligible in preleptotene to pachytene spermatocytes but strong in round and elongating spermatids. In Sertoli cells, nuclear Sirt1 immunoreactivity was absent at birth, increased at 14 days pp and markedly increased at 28 days pp onwards. In immature Sertoli cells culture, FSH and testosterone increased sirt1 mRNA, suggesting that Sirt1 participates in protein deacetylation events during the differentiation of Sertoli cells by gonadotropin. In the Leydig cells, nuclear Sirt1 immunoreactivity was weak until 2 weeks pp and decreased in 4 weeks pp onward. suggesting the protein deacetylation by Sirt1 in Leydig cell precursor/progenitor cells. Mutually exclusive expression between Sirt1 and H3k9ac in pachytene spermatocytes in testis suggests that deacetylation of H3K9ac by Sirt1 participates in the gene silencing and/or chromosome behavior in pachytene sspermatocytes.

Curcumin Upregulates Antioxidant Defense, Lon Protease, and Heat-Shock Protein 70 Under Hyperglycemic Conditions in Human Hepatoma Cells

Shivona Gounden,Anil Chuturgoon 한국식품영양과학회 2017 Journal of medicinal food Vol.20 No.5

Sirtuin 3 (SIRT3) regulates mitochondrial antioxidant (AO) defense and improves mitochondrial disorders. Curcumin protects mitochondria; however, the mechanisms need investigation. We postulated that curcumin increases AO defense under hyperglycemic conditions in HepG2 cells through SIRT3-mediated mechanisms. Cell viability was determined in HepG2 cells cultured with 5 mM glucose, 19.9 mM mannitol, vehicle control, 10 mM glucose, and 30 mM glucose in the absence or presence of curcumin for 24 h. SIRT3, nuclear factor-kappa B (NF-κB), heat-shock protein 70 (Hsp70), and Lon protein expressions were determined using western blot. Transcript levels of SIRT3, peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), cAMP response element-binding protein (CREB), glutathione peroxidase 1 (GPx1), and superoxide dismutase 2 (SOD2) were measured by quantitative polymerase chain reaction. Cell viability, SIRT3 protein expression, transcript levels of SIRT3, PGC-1α, CREB, GPx1, and SOD2 and protein expressions of NF-κB, Lon, and Hsp70 were significantly increased in the curcumin-treated hyperglycemic groups. Since curcumin and SIRT3 both improve mitochondrial function and AO defense, SIRT3 may be involved in the protective effects of curcumin.

Prognostic Significance of Sirtuins Expression in Papillary Thyroid Carcinoma

강예은,송민호,김진만,구본석 대한갑상선학회 2018 International Journal of Thyroidology Vol.11 No.2

Background and Objectives: Sirtuins (SIRTs) play important roles in cellular and organismal homeostasis. They have distinct gene expression patterns in various cancers; however, the relationship between SIRT expression and the progression of thyroid cancer is unclear. We investigated the expression of SIRTs in patients with papillary thyroid carcinoma (PTC) and their role as biomarkers for predicting the aggressiveness of this disease. Materials and Methods: We used immunohistochemical staining to evaluate the expression of SIRT1 and SIRT3 in tumor specimens from 270 patients with PTC. We also evaluated the potential association between SIRT expression and diverse clinicopathological features. Results: High SIRT1 expression was negatively correlated with lymphovascular invasion, central lymph node metastasis, and lateral lymph node metastasis. Multivariate analyses revealed that high SIRT1 expression was a negative independent risk factor for lateral lymph node metastasis. By contrast, high SIRT3 expression was positively correlated with locoregional recurrence. Interestingly, when patients were grouped by tumor SIRT expression patterns, the group with low SIRT1 expression and high SIRT3 expression was correlated with more aggressive cancer phenotypes including central lymph node metastasis and lateral lymph node metastasis. Conclusion: Our results suggest that SIRTs play dual roles in tumor progression, and the combination of decreased SIRT1 expression and increased SIRT3 expression is significantly associated with a poor prognosis in patients with PTC.

SIRT1 and AROS suppress doxorubicin-induced apoptosis via inhibition of GSK3β activity in neuroblastoma cells

김정우,양지혜,김은주 한국통합생물학회 2020 Animal cells and systems Vol.24 No.1

SIRT1, the best-characterized member of the sirtuin family of deacetylases, is involved in cancer, apoptosis, inflammation, and metabolism. Active regulator of SIRT1 (AROS) was the first identified direct regulator of SIRT1. An increasing number of reports have indicated that SIRT1 plays an important role in controlling brain tumors. Here, we demonstrated that depletion of SIRT1 and AROS increases doxorubicin-mediated apoptosis in human neuroblastoma SH-SY5Y cells. Glycogen synthase kinase 3β (GSK3β) promoted doxorubicin-mediated apoptosis, but this effect was abolished by overexpression of SIRT1 and AROS. Interestingly, SIRT1 and AROS interacted with GSK3β and increased inhibitory phosphorylation of GSK3β on Ser9. Finally, we determined that AROS cooperates with SIRT1 to suppress GSK3β acetylation. Taken together, our results suggest that SIRT1 and AROS inhibit GSK3β activity and provide additional insight into drug resistance in the treatment of neuroblastoma.

Defect of SIRT1-FoxO3a axis is associated with the production of reactive oxygen species during protein kinase CK2 downregulation-mediated cellular senescence and nematode aging

( Hye-jun Ham ),( Jeong-woo Park ),( Young-seuk Bae ) 생화학분자생물학회 2019 BMB Reports Vol.52 No.4

We investigated whether SIRT1 is associated with reactive oxygen species (ROS) accumulation during CK2 downregulationmediated senescence. SIRT1 overexpression suppressed ROS accumulation, reduced transcription of FoxO3a target genes, and nuclear export and acetylation of FoxO3a, which were induced by CK2 downregulation in HCT116 and MCF-7 cells. Conversely, overexpression of a dominant-negative mutant SIRT1 (H363Y) counteracted decreased ROS levels, increased transcriptional activity of FoxO3a, and increased nuclear import and decreased acetylation of FoxO3a, which were induced by CK2 upregulation. CK2 downregulation destabilized SIRT1 protein via an ubiquitin-proteasome pathway in human cells, whereas CK2 overexpression reduced ubiquitination of SIRT1. Finally, the SIRT1 activator resveratrol attenuated the accumulation of ROS and lipofuscin as well as lifespan shortening, and reduced expression of the DAF-16 target gene sod-3, which were induced by CK2 downregulation in nematodes. Altogether, this study demonstrates that inactivation of the SIRT1-FoxO3a axis, at least in part, is involved in ROS generation during CK2 downregulation-mediated cellular senescence and nematode aging. [BMB Reports 2019; 52(4): 265-270]

Dietary schizophyllan reduces mitochondrial damage by activating SIRT3 in mice

Daeun Lee,Ye‑Ram Kim,김재성,Donggyu Kim,Sojin Kim,Sun Young Kim,Kiseok Jang,Jong‑Dae Lee,Chul‑Su Yang 대한약학회 2020 Archives of Pharmacal Research Vol.43 No.4

Schizophyllan (SPG), produced by Schizophyllumcommune, is an exopolysaccharide with multiple academicand commercial uses, including in the food industryand for various medical functions. We previously demonstratedthat SPG conjugated with c-Src peptide exerted asignificant therapeutic effect on mouse models of the acuteinflammatory diseases polymicrobial sepsis and ulcerativecolitis. Here we extended these results by investigatingwhether SPG exerted a protective effect against mitochondrialdamage in the liver via sirtuin 3 (SIRT3) induction,focusing on the deacetylation of succinate dehydrogenase A(SDHA) and superoxide dismutase 2 (SOD2). Liver damagemodels induced by alcohol or conjugated linoleic acid (CLA,which simulates lipodystrophy) in SIRT3−/−,SOD2−/−,andSDHA−/−mice were used. Results showed that dietary supplementationwith SPG induced SIRT3 activation; this wasinvolved in mitochondrial metabolic resuscitation that counteredthe adverse effects of alcoholic liver disease and CLAinduceddamage. The mitochondrial SIRT3 mediated thedeacetylation and activation of SOD2 in the liver and SDHA in adipose tissues, suggesting that SPG supplementationreduced ethanol-induced liver damage and CLA-inducedadverse dietary effects via SIRT3–SOD2 and SIRT3–SDHAsignaling, respectively. Together, these results suggest thatdietary SPG has a previously unrecognized role in SIRT3-mediated mitochondrial metabolic resuscitation duringmitochondria-related diseases.

Medicinal Chemistry : ELSEVIER ; Characterization of novel mechanisms for steatosis from global protein hyperacetylation in ethanol-induced mouse hepatocytes

( Sun Ju Kim ),( Oh Kwang Kwon ),( Sung Hwan Ki ),( Tae Cheon Jeong ),( Sang Kyu Lee ) 영남대학교 약품개발연구소 2015 영남대학교 약품개발연구소 연구업적집 Vol.25 No.-

Steatosis is the earliest and most common disease of the liver due to chronic ethanol consumption, and stems from alterations in the function of transcription factors related to lipid metabolism. Protein acetylation at the lysine residue (kac) is known to have diverse functions in cell metabolism. Recent studies showed that ethanol exposure induces global protein hyperacetylation by reducing the deace-tylase activities of SIRT1 and SIRT3. Although global acetylome analyses have revealed the involvement of a variety of lysine acetylation sites, the exact sites directly regulated by ethanol exposure are unknown, ln this study, to elucidate the exact hyperacetylation sites that contribute to SIRT1 and SIRT3 down-regulation, we identified and quantified a total of 1285 Kac sites and 686 Kac proteins in AML-12 cells after ethanol treatment (100mM) for 3 days. All quantified Kac ssites were divided into four quantiles: Q1 (0-15%). Q2 (15-50%), Q3 (50-85%), and Q4 (85-100%). Q4 had 192 Kac sites indicating ethanol-induced hyperacetylation. Using the Motif-x program, the [LXKL]. [KH], and [KW] motifs were included in the Q4 category, where [KW] was a specific residue for SIRT3. We also performed gene ontology term and KEGG pathway enrichment analyses. Hyperacetylation sites were significantly enriched in biosynthetic pro-cesses and ATPase activities within the biological process and molecular function categories, respectively, In conclusion, ethanol regulates the acetylation of proteins in a variety of metabolic pathways mediated by SIRT1 and SIRT3. As a result, ethanol stimulates increased de novo fatty acid synthesis in hepatocytes. ⓒ 2015 Elsevier Inc. All rights reserved.

Mitochondrial Sirt3 supports cell proliferation by regulating glutamine-dependent oxidation in renal cell carcinoma

Choi, J.,Koh, E.,Lee, Y.S.,Lee, H.W.,Kang, H.G.,Yoon, Y.E.,Han, W.K.,Choi, K.H.,Kim, K.S. Academic Press 2016 Biochemical and biophysical research communication Vol.474 No.3

Clear cell renal carcinoma (RCC), the most common malignancy arising in the adult kidney, exhibits increased aerobic glycolysis and low mitochondrial respiration due to von Hippel-Lindau gene defects and constitutive hypoxia-inducible factor-α expression. Sirt3 is a major mitochondrial deacetylase that mediates various types of energy metabolism. However, the role of Sirt3 as a tumor suppressor or oncogene in cancer depends on cell types. We show increased Sirt3 expression in the mitochondrial fraction of human RCC tissues. Sirt3 depletion by lentiviral short-hairpin RNA, as well as the stable expression of the inactive mutant of Sirt3, inhibited cell proliferation and tumor growth in xenograft nude mice, respectively. Furthermore, mitochondrial pyruvate, which was used for oxidation in RCC, might be derived from glutamine, but not from glucose and cytosolic pyruvate, due to depletion of mitochondrial pyruvate carrier and the relatively high expression of malic enzyme 2. Depletion of Sirt3 suppressed glutamate dehydrogenase activity, leading to impaired mitochondrial oxygen consumption. Our findings suggest that Sirt3 plays a tumor-progressive role in human RCC by regulating glutamine-derived mitochondrial respiration, particularly in cells where mitochondrial usage of cytosolic pyruvate is severely compromised.