PGC-1α Overexpression Research Articles

Exogenous expression of PGC-1α during in vitro maturation impairs the developmental competence of porcine oocytes

Objectives of the current study were to examine the effects of exogenous expression of PGC-1α, which is a transcription factor responsive for controlling mitochondrial DNA (mtDNA) replication, mitochondria quantity control, mitochondrial biogenesis, and reactive oxygen species (ROS) maintenance, in porcine oocytes during in-vitro maturation (IVM) on the developmental competence, as well as mitochondrial quantity and function. Exogenous over-expression of PGC-1α by injection of the mRNA construct into oocytes 20 h after the start of IVM culture significantly increased the copy number of mtDNA in the oocytes, but reduced the incidences of oocytes matured to the metaphase-II stage after the IVM culture for totally 44 h and completely suppressed the early development in vitro to the blastocyst stage following parthenogenetic activation. The exogenous expression of PGC-1α also significantly induced spindle defects and chromosome misalignments. Furthermore, markedly higher ROS levels were observed in the PGC-1α-overexpressed mature oocytes, whereas mRNA level of SOD1, encoded for a ROS scavenging enzyme, was decreased. These results conclude that forced expression of PGC-1α successfully increase mtDNA copy number but led to increased ROS production, evidently by downregulation of SOD1 gene expression, inducement of spindle aberration/chromosomal misalignment, and consequently reduction in the meiotic and developmental competences of porcine oocytes.

PGC-1α drives small cell neuroendocrine cancer progression towards an ASCL1-expressing subtype with increased mitochondrial capacity.

Our study provides functional evidence that metabolic reprogramming can directly impact cancer phenotypes and establishes PGC-1α-induced mitochondrial metabolism as a driver of SCNC progression and lineage determination. These mechanistic insights reveal common metabolic vulnerabilities across SCNCs originating from multiple tissues, opening new avenues for pan-SCN cancer therapeutic strategies.

Autophagy aggravates multi-walled carbon nanotube-induced ferroptosis by suppressing PGC-1 dependent-mitochondrial biogenesis in lung epithelial cells

Multi-walled carbon nanotube (MWCNT) induced respiratory toxicity has become a growing concern, with ferroptosis emerging as a novel mechanism implicated in various respiratory diseases. However, whether ferroptosis is involved in MWCNT-elicited lung injury and the underlying molecular mechanisms warrant further exploration. In this study, we found that MWCNT-induced ferroptosis is autophagy-dependent, contributing to its cellular toxicity. Inhibiting of autophagy by pharmacological inhibitors 3-MA or ATG5 gene knockdown significantly attenuated MWCNT-induced ferroptosis, concomitant with rescued mitochondrial biogenesis. Rapamycin, the autophagy agonist, exacerbated the mitochondrial damage and MWCNT-induced ferroptosis. Moreover, lentivirus-mediated overexpression of PGC-1α inhibited ferroptosis, while inhibition of PGC-1α aggravated ferroptosis. In summary, our study unveils ferroptosis as a novel mechanism underlying MWCNT-induced respiratory toxicity, with autophagy promoting MWCNT-induced ferroptosis by hindering PGC-1α-dependent mitochondrial biogenesis.

PGC-1α regulates endoplasmic reticulum stress in IPF-derived fibroblasts

Idiopathic pulmonary fibrosis (IPF) is considered to be associated with aging. Both ER stress and the unfolded protein response (UPR) have been associated with pulmonary fibrosis via key mechanisms including AEC apoptosis, EMT, altered myofibroblast differentiation, and M2 macrophage polarization. A relationship between ER stress and aging has also been demonstrated in vitro, with increased p16 and p21 levels seen in lung epithelial cells of older IPF patients. The mechanism underlying ER stress regulation of IPF fibroblasts is still unclear. In this study, we aimed to delineate ER stress regulation in IPF-derived fibroblasts. Here, we found that ER stress markers (p-eIF2α, p-IREα, ATF6) and fibrosis markers (α-SMA and Collagen-I) were significantly increased in lung tissues of IPF patients and bleomycin-induced mouse models. Notably, the expression of PGC-1α was decreased in fibroblasts. In vivo experiments were designed using an AAV-6 vector mediated conditional PGC-1α knockout driven by a specific α-SMA promoter. Ablation of PGC-1α expression in fibroblasts promoted ER stress and supported the development of pulmonary fibrosis in a bleomycin-induced mouse model. In another experimental group, mice with conditional knockout of PGC-1α in fibroblasts and injected intraperitoneally with 4-PBA (an endoplasmic reticulum stress inhibitor) were protected from lung fibrosis. We further constructed an AAV-6 vector mediated PGC-1α overexpression model driven by a specific Collagen-I promoter. Overexpression of PGC-1α in fibroblasts suppressed ER stress and attenuated development of pulmonary fibrosis in bleomycin-induced mouse models. Taken together, this study identified PGC-1α as a promising target for developing novel therapeutic options for the treatment of lung fibrosis.

MECHANISM OF MICRORNA-218-5P IN MITOCHONDRIAL BIOGENESIS OF SEPSIS-INDUCED ACUTE KIDNEY INJURY BY THE REGULATION OF PGC-1Α.

Background: Sepsis-induced acute kidney injury (SI-AKI) is a kind of kidney dysfunction, which brings a lot of suffering. This study aimed to figure out the role of the miR-218-5p/PGC-1α axis in SI-AKI. Methods: AKI mouse model was established through cecal ligation and puncture. PGC-1α expression was activated using an activator ZLN005 before the serum and tissue samples were collected. Next, pathological structure and apoptosis of kidney tissues were observed. Levels of blood urea nitrogen, serum creatinine, and indicators of inflammation and oxidative stress were assessed. Moreover, reactive oxygen species and mitochondrial membrane potential levels, adenosine 5'-triphosphate content, and mitochondrial ultrastructure of kidney tissues were observed. HK2 cells were treated by lipopolysaccharide (LPS) to mimic sepsis in vitro , followed by evaluation of cell survival and apoptosis, inflammation, and oxidative stress. Subsequently, the binding relation between PGC-1α and miR-218-5p was predicted and validated. Then expression of PGC-1α and miR-218-5p was detected. PGC-1α and miR-218-5p expression were intervened to detect their influences in mitochondrial biogenesis. At last, miR-218-5p was overexpressed in ZLN005 (PGC-1α activating agent) pretreated SI-AKI mice to validate the mechanism. Results: PGC-1α is poorly expressed in SI-AKI, but overexpression of PGC-1α using ZLN005 alleviated SI-AKI injury and promoted mitochondrial biogenesis in AKI mice, and relieved LPS-induced cell injury. PGC-1α is a target of miR-218-5p. Downregulation of miR-218-5p expression in HK2 cells attenuated mitochondrial biogenesis disorder. Inhibition of PGC-1α annulled the role of miR-218-5p silencing in cells. In vivo , miR-218-5p overexpression partly reversed the protective role of ZLN005 in SI-AKI mice. Conclusion: miR-218-5p targeted PGC-1α to disrupt mitochondrial biogenesis, thereby exacerbating SI-AKI.

Muscle-specific PGC-1α modulates mitochondrial oxidative stress in aged sarcopenia through regulating Nrf2

BackgroundAged sarcopenia is characterized by loss of skeletal muscle mass and strength, and mitochondrial dysregulation in skeletal myocyte is considered as a major factor. Here, we aimed to analyze the effects of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) on mitochondrial reactive oxygen species (ROS) and nuclear factor erythroid 2-related factor 2 (Nrf2) in aged skeletal muscles. MethodsC2C12 cells were stimulated by 50 μM 7β-hydroxycholesterol (7β-OHC) to observe the changes of cellular ROS, mitochondrial ROS, and expression of PGC-1α and Nrf2. Different PGC-1α expression in cells was established by transfection with small interfering RNA (siRNA) or plasmids overexpressing PGC-1α (pEX-3-PGC-1α). The effects of different PGC-1α expression on cellular ROS, mitochondrial ROS and Nrf2 expression were measured in cells. Wild type (WT) mice and PGC-1α conditional knockout (CKO) mice were used to analyze the effects of PGC-1α on aged sarcopenia and expression of Nrf2 and CD38 in gastrocnemius muscles. Diethylmaleate, a Nrf2 activator, was used to analyze the connection between PGC-1α and Nrf2 in cells and in mice. ResultsIn C2C12 cells, the expressions of PGC-1α and Nrf2 were declined by the 7β-OHC treatment or PGC-1α silence. Moreover, PGC-1α silence increased the harmful ROS and decreased the Nrf2 protein expression in the 7β-OHC-treated cells. PGC-1α overexpression decreased the harmful ROS and increased the Nrf2 protein expression in the 7β-OHC-treated cells. Diethylmaleate treatment decreased the harmful ROS in the 7β-OHC-treated or PGC-1α siRNA-transfected cells. At the same age, muscle-specific PGC-1α deficiency aggravated aged sarcopenia, decreased Nrf2 expression and increased CD38 expression in gastrocnemius muscles compared with the WT mice. Diethylmaleate treatment improved the muscle function and decreased the CD38 expression in the old two genotypes. ConclusionsOur study demonstrated that PGC-1α modulated mitochondrial oxidative stress in aged sarcopenia through regulating Nrf2.

PGC-1α loss promotes mitochondrial protein lactylation in acetaminophen-induced liver injury via the LDHB-lactate axis

Coronavirus disease 2019 (COVID-19) affected people worldwide, and fever is one of the major symptoms of this disease. Although Acetaminophen (APAP) is a common fever-reducing medication, it can also mediate liver injury. However, the role of PGC-1α in regulating mitochondrial quality control by lactate dehydrogenase B (LDHB), a vital enzyme catalyzing the conversion of lactate to pyruvate, in APAP-induced hepatotoxicity, is unclear. Here, gene expression omnibus data of patients with APAP-induced liver injury were used to explore gene expression profiles. AML12 cells and C57/BL6 mice were used to establish models of APAP-induced acute liver injury. SIRT1 and PGC-1α were overexpressed in vitro via lentiviral transfection to establish stable cell lines. The results showed that APAP treatment decreased SIRT1/PGC-1α/LDHB expression and increased protein lactylation, mitochondrial lactate levels, and pathological damage in liver mitochondria. PGC-1α upregulation or activation ameliorated APAP-induced damage in the cells and liver. Furthermore, PGC-1α overexpression increased LDHB synthesis, reduced lactylation, and induced a switch from lactate to pyruvate production. These results suggest that PGC-1α and LDHB play a role in APAP-induced liver injury by regulating mitochondrial quality control and lactate metabolic reprogramming. Therefore, the PGC-1α/LDHB axis is a potential therapeutic target for APAP-induced liver injury.

Skeletal muscle PGC-1α remodels mitochondrial phospholipidome but does not alter energy efficiency for ATP synthesis.

Exercise training is thought to improve the mitochondrial energy efficiency of skeletal muscle. Some studies suggest exercise training increases the efficiency for ATP synthesis by oxidative phosphorylation (OXPHOS), but the molecular mechanisms are unclear. We have previously shown that exercise remodels the lipid composition of mitochondrial membranes, and some of these changes could contribute to improved OXPHOS efficiency (ATP produced by O2 consumed or P/O). Peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) is a transcriptional co-activator that coordinately regulates exercise-induced adaptations including mitochondria. We hypothesized that increased PGC-1α activity is sufficient to remodel mitochondrial membrane lipids and promote energy efficiency. Mice with skeletal muscle-specific overexpression of PGC-1α (MCK-PGC-1α) and their wildtype littermates were used for this study. Lipid mass spectrometry and quantitative PCR were used to assess muscle mitochondrial lipid composition and their biosynthesis pathway. The abundance of OXPHOS enzymes was determined by western blot assay. High-resolution respirometry and fluorometry analysis were used to characterize mitochondrial bioenergetics (ATP production, O2 consumption, and P/O) for permeabilized fibers and isolated mitochondria. Lipidomic analyses of skeletal muscle mitochondria from wildtype and MCK-PGC-1α mice revealed that PGC-1α increases the concentrations of cone-shaped lipids such as phosphatidylethanolamine (PE), cardiolipin (CL), and lysophospholipids, while decreases the concentrations of phosphatidylcholine (PC), phosphatidylinositol (PI) and phosphatidic acid (PA). However, while PGC-1α overexpression increased the abundance of OXPHOS enzymes in skeletal muscle and the rate of O2 consumption (JO2), P/O values were unaffected with PGC-1α in permeabilized fibers or isolated mitochondria. Collectively, overexpression of PGC-1α promotes the biosynthesis of mitochondrial PE and CL but neither PGC-1α nor the mitochondrial membrane lipid remodeling induced in MCK-PGC-1α mice is sufficient to increase the efficiency for mitochondrial ATP synthesis. These findings suggest that exercise training may increase OXPHOS efficiency by a PGC-1α-independent mechanism, and question the hypothesis that mitochondrial lipids directly affect OXPHOS enzymes to improve efficiency for ATP synthesis.

PGC-1α/LDHA signaling facilitates glycolysis initiation to regulate mechanically induced bone remodeling under inflammatory microenvironment

The mechanosensitivity of inflammation can alter cellular mechanotransduction. However, the underlying mechanism remains unclear. This study aims to investigate the metabolic mechanism of inflammation under mechanical force to guide tissue remodeling better. Herein, we found that inflammation hindered bone remodeling under mechanical force, accompanied by a simultaneous enhancement of oxidative phosphorylation (OXPHOS) and glycolysis. The control of metabolism direction through GNE-140 and Visomitin revealed that enhanced glycolysis might act as a compensatory mechanism to resist OXPHOS-induced osteoclastogenesis by promoting osteogenesis. The inhibited osteogenesis induced by inflammatory mechanical stimuli was concomitant with a reduced expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). PGC-1α knockdown impeded osteogenesis under mechanical force and facilitated osteoclastogenesis by enhancing OXPHOS. Conversely, PGC-1α overexpression attenuated the impairment of bone remodeling by inflammatory mechanical signals through promoting glycolysis. This process benefited from the PGC-1α regulation on the transcriptional and translational activity of lactate dehydrogenase A (LDHA) and the tight control of the extracellular acidic environment. Additionally, the increased binding between PGC-1α and LDHA proteins might contribute to the glycolysis promotion within the inflammatory mechanical environment. Notably, LDHA suppression effectively eliminated the bone repair effect mediated by PGC-1α overexpression within inflammatory mechanical environments. In conclusion, this study demonstrated a novel molecular mechanism illustrating how inflammation orchestrated glucose metabolism through glycolysis and OXPHOS to affect mechanically induced bone remodeling.

PGC-1α inhibits NLRP3 signaling through transcriptional activation of POP1 to alleviate inflammation and strengthen osteogenic differentiation of lipopolysaccharide-induced human periodontal stem cells

Periodontitis is a chronic infectious disease that affects the oral health of adults. Periodontal stem cells (PDLSCs) have good self-renewal and multipotential differentiation abilities to maintain the integrity of periodontal support structure and repair defects. This study aimed to elucidate the role of peroxisome proliferator activated receptor-γ co-activator 1-α (PGC-1α) in lipopolysaccharide (LPS)-induced PDLSCs and the underlying mechanisms related to predicated that pyrin domain (PYD)-only protein 1 (POP1). Notably downregulated PGC-1α and POP1 expression was observed in LPS-induced PDLSCs. PGC-1α or POP1 overexpression significantly reduced the inflammation and enhanced the osteogenic differentiation of LPS-treated PDLSCs. Particularly, PGC-1 bound to POP1 promoter region and upregulated POP1 expression. Moreover, POP1 knockdown ameliorated the impacts of PGC-1α overexpression on the inflammation and osteogenic differentiation in LPS-induced PDLSCs. Besides, PGC-1α inactivated NLRP3 signaling in LPS-treated PDLSCs, which was reversed by POP1 knockdown. Taken together, PGC-1α inhibits NLRP3 signaling through transcriptional activation of POP1, thereby alleviating inflammation and strengthening osteogenic differentiation of LPS-induced PDLSCs.

The critical role of P2XR/PGC-1α signalling pathway in hypoxia-mediated pyroptosis and M1/M2 phenotypic differentiation of mouse microglia.

Microglia are endogenous immune cells in the brain, and their pyroptosis and phenotype dichotomy are proved to play roles in neurodegenerative diseases. We investigated whether and how hypoxia affected pyroptosis and phenotype polarization in mouse microglia. Primary mouse microglia and BV2 microglia were exposed to hypoxia. Pyroptosis and M1/M2 phenotype were assessed by measuring gasdermin D truncation and M1/M2 surface marker expression. Mechanisms including purinergic ionotropic receptor (P2XR), peroxisome proliferator-activated receptor coactivator-1α (PGC-1α) and NOD-like receptor protein 3 (NLRP3) inflammasome were investigated. We reported hypoxia (90% N2, 5% O2 and 5% CO2) induced pyroptosis and promoted M1 phenotype polarization in primary mouse microglia and BV2 microglia, and the effect appeared after 6h exposure. Although hypoxia (90% N2, 5% O2 and 5% CO2, 6h) had no effect on P2X1R and P2X7R expression, it increased P2X4R expression and decreased PGC-1α expression. Interestingly, blockade of P2X4R or P2X7R abolished hypoxia-modulated PGC-1α expression, pyroptosis and M1 polarization. PGC-1α overexpression or overactivation alleviated hypoxia-induced pyroptosis and M1 polarization, while PGC-1α knockdown or deactivation promoted pyroptosis and M1 polarization under normoxic situation. Further, hypoxia induced NLRP3 expression and activated caspase-1 and induced the phosphorylation of NF-κB and reduced the phosphorylation of STAT3/6. NLRP3 inhibitor and caspase-1 inhibitor abolished hypoxia-induced pyroptosis, while NF-κB inhibitor and STAT phosphorylation inducer ameliorated hypoxia-induced M1 polarization. In addition, NF-κB activator and STAT3/6 inhibitor caused microglia M1 polarization under normoxic situation. We concluded in cultured mouse microglia, hypoxia may induce pyroptosis via P2XR/PGC-1α/NLRP3/caspase-1 pathway and trigger M1 polarization through P2XR/PGC-1α/NF-κB/STAT3/6 pathway.

PGC-1α activation boosts exercise-dependent cellular response in the skeletal muscle

The role of Peroxisome proliferator-activated receptor-gamma coactivator alpha (PGC-1α) in fat metabolism is not well known. In this study, we compared the mechanisms of muscle-specific PGC-1α overexpression and exercise-related adaptation-dependent fat metabolism. PGC-1α trained (PGC-1α Ex) and wild-trained (wt-ex) mice were trained for 10 weeks, five times a week at 30 min per day with 60 percent of their maximal running capacity. The PGC-1α overexpressed animals exhibited higher levels of Fibronectin type III domain-containing protein 5 (FNDC5), 5' adenosine monophosphate-activated protein kinase alpha (AMPK-α), the mammalian target of rapamycin (mTOR), Sirtuin 1 (SIRT1), Lon protease homolog 1 (LONP1), citrate synthase (CS), succinate dehydrogenase complex flavoprotein subunit A (SDHA), Mitofusin-1 (Mfn1), endothelial nitric oxide synthase (eNOS), Hormone-sensitive lipase (HSL), adipose triglyceride lipase (ATGL), G protein-coupled receptor 41 (GPR41), and Phosphatidylcholine Cytidylyltransferase 2 (PCYT2), and lower levels of Sirtuin 3 (SIRT3) compared to wild-type animals. Exercise training increased the protein content levels of SIRT1, HSL, and ATGL in both the wt-ex and PGC-1α trained groups. PGC-1α has a complex role in cellular signaling, including the upregulation of lipid metabolism-associated proteins. Our data reveals that although exercise training mimics the effects of PGC-1α overexpression, it incorporates some PGC-1α-independent adaptive mechanisms in fat uptake and cell signaling.

Peroxisome proliferator-activated receptor γ coactivator 1α regulates downstream of tyrosine kinase-7 (Dok-7) expression important for neuromuscular junction formation

The neuromuscular junction (NMJ)—formed between a motor nerve terminal and skeletal muscle fiber—plays an important role in muscle contraction and other muscle functions. Aging and neurodegeneration worsen NMJ formation and impair muscle function. Downstream of tyrosine kinase-7 (Dok-7), expressed in skeletal muscle fibers, is essential for the formation of NMJ. Exercise increases the expression of the transcriptional coactivator peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) in skeletal muscles and restores NMJ formation. In this study, we used skeletal muscle-specific PGC1α knockout or overexpression mice to examine the role of PGC1α in regulating Dok-7 expression and NMJ formation. Our findings revealed that Dok-7 expression is regulated by PGC1α, and luciferase activity of the Dok-7 promoter is greatly increased by coexpressing PGC1α and estrogen receptor-related receptor α. Thus, we suggest PGC1α is involved in exercise-mediated restoration of NMJ formation.

Retention of stress susceptibility in the mdx mouse model of Duchenne muscular dystrophy after PGC-1α overexpression or ablation of IDO1 or CD38.

Duchenne muscular dystrophy (DMD) is a lethal degenerative muscle wasting disease caused by the loss of the structural protein dystrophin with secondary pathological manifestations including metabolic dysfunction, mood and behavioral disorders. In the mildly affected mdx mouse model of DMD, brief scruff stress causes inactivity, while more severe subordination stress results in lethality. Here, we investigated the kynurenine pathway of tryptophan degradation and the nicotinamide adenine dinucleotide (NAD+) metabolic pathway in mdx mice and their involvement as possible mediators of mdx stress-related pathology. We identified downregulation of the kynurenic acid shunt, a neuroprotective branch of the kynurenine pathway, in mdx skeletal muscle associated with attenuated peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α) transcriptional regulatory activity. Restoring the kynurenic acid shunt by skeletal muscle-specific PGC-1α overexpression in mdx mice did not prevent scruff -induced inactivity, nor did abrogating extrahepatic kynurenine pathway activity by genetic deletion of the pathway rate-limiting enzyme, indoleamine oxygenase 1. We further show that reduced NAD+ production in mdx skeletal muscle after subordination stress exposure corresponded with elevated levels of NAD+ catabolites produced by ectoenzyme cluster of differentiation 38 (CD38) that have been implicated in lethal mdx response to pharmacological β-adrenergic receptor agonism. However, genetic CD38 ablation did not prevent mdx scruff-induced inactivity. Our data do not support a direct contribution by the kynurenine pathway or CD38 metabolic dysfunction to the exaggerated stress response of mdx mice.

Fenofibrate alleviates NAFLD by enhancing the PPARα/PGC-1α signaling pathway coupling mitochondrial function

BackgroundTo comprehend the influences of fenofibrate on hepatic lipid accumulation and mitochondrial function-related signaling pathways in mice with non-alcoholic fatty liver disease (NAFLD) secondary to high-fat diets together with free fatty acids-influenced HepG2 cells model.Materials and methodsA random allocation of male 6-week C57BL/6J mice into three groups was done, including controls, model (14 weeks of a high-fat diet), and fenofibrate [similar to the model one with administered 0.04 g/(kg.d) fenofibrate by gavage at 11 weeks for 4 weeks] groups, which contained 10 mice each. This study verified NAFLD pathogenesis via mitochondrial functions in hepatic pathological abnormalities, liver index and weight, body weight, serum biochemical indexes, oxidative stress indicators, mitochondrial function indexes, and related signaling pathways. The effect of fenofibrate intervention was investigated in NAFLD model mice. In vitro, four groups based on HepG2 cells were generated, including controls, the FFA model (1.5 mmol/L FFA incubation for 24 h), LV-PGC-1α intervention (similar to the FFA model one after PPARGC1A lentivirus transfection), and LV control intervention (similar to the FFA model one after negative control lentivirus transfection) groups. The study investigated the mechanism of PGC-1α related to lipid decomposition and mitochondrial biosynthesis by Oil red O staining, colorimetry and western blot.ResultsIn vivo experiments, a high-fat diet achieved remarkable changes regarding liver weight, liver index, serum biochemical indicators, oxidative stress indicators, liver pathological changes, mitochondrial function indicators, and body weight of the NAFLD model mice while fenofibrate improved the objective indicators. In the HepG2 cells model, the lipid accumulation increased significantly within the FFA model group, together with aggravated hepatocytic damage and boosted oxidative stress levels. Moreover, FFA induced excessive mitosis into fragmented in mitochondrial morphology, ATP content in cells decreased, mtDNA replication fold decreased, the expression of lipid decomposition protein PPARα reduced, mitochondrial biosynthesis related protein PGC-1α, NRF-1 and TFAM decreased. PGC-1α overexpression inhibited lipid deposition by improving mitochondrial biosynthesis and lipid decomposition.ConclusionFenofibrate up-regulated PPARα/PGC-1α signaling pathway, promoted mitochondrial β-oxidation, reduced oxidative stress damage and lipid accumulation of liver. PGC-1α overexpression enhanced mitochondrial biosynthesis and ATP production, and reduced HepG2 intracellular accumulation of lipids and oxidative stress.

PGC1α as a downstream effector of KDM5B promotes the progression of androgen receptor-positive and androgen receptor-negative prostate cancers.

PPARγ coactivator-1α (PGC1α), as a co-activator, is known to optimize the action of several transcription factors, including androgen receptor (AR). However, the precise functions of PGC1α in prostate cancer, particularly those via the non-AR pathways, remain poorly understood. Meanwhile, our bioinformatics search suggested that PGC1α could be a direct downstream target of lysine-specific demethylase 5B (KDM5B/JARID1B/PLU1). We herein aimed to investigate how PGC1α induced prostate cancer outgrowth. Immunohistochemistry in radical prostatectomy specimens showed that the levels of PGC1α expression were significantly higher in prostatic adenocarcinoma [H-score (mean ± SD): 179.0 ± 111.6] than in adjacent normal-appearing tissue (16.7 ± 29.9, P<0.001) or high-grade prostatic intraepithelial neoplasia (79.0 ± 94.7, P<0.001). Although there were no strong associations of PGC1α expression with tumor grade or stage, outcome analysis revealed that patients with high PGC1α (H-score of ≥200) tumor had a significantly higher risk of postoperative biochemical recurrence even in a multivariable setting (hazard ratio 5.469, P=0.004). In prostate cancer LNCaP and C4-2 cells, PGC1α silencing resulted in considerable reduction in the levels of prostate-specific antigen expression. Interestingly, PGC1α silencing inhibited the cell viability of not only AR-positive LNCaP/C4-2/22Rv1 lines but also AR-negative PC3/DU145 lines. Chromatin immunoprecipitation assay further revealed the binding of KDM5B to the promoter region of PGC1α in these lines. Additionally, treatment with a KDM5 inhibitor KDM5-C70 considerably reduced the expression of PGC1α and prostate-specific antigen, as well as the cell viability of all the AR-positive and AR-negative lines examined. PGC1α silencing or KDM5-C70 treatment also down-regulated the expression of phospho-JAK2 and phospho-STAT3 in both AR-positive and AR-negative cells. These findings suggest the involvement of PGC1α, as a downstream effector of KDM5B, in prostate cancer progression via both AR-dependent and AR-independent pathways. KDM5B-PGC1α is thus a potential therapeutic target for both androgen-sensitive and castration-resistant tumors. Meanwhile, PGC1α overexpression may serve as a useful prognosticator in those undergoing radical prostatectomy.

Empagliflozin ameliorates diabetic cardiomyopathy probably via activating AMPK/PGC-1α and inhibiting the RhoA/ROCK pathway.

Diabetic cardiomyopathy (DCM) increases the risk of hospitalization for heart failure (HF) and mortality in patients with diabetes mellitus. However, no specific therapy to delay the progression of DCM has been identified. Mitochondrial dysfunction, oxidative stress, inflammation, and calcium handling imbalance play a crucial role in the pathological processes of DCM, ultimately leading to cardiomyocyte apoptosis and cardiac dysfunctions. Empagliflozin, a novel glucose-lowering agent, has been confirmed to reduce the risk of hospitalization for HF in diabetic patients. Nevertheless, the molecular mechanisms by which this agent provides cardioprotection remain unclear. To investigate the effects of empagliflozin on high glucose (HG)-induced oxidative stress and cardiomyocyte apoptosis and the underlying molecular mechanism. Twelve-week-old db/db mice and primary cardiomyocytes from neonatal rats stimulated with HG (30 mmol/L) were separately employed as in vivo and in vitro models. Echocardiography was used to evaluate cardiac function. Flow cytometry and TdT-mediated dUTP-biotin nick end labeling staining were used to assess apoptosis in myocardial cells. Mitochondrial function was assessed by cellular ATP levels and changes in mitochondrial membrane potential. Furthermore, intracellular reactive oxygen species production and superoxide dismutase activity were analyzed. Real-time quantitative PCR was used to analyze Bax and Bcl-2 mRNA expression. Western blot analysis was used to measure the phosphorylation of AMP-activated protein kinase (AMPK) and myosin phosphatase target subunit 1 (MYPT1), as well as the peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) and active caspase-3 protein levels. In the in vivo experiment, db/db mice developed DCM. However, the treatment of db/db mice with empagliflozin (10 mg/kg/d) for 8 wk substantially enhanced cardiac function and significantly reduced myocardial apoptosis, accompanied by an increase in the phosphorylation of AMPK and PGC-1α protein levels, as well as a decrease in the phosphorylation of MYPT1 in the heart. In the in vitro experiment, the findings indicate that treatment of cardiomyocytes with empagliflozin (10 μM) or fasudil (FA) (a ROCK inhibitor, 100 μM) or overexpression of PGC-1α significantly attenuated HG-induced mitochondrial injury, oxidative stress, and cardiomyocyte apoptosis. However, the above effects were partly reversed by the addition of compound C (CC). In cells exposed to HG, empagliflozin treatment increased the protein levels of p-AMPK and PGC-1α protein while decreasing phosphorylated MYPT1 levels, and these changes were mitigated by the addition of CC. Adding FA and overexpressing PGC-1α in cells exposed to HG substantially increased PGC-1α protein levels. In addition, no sodium-glucose cotransporter (SGLT)2 protein expression was detected in cardiomyocytes. Empagliflozin partially achieves anti-oxidative stress and anti-apoptotic effects on cardiomyocytes under HG conditions by activating AMPK/PGC-1α and suppressing of the RhoA/ROCK pathway independent of SGLT2.

Irisin ameliorates diabetic kidney disease by restoring autophagy in podocytes.

Many studies have highlighted the importance of moderate exercise. While it can attenuate diabetic kidney disease, its mechanism has remained unclear. The level of myokine irisin in plasma increases during exercise. We found that irisin was decreased in diabetic patients and was closely related to renal function, proteinuria, and podocyte autophagy injury. Muscle-specific overexpression of PGC-1α (mPGC-1α) in a mouse model is known to increase plasma irisin levels. The mPGC-1α mice were crossed with db/m mice to obtain db/db mPGC-1α+ mice in the present study. Compared to db/db mice without mPGC-1α, plasma irisin was increased, and albuminuria and glomerular pathological damage were both alleviated in db/db mPGC-1α+ mice. Impaired autophagy in podocytes was restored as well. Irisin inhibited the activation of the PI3K/AKT/mTOR signaling pathway in cultured human podocytes and improved damaged autophagy induced by high glucose levels. Then, db/db mice were treated with recombinant irisin, which had similar beneficial effects on the kidney as those in db/db mPGC-1α+ mice, with alleviated glomerular injury and albuminuria. Moreover, the autophagy in podocytes was also significantly restored. These results suggest that irisin secreted by skeletal muscles protects the kidney from diabetes mellitus damage. It also restores autophagy in podocytes by inhibiting the abnormal activation of the PI3K/AKT/mTOR signaling pathway. Thus, irisin may become a new drug for the prevention and treatment of diabetic nephropathy.

PGC-1α inhibits M2 macrophage polarization and alleviates liver fibrosis following hepatic ischemia reperfusion injury

Oxidative stress can induce inflammation, promoting macrophage polarization and liver fibrosis following hepatic ischemia-reperfusion (I/R). Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) has anti-oxidant and anti-inflammatory activity. However, how PGC-1α regulates macrophage polarization following hepatic I/R remains largely unknown. Male C57BL/6 wild-type mice were pre-treated with vehicle or trichostatin A (TSA) for 2 days and subjected to surgical induction of I/R. Liver injury and fibrosis in individual mice were examined longitudinally and the expression levels of IL-6, STAT3, M2-type macrophage markers, Collagen I and α-SMA in the liver of mice were analyzed by immunohistochemistry, RT-qPCR and Western blot. The potential interaction of PGC-1α with phosphorylated NF-kBp65 was determined by immunoprecipitation. The impacts of PGC-1α deficiency in hepatocytes on their IL-6 production and macrophage polarization were tested in a Transwell co-culture system. Moreover, the M2-type macrophage polarization and liver fibrosis were examined in hepatocyte-specific PGC-1α knockout mice and AAV8-mediated PGC-1α over-expressing mice following liver I/R. The down-regulated PGC-1α expression by I/R was negatively correlated with IL-6 levels in the liver of I/R mice and PGC-1α deficiency enhanced IL-6 expression, STAT3 activation and M2-type macrophage polarization in the I/R mice, which were abrogated by TSA treatment. In addition, PGC-1α directly interacted with phosphorylated NF-kBp65 in I/R livers. Hepatocyte-specific PGC-1α deficiency increased IL-6 production and promoted macrophage polarization toward M2 type when co-culture. More importantly, administration with AAV8-PGC-1α rescued the I/R-induced liver fibrosis by inhibiting the IL-6/JAK2/STAT3 signaling and M2-type macrophage polarization in the liver. These results suggest that PGC-1α may alleviate the I/R-induced liver fibrosis by attenuating the IL-6/JAK2/STAT3 signaling to limit M2-type macrophage polarization. PGC-1α may be a therapeutic target for the treatment of liver fibrosis.

Abstract P3180: Cardiomyocyte Pgc-1α Mediates The Adaptive Response To Endurance Exercise Training In Mice

Exercise has myriad systemic benefits in reducing the incidence from and morbidity of cardio-metabolic diseases. In healthy individuals, aerobic exercise promotes physiologic hypertrophy of the heart, which requires increased mitochondrial numbers and function. In skeletal muscle and heart, a key orchestrator of the adaptation to increased energetic needs is the transcriptional regulator PGC-1α. PGC-1α may mediate cardiac adaptation to physiological stress through its function in mitochondrial biogenesis but also through other mechanisms. The role of cardiac PGC-1α to the systemic training response is poorly understood. We generated PGC-1α cardiomyocyte-specific knockout (cKO) mice to study its role in endurance exercise training. Sedentary cKO mice demonstrated normal cardiac function and no significant differences in acute treadmill exercise tolerance. However, cKO mice demonstrated a lack of ability to augment exercise capacity after 6 weeks of wheel running compared to WT (work achieved 32.9 J in WT [39% increase] vs 23.1 J in cKOs [no change vs baseline], p&lt;0.001, unpaired t-test). This was despite comparable voluntary wheel distance run during training (2.93-3.67 km/day for both over 5 weeks, p=0.58). Unexpectedly, after 6 weeks of training, cKO mice developed a dilated cardiomyopathy at rest and exercise-related dysfunction (contractile reserve [ΔFS stress-rest ] +6.0 in WT vs -6.4% in KO, p&lt;0.05, unpaired t-test). They also demonstrated features of cardiac cachexia as measured by 30% and 21% reductions in inguinal adipose and gastrocnemius mass, respectively (P&lt;0.05, unpaired t-test). Gene expression profiling demonstrated activation of pathological ( Nppa , Nppb , Myh7/Myh6 ) and atrophic pathways ( Gdf11 , Gdf15 , Fstl3 ) in the trained cKOs. In vitro, gain of function studies using adenoviral expression in neonatal rat ventricular myocytes demonstrated that PGC-1α overexpression could abrogate pathologic hypertrophy and atrophy gene expression pathways stimulated by phenylephrine. Our preliminary studies support cardiomyocyte PGC-1α as a key mediator of the adaptive response to exercise training and unveil a key role of this transcriptional activator in protecting from exercise-related cardiac dysfunction in mice.