Muscle Psn gene combined with exercise contribute to healthy aging of skeletal muscle and lifespan by adaptively regulating Sirt1/PGC-1α and arm pathway.

The Presenilin (Psn) gene is closely related to aging, but it is still unclear the role of Psn genes in skeletal muscle. Here, the Psn-UAS/Mhc-GAL4 system in Drosophila was used to regulate muscle Psn overexpression(MPO) and muscle Psn knockdown(MPK). Drosophila were subjected to endurance exercise from 4 weeks to 5 weeks old. The results showed that MPO and exercise significantly increased climbing speed, climbing endurance, lifespan, muscle SOD activity, Psn expression, Sirt1 expression, PGC-1α expression, and armadillo (arm) expression in aged Drosophila, and they significantly decreased muscle malondialdehyde levels. Interestingly, when the Psn gene is knockdown by 0.78 times, the PGC-1α expression and arm expression were also down-regulated, but the exercise capacity and lifespan were increased. Furthermore, exercise combined with MPO further improved the exercise capacity and lifespan. MPK combined with exercise further improves the exercise capacity and lifespan. Thus, current results confirmed that the muscle Psn gene was a vital gene that contributed to the healthy aging of skeletal muscle since whether it was overexpressed or knocked down, the aging progress of skeletal muscle structure and function was slowed down by regulating the activity homeostasis of Sirt1/PGC-1α pathway and Psn/arm pathway. Exercise enhanced the function of the Psn gene to delay skeletal muscle aging by up regulating the activity of the Sirt1/PGC-1α pathway and Psn/arm pathway.

SLC25A28 Overexpression Promotes Adipogenesis by Reducing ATGL.

Adipose tissue dysfunction is seen among obese and type 2 diabetic individuals. Adipocyte proliferation and hypertrophy are the root causes of adipose tissue expansion. Solute carrier family 25 member 28 (SLC25A28) is an iron transporter in the inner mitochondrial membrane. This study is aimed at validating the involvement of SLC25A28 in adipose accumulation by tail vein injection of adenovirus (Ad)-SLC25A28 and Ad-green fluorescent protein viral particles into C57BL/6J mice. After 16 weeks, the body weight of the mice was measured. Subsequently, morphological analysis was performed to establish a high-fat diet (HFD)-induced model. SLC25A28 overexpression accelerated lipid accumulation in white and brown adipose tissue (BAT), enhanced body weight, reduced serum triglyceride (TG), and impaired serum glucose tolerance. The protein expression level of lipogenesis, lipolysis, and serum adipose secretion hormone was evaluated by western blotting. The results showed that adipose TG lipase (ATGL) protein expression was reduced significantly in white and BAT after overexpression SLC25A28 compared to the control group. Moreover, SLC25A28 overexpression inhibited the BAT formation by downregulating UCP-1 and the mitochondrial biosynthesis marker PGC-1α. Serum adiponectin protein expression was unregulated, which was consistent with the expression in inguinal white adipose tissue (iWAT). Remarkably, serum fibroblast growth factor (FGF21) protein expression was negatively related to the expansion of adipose tissue after administrated by Ad-SLC25A28. Data from the current study indicate that SLC25A28 overexpression promotes diet-induced obesity and accelerates lipid accumulation by regulating hormone secretion and inhibiting lipolysis in adipose tissue.

Mitochondrial SIRT3 as a protective factor against cyclosporine A-induced nephrotoxicity.

Sirtuin3 (SIRT3), a mitochondrial deacetylase, has been shown to be involved in various kidney diseases. In this study, we aimed to clarify the role of SIRT3 in cyclosporine-induced nephrotoxicity and the associated mitochondrial dysfunction. Madin-Darby canine kidney (MDCK) cells were transfected with Flag-tagged SIRT3 for SIRT3 overexpression or SIRT3 siRNA for the inhibition of SIRT3. Subsequently, the cells were treated with cyclosporine A (CsA) or vehicle. Wild-type and SIRT3 knockout (KO) mice were randomly assigned to receive cyclosporine A or olive oil. Furthermore, SIRT3 activator, honokiol, was treated alongside CsA to wild type mice. Our results revealed that CsA treatment inhibited mitochondrial SIRT3 expression in MDCK cells. Inhibition of SIRT3 through siRNA transfection exacerbated apoptosis, impaired the expression of the AMP-activated protein kinase-peroxisome proliferator-activated receptor gamma coactivator 1 alpha (AMPK-PGC1α) pathway, and worsened mitochondrial dysfunction induced by CsA treatment. Conversely, overexpression of SIRT3 through Flag-tagged SIRT3 transfection ameliorated apoptosis, increased the expression of mitochondrial superoxide dismutase 2, and restored the mitochondrial regulator pathway, AMPK-PGC1α. In SIRT3 KO mice, CsA treatment led to aggravated kidney dysfunction, increased kidney tubular injury, and accumulation of oxidative end products indicative of oxidative stress injury. Meanwhile, SIRT3 activation in vivo significantly mitigated these adverse effects, improving kidney function, reducing oxidative stress markers, and enhancing mitochondrial health following CsA treatment. Overall, our findings suggest that SIRT3 plays a protective role in alleviating mitochondrial dysfunction caused by CsA through the activation of the AMPK-PGC1α pathway, thereby preventing further kidney injury.

Clostridium butyricum upregulates GPR109A/AMPK/PGC-1α and ameliorates acute pancreatitis-associated intestinal barrier injury in mice.

Acute pancreatitis frequently causes intestinal barrier damage, which aggravates pancreatitis. Although Clostridium butyricum exerts anti-inflammatory and protective effects on the intestinal barrier during acute pancreatitis, the underlying mechanism is unclear. The G protein-coupled receptors 109 A (GPR109A) and adenosine monophosphate-activated protein kinase (AMPK)/ peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α) signaling pathways can potentially influence the integrity of the intestinal barrier. Our study generated acute pancreatitis mouse models via intraperitoneal injection of cerulein and lipopolysaccharides. After intervention with Clostridium butyricum, the model mice showed reduced small intestinal and colonic intestinal barrier damage, dysbiosis amelioration, and increased GPR109A/AMPK/PGC-1α expression. In conclusion, Clostridium butyricum could improve pancreatic and intestinal inflammation and pancreatic injury, and relieve acute pancreatitis-induced intestinal barrier damage in the small intestine and colon, which may be associated with GPR109A/AMPK/PGC-1α.

IGF1 promotes human myotube differentiation toward a mature metabolic and contractile phenotype.

Skeletal muscle mediates the beneficial effects of exercise, thereby improving insulin sensitivity and reducing the risk for type 2 diabetes. Current human skeletal muscle models in vitro are incapable of fully recapitulating its physiological functions especially muscle contractility. By supplementation of insulin-like growth factor 1 (IGF1), a growth factor secreted by myofibers in vivo, we aimed to overcome these limitations. We monitored the differentiation process starting from primary human CD56-positive myoblasts in the presence/absence of IGF1 in serum-free medium in daily collected samples for 10 days. IGF1-supported differentiation formed thicker multinucleated myotubes showing physiological contraction upon electrical pulse stimulation (EPS) following day 6. Myotubes without IGF1 were almost incapable of contraction. IGF1 treatment shifted the proteome toward skeletal muscle-specific proteins that contribute to myofibril and sarcomere assembly, striated muscle contraction, and ATP production. Elevated PPARGC1A, MYH7, and reduced MYH1/2 suggest a more oxidative phenotype further demonstrated by higher abundance of proteins of the respiratory chain and elevated mitochondrial respiration. IGF1-treatment also upregulated glucose transporter (GLUT)4 and increased insulin-dependent glucose uptake compared with myotubes differentiated without IGF1. To conclude, addition of IGF1 to serum-free medium significantly improves the differentiation of human myotubes that showed enhanced myofibril formation, response to electrical pulse stimulation, oxidative respiratory capacity, and glucose metabolism overcoming limitations of previous standards. This novel protocol enables investigation of muscular exercise on a molecular level.NEW & NOTEWORTHY Human skeletal muscle models are highly valuable to study how exercise prevents type 2 diabetes without invasive biopsies. Current models did not fully recapitulate the function of skeletal muscle especially during exercise. By supplementing insulin-like growth factor 1 (IGF1), the authors developed a functional human skeletal muscle model characterized by inducible contractility and increased oxidative and insulin-sensitive metabolism. The novel protocol overcomes the limitations of previous standards and enables investigation of exercise on a molecular level.

Salidroside Ameliorates Lung Injury Induced by PM 2.5by Regulating SIRT1-PGC-1α in Mice.

Objective: This study aimed to clarify the intervention effect of salidroside (SAL) on lung injury caused by PM 2.5 in mice and illuminate the function of SIRT1-PGC-1ɑ axis. Methods: Specific pathogen-free (SPF) grade male C57BL/6 mice were randomly assigned to the following groups: control group, SAL group, PM 2.5 group, SAL+PM 2.5 group. On the first day, SAL was given by gavage, and on the second day, PM 2.5 suspension was given by intratracheal instillation. The whole experiment consist of a total of 10 cycles, lasting 20 days. At the end of treatment, blood samples and lung tissues were collected and analyzed. Observation of pathological changes in lung tissue using inverted microscopy and transmission electron microscopy. The expression of inflammatory, antioxidants, apoptosis, and SIRT1-PGC-1ɑ proteins were detected by Western blotting. Results: Exposure to PM 2.5 leads to obvious morphological and pathologica changes in the lung of mice. PM 2.5 caused a decline in levels of antioxidant-related enzymes and protein expressions of HO-1, Nrf2, SOD2, SIRT1 and PGC-1ɑ, and an increase in the protein expressions of IL-6, IL-1ß, Bax, caspase-9 and cleaved caspase-3. However, SAL reversed the aforementioned changes caused by PM 2.5 by activating the SIRT1-PGC-1α pathway. Conclusion: SAL can activate SIRT1-PGC-1ɑ to ameliorate PM 2.5-induced lung injury.

PGC-1α regulates the interplay between oxidative stress, senescence and autophagy in the ageing retina important in age-related macular degeneration.

We previously showed that mice with knockout in the peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PPARGC1A) gene encoding the PGC-1α protein, and nuclear factor erythroid 2 like 2 (NFE2L2) gene, exhibited some features of the age-related macular degeneration (AMD) phenotype. To further explore the mechanism behind the involvement of PGC-1α in AMD pathogenesis we used young (3-month) and old (12-month) mice with knockout in the PPARGC1A gene and age-matched wild-type (WT) animals. An immunohistochemical analysis showed age-dependent different expression of markers of oxidative stress defence, senescence and autophagy in the retinal pigment epithelium of KO animals as compared with their WT counterparts. Multivariate inference testing showed that senescence and autophagy proteins had the greatest impact on the discrimination between KO and WT 3-month animals, but proteins of antioxidant defence also contributed to that discrimination. A bioinformatic analysis showed that PGC-1α might coordinate the interplay between genes encoding proteins involved in antioxidant defence, senescence and autophagy in the ageing retina. These data support importance of PGC-1α in AMD pathogenesis and confirm the utility of mice with PGC-1α knockout as an animal model to study AMD pathogenesis.

Cadmium exposure activates mitophagy through downregulating thyroid hormone receptor/PGC1α signal in preeclampsia.

Gestational cadmium exposure increases the risk of preeclampsia. Placenta mitophagy was activated in preeclampsia. The aim of present study was to explore the mechanism of cadmium-induced mitophagy activation and its association with preeclampsia. Mitophagy markers expression levels were detected by quantitative real-time PCR, Western blot, immunofluorescence and immunochemistry in preeclampsia placenta. JEG3 cells were treated with CdCl2, iopanoic acid (IOP), 3-methyladenine and PGC1α SiRNA to verify mechanism of cadmium-induced mitophagy. Mitophagy marker LC3BII/I and P62 expression were increased and mitochondrial membrane receptor protein TOM20 and FUNDC1 expression were decreased in preeclampsia placenta as compared with that in normotension control. Mitophagy marker LC3BII/I and P62 expression were increased and TOM20 and FUNDC1 expression was decreased in CdCl2-treated JEG3 cells. Meanwhile, mitochondrial biogenesis regulator, PGC1α expression was decreased in preeclampsia and CdCl2-treated JEG3 cells. The expressions of LC3B and P62 were increased and the expressions of TOM20, FUNDC1 and PGC1α were decreased in IOP-treated cell. PGC1α SiRNA transfection led to increased expression of LC3BII/I and P62 and decreased expression of TOM20 and FUNDC1. The expression of sFlt1 was increased in preeclampsia placenta, CdCl2-treated cells, in IOP-treated cells and in PGC1α SiRNA transfected cells. 3-methyladenine treatment protected the increased expression of sFlt1 in CdCl2-treated cells, in IOP-treated cells and in PGC1α SiRNA transfected cells. Meanwhile, co-treatment of cadmium and IOP or PGC1αSiRNA led to a reduce expressions of OPA1, MFN1, MFN2 and FUNDC1 as compared to cadmium-treated, IOP-treated and PGC1α SiRNA-treated cells. These results elucidated that maternal cadmium exposure activated placenta mitophagy through downregulation of thyroid hormone receptor signal mediated decreased expression of PGC1α and was associated with the occurrence of preeclampsia.

[Genetic basis of postoperative cognitive dysfunction]. / Geneticheskie osnovy postoperatsionnoi kognitivnoi disfunktsii.

This review highlights literature data on potential genetic markers that potentially influence the development of postoperative cognitive dysfunction, such as TOMM40, APOE, TREM2, METTL3, PGC1a, HMGB1 and ERMN. The main pathogenetic mechanisms triggered by these genes and leading to the development of cognitive impairment after anesthesia are described. The paper systematizes previously published works that provide evidence of the impact of specific genetic variants on the development of postoperative cognitive dysfunction.

The role of uterus mitochondrial function in high-fat diet-related adverse pregnancy outcomes and protection by resveratrol.

This study elucidates the mechanism of obesity-related adverse pregnancy outcomes and further investigates the effect of resveratrol on reproductive performance in a short- or long-term HFD-induced obese mouse model. Results show that maternal weight had a significant positive correlation with litter mortality in mice. A long-term HFD increased body weight and litter mortality with decreased expression of uterine cytochrome oxidase 4 (COX4), which was recovered by resveratrol in mice. Moreover, HFD decreased the expression of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), nuclear respiratory factors-1 (Nrf-1), and phosphorylated adenosine 5'-monophosphate (AMP)-activated protein kinase (p-AMPK) and increased the expression of phosphorylated extracellular regulated protein kinases (p-ERK) in the uterus. Resveratrol, a polyphenol that can directly bind to the ERK protein, suppressed the phosphorylation of ERK, increased the expression of p-AMPK, PGC-1α and Nrf-1, and decreased litter mortality in mice.

Liraglutide promotes UCP1 expression and lipolysis of adipocytes by promoting the secretion of irisin from skeletal muscle cells.

Although Liraglutide (Lira) increases serum irisin levels in type 2 diabetes mellitus (T2DM), it is unclear whether it induces expression of uncoupling protein 1 (UCP1) of adipocytes via promoting irisin secretion from skeletal muscle. Male T2DM rats were treated with 0.4 mg/kg/d Lira twice a day for 8 weeks, and the protein expression of phosphorylated AMP kinase (p-AMPK), phosphorylated acetyl-CoA carboxylase 1 (p-ACC1) and UCP1 in white adipose tissues were detected. Differentiated C2C12 cells were treated with palmitic acid (PA) and Lira to detect the secretion of irisin. Differentiated 3T3-L1 cells were treated with irisin, supernatant from Lira-treated C2C12 cells, Compound C or siAMPKα1, the triglyceride (TG) content and the related gene expression were measured. The transcriptome in irisin-treated differentiated 3T3-L1 cells was analyzed. Lira elevated serum irisin levels, decreased the adipocyte size and increased the protein expression of UCP1, p-AMPK and p-ACC1 in WAT. Moreover, it promoted the expression of PGC1α and FNDC5, the secretion of irisin in PA-treated differentiated C2C12 cells. The irisin and supernatant decreased TG synthesis and promoted the expression of browning- and lipolysis-related genes in differentiated 3T3-L1 cells. While Compound C and siAMPKα1 blocked AMPK activities and expression, irisin partly reversed the pathway. Finally, the transcriptome analysis indicated that differently expressed genes are mainly involved in browning and lipid metabolism. Overall, our findings showed that Lira modulated muscle-to-adipose signaling pathways in diabetes via irisin-mediated AMPKα/ACC1/UCP1/PPARα pathway. Our results suggest a new mechanism for the treatment of T2DM by Lira.

Inhibition of DAPK3 Suppresses Radiation-Induced Cellular Senescence by Activation of a PGC1α-Dependent Metabolism Pathway in Brain Endothelial Cells.

In the brain, environmental changes, such as neuroinflammation, can induce senescence, characterized by the decreased proliferation of neurons and dendrites and synaptic and vascular damage, resulting in cognitive decline. Senescence promotes neuroinflammatory disorders by senescence-associated secretory phenotypes and reactive oxygen species. In human brain microvascular endothelial cells (HBMVECs), we demonstrate that chronological aging and irradiation increase death-associated protein kinase 3 (DAPK3) expression. To confirm the role of DAPK3 in HBMVEC senescence, we disrupted DAPK3 activity using small interfering RNA (siRNA) or a dominant-negative mutant (DAPK3-P216S), which reduced cellular senescence phenotypes, as assessed by changes in tube formation, senescence-associated beta-galactosidase activity, and cell proliferation. In endothelial cells, DAPK3 promotes cellular senescence by regulating the phosphorylation and inactivation of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC1α) via the protein kinase B pathway, resulting in the decreased expression of mitochondrial metabolism-associated genes, such as ATP5G1, BDNF, and COX5A. Our studies show that DAPK3 is involved in cellular senescence and PGC1α regulation, suggesting that DAPK3 regulation may be important for treating aging-related brain diseases or the response to radiation therapy.

Cholesterol 25-hydroxylase prevents type 2 diabetes mellitus induced cardiomyopathy by alleviating cardiac lipotoxicity.

OBJECTIVES: Diabetic cardiomyopathy (DCM) is the leading cause of mortality in type 2 diabetes mellitus (T2DM) patients, with its underlying mechanisms still elusive. This study aims to investigate the role of cholesterol-25-monooxygenase (CH25H) in T2DM induced cardiomyopathy. METHODS: High fat diet combined with streptozotocin (HFD/STZ) were used to establish a T2DM model. CH25H and its product 25-hydroxycholesterol (25HC) were detected in the hearts of T2DM model. Gain- or loss-of-function of CH25H were performed by receiving AAV9-cTNT-CH25H or CH25H knockout (CH25H-/-) mice with HFD/STZ treatment. Cardiac function was evaluated using echocardiography, and cardiac tissues were collected for immunoblot analysis, histological assessment and quantitative polymerase chain reaction (qPCR). Mitochondrial morphology and function were evaluated using transmission electron microscopy (TEM) and Seahorse XF Cell Mito Stress Test Kit. RNA-sequence analysis was performed to determine the molecular changes associated with CH25H deletion. RESULTS: CH25H and 25HC were significantly decreased in the hearts of T2DM mice. CH25H-/- mice treated with HFD/STZ exhibited impaired mitochondrial function and structure, increased lipid accumulation, and aggregated cardiac dysfunction. Conversely, T2DM mice receiving AAV9-CH25H displayed cardioprotective effects. Mechanistically, RNA sequencing and qPCR analysis revealed that CH25H deficiency decreased peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) and its target gene expression. Additionally, administration of ZLN005, a potent PGC-1α activator, partially protected against high glucose and palmitic acid induced mitochondria dysfunction and lipid accumulation in vitro. CONCLUSION: Our study provides compelling evidence supporting the protective role of CH25H in T2DM-induced cardiomyopathy. Furthermore, the regulation of PGC-1α may be intricately involved in this cardioprotective process.

Tauroursodeoxycholic Acid Mitigates Oxidative Stress and Promotes Differentiation in High Salt-Stimulated Osteoblasts via NOX1 Mediated by PGC-1α.

BACKGROUND: High-salt diet (HSD) is a pivotal risk factor for osteoporosis (OP). Accumulating evidence has supported that tauroursodeoxycholic acid (TUDCA), a naturally produced hydrophilic bile acid, exerts positive effects on the treatment of OP. This study is committed to shedding light on the impacts of TUDCA on high salt-treated osteoblasts and probing into its underlying mechanisms of action. METHODS: Cell counting kit-8 (CCK-8) assay was used to determine the viability of osteoblasts. Alkaline phosphatase (ALP) staining and Alizarin red S (ARS) staining were used to measure osteoblast differentiation. Reverse transcription-quantitative PCR (RT-qPCR) and western blot were used to examine the expression of osteogenic markers. Western blot was also used to analyze the expression of superoxide dismutase-2 (SOD2), peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1α), and NADPH oxidase 1 (NOX1). The production of reactive oxygen species (ROS) was evaluated via dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay. Following PGC-1α knockdown in TUDCA-pretreated osteoblasts exposed to NaCl, the aforementioned functional experiments were implemented again. RESULTS: MC3T3-E1 cell viability was not significantly impacted by increasing concentrations of TUDCA. However, in NaCl-exposed MC3T3-E1 cells, the viability loss, oxidative stress, and decline of differentiation were all dose-dependently obstructed by TUDCA treatment. Moreover, NaCl exposure reduced PGC-1α expression and increased NOX1 expression, which was then reversed by TUDCA. PGC-1α deletion partially abolished the effects of TUDCA on PGC-1α and NOX1, differentiation, and oxidative stress in NaCl-treated osteoblasts. CONCLUSIONS: TUDCA might protect against high salt-induced OP via modulation of NOX1 mediated by PGC-1α.

ZLN005 alleviates PBDE-47 induced impairment of mitochondrial translation and neurotoxicity through PGC-1α/ERRα axis.

Recent studies are identified the mitochondria as critical targets of 2, 2', 4, 4'-tetrabromodiphenyl ether (PBDE-47) induced neurotoxicity. This study aimed at examining the impact of PBDE-47 exposure on mitochondrial translation, and its subsequent effect on PBDE-47 neurotoxicity. The Sprague-Dawley (SD) rat model and neuroendocrine pheochromocytoma (PC12) cells were adopted for the measurements of mitochondrial ATP levels, mitochondrial translation products, and expressions of important mitochondrial regulators, such as required meiotic nuclear division 1 (RMND1), estrogen-related receptor α (ERRα), and peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α). To delve into the role of PGC-1α/ERRα axis in mitochondrial translation, 2-(4-tert-butylphenyl) benzimidazole (ZLN005) was employed. Both cellular and animal model results shown that PBDE-47 impeded PGC-1α/ERRα axis and mitochondrial translation. PBDE-47 suppressed mitochondrial function in rat hippocampus and PC12 cells by decreasing relative mitochondrial DNA (mtDNA) content, mitochondrial translation products, and mitochondrial ATP levels. Particularly, ZLN005 reversed PBDE-47 neurotoxicity by enhancing mitochondrial translation through activation of PGC-1α/ERRα axis, yet suppressing PGC-1α with siRNA attenuates its neuroprotective effect in vitro. In conclusion, this work highlights the importance of mitochondrial translation in PBDE-47 neurotoxicity by presenting results from cellular and animal models and suggests a potential therapeutic approach through activation of PGC-1α/ERRα axis. ENVIRONMENTAL IMPLICATION: PBDEs have attracted extensive attention because of their high lipophilicity, persistence, and detection levels in various environmental media. Increasing evidence has shown that neurodevelopmental disorders in children are associated with PBDE exposure. Several studies have also found that perinatal PBDE exposure can cause long-lasting neurobehavioral abnormalities in experimental animals. Our recent studies have also demonstrated the impact of PBDE-47 exposure on mitochondrial biogenesis and dynamics, leading to memory and neurobehavioral deficits. Therefore, we explore whether the pathological mechanism of PBDE-47-induced neurotoxicity involves the regulation of mitochondrial translation through the PGC-1α/ERRα axis.

Butyrate promotes kidney resilience through a coordinated kidney protective response in tubular cells.

Acute kidney injury (AKI) is common in hospitalized patients and increases short-term and long-term mortality. Treatment options for AKI are limited. Gut microbiota products such as the short-chain fatty acid butyrate have anti-inflammatory actions that may protect tissues, including the kidney, from injury. However, the molecular mechanisms of tissue protection by butyrate are poorly understood. Treatment with oral butyrate for two weeks prior to folic acid-induced AKI and during AKI improved kidney function and decreased tubular injury and kidney inflammation while stopping butyrate before AKI was not protective. Continuous butyrate preserved the expression of kidney protective factors such as Klotho, PGC-1α and Nlrp6 which were otherwise downregulated. In cultured tubular cells, butyrate blunted the maladaptive tubular cell response to a proinflammatory milieu, preserving the expression of kidney protective factors. Kidney protection afforded by this continuous butyrate schedule was confirmed in a second model of nephrotoxic AKI, cisplatin nephrotoxicity, where the expression of kidney protective factors was also preserved. To assess the contribution of preservation of kidney protective factors to kidney resilience, recombinant Klotho was administered to mice with cisplatin-AKI and shown to preserve the expression of PGC-1α and Nlrp6, decrease kidney inflammation and protect from AKI. In conclusion, butyrate promotes kidney resilience to AKI and decreases inflammation by preventing the downregulation of kidney protective genes such as Klotho. This information may be relevant to optimize antibiotic management during hospitalization.

Integrin αvß3 Upregulation in Response to Nutrient Stress Promotes Lung Cancer Cell Metabolic Plasticity.

Cancer stem/tumor-initiating cells display stress tolerance and metabolic flexibility to survive in a harsh environment with limited nutrient and oxygen availability. The molecular mechanisms underlying this phenomenon could provide targets to prevent metabolic adaptation and halt cancer progression. Here, we showed in cultured cells and live human surgical biopsies of non-small cell lung cancer that nutrient stress drives the expression of the epithelial cancer stem cell marker integrin αvß3 via upregulation of the ß3 subunit, resulting in a metabolic reprogramming cascade that allows tumor cells to thrive despite a nutrient-limiting environment. Although nutrient deprivation is known to promote acute, yet transient, activation of the stress sensor AMP-activated protein kinase (AMPK), stress-induced αvß3 expression via Src activation unexpectedly led to secondary and sustained AMPK activation. This resulted in the nuclear localization of peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC1α) and upregulation of glutamine metabolism, the tricarboxylic acid cycle, and oxidative phosphorylation. Pharmacological or genetic targeting of this axis prevented lung cancer cells from evading the effects of nutrient stress, thereby blocking tumor initiation in mice following orthotopic implantation of lung cancer cells. These findings reveal a molecular pathway driven by nutrient stress that results in cancer stem cell reprogramming to promote metabolic flexibility and tumor initiation. SIGNIFICANCE: Upregulation of integrin αvß3, a cancer stem cell marker, in response to nutrient stress activates sustained AMPK/PGC1α signaling that induces metabolic reprogramming in lung cancer cells to support their survival. See related commentary by Rainero, p. 1543.

Neuronal innervation regulates the secretion of neurotrophic myokines and exosomes from skeletal muscle.

Myokines and exosomes, originating from skeletal muscle, are shown to play a significant role in maintaining brain homeostasis. While exercise has been reported to promote muscle secretion, little is known about the effects of neuronal innervation and activity on the yield and molecular composition of biologically active molecules from muscle. As neuromuscular diseases and disabilities associated with denervation impact muscle metabolism, we hypothesize that neuronal innervation and firing may play a pivotal role in regulating secretion activities of skeletal muscles. We examined this hypothesis using an engineered neuromuscular tissue model consisting of skeletal muscles innervated by motor neurons. The innervated muscles displayed elevated expression of mRNAs encoding neurotrophic myokines, such as interleukin-6, brain-derived neurotrophic factor, and FDNC5, as well as the mRNA of peroxisome-proliferator-activated receptor γ coactivator 1α, a key regulator of muscle metabolism. Upon glutamate stimulation, the innervated muscles secreted higher levels of irisin and exosomes containing more diverse neurotrophic microRNAs than neuron-free muscles. Consequently, biological factors secreted by innervated muscles enhanced branching, axonal transport, and, ultimately, spontaneous network activities of primary hippocampal neurons in vitro. Overall, these results reveal the importance of neuronal innervation in modulating muscle-derived factors that promote neuronal function and suggest that the engineered neuromuscular tissue model holds significant promise as a platform for producing neurotrophic molecules.

Electroacupuncture improves peripheral neuropathy by up-regulating Sirt1/PGC-1α/TFAM pathway in type 2 diabetes rats with peripheral neuropathy. / 基于Sirt1/PGC-1α/TFAM通路探讨电针治疗2åž‹ç³–å°¿ç— å‘¨å›´ç¥žç»ç— å˜çš„æœºåˆ¶.

OBJECTIVES: To observe the effect of electroacupuncture (EA) on activation of silent information regulator 1 (Sirt1)/peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α)/mitochondrial transcription factor A (TFAM) pathway in type 2 diabetes (T2DM) rats with peripheral neuropathy (DPN) , so as to explore its possible mechanisms underlying improvement of DPN. METHODS: Thirty male SD rats were randomly divided into blank control group (n=8) and DPN model group (n=22) which were further divided into model group (n=8) and EA group (n=8) after successful modeling. The model of T2DM was established by high-fat diet and low-dose intraperitoneal injection of streptozocin (35 mg/kg). For rats of the EA group (anesthetized with isoflurane), EA stimulation (2 Hz/15 Hz, 2 mA) was applied to "Tianshu"(ST25) for 20 min, once daily, 6 times a week for 6 weeks. The blood glucose level, body weight, area under curve (AUC) of glucose tolerance test, and hind-paw mechanical pain threshold and thermal pain threshold were observed. The intra-epidermal nerve fiber density (IENFD) of the hind-foot pad was observed by immunofluorescence staining. The motor nerve conduction velocity (MNCV) of the sciatic nerve was measured by using electrophysiological method. H.E. staining was used to observe the histopathological changes of the sciatic nerve after modeling. Transmission electron microscopy (TEM) was used to observe the ultrastructural changes of the sciatic nerve. The protein expressions of energy-related Sirt1, PGC-1α and TFAM in the sciatic nerve was detected by Western blot. RESULTS: Compared with the blank control group, the model group had a higher blood glucose contents and AUC (P<0.001), a slower MNCV (P<0.01), and a decrease in the body weight and in the mechanical and thermal pain thresholds (P<0.001) and IENFD (P<0.001), and in the expression levels of Sirt1, PGC-1α and TFAM (P<0.05, P<0.01). In contrast to the model group, the EA group had a decrease in the blood glucose contents and AUC (P<0.05, P<0.01), and an increase in mechanical and thermal pain thresholds, MNCV, IENFD, and expression levels of Sirt1, PGC-1α and TFAM proteins (P<0.01, P<0.05). In addition, results of histopathological and ultrastructural changes of the sciatic nerve showed more fragmented and disordered distribution of axons on the transverse section, and extensive separation of myelin and axons, uneven myelin thickness, axonal degeneration and irregular shape in the model group, whereas in the EA group, the axons on the transverse section were relatively more dense and more complete, the myelin sheath of the sciatic nerve was relatively uniform, and the axonal shape was relatively regular with relatively milder lesions. CONCLUSIONS: EA up-regulates the expressions of Sirt1, PGC-1α, TFAM in T2DM rats with DPN, which may be associated with its functions in improving and repairing the injured peripheral nerves in rats with DPN.

Mitochondrial damage and clearance in retinal pigment epithelial cells.

Age-related macular degeneration (AMD) is a devastating eye disease that causes permanent vision loss in the central part of the retina, known as the macula. Patients with such severe visual loss face a reduced quality of life and are at a 1.5 times greater risk of death compared to the general population. Currently, there is no cure for or effective treatment for dry AMD. There are several mechanisms thought to underlie the disease, for example, ageing-associated chronic oxidative stress, mitochondrial damage, harmful protein aggregation and inflammation. As a way of gaining a better understanding of the molecular mechanisms behind AMD and thus developing new therapies, we have created a peroxisome proliferator-activated receptor gamma coactivator 1-alpha and nuclear factor erythroid 2-related factor 2 (PGC1α/NFE2L2) double-knockout (dKO) mouse model that mimics many of the clinical features of dry AMD, including elevated levels of oxidative stress markers, damaged mitochondria, accumulating lysosomal lipofuscin and extracellular drusen-like structures in retinal pigment epithelial cells (RPE). In addition, a human RPE cell-based model was established to examine the impact of non-functional intracellular clearance systems on inflammasome activation. In this study, we found that there was a disturbance in the autolysosomal machinery responsible for clearing mitochondria in the RPE cells of one-year-old PGC1α/NFE2L2-deficient mice. The confocal immunohistochemical analysis revealed an increase in autophagosome marker microtubule-associated proteins 1A/1B light chain 3B (LC3B) as well as multiple mitophagy markers such as PTE-induced putative kinase 1 (PINK1) and E3 ubiquitin ligase (PARKIN), along with signs of damaged mitochondria. However, no increase in autolysosome formation was detected, nor was there a colocalization of the lysosomal marker LAMP2 or the mitochondrial marker, ATP synthase ß. There was an upregulation of late autolysosomal fusion Ras-related protein (Rab7) in the perinuclear space of RPE cells, together with autofluorescent aggregates. Additionally, we observed an increase in the numbers of Toll-like receptors 3 and 9, while those of NOD-like receptor 3 were decreased in PGC1α/NFE2L2 dKO retinal specimens compared to wild-type animals. There was a trend towards increased complement component C5a and increased involvement of the serine protease enzyme, thrombin, in enhancing the terminal pathway producing C5a, independent of C3. The levels of primary acute phase C-reactive protein and receptor for advanced glycation end products were also increased in the PGC1α/NFE2L2 dKO retina. Furthermore, selective proteasome inhibition with epoxomicin promoted both nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and mitochondrial-mediated oxidative stress, leading to the release of mitochondrial DNA to the cytosol, resulting in potassium efflux-dependent activation of the absent in melanoma 2 (AIM2) inflammasome and the subsequent secretion of interleukin-1ß in ARPE-19 cells. In conclusion, the data suggest that there is at least a relative decrease in mitophagy, increases in the amounts of C5 and thrombin and decreased C3 levels in this dry AMD-like model. Moreover, selective proteasome inhibition evoked mitochondrial damage and AIM2 inflammasome activation in ARPE-19 cells.