Histone lysine-specific demethylase 1 induced renal fibrosis via decreasing sirtuin 3 expression and activating TGF-β1/Smad3 pathway in diabetic nephropathy

Objective Diabetic nephropathy (DN) is the leading cause of end-stage renal disease. Histone lysine-specific demethylase 1 (LSD1) is a flavin-containing amino oxidase that can repress or activate transcription. The aim of this study is to explore the mechanism of LSD1 aggravating DN-induced renal fibrosis. Methods The STZ-induced DN rat model was established for in vivo study. The rats were divided into four groups: Sham, STZ, STZ + Ad-shNC and Ad-shLSD1. The Hematoxylin–eosin (HE) staining was used to evaluate the renal injury. The Immunofluorescence assay was used to determine the LSD1, Fibronectin and α-SMA expression. The related protein expression was detected by western blot. Results Knockdown of LSD1 alleviated STZ-induced renal injury. Moreover, knockdown of LSD1 decreased the expression of serum biochemical markers, containing urine output (24 h), urinary protein (24 h), serum creatinine, BUN and UACR. Furthermore, we proved that knockdown of LSD1 alleviated renal fibrosis in STZ-induced DN rats. In vitro, knockdown of LSD1 suppressed NRK-49F cells activation and overexpression of LSD1 induced renal fibrosis. In addition, knockdown of LSD1 could deactivate TGF-β1/Smad3 pathway and promote sirtuin 3 (SIRT3) expression in vivo and in vitro. The rescue experiments confirmed that LSD1 induced renal fibrosis via decreasing SIRT3 expression and activating TGF-β1/Smad3 pathway. Conclusion LSD1 deficiency leads to alleviate STZ-induced renal injury and overexpression of LSD1 induces renal fibrosis via decreasing SIRT3 expression and activating TGF-β1/Smad3 pathway, which provides a reasonable strategy for developing novel drugs targeting LDS1 to block renal fibrosis.

Circular RNA CCDC66 Regulates Osteoarthritis Progression by Targeting miR-3622b-5p

<b><i>Objective:</i></b> CircCCDC66 is involved in cancer progression, but its role in osteoarthritis (OA) remains unknown. This study was carried out to explore the biological role of circCCDC66 in OA and its underlying mechanism. <b><i>Methods:</i></b> The expression levels of miR-3622b-5p and circCCDC66 in OA cartilage tissues were detected by qRT-PCR. Cell Counting Kit-8 (CCK8) and flow cytometry were used to detect the chondrocyte viability and apoptosis. The expression of chondrocyte inflammatory factors (IL-6 and TNF-α) was measured by ELISA. The target genes of circCCDC66 and miR-3622b-5p were analyzed by bioinformatics analysis and luciferase reporter gene assay. The relationship between circCCDC66 and miR-3622b-5p was analyzed by bioinformatics analysis and luciferase reporter gene assay. <b><i>Results:</i></b> It was found that circCCDC66 expression in OA cartilage tissues was upregulated. CircCCDC66 overexpression inhibited proliferation and promoted apoptosis of chondrocytes and increased IL-6 and TNF-α levels in chondrocytes. miR-3622b-5p was predicted to be a downstream target gene of circCCDC66, and circCCDC66 overexpression inhibited miR-3622b-5p expression in chondrocytes. Moreover, miR-3622b-5p expression was downregulated in OA cartilage tissues. miR-3622b-5p overexpression increased chondrocyte proliferation, inhibited chondrocyte apoptosis, and enhanced the expression of IL-6 and TNF-α in chondrocytes. In addition, circCCDC66 overexpression enhanced SIRT3 expression in chondrocytes, while miR-3622b-5p overexpression inhibited SIRT3 expression in chondrocytes. <b><i>Conclusion:</i></b> CircCCDC66 promoted OA chondrocyte apoptosis by regulating the miR-3622b-5p/SIRT3 axis. CircCCDC66 may be a new therapeutic target of OA.

Abstract P425: Sirtuin 3 Attenuates Doxorubicin Induced Cardiac Dysfunction By Regulating The Mitochondrial Acetylome And Alterations Of The Cardiac Lipidome

Doxorubicin (DOX) is a chemotherapeutic with dose-dependent cardiotoxic effects that limits its use in patients. Previously we showed that DOX decreases expression of the mitochondrial lysine deacetylase SIRT3 in the mouse heart. We hypothesize that DOX impairs cardiac function and energy production through reduced SIRT3 and altered mitochondrial acetylation. We further hypothesize that increased SIRT3 expression could attenuate DOX-induced cardiac dysfunction via alterations of protein acetylation to enzymes involved in lipid remodeling and metabolic processes. Mice expressing cardiac restricted full length M1-SIRT3 (mitochondrial localized), and short M3-SIRT3 (lacking localization signal) received saline or DOX injections of 8 mg/kg body weight for 4 weeks and compared to non-transgenic (Non-Tg) littermates. Transthoracic echocardiography was performed on all mice (n=10). Total cardiac lipids were isolated from DOX treated cardiac tissue by chloroform:methanol extraction and global lipid analysis was performed by QTRAP LC-MS/MS (n=6). Cardiac mitochondria were and an anti-acetylated lysine antibody was used to enrich for tryptic digested peptides containing Acetyl-K and analyzed by QTRAP LC-MS/MS (n=6). In non-Tg mice, DOX caused cardiac dysfunction and expression of M1-SIRT3 and M3-SIRT3 transgenes in the heart preserved left ventricular posterior wall thickness (P<0.05) and ejection fraction (P<0.05) in DOX treated mice. Triglycerides and phospholipids (PE, PI, PC) were decreased in DOX treated mouse hearts while phosphatidylserine (PS), sphingomyelin and ganglioside (GM3) lipid species were increased (p<0.05). A negative correlation between decreased cardiac output and increased GM3 24:1 (R=-0.62, P<0.05), PS 38:4 levels (R=-0.81, P<0.005) and SM 35:1 (R=-0.65, P<0.05) was identified. 36 acetylated peptides involved in metabolic processes, oxidative stress resistance and lipid remodeling (eg. IDH2, SOD2, HADHA, P<0.05) were significantly altered in DOX-treated mice. Increased SIRT3 expression in the heart rescues DOX-induced cardiac dysfunction. DOX-induced cardiac dysfunction involved alterations in cardiac lipids and acetylated proteins that could be rescued by increased SIRT3 expression in the heart.

Sex differences in the impact of parental obesity on offspring cardiac SIRT3 expression, mitochondrial efficiency and diastolic function early in life

Previous studies suggest that parental obesity may adversely impact long-term metabolic health of the offspring. We tested the hypothesis that parental (paternal + maternal) obesity impairs cardiac function in the offspring early in life. Within 1-3 days after weaning, offspring from obese rats fed a high fat diet (HFD-Offs) and age-matched offspring from lean rats (ND-Offs) were submitted to echocardiography and cardiac catheterization for assessment of pressure-volume relationships. Then, hearts were digested and isolated cardiomyocytes were used to determine contractile function, calcium transients, proteins related to calcium signaling, and mitochondrial bioenergetics. Female and male HFD-Offs were heavier (72±2 and 61±4 vs 57±2 and 49 ±1 g), hyperglycemic (112±8 and 115±12 vs 92±10 and 96±8 mg/dL), with higher plasma insulin and leptin concentrations compared to female and male ND-Offs. Compared to male controls, male HFD-Offs exhibited similar systolic function but impaired diastolic function as indicated by increased IVRT (22±1 vs. 17±1), E/E' ratio (29±2 vs. 23±1) and Tau (5.7±0.2 vs. 4.8±0.2). The impaired diastolic function was associated with reduced resting free Ca2+ levels and phospholamban protein expression, increased activated matrix metalloproteinase 2 and reduced SIRT3 protein expression, mitochondrial ATP reserve and ATP-linked respiration. These results indicate that male and female Offs from obese parents have multiple metabolic abnormalities early in life (1-3 days after weaning) and that male, but not female, Offs have impaired diastolic dysfunction as well as reductions in cardiac SIRT3, resting free Ca+2 levels and mitochondrial biogenesis.

Jabuticaba [Plinia trunciflora (O. Berg) Kausel] Protects Liver of Diabetic Rats Against Mitochondrial Dysfunction and Oxidative Stress Through the Modulation of SIRT3 Expression

Complications generated by hyperglycemia present in diabetes mellitus (DM) have been constantly related to oxidative stress and dysfunction in the mitochondrial electron transport chain (ETC). Sirtuin 3 (SIRT3), which is present in mitochondria, is responsible for regulating several proteins involved in metabolic homeostasis and oxidative stress. Studies have suggested alterations in the expression of SIRT3 in DM. The objective of this study was to evaluate the effects of phenolic compounds in jabuticaba (Plinia trunciflora), a berry native to Brazil, on the activity of mitochondrial ETC complexes, SIRT3 protein expression, and oxidative stress parameters in liver of diabetic rats induced by streptozotocin. After type 1 DM induction (streptozotocin 65 mg/kg), diabetic and healthy rats were treated with jabuticaba peel extract (JPE) by gavage (0.5 g/kg of weight) for 30 days. After treatments, those diabetic rats presented impaired activities of complexes I, II, and III of ETC along with an overexpression of SIRT3. In addition, an increase in lipid peroxidation and superoxide dismutase and catalase activities was observed in the diabetic group. The treatment with JPE was able to recover the activity of the mitochondrial complexes and reduce the expression of SIRT3. Furthermore, JPE treatment reduced oxidative damage to lipids and brought the antioxidants enzyme activities to basal levels in diabetic rats. Together, these results demonstrate that JPE can reduce oxidative stress related to DM by restoring mitochondrial complexes activity and regulating SIRT3 expression. Thus, JPE could become an alternative to reduce the development of complications related to DM.

LCZ696 Attenuates ROS/NLRP3 Mediated Pyroptosis in Trastuzumab-induced H9C2 Cell Model Via Ameliorating Sirt3 Expression

Trastuzumab-induced cardiomyopathy have been a kind of clinical crucial problems in the field of cardio-oncology. LCZ696, clinically named sacubitril/valsartan, was administered to treat the patients with heart failure, so that it may be a substantial prevention to attenuate chemotherapy-induced cardiotoxicity. We firstly confirmed that LCZ696 and trastuzumab can affect the content of Sirt3 and NLRP3 in H9C2 cell, which confirmed the concentration of LCZ696 (10μM) and trastuzumab (100nM). Then H9C2 cells were allocated into 3 groups: (1) Con group; (2) TRA group; (3) TRA+LCZ696 group. We investigated the change of mRNA expression and protein synthesis of cultured H9c2 cardiocardiomyocytes on exposure to trastuzumab alone or plus LCZ696. Meanwhile, it turns out that LCZ696 can ameliorate the mRNA expression and content of Sirt3, inhibit the level of ROS, NLRP3, ACS, Caspase-1 and IL-1β in trastuzumab-induced H9C2 cell model. In summary, LCZ696 reduces the oxidative stress caused by ROS and NLRP3-mediated pyroptosis by protecting the activity of Sirt3 in H9C2 cells.

Anti-tumor NAMPT inhibitor, KPT-9274, mediates gender-dependent murine anemia and nephrotoxicity by regulating SIRT3-mediated SOD deacetylation

KPT-9274 is a phase 1 first-in-class dual PAK4/NAMPT inhibitor for solid tumor and non-Hodgkin’s lymphoma. It demonstrates pre-clinical efficacy toward a broad spectrum of acute myeloid leukemia (AML) subtypes by inhibiting NAMPT-dependent NAD+ production. NAMPT is the rate-limiting enzyme in the salvage metabolic pathway leading to NAD+ generation. Tumor cells which are deficient in de novo pathway enzyme NAPRT1 are addicted to NAMPT. In clinical trials, treatment with NAMPT inhibitors resulted in dose-limiting toxicities. In order to dissect the mechanism of toxicity, mice were treated with KPT-9274 and resulting toxicities were characterized histopathologically and biochemically. KPT-9274 treatment caused gender-dependent stomach and kidney injuries and anemia. Female mice treated with KPT-9274 had EPO deficiency and associated impaired erythropoiesis. KPT-9274 treatment suppressed SIRT3 expression and concomitantly upregulated acetyl-manganese superoxide dismutase (MnSOD) in IMCD3 cells, providing a mechanistic basis for observed kidney toxicity. Importantly, niacin supplementation mitigated KPT-9274-caused kidney injury and EPO deficiency without affecting its efficacy. Altogether, our study delineated the mechanism of KPT-9274-mediated toxicity and sheds light onto developing strategies to improve the tolerability of this important anti-AML inhibitor.

Protective effect of Anthocyanins on Radiation-induced Hippocampal Injury through Activation of SIRT3

Background: Neuronal cell apoptosis is associated with radiation exposure. It is urgent to study the radiation protection of hippocampal neurons. Objective: The purpose of this study was to investigate the protective effect of anthocyanins on radiation and its potential mechanism. Materials and Methods: The irradiation was carried out at room temperature with 4-Gy dose. Anthocyanins were intraperitoneally administered to rats prior to radiation exposure. The immunohistology and survival of neurons within the hippocampi，neuroprotective effects of anthocyanin，mean ROS accumulation and SIRT3 expression by Western Blot and qRTPCR were performed. Results: Anthocyanins inhibit radiation-induced apoptosis by activating SIRT3. SIRT3 mRNA increased 24 hours after anthocyanin performed, accompanied by an increase in SIRT3 protein and activity. Conclusions : Anthocyanin can effectively resist radiation-induced oxidation and support its role in scavenging cellular reactive oxygen species. The results showed that anthocyanin protected hippocampal neurons from apoptosis through the activity of SIRT3 after irradiation.

Icariin Treatment Protects Against Gentamicin-Induced Ototoxicity via Activation of the AMPK-SIRT3 Pathway

Ototoxicity is a serious health problem that greatly affects millions of people worldwide. This condition is caused by the entry of aminoglycosides into auditory hair cells, subsequently inducing reactive oxygen species (ROS) production and accumulation. Several strategies have been adopted to overcome irreversible ROS-induced hair cell loss in mammals. In recent years, icariin, a major active component of the traditional herb Epimedium, has been widely studied and revealed to have antioxidant, anti-inflammatory, and anti-apoptotic properties. In this study, we found that icariin pretreatment improved the survival rate of gentamicin-treated House Ear Institute-Organ of Corti 1 (HEI-OC1) cells and cochlear explants. Icariin remarkably suppressed HEI-OC1 cell apoptosis and inhibited ROS production in cells. Notably, icariin upregulated PGC-1α (SIRT3 promoter) and SIRT3 expression in HEI-OC1 cells. In addition, SIRT3 inhibition significantly attenuated the anti-apoptotic effect of icariin. We also found that icariin can increase AMPK phosphorylation. Further studies showed that inhibition of SIRT3 activity had no significant effect on AMPK phosphorylation. Furthermore, the AMPK inhibitor compound C significantly suppressed SIRT3 expression, meaning that AMPK, as an upstream molecule, regulates SIRT3 expression. Meanwhile, inhibition of AMPK activity significantly reduced the protective effect of icariin on gentamicin ototoxicity. Based on these results, icariin exerts its protective effect on gentamicin-induced ototoxicity via activation of the AMPK-SIRT3 signaling pathway, thus providing a new strategy for treating ototoxicity caused by aminoglycoside antibiotics.