PGC-1α Activity Research Articles

Protective efficacy of Shenge San on mitochondria in H9c2 cardiomyocytes.

To investigate whether peroxisome proliferator-activated receptor γ-coactivator-1α/nuclear respiratory factor 1 (PGC-1α/NRF1) activity can protect mitochondrial function in the setting of cardiac hypertrophy and improve cardiomyocyte energy metabolism. Cardiac hypertrophy was modeled in H9c2 cells treated with isoproterenol (ISO) to assess the effects of Shenge San (, SGS) on cell viability and mitochondrial membrane potential. We assessed mitochondrial complex mRNA levels and mitochondrial oxidative phosphorylation factor mRNA and protein levels. Compared with the 100 μM ISO group, cell size was significantly decreased in the 0.3 mg/mL SGS and 20 μM ZLN005 (PGC-1α activator) groups ( < 0.01). Compared with the SGS (0.3) +ISO group, we observed lower phosphorylated adenosine monophosphate-activated kinase (AMPK) protein levels in the ISO and ZLN005+SGS+ISO groups ( < 0.01). Compared with the compound C group, SGS significantly increased PGC-1α expression in ISO-induced cardiac hypertrophy cells ( < 0.01), and this was inhibited by compound C pretreatment ( < 0.05). Compared with the ISO group, the mitochondrial red-green fluorescence ratio increased in the 0.3 mg/mL SGS group ( < 0.05). mRNA levels of cytochrome c oxidase subunit 1 (CO1) in the ISO and compound C groups were lower than those in control group ( 0.01), and the mRNA levels of CO1 and ATP8 were significantly lower in the ISO and compound C groups versus control ( 0.01). Compared with the SGS (0.3) +ISO group, ATP synthetase subunit 8 (ATP8) mRNA was significantly decreased in the ISO group ( < 0.01) and compound C+SGS+ISO group ( < 0.05). Compared with the SGS (0.3) +ISO group, NRF1 mRNA levels were significantly decreased ( < 0.05) in the ISO and compound C+SGS+ISO groups. SGS can attenuate ISO-induced cardiomyocyte hypertrophy, restore the decrease in mitochondrial membrane potential, and upregulate PGC-1α/NRF1 levels. Notably, these effects can be blocked by AMPK inhibitor-compound C.

PGC-1α in mediating mitochondrial biogenesis and intestinal epithelial differentiation promoted by purple potato extract

• Purple potato polyphenolic extract (PPE) promotes gut epithelial differentiation. • PPE upregulates PGC-1α and enhances mitochondria biogenesis in Caco-2 cells. • PPE promotes intracellular oxidative metabolism. • PGC-1α is indispensable in PPE-induced differentiation & mitochondrial biogenesis. Intestinal epithelial differentiation plays an important role in maintaining gut health and is impaired due to many diseases. Purple potatoes are rich in polyphenols that promote the differentiation of intestinal epithelial cells. In this study, we found that purple potato (PP) extract up-regulated the level of peroxisome proliferator-activated receptor γ coactivator (PGC)-1α, the expression of mitochondrial-related enzymes, the content of mitochondrial DNA, and the levels of tricarboxylic acid cycle metabolites in human intestinal epithelial Caco-2 cells. Inhibition of PGC-1α by either PGC-1α inhibitor SR-18292 or siRNA-mediated knockdown eliminated the enhancing effects of PP extract on the expression of differentiation markers, mitochondrial metabolite contents and mitochondrial DNA copy number, as well as the expression of mitochondrial DNA-encoded enzymes. In summary, PP extract promoted mitochondrial biogenesis and the differentiation of intestinal epithelial cells, and these promotion effects are dependent on the activation of PGC-1α.

Emerging Protective Actions of PGC-1α in Diabetic Nephropathy.

Renal impairment is affected by various mechanisms of oxidative stress, mitochondrial dysfunction, and basement membrane thickening, which are the major causes of renal dysfunction in diabetes. Of note, hyperglycemia-induced mitochondrial dysfunction has been identified as a common cause of diabetic nephropathy and renal impairment, and the decrease in PGC-1α expression brought on by hyperglycemia plays an immensurable role in both the reduction of mitochondrial biogenesis and the rise in oxidative stress. Reduced PGC-1α expression levels may occur with rising SGLT2-dependent increase of cytoplasmic sodium and protons in the renal cells of diabetes, even if the precise mechanism of hyperglycemia-induced disruption of PGC-1α expression has not been identified. Additionally, it has been observed that SGLT2 inhibitors enhance PGC-1α expression and activity and decrease cytoplasmic sodium and protons in many kidney cells, which may be helpful in reducing renal impairment brought on by diabetes. This review summarizes our and other recent studies on the function of PGC-1α in diabetic nephropathy, provides another potential mediator of the lower PGC-1α expression levels brought on by hyperglycemia in diabetics, and identifies a new pathogenesis of diabetes-related renal impairment. It also explains the mechanism underlying the protective effects of SGLT2 inhibitors on diabetic nephropathy. Therefore, it should be taken into account that SGLT2 inhibitors are an effective therapeutic strategy for reducing renal dysfunction caused by diabetes.

Effect of caffeine on mitochondrial biogenesis in the skeletal muscle - A narrative review.

Caffeine is one of the most widely used substances as recreational drug for performance-enhancement in sport, underpinned by a strong evidence base. Although the effects of caffeine are widely investigated within the scope of performance physiology, the molecular effects of caffeine within skeletal muscle remain unclear. Evidence from invitro and invivo models suggest that caffeine regulates the glucose metabolism in the skeletal muscle. Moreover, caffeine seems to stimulate CaMKII, PPARδ/β, AMPK and PGC1α, classical markers of exercise-adaptations, including mitochondrial biogenesis and mitochondrial content. This review summarizes evidence to suggest caffeine-effects within skeletal muscle fibers, focusing on the putative role of caffeine on mitochondrial biogenesis to explore whether caffeine supplementation might be a strategy to enhance mitochondrial biogenesis.

PGC-1α activity and mitochondrial dysfunction in preterm infants.

Extremely low gestational age neonates (ELGANs) are born in a relatively hyperoxic environment with weak antioxidant defenses, placing them at high risk for mitochondrial dysfunction affecting multiple organ systems including the nervous, respiratory, ocular, and gastrointestinal systems. The brain and lungs are highly affected by mitochondrial dysfunction and dysregulation in the neonate, causing white matter injury (WMI) and bronchopulmonary dysplasia (BPD), respectively. Adequate mitochondrial function is important in providing sufficient energy for organ development as it relates to alveolarization and axonal myelination and decreasing oxidative stress via reactive oxygen species (ROS) and reactive nitrogen species (RNS) detoxification. Peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) is a master regulator of mitochondrial biogenesis and function. Since mitochondrial dysfunction is at the root of WMI and BPD pathobiology, exploring therapies that can regulate PGC-1α activity may be beneficial. This review article describes several promising therapeutic agents that can mitigate mitochondrial dysfunction through direct and indirect activation and upregulation of the PGC-1α pathway. Metformin, resveratrol, omega 3 fatty acids, montelukast, L-citrulline, and adiponectin are promising candidates that require further pre-clinical and clinical studies to understand their efficacy in decreasing the burden of disease from WMI and BPD in preterm infants.

Lipoxin A4 attenuated dexamethasone-induced muscle atrophy via activation of PGC-1α/Nrf2/TFAM pathway

Prolonged dexamethasone (DEX) administration causes skeletal muscle atrophy through induction of both oxidative stress and mitochondrial dysfunction. Lipoxin A4 (LXA4) is a recognized antioxidant but its effect against DEX-induced muscle atrophy has not been studied yet. This study aimed to assess the potential ameliorating effect of LXA4 on DEX-induced muscle atrophy and investigate the possible involvement of the mitochondrial dynamics pathway and the redox state in this effect. Forty male rats were divided into four groups; normal control, LXA4-treated, DEX-treated, and LXA4 plus DEX-treated. At the end of the experiment, LXA4 counteracted the effect of DEX on different parameters including muscle weight, muscle strength, serum creatine kinase activity, malondialdehyde and protein carbonyl contents, Na/K-ATPase and citrate synthase activities, mitochondrial transmembrane potential, mitochondrial transcription factor (TFAM), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), and nuclear factor erythroid 2-related factor 2 (Nrf2). These findings signify the promising therapeutic effect of LXA4 against DEX-induced skeletal muscle atrophy and indicate the possible involvement of LXA4-induced mitochondrial activation in addition to its well-known antioxidant effects.

Morinda officinalis polysaccharide attenuates osteoporosis in rats underwent bilateral ovariectomy by suppressing the PGC-1α/PPARγ pathway.

Osteoporosis (OP) is a widespread disease that causes risks of spine and hip fractures. Morinda officinalis polysaccharide (MOP) shows therapeutic potential in OP. This article intended to understand the mechanism by which MOP impacts bone mineral density (BMD) and serum trace elements in OP rats. OP rat models were established by bilateral ovariectomy (OVX). Rats were intragastrically administered with MOP or ZLN005 [the activator of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α)] since the first day after operation for 8 weeks. Microstructural changes in OP rats were analyzed using micro-computed tomography system. Contents of serum Zn, Cu, Fe, and Mg in rats were measured. Levels of serum superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), GSH, and malondialdehyde (MDA) in rats were determined by Enzyme-linked immunosorbent assay. Protein levels of PGC-1α and peroxisome proliferator-activated receptor γ (PPARγ) in cartilage tissues of rats were determined via Western blotting. MOP enhanced BMD, bone volume per trabecular volume (BV/TV), Tb.N, and Tb.Th and reduced Tb.Sp in the distal femur of OVX rats, elevated levels of serum Cu, Fe, and Mg and contents of SOD, GSH, and GSH-PX and decreased MDA content. Moreover, MOP suppressed the PGC-1α/PPARγ pathway. Activation of PGC-1α partially abolished the action of MOP on ameliorating OP in OVX rats and strengthening anti-oxidation ability. MOP mitigated OP in OVX rats by inhibiting the PGC-1α/PPARγ pathway.

Supplementation of Dimethylglycine Sodium Salt in Sow Milk Reverses Skeletal Muscle Redox Status Imbalance and Mitochondrial Dysfunction of Intrauterine Growth Restriction Newborns.

The current study sought to understand the mechanism underlying skeletal muscle dysfunction brought on by intrauterine growth restriction (IUGR) and to explore the treatment benefits of applying dimethylglycine sodium salt (DMG-Na) in sow milk to newborns during the suckling period. Each of the 10 sows delivered one newborn with a normal birth weight (NBW) and one with an IUGR. Additionally, two NBW and two IUGR newborns were collected per litter of another 10 sows. The 20 NBW newborns were divided between the N (sow milk) and ND (sow milk + 0.1% DMG-Na) groups, while 20 IUGR newborns were divided between the I (sow milk) and ID (sow milk + 0.1% DMG-Na) groups. The skeletal muscle histomorphology, redox status, and levels of gene and protein expression were worse (p < 0.05) in the I group than in the N group. In addition, supplementation with DMG-Na (ND and ID groups) improved (p < 0.05) those parameters compared to the unsupplemented groups (N and I groups). Inhibited nuclear factor erythroid 2-related factor 2 (Nrf2)/sirtuin 1 (SIRT1)/peroxisome proliferator-activated receptorγcoactivator-1α (PGC-1α) activity resulted in decreased redox status, skeletal muscle structural damage, skeletal muscle mitochondrial function impairment, and decreased performance in IUGR newborns. Supplementation of DMG-Na in sow milk activated the Nrf2/SIRT1/PGC-1α in IUGR newborns, thereby improving their skeletal muscle performance.

5′-CMP and 5′-UMP promote myogenic differentiation and mitochondrial biogenesis by activating myogenin and PGC-1α in a mouse myoblast C2C12 cell line

Ribonucleotides are basic monomeric building blocks for RNA considered as conditionally essential nutrients. They are normally produced in sufficient quantity, but can become insufficient upon stressful challenges. The administration of pyrimidine nucleotides, such as cytidine-5′-monophosphate (5′-CMP) and uridine-5′-monophosphate (5′-UMP), enables rats to endure prolonged exercise. However, the underlying mechanisms have remained elusive. To investigate these mechanisms, we studied the effect of 5′-CMP and 5′-UMP on muscular differentiation and mitochondrial biogenesis in myoblast C2C12 cells. 5′-CMP and 5′-UMP were found to increase the mRNA levels of myogenin, which is a myogenic regulatory protein expressed during the final differentiation step and fusion of myoblasts into myotubes. 5′-CMP and 5′-UMP also promoted myoblast differentiation into myotube cells. 5′-CMP and 5′-UMP further increased the mRNA levels of PGC-1α which regulates mitochondrial biogenesis and skeletal muscle fiber type. In addition, 5′-CMP and 5′-UMP increased mitochondrial DNA copy number and enhanced mRNA levels of slow-muscle myosin heavy chains. Moreover, cytidine and uridine, nucleosides corresponding to 5′-CMP and 5′-UMP, markedly promoted myotube formation in C2C12 cells. Considering the metabolism and absorption of nucleotides, the active bodies underlying the effects observed with 5′-CMP and 5′-UMP could be cytidine and uridine. In conclusion, our results indicate that 5′-CMP and 5′-UMP can promote myogenic differentiation and mitochondrial biogenesis, as well as increase slow-twitch fiber via the activation of myogenin and PGC-1α. In addition, 5′-CMP and 5′-UMP may be considered as safe and effective agents to enhance muscle growth and improve the endurance in skeletal muscles.

Metformin mitigates gas explosion‑induced blast lung injuries through AMPK‑mediated energy metabolism and NOX2‑related oxidation pathway in rats

Gas explosions are a recurrent event in coal mining that cause severe pulmonary damage due to shock waves, and there is currently no effective targeted treatment. To illustrate the mechanism of gas explosion-induced lung injury and to explore strategies for blast lung injury (BLI) treatment, the present study used a BLI rat model and supplementation with metformin (MET), an AMP-activated protein kinase (AMPK) activator, at a dose of 10 mg/kg body weight by intraperitoneal injection. Protein expression levels were detected by western blotting. Significantly decreased expression of phosphorylated (p)-AMPK, peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α) and metabolic activity were observed in the BLI group compared with those in the control group. However, the mitochondrial stability, metabolic activity and expression of p-AMPK and PGC1α were elevated following MET treatment. These results suggested that MET could attenuate gas explosion-induced BLI by improving mitochondrial homeostasis. Meanwhile, high expression of nicotinamide adenine dinucleotide phosphate oxidase (NOX2) and low expression of catalase (CAT) were observed in the BLI group. The expression levels of NOX2 and CAT were restored in the BLI + MET group relative to changes in the BLI group, and the accumulation of oxidative stress was successfully reversed following MET treatment. Overall, these findings revealed that MET could alleviate BLI by activating the AMPK/PGC1α pathway and inhibiting oxidative stress caused by NOX2 activation.

Kynurenine Metabolism as a Mechanism to Improve Fatigue and Physical Function in Postmenopausal Breast Cancer Survivors Following Resistance Training.

This pilot examines whether resistance training (RT) can induce changes in kynurenine (KYN) metabolism, which may contribute to improved physical function in breast cancer survivors (BCSs). Thirty-six BCSs (63.2 ± 1.1 years) underwent assessments of physical function and visual analog scale (100 cm) fatigue and quality of life before and after 12 weeks of RT (N = 22) or non-exercise control (CBCT©: Cognitively Based Compassion Training, N = 10). Blood was collected before and after interventions for assessment of KYN, kynurenic acid (KYNA), and peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α). At baseline, the women were moderately fatigued (mean score: 46 cm) and at risk of poor functional mobility. A group*time interaction was observed for all measures of strength with improvements (~25–35%) following RT (p’s < 0.01), but not CBCT. Time effects were observed for fatigue (−36%) and quality of life (5%) (p’s < 0.01), where both groups improved in a similar manner. A group*time interaction was observed for KYN (p = 0.02) and PGC-1α (p < 0.05), with KYN decreasing and PGC-1α increasing following RT and the opposite following CBCT. These changes resulted in KYN/KYNA decreasing 34% post-RT, but increasing 21% following CBCT. These data support RT as a therapeutic intervention to counteract the long-term side effect of fatigue and physical dysfunction in BCSs. Additionally, the results suggest that this effect may be mediated through the activation of PGC-1α leading to alterations in KYN metabolism.

Bisphenol-A Mediated Impaired DRP1-GFER Axis and Cognition Restored by PGC-1α Upregulation Through Nicotinamide in the Rat Brain Hippocampus.

The regulatory network of mitochondrial biogenesis and dynamics is vital for mitochondrial functions and cellular homeostasis. Any impairment in the mitochondrial network leads to neurodegenerative disorders. Our earlier studies suggest that environmental toxicant Bisphenol-A (BPA) exposure reduces neurogenesis by abnormal mitochondrial dynamics and mitochondrial biogenesis through impairment of mitochondrial fission factor dynamin-related protein (DRP1) and mitochondrial import protein GFER, which leads to demyelination, neurodegeneration, and cognitive deficits in the rats. In the present study, we found that chronic BPA exposure reduces PGC-1α levels (master regulator of mitochondrial biogenesis), alters mitochondrial localization of DRP1 and GFER, and reduces the number of PGC-1α/NeuN+ and PGC-1α/β-tubulin+ neurons in the rat hippocampus, suggesting reduced PGC-1α-mediated neurogenesis. Nicotinamide significantly increased PGC-1α protein levels, PGC-1α/NeuN+ co-labeled cells in BPA-treated rat hippocampus and PGC-1α/β-tubulin+ co-labeled cells in neuron culture derived from hippocampal neural stem cells. Interestingly, PGC-1α upregulation by nicotinamide also resulted in increased GFER levels and restored mitochondrial localization of GFER (increased GFER/TOMM20 co-labeled cells) in vitro and in vivo following BPA treatment. Nicotinamide also reduced DRP1 levels and prevented DRP1 mitochondrial localization in BPA-treated neuronal cultures and hippocampus, suggesting reduced mitochondrial fission. This resulted in reduced cytochrome c levels in neuronal culture and reduced hippocampal neurodegeneration (reduced caspase-3/NeuN+ co-labeled neurons) following nicotinamide treatment in BPA-treated group. Consequently, activation of PGC-1α by nicotinamide restored BPA-mediated cognitive deficits in rats. Results suggest that the treatment of nicotinamide has therapeutic potential and rescues BPA-mediated neuronal death and cognitive deficits by upregulating the PGC-1α and GFER-DRP1 link, thus balancing mitochondrial homeostasis.

Ablation of FUNDC1-dependent mitophagy renders myocardium resistant to paraquat-induced ferroptosis and contractile dysfunction

Paraquat is a quaternary nitrogen herbicide evoking mitochondrial damage and heart failure with little therapeutic remedies available. Recent reports depicted a role for unchecked autophagy in paraquat-induced cardiotoxicity. This study was designed to examine the role of the mitophagy receptor protein FUNDC1 in paraquat-induced cardiac contractile and mitochondrial injury using a murine model of FUNDC1 knockout (FUNDC1−/−) mice. WT and FUNDC1−/− mice were challenged with paraquat (45 mg/kg, single injection, i.p.) for 72 h prior to examination of cardiac contractile and intracellular Ca2+ properties, mitochondrial integrity, mitochondrial function, O2− production, apoptosis, autosis and ferroptosis. Our results found that paraquat challenge compromised echocardiographic, contractile and intracellular Ca2+ properties in conjunction with mitochondrial damage (reduced levels of PGC1α, UCP2, NAD+, and citrate synthase activity along with fragmentation manifested by elevated Drp1 and TEM ultrastructural changes), the effects of which were overtly attenuated or obliterated by FUNDC1 ablation. Paraquat triggered ferroptosis, apoptosis (but not autosis) and unchecked mitophagy as evidenced by downregulation of GPx4, SLC7A11, Bcl2, TOM20 and ferritin as well as upregulated levels of Bax, TNFα, IL6, NCOA4 and FUNDC1, the effects of which were relieved by FUNDC1 ablation. Further study noted dephosphorylation of JNK upon paraquat challenge, the effect of which was obliterated by FUNDC1 knockout. In vitro evaluation of BODIPY ferroptosis and cardiomyocyte function revealed FUNDC1 ablation inhibited paraquat-induced increase in BODIPY lipid peroxidation and cardiomyocyte contractile dysfunction, the effects of which were nullified and mimicked by inhibition of JNK or ferroptosis and activation of JNK, respectively. Taken together, our data suggest an essential role for FUNDC1/JNK-mediated ferroptosis in paraquat exposure-evoked cardiac and mitochondrial injury.

NEU1 Regulates Mitochondrial Energy Metabolism and Oxidative Stress Post-myocardial Infarction in Mice via the SIRT1/PGC-1 Alpha Axis.

ObjectiveNeuraminidase 1 (NEU1) participates in the response to multiple receptor signals and regulates various cellular metabolic behaviors. Importantly, it is closely related to the occurrence and progression of cardiovascular diseases. Because ischemic heart disease is often accompanied by impaired mitochondrial energy metabolism and oxidative stress. The purpose of this study was to investigate the functions and possible mechanisms of NEU1 in myocardial remodeling and mitochondrial metabolism induced by myocardial infarction (MI).MethodsIn this study, the MI-induced mouse mode, hypoxia-treated H9C2 cells model, and hypoxia-treated neonatal rat cardiomyocytes (NRCMs) model were constructed. Echocardiography and histological analysis were adopted to evaluate the morphology and function of the heart at the whole heart level. Western blot was adopted to determine the related expression level of signaling pathway proteins and mitochondria. Mitochondrial energy metabolism and oxidative stress were detected by various testing kits.ResultsNeuraminidase 1 was markedly upregulated in MI cardiac tissue. Cardiomyocyte-specific NEU1 deficiency restored cardiac function, cardiac hypertrophy, and myocardial interstitial fibrosis. What is more, cardiomyocyte-specific NEU1 deficiency inhibited mitochondrial dysfunction and oxidative stress induced by MI. Further experiments found that the sirtuin-1/peroxisome proliferator-activated receptor γ coactivator α (SIRT1/PGC-1α) protein level in MI myocardium was down-regulated, which was closely related to the above-mentioned mitochondrial changes. Cardiomyocyte-specific NEU1 deficiency increased the expression of SIRT1, PGC-1α, and mitochondrial transcription factor A (TFAM); which improved mitochondrial metabolism and oxidative stress. Inhibition of SIRT1 activity or PGC-1α activity eliminated the beneficial effects of cardiomyocyte-specific NEU1 deficiency. PGC-1α knockout mice experiments verified that NEU1 inhibition restored cardiac function induced by MI through SIRT1/PGC-1α signaling pathway.ConclusionCardiomyocyte-specific NEU1 deficiency can alleviate MI-induced myocardial remodeling, oxidative stress, and mitochondrial energy metabolism disorder. In terms of mechanism, the specific deletion of NEU1 may play a role by enhancing the SIRT1/PGC-1α signaling pathway. Therefore, cardiomyocyte-specific NEU1 may provide an alternative treatment strategy for heart failure post-MI.

ZLN005 Alleviates In Vivo and In Vitro Renal Fibrosis via PGC-1α-Mediated Mitochondrial Homeostasis.

Currently, chronic kidney disease (CKD) is one of the most common diseases; it is also a serious threat to human health due to its high mortality, and its treatment is still a major clinical challenge. Mitochondrial dyshomeostasis plays an important role in the development of CKD. ZLN005 is a novel peroxisome-proliferator-activated receptor-γ coactivator-1α (PGC-1α) activator from our laboratory. To explore whether ZLN005 can protect against CKD in vivo and in vitro, a unilateral ureteral obstruction (UUO) model and TGF-β1-treated renal tubular epithelial cells (TECs), respectively, were used in this study. We found that ZLN005-administrated UUO mice showed less kidney damages than control mice, as indicated by the reduced expression of fibrotic biomarkers in the kidney of UUO mice. ZLN005 treatment also alleviated the TGF-β1-induced fibrotic phenotype and lipid accumulation in TECs. Our study demonstrated ZLN005 treatment improved mitochondrial homeostasis at least partially via the activation of PGC-1α, thus maintaining mitochondria function and energy homeostasis. In summary, ZLN005 treatment ameliorates UUO-induced renal fibrosis, providing conceptional support for mitochondria-targeting therapies for chronic kidney disease.

Regulation of PGC1α Downstream of the Insulin Signaling Pathway Plays a Role in the Hepatic Proteotoxicity of Mutant α1-Antitrypsin Deficiency Variant Z

Insulin signaling is known to regulate essential proteostasis mechanisms. The analyses here examined effects of insulin signaling in the PiZ mouse model of α1-antitrypsin deficiency in which hepatocellular accumulation and proteotoxicity of the misfolded α1-antitrypsin Z variant (ATZ) causes liver fibrosis and cancer. We first studied the effects of breeding PiZ mice to liver-insulin-receptor knockout (LIRKO) mice (with hepatocyte-specific insulin-receptor gene disruption). The results showed decreased hepatic ATZ accumulation and liver fibrosis in PiZ x LIRKO vs PiZ mice, with reversal of those effects when we bred PiZ x LIRKO mice onto a FOXO1-deficient background. Increased intracellular degradation of ATZ mediated by autophagy was identified as the likely mechanism for diminished hepatic proteotoxicity in PiZ x LIRKO mice and the converse was responsible for enhanced toxicity in PiZ x LIRKO x FOXO1-KO animals. Transcriptomic studies showed major effects on oxidative phosphorylation and autophagy genes, and significant induction of peroxisome proliferator-activated-receptor-γ-coactivator-1α (PGC1α) expression in PiZ-LIRKO mice. Because PGC1α plays a key role in oxidative phosphorylation, we further investigated its effects on ATZ proteostasis in our ATZ-expressing mammalian cell model. The results showed PGC1α overexpression or activation enhances autophagic ATZ degradation. These data implicate suppression of autophagic ATZ degradation by down-regulation of PGC1α as one mechanism by which insulin signaling exacerbates hepatic proteotoxicity in PiZ mice, and identify PGC1α as a novel target for development of new human α1-antitrypsin deficiency liver disease therapies.

5-HT1F Receptor Agonist Ameliorates Mechanical Allodynia in Neuropathic Pain via Induction of Mitochondrial Biogenesis and Suppression of Neuroinflammation.

Neuropathic pain is a devastating disease that affects millions of people worldwide. Serotonin (5-hydroxytryptamine, 5-HT) is involved in pain modulation. Several lines of evidence have indicated that 5-HT1F receptor agonists are potent inducers of mitochondrial biogenesis. In this study, we tested the hypothesis that 5-HT1F receptor agonists ameliorate mechanical allodynia in neuropathic pain via the induction of mitochondrial biogenesis and suppression of neuroinflammation. Male Sprague–Dawley rats were used to establish a neuropathic pain model via spared nerve injury (SNI). The paw withdrawal threshold (PWT) was used to evaluate mechanical allodynia. Real-time polymerase chain reaction was used to examine the mitochondrial DNA (mtDNA) copy number. Western blotting and immunofluorescence were used to examine the expression of target proteins. Our results showed that mitochondrial biogenesis was impaired in the spinal cord of rats with SNI. Moreover, activation of PGC-1α, the master regulator of mitochondrial biogenesis, attenuates established mechanical allodynia in rats with neuropathic pain. In addition, the neuronal 5-HT1F receptor is significantly downregulated in the spinal cord of rats with neuropathic pain. Furthermore, the selective 5-HT1F receptor agonist lasmiditan attenuated established mechanical allodynia in rats with neuropathic pain. Finally, lasmiditan (Las) treatment restored mitochondrial biogenesis and suppressed neuroinflammation in the spinal cord of rats with SNI. These results provide the first evidence that lasmiditan ameliorates mechanical allodynia in neuropathic pain by inducing mitochondrial biogenesis and suppressing neuroinflammation in the spinal cord. Inducers of mitochondrial biogenesis may be an encouraging therapeutic option for the management of neuropathic pain.

Advanced Glycation End Products Induced Mitochondrial Dysfunction of Chondrocytes through Repression of AMPKα-SIRT1-PGC-1α Pathway

Introduction: Our previous studies have demonstrated advanced glycation end products (AGEs) was an important mediator in osteoarthritis (OA) which may induce mitochondrial dysfunction. AMP-activated protein kinase (AMPK), sirtuin 1 (SIRT1), and its downstream target peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) are the critical sensors that regulate mitochondrial biogenesis and have been recognized as therapeutic targets in OA. This study was designed to test whether AGEs caused mitochondrial dysfunction through modulation of AMPKα/SIRT1/PGC-1α. Methods: We knocked down or overexpressed AMPKα, SIRT1, and PGC-1α by small interfering RNA or plasmid DNA transfection, respectively. Mitochondrial membrane potential (△Ψ) was detected by tetraethylbenzimidazolyl carbocyanine iodide (JC-1) fluorescence probe. Results: The results showed that AGEs impaired △Ψ, intracellular ATP level, and mitochondrial DNA content, linked to decreased AMPKα, SIRT1, and PGC-1α expression in chondrocyte. AMPKα pharmacologic activation or overexpression of AMPKα, SIRT1, and PGC-1α reversed impairments of mitochondrial biogenesis, oxidative stress, and inflammation in AGEs-induced chondrocytes. However, AMPKα activation using AICAR had decreased capacity to increase each of those same effect readouts in AGEs-treated SIRT1-siRNA or PGC-1α-siRNA chondrocyte. Conclusion: Taken together, AGEs reduced the AMPKα/SIRT1/PGC-1α signaling in chondrocytes, leading to mitochondrial dysfunction as a result of increased oxidative stress, inflammation, and apoptosis. These results indicated that target AMPK may be as a novel therapeutic strategy for AGEs-related OA prevention.

Activating PGC-1α-mediated signaling cascades in the aorta contributes to the amelioration of vascular senescence and atherosclerosis by 2,3,4′,5-tetrahydroxystilbene-2-O-β-d-glycoside

Background2,3,4′,5-tetrahydroxystilbene-2-O-β-d-glycoside (TSG), the main active polyphenolic component of Polygonum multiflorum, possesses many pharmacological activities. Its anti-aging effect influences a variety of tissues with diverse mechanisms. However, the effectiveness and exact mechanisms of TSG against vascular senescence in atherosclerosis remain unclear. The present study is aimed to investigate the effects of TSG against vascular senescence in atherosclerosis both in vivo and in vitro, and the possible underlying mechanisms focusing on aortic peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α)-mediated signaling cascades which have never been studied. MethodsIn vivo, 12-mo-old male LDLr−/− mice were randomly separated into control, high-fat diet (HFD), and TSG -treatment groups. At the end of the 12 weeks, the blood samples and aorta tissues of mice were collected for further analysis. In vitro, to mimic the condition of endothelial senescence in hyperlipidemic mice, human aortic endothelial cells (HAECs) were incubated with oxidized low-density lipoprotein (ox-LDL) to induce senescence. ResultsTSG administration improved lipid profiles, ameliorated HFD-exacerbated vascular senescence and atherosclerosis. The protective effect of TSG via inhibiting telomere malfunction, oxidative stress, and mitochondrial damage was found both in vivo and in vitro. Notably, TSG administration increased aortic PGC-1α mRNA and protein expression along with the regulation of its targeted genes TERT, NRF1, TFAM, Mn-SOD, and catalase. Further, by using PGC-1α siRNA in ox-LDL-treated HAECs, it is proved that TSG reduced endothelial senescence, telomere malfunction, oxidative stress, and mitochondrial damage at least partly through activating the PGC-1α pathway. ConclusionsThese results provide new evidence for TSG in the treatment of atherosclerosis and the activation of aortic PGC-1α is involved in its beneficial effects.

A41 THE ROLE OF PGC-1α IN MURINE BONE MARROW DENDRITIC CELLS

BackgroundThe intestinal immune system tolerates food antigens and the commensal microbiota to prevent chronic inflammation. Inflammatory bowel diseases (IBD) such as ulcerative colitis and Crohn’s disease, are characterized by the loss of tolerance towards the microbiota, leading to inflammation, which is characterized by the high production of cytokines such as TNF and the influx of macrophages and neutrophils to the gut. Tolerance is driven by tolerogenic dendritic cells (tolDCs). Currently, there is no cure for IBD and while available treatments may reduce symptoms, there are no pharmacological therapies that specifically seek to rescue tolerance. Inducing tolDCs in patients with IBD may be a promising therapy since it is a way to directly target the main cause of the disease. tolDCs have been defined by down-regulating TNF (pro-inflammatory cytokine), producing IL-10 (anti-inflammatory cytokine), and active oxidative phosphorylation (OXPHOS) in the mitochondria.AimsGiven the tolDC characteristic of active OXPHOS, the objective of our project was to evaluate the role of PGC-1α, a major mediator of mitochondria biogenesis, in generating toDCs using murine bone marrow-derived dendritic cells (BMDC). Our hypothesis is that tolDCs would be (1) generated by pharmacological activation of PGC-1α by ZLN005, and (2) constrained by inhibition of PGC-1α by SR18292.MethodsWe treated BMDC cultures with ZLN005 (PGC-1α activator) or SR18292 (PGC-1α inhibitor), and LPS. We characterized the effect of PGC-1α manipulation on the metabolism of BMDCs by metabolomics and Seahorse XF Cell Mito Stress Test. In addition, we evaluated features of tolDCs, such as gene expression by qPCR, and cytokine production by ELISA.ResultsWe observed that activation of PGC-1α altered the metabolic profile of BMDC, and upregulates genes known to be expressed in tolDCs. However, this transcriptional upregulation was lost after LPS stimulation and did not alter TNF or IL-10 levels in BMDCs. PGC-1α inhibition, on other hand, decreased features of tolDCs, such as metabolic profile, transcriptional activation, and the levels of LPS-induced IL-10. Our data suggest that PGC-1α activation with ZLN005 does not increase the generation of tolDCs in vitro. However, inhibition of PGC-1α with SR18292 constrains tolDCs generation.ConclusionsPGC-1α is important for the development of tolDCs in murine dendritic cells.Funding AgenciesNSERC and FRQNT