RESUMO
Skeletal muscle atrophy, characterized by diminished muscle strength and mass, arises from various causes, including malnutrition, aging, nerve damage, and disease-related secondary atrophy. Aging markedly escalates the prevalence of sarcopenia. Concurrently, the incidence of muscle atrophy significantly rises among patients with chronic ailments such as heart failure, diabetes, and chronic obstructive pulmonary disease (COPD). Epigenetics plays a pivotal role in skeletal muscle atrophy. Aging elevates methylation levels in the promoter regions of specific genes within muscle tissues. This aberrant methylation is similarly observed in conditions like diabetes, neurological disorders, and cardiovascular diseases. This study aims to explore the relationship between epigenetics and skeletal muscle atrophy, thereby enhancing the understanding of its pathogenesis and uncovering novel therapeutic strategies.
Assuntos
Metilação de DNA , Epigênese Genética , Músculo Esquelético , Atrofia Muscular , Humanos , Atrofia Muscular/genética , Atrofia Muscular/patologia , Atrofia Muscular/metabolismo , Músculo Esquelético/patologia , Músculo Esquelético/metabolismo , Animais , Envelhecimento/genética , Envelhecimento/patologiaRESUMO
Our recent studies have identified p21-activated kinase 4 (PAK4) as a key regulator of lipid catabolism in the liver and adipose tissue, but its role in glucose homeostasis in skeletal muscle remains to be explored. In this study, we find that PAK4 levels are highly upregulated in the skeletal muscles of diabetic humans and mice. Skeletal muscle-specific Pak4 ablation or administering the PAK4 inhibitor in diet-induced obese mice retains insulin sensitivity, accompanied by AMPK activation and GLUT4 upregulation. We demonstrate that PAK4 promotes insulin resistance by phosphorylating AMPKα2 at Ser491, thereby inhibiting AMPK activity. We additionally show that skeletal muscle-specific expression of a phospho-mimetic mutant AMPKα2S491D impairs glucose tolerance, while the phospho-inactive mutant AMPKα2S491A improves it. In summary, our findings suggest that targeting skeletal muscle PAK4 may offer a therapeutic avenue for type 2 diabetes.
Assuntos
Proteínas Quinases Ativadas por AMP , Diabetes Mellitus Tipo 2 , Glucose , Resistência à Insulina , Músculo Esquelético , Quinases Ativadas por p21 , Animais , Quinases Ativadas por p21/metabolismo , Quinases Ativadas por p21/genética , Glucose/metabolismo , Fosforilação , Músculo Esquelético/metabolismo , Proteínas Quinases Ativadas por AMP/metabolismo , Humanos , Camundongos , Diabetes Mellitus Tipo 2/metabolismo , Masculino , Transportador de Glucose Tipo 4/metabolismo , Transportador de Glucose Tipo 4/genética , Camundongos Endogâmicos C57BL , Camundongos Knockout , Obesidade/metabolismoRESUMO
Skeletal disorders, including fractures, osteoporosis, osteoarthritis, rheumatoid arthritis, and spinal degenerative conditions, along with associated spinal cord injuries, significantly impair daily life and impose a substantial burden. Many of these conditions are notably linked to inflammation, with some classified as inflammatory diseases. Pyroptosis, a newly recognized form of inflammatory cell death, is primarily triggered by inflammasomes and executed by caspases, leading to inflammation and cell death through gasdermin proteins. Emerging research underscores the pivotal role of pyroptosis in skeletal disorders. This review explores the pyroptosis signaling pathways and their involvement in skeletal diseases, the modulation of pyroptosis by other signals in these conditions, and the current evidence supporting the therapeutic potential of targeting pyroptosis in treating skeletal disorders, aiming to offer novel insights for their management.
Assuntos
Inflamassomos , Piroptose , Humanos , Piroptose/efeitos dos fármacos , Animais , Inflamassomos/metabolismo , Inflamação/metabolismo , Inflamação/patologia , Inflamação/tratamento farmacológico , Transdução de Sinais/efeitos dos fármacos , Doenças Ósseas/metabolismo , Doenças Ósseas/patologia , Doenças Ósseas/terapia , Morte CelularRESUMO
Adipose tissue lipolysis is mediated by cAMP-protein kinase A (PKA)-dependent intracellular signalling. Here, we show that PKA targets p21-activated kinase 4 (PAK4), leading to its protein degradation. Adipose tissue-specific overexpression of PAK4 in mice attenuates lipolysis and exacerbates diet-induced obesity. Conversely, adipose tissue-specific knockout of Pak4 or the administration of a PAK4 inhibitor in mice ameliorates diet-induced obesity and insulin resistance while enhancing lipolysis. Pak4 knockout also increases energy expenditure and adipose tissue browning activity. Mechanistically, PAK4 directly phosphorylates fatty acid-binding protein 4 (FABP4) at T126 and hormone-sensitive lipase (HSL) at S565, impairing their interaction and thereby inhibiting lipolysis. Levels of PAK4 and the phosphorylation of FABP4-T126 and HSL-S565 are enhanced in the visceral fat of individuals with obesity compared to their lean counterparts. In summary, we have uncovered an important role for FABP4 phosphorylation in regulating adipose tissue lipolysis, and PAK4 inhibition may offer a therapeutic strategy for the treatment of obesity.
Assuntos
Lipólise , Esterol Esterase , Animais , Camundongos , Proteínas de Ligação a Ácido Graxo/genética , Proteínas de Ligação a Ácido Graxo/metabolismo , Lipólise/fisiologia , Obesidade/metabolismo , Quinases Ativadas por p21/genética , Quinases Ativadas por p21/metabolismo , Esterol Esterase/genética , Esterol Esterase/metabolismoRESUMO
SCOPE: Cannabidiol (CBD), the most abundant non-psychoactive constituent of the plant Cannabis sativa, is known to possess immune modulatory properties. This study investigates the effects of CBD on mast cell degranulation in human and mouse primary mast cells and passive cutaneous anaphylaxis in mice. METHODS AND RESULTS: Mouse bone marrow-derived mast cells and human cord-blood derived mast cells are generated. CBD suppressed antigen-stimulated mast cell degranulation in a concentration-dependent manner. Mechanistically, CBD inhibited both the phosphorylation of FcεRI downstream signaling molecules and calcium mobilization in mast cells, while exerting no effect on FcεRI expression and IgE binding to FcεRI. These suppressive effects are preserved in the mast cells that are depleted of type 1 (CB1) and type 2 (CB2) cannabinoid receptors, as well as in the presence of CB1 agonist, CB2 agonist, CB1 inverse agonist, and CB2 inverse agonist. CBD also inhibited the development of mast cells in a long-term culture. The intraperitoneal administration of CBD suppressed passive cutaneous anaphylaxis in mice as evidenced by a reduction in ear swelling and decrease in the number of degranulated mast cells. CONCLUSION: Based on these results, the administration of CBD is a new therapeutic intervention in mast cell-associated anaphylactic diseases.
Assuntos
Anafilaxia , Canabidiol , Camundongos , Humanos , Animais , Anafilaxia/tratamento farmacológico , Mastócitos , Canabidiol/farmacologia , Canabidiol/metabolismo , Degranulação Celular , Agonismo Inverso de Drogas , Imunoglobulina E/metabolismo , Receptores de IgE/metabolismoRESUMO
PPARα corepressor NCoR1 is a key regulator of fatty acid ß-oxidation and ketogenesis. However, its regulatory mechanism is largely unknown. Here, we report that oncoprotein p21-activated kinase 4 (PAK4) is an NCoR1 kinase. Specifically, PAK4 phosphorylates NCoR1 at T1619/T2124, resulting in an increase in its nuclear localization and interaction with PPARα, thereby repressing the transcriptional activity of PPARα. We observe impaired ketogenesis and increases in PAK4 protein and NCoR1 phosphorylation levels in liver tissues of high fat diet-fed mice, NAFLD patients, and hepatocellular carcinoma patients. Forced overexpression of PAK4 in mice represses ketogenesis and thereby increases hepatic fat accumulation, whereas genetic ablation or pharmacological inhibition of PAK4 exhibites an opposite phenotype. Interestingly, PAK4 protein levels are significantly suppressed by fasting, largely through either cAMP/PKA- or Sirt1-mediated ubiquitination and proteasome degradation. In this way, our findings provide evidence for a PAK4-NCoR1/PPARα signaling pathway that regulates fatty acid ß-oxidation and ketogenesis.
Assuntos
Ácidos Graxos , PPAR alfa , Quinases Ativadas por p21 , Animais , Camundongos , Proteínas Correpressoras , Ácidos Graxos/metabolismo , Quinases Ativadas por p21/genética , PPAR alfa/genética , Correpressor 1 de Receptor Nuclear/genética , Humanos , Fosforilação , Transdução de SinaisRESUMO
Adipose tissue (AT) inflammation is strongly associated with obesity-induced insulin resistance. When subjected to metabolic stress, adipocytes become inflamed and secrete a plethora of cytokines and chemokines, which recruit circulating immune cells to AT. Although sirtuin 6 (Sirt6) is known to control genomic stabilization, aging, and cellular metabolism, it is now understood to also play a pivotal role in the regulation of AT inflammation. Sirt6 protein levels are reduced in the AT of obese humans and animals and increased by weight loss. In this review, we summarize the potential mechanism of AT inflammation caused by impaired action of Sirt6 from the immune cells' point of view. We first describe the properties and functions of immune cells in obese AT, with an emphasis on discrete macrophage subpopulations which are central to AT inflammation. We then highlight data that links Sirt6 to functional phenotypes of AT inflammation. Importantly, we discuss in detail the effects of Sirt6 deficiency in adipocytes, macrophages, and eosinophils on insulin resistance or AT browning. In our closing perspectives, we discuss emerging issues in this field that require further investigation.
Assuntos
Resistência à Insulina , Sirtuínas , Animais , Humanos , Resistência à Insulina/fisiologia , Tecido Adiposo , Inflamação/metabolismo , Obesidade/metabolismo , Sirtuínas/metabolismoRESUMO
Prostate cancer (PCa) is the most commonly diagnosed genital cancer in men worldwide. Around 80% of the patients who developed advanced PCa suffered from bone metastasis, with a sharp drop in the survival rate. Despite great efforts, the detailed mechanisms underlying castration-resistant PCa (CRPC) remain unclear. Sirtuin 5 (SIRT5), an NAD+-dependent desuccinylase, is hypothesized to be a key regulator of various cancers. However, compared to other SIRTs, the role of SIRT5 in cancer has not been extensively studied. Here, we revealed significantly decreased SIRT5 levels in aggressive PCa cells relative to the PCa stages. The correlation between the decrease in the SIRT5 level and the patient's reduced survival rate was also confirmed. Using quantitative global succinylome analysis, we characterized a significant increase in the succinylation at lysine 118 (K118su) of lactate dehydrogenase A (LDHA), which plays a role in increasing LDH activity. As a substrate of SIRT5, LDHA-K118su significantly increased the migration and invasion of PCa cells and LDH activity in PCa patients. This study reveals the reduction of SIRT5 protein expression and LDHA-K118su as a novel mechanism involved in PCa progression, which could serve as a new target to prevent CPRC progression for PCa treatment.
Assuntos
Neoplasias da Próstata , Sirtuínas , Humanos , Masculino , Lactato Desidrogenase 5 , Neoplasias da Próstata/genética , Neoplasias da Próstata/metabolismo , Sirtuínas/genética , Sirtuínas/química , Sirtuínas/metabolismoRESUMO
The purpose of this study was to examine whether Limonium tetragonum, cultivated in a smart-farming system with LED lamps, could increase exercise capacity in mice. C57BL/6 male mice were orally administered vehicle or Limonium tetragonum water extract (LTE), either 30 or 100 mg/kg, and were subjected to moderate intensity treadmill exercise for 4 weeks. Running distance markedly increased in the LTE group (100 mg/kg) by 80 ± 4% compared to the vehicle group, which was accompanied by a higher proportion of oxidative fibers (6 ± 6% vs. 10 ± 4%). Mitochondrial DNA content and gene expressions related to mitochondrial biogenesis were significantly increased in LTE-supplemented gastrocnemius muscles. At the molecular level, the expression of PGC-1α, a master regulator of fast-to-slow fiber-type transition, was increased downstream of the PKA/CREB signaling pathway. LTE induction of the PKA/CREB signaling pathway was also observed in C2C12 cells, which was effectively suppressed by PKA inhibitors H89 and Rp-cAMP. Altogether, these findings indicate that LTE treatment enhanced endurance exercise capacity via an improvement in mitochondrial biosynthesis and the increases in the formation of oxidative slow-twitch fibers. Future study is warranted to validate the exercise-enhancing effect of LTE in the human.
Assuntos
Condicionamento Físico Animal , Extratos Vegetais , Plumbaginaceae , Corrida , Animais , DNA Mitocondrial/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Músculo Esquelético/metabolismo , Biogênese de Organelas , Estresse Oxidativo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/genética , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Condicionamento Físico Animal/fisiologia , Resistência Física , Extratos Vegetais/farmacologia , Plumbaginaceae/químicaRESUMO
Switching myofibers from the fast-glycolytic type to the slow-oxidative type is associated with an alleviation of the symptoms associated with various cardiometabolic diseases. This study investigates the effect of Vitis vinifera Jingzaojing leaf and shoot extract (JLSE), which is rich in phenolic compounds, on the regulation of skeletal muscle fiber-type switching, as well as the associated underlying mechanism. Male C57BL/6N mice were supplemented orally with vehicle or JLSE (300 mg/kg) and subjected to treadmill exercise training. After four weeks, mice in the JLSE-supplemented group showed significantly improved exercise endurance and mitochondrial oxidative capacity. JLSE supplementation increased the expression of sirtuin 6 and decreased Sox6 expression, thereby elevating the number of mitochondria and encouraging fast-to-slow myofiber switching. The results of our experiments suggest that JLSE supplementation reprograms myofiber composition to favor the slow oxidative type, ultimately enhancing exercise endurance.
Assuntos
Condicionamento Físico Animal , Sirtuínas , Vitis , Animais , Suplementos Nutricionais , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Músculo Esquelético/metabolismo , Condicionamento Físico Animal/fisiologia , Resistência Física/fisiologia , Folhas de Planta , Sirtuínas/metabolismoRESUMO
p21-Activated kinase 4 (PAK4), one of the serine/threonine kinases activated by Rho-family GTPases, has been widely studied as an oncogenic protein that is overexpressed in many types of cancers. In our recent study, PAK4 upregulation was observed in mice exhibiting hepatic ischaemia-reperfusion (I/R) and in liver transplantation patients. Liver I/R injury was also attenuated in Pak4 KO mice. Herein, we report a novel series of pyrazolo[3,4-d]pyrimidine derivatives of type I ½ PAK4 inhibitors. The most potent compound SPA7012 was evaluated to determine the pharmacological potential of PAK4 inhibitor in I/R injury in mice. Mice with I/R injury showed typical patterns of liver damage, as demonstrated by increases in serum levels of aminotransferases and proinflammatory cytokines, hepatocellular necrosis and apoptosis, and inflammatory cell infiltration, relative to sham mice. Conversely, intraperitoneal administration of SPA7012 dramatically attenuated biochemical and histopathologic changes. Mechanistically, stabilisation of nuclear factor-erythroid 2-related factor 2 (Nrf2), a master regulator of anti-oxidative response, was observed following SPA7012 treatment. SPA7012 treatment in primary hepatocytes also attenuated hypoxia-reoxygenation-induced apoptotic cell death and inflammation. Together, these results provide experimental evidence supporting the use of PAK4 inhibitors for alleviation of I/R-induced liver damage.
Assuntos
Traumatismo por Reperfusão , Quinases Ativadas por p21 , Animais , Apoptose , Fígado/metabolismo , Camundongos , Proteínas Serina-Treonina Quinases , Pirimidinas/farmacologia , Traumatismo por Reperfusão/tratamento farmacológico , Traumatismo por Reperfusão/metabolismo , Quinases Ativadas por p21/metabolismoRESUMO
Cholestatic liver disease, or cholestasis, is a condition characterized by liver inflammation and fibrosis following a bile duct obstruction and an intrahepatic accumulation of bile acids. Inhibiting inflammation is a promising therapeutic strategy for cholestatic liver diseases. Acer tegmentosum Maxim extract (ATE) is best known for its anti-inflammatory and antioxidative properties. In this study, we investigated the effects of ATE on liver injury and fibrosis in mice with bile duct ligation (BDL)-induced cholestasis through analysis of gene expression, cytokines, and histological examination. Oral administration of ATE (20 or 50 mg/kg) for 14 days significantly attenuated hepatocellular necrosis compared to vehicle-treated BDL mice, which was accompanied by the reduced level of serum bile acids and bilirubin. We determined that ATE treatment reduced liver inflammation, oxidative stress, and fibrosis. These beneficial effects of ATE were concurrent with the decreased expression of genes involved in the NF-κB pathway, suggesting that the anti-inflammatory effect of ATE could be a possible mechanism against cholestasis-associated liver injury. Our findings substantiate ATE's role as an alternative therapeutic agent for cholestasis-induced liver injury and fibrosis.
Assuntos
Acer , Colestase , Hepatite , Animais , Anti-Inflamatórios/metabolismo , Anti-Inflamatórios/farmacologia , Anti-Inflamatórios/uso terapêutico , Ácidos e Sais Biliares/metabolismo , Ácidos e Sais Biliares/farmacologia , Ácidos e Sais Biliares/uso terapêutico , Ductos Biliares/metabolismo , Ductos Biliares/cirurgia , Colestase/tratamento farmacológico , Colestase/metabolismo , Colestase/patologia , Fibrose , Hepatite/complicações , Hepatite/tratamento farmacológico , Hepatite/patologia , Inflamação/tratamento farmacológico , Fígado/metabolismo , Cirrose Hepática/tratamento farmacológico , Cirrose Hepática/etiologia , Camundongos , Extratos Vegetais/farmacologiaRESUMO
Nicotinamide adenine dinucleotide (NAD+) acts as a cofactor for multiple biological processes. While previous research has revealed that the NAD+ declines associated with aging contributes to an impairment of immune cells, its role in mast cell function, especially in response to an anaphylactic condition, has remained unexplored. We tested whether the restoration of cellular NAD+ concentration by the supplementation of NAD+ boosting molecules prevented mast cell degranulation and anaphylactic responses. Methods: Bone marrow derived mast cells (BMMCs) and human cord blood derived mast cells were treated with NAD+ precursors nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR), and FcεRI downstream signaling was assessed. Animal models of passive systemic anaphylaxis (PSA) and passive cutaneous anaphylaxis (PCA) were used to investigate the effects of NAD+ precursors in the anaphylactic responses of mice. Results: Treatment of murine BMMCs and human cord blood derived mast cells with NAD+ precursors repressed intracellular signaling downstream of FcεRI, as well as the release of inflammatory cytokines and lipid mediators. The intraperitoneal administration of NMN or NR also markedly attenuated IgE-mediated anaphylactic responses in mouse models of PSA and PCA. These beneficial effects of NAD+ precursors, however, were attenuated in mast cell-specific Sirt6 knockout mice, indicating a Sirt6 dependency for their action. Conclusion: NAD+ precursors may serve as an effective therapeutic strategy that limits mast cell-mediated anaphylactic responses.
Assuntos
Anafilaxia , Sirtuínas , Anafilaxia/tratamento farmacológico , Animais , Degranulação Celular , Humanos , Masculino , Mastócitos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , NAD , Antígeno Prostático Específico , Sirtuínas/farmacologiaRESUMO
Although multiple studies have shown that Angelica keiskei of the Umbelliferae family has potent anti-inflammatory and antioxidative activities and that it reduces the serum bile acids in humans, whether A. keiskei has protective effects against cholestasis-induced liver injury remains unexplored until now. This study tests the hypothesis that Angelica keiskei root extract (AKE) alleviates liver injury, inflammation, and fibrosis in mouse models of acute cholestasis induced by bile duct ligation (BDL). Oral administration of AKE (200 or 500 mg/kg) attenuated hepatocellular necrosis and significantly reduced serum levels of bile acids and bilirubin in BDL mice. The critical enzyme of bile acid synthesis, CYP7A1, was repressed by AKE, suggesting that reduced bile acid production may contribute to liver protection. Moreover, we determined through gene expression and cytokine analysis and histological examination that AKE treatment decreased liver inflammation, oxidative stress, and fibrosis. AKE also suppressed the NF-κB pathway, suggesting this as a possible mediator of its anti-inflammatory effect. Our findings substantiate that AKE may be promising for treating cholestatic liver diseases in the future.
Assuntos
Angelica , Doença Hepática Crônica Induzida por Substâncias e Drogas , Colestase , Animais , Anti-Inflamatórios/metabolismo , Anti-Inflamatórios/farmacologia , Anti-Inflamatórios/uso terapêutico , Ácidos e Sais Biliares/metabolismo , Ácidos e Sais Biliares/farmacologia , Ácidos e Sais Biliares/uso terapêutico , Ductos Biliares/metabolismo , Ductos Biliares/cirurgia , Colestase/tratamento farmacológico , Colestase/metabolismo , Colestase/patologia , Fibrose , Inflamação/metabolismo , Fígado/metabolismo , Camundongos , Extratos Vegetais/uso terapêuticoRESUMO
Expanding the exercise capacity of skeletal muscle is an emerging strategy to combat obesity-related metabolic diseases and this can be achieved by shifting skeletal muscle fibers toward slow-twitch oxidative type. Here, we report that Sirt6, an anti-aging histone deacetylase, is critical in regulating myofiber configuration toward oxidative type and that Sirt6 activator can be an exercise mimetic. Genetic inactivation of Sirt6 in skeletal muscle reduced while its transgenic overexpression increased mitochondrial oxidative capacity and exercise performance in mice. Mechanistically, we show that Sirt6 downregulated Sox6, a key repressor of slow fiber specific gene, by increasing the transcription of CREB. Sirt6 expression is elevated in chronically exercised humans, and mice treated with an activator of Sirt6 showed an increase in exercise endurance as compared to exercise-trained controls. Thus, the current study identifies Sirt6 as a molecular target for reprogramming myofiber composition toward the oxidative type and for improving muscle performance.
Assuntos
Músculo Esquelético , Sirtuínas , Animais , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico , Camundongos , Mitocôndrias/metabolismo , Fibras Musculares Esqueléticas/metabolismo , Músculo Esquelético/metabolismo , Oxirredução , Estresse Oxidativo , Fatores de Transcrição SOXD , Sirtuínas/genética , Sirtuínas/metabolismoRESUMO
Alcoholic liver disease is the major cause of chronic liver diseases. Excessive alcohol intake results in endoplasmic reticulum (ER) stress. ERdj5, a member of DNAJ family, is an ER-resident chaperone protein, whose role in alcoholic liver disease remains to be investigated. In this study, we aim to address the effect of ERdj5 on alcoholic liver disease and the underlying mechanism. Hepatic Dnajc10 (ERdj5) mRNA expression was elevated in both human and mouse alcoholic hepatitis. In mice subjected to chronic and binge ethanol feeding, ERdj5 levels were also markedly increased. Hepatic Dnajc10 correlated with Xbp1s mRNA. Tunicamycin, an ER stress inducer, increased ERdj5 levels. Dnajc10 knockout mice exhibited exacerbated alcohol-induced liver injury and hepatic steatosis. However, the macrophage numbers and chemokine levels were similar to those in wild-type mice. Depletion of Dnajc10 promoted oxidative stress. Ethanol feeding increased hepatic H2O2 levels, and these were further increased in Dnajc10 knockout mice. Additionally, Dnajc10-deficient hepatocytes produced large amounts of reactive oxygen species. Notably, Nrf2, a central regulator of oxidative stress, was decreased by depletion of Dnajc10 in the nuclear fraction of ethanol-treated mouse liver. Consistently, liver tissues from ethanol-fed Dnajc10 knockout mice had reduced expression of downstream antioxidant genes. Furthermore, hepatic glutathione content in the liver of knockout mice declined compared to wild-type mice. In conclusion, our results demonstrate that ethanol-induced ERdj5 may regulate the Nrf2 pathway and glutathione contents, and have protective effects on liver damage and alcohol-mediated oxidative stress in mice. These suggest that ERdj5 has the potential to protect against alcoholic liver disease.
Assuntos
Proteínas de Choque Térmico HSP40 , Hepatopatias Alcoólicas , Chaperonas Moleculares , Fator 2 Relacionado a NF-E2 , Animais , Camundongos , Etanol/toxicidade , Glutationa/metabolismo , Proteínas de Choque Térmico HSP40/genética , Proteínas de Choque Térmico HSP40/metabolismo , Peróxido de Hidrogênio/metabolismo , Fígado/metabolismo , Hepatopatias Alcoólicas/genética , Camundongos Knockout , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Fator 2 Relacionado a NF-E2/genética , Fator 2 Relacionado a NF-E2/metabolismo , Estresse Oxidativo , RNA Mensageiro/metabolismoRESUMO
BACKGROUND AND AIMS: p21-activated kinase 4 (PAK4), an oncogenic protein, has emerged as a promising target for anticancer drug development. Its role in oxidative stress conditions, however, remains elusive. We investigated the effects of PAK4 signaling on hepatic ischemia/reperfusion (I/R) injury. APPROACH AND RESULTS: Hepatocyte- and myeloid-specific Pak4 knockout (KO) mice and their littermate controls were subjected to a partial hepatic I/R (HIR) injury. We manipulated the catalytic activity of PAK4, either through genetic engineering (gene knockout, overexpression of wild-type [WT] or dominant-negative kinase) or pharmacological inhibitor, coupled with a readout of nuclear factor erythroid 2-related factor 2 (Nrf2) activity, to test the potential function of PAK4 on HIR injury. PAK4 expression was markedly up-regulated in liver during HIR injury in mice and humans. Deletion of PAK4 in hepatocytes, but not in myeloid cells, ameliorated liver damages, as demonstrated in the decrease in hepatocellular necrosis and inflammatory responses. Conversely, the forced expression of WT PAK4 aggravated the pathological changes. PAK4 directly phosphorylated Nrf2 at T369, and it led to its nuclear export and proteasomal degradation, all of which impaired antioxidant responses in hepatocytes. Nrf2 silencing in liver abolished the protective effects of PAK4 deficiency. A PAK4 inhibitor protected mice from HIR injury. CONCLUSIONS: PAK4 phosphorylates Nrf2 and suppresses its transcriptional activity. Genetic or pharmacological suppression of PAK4 alleviates HIR injury. Thus, PAK4 inhibition may represent a promising intervention against I/R-induced liver injury.
Assuntos
Hepatopatias , Traumatismo por Reperfusão , Quinases Ativadas por p21 , Animais , Apoptose , Humanos , Isquemia/metabolismo , Isquemia/patologia , Fígado/patologia , Hepatopatias/etiologia , Hepatopatias/metabolismo , Hepatopatias/prevenção & controle , Camundongos , Camundongos Knockout , Fator 2 Relacionado a NF-E2/metabolismo , Fosforilação , Traumatismo por Reperfusão/metabolismo , Quinases Ativadas por p21/genética , Quinases Ativadas por p21/metabolismoRESUMO
BACKGROUND/AIM: Prostate cancer (PCa) is the most commonly diagnosed genital cancer in men globally. Among patients who develop advanced PCa, 80% are affected by bone metastasis, with a sharp drop in survival rate. Despite efforts, the details of mechanisms of metastasis of PCa remain unclear. SIRT5, an NAD+-dependent deacylase, is hypothesized to be a crucial regulator of various cancers. The role of SIRT5 in cancer has not been extensively studied compared to other SIRTs. In this study, we showed significantly decreased levels of SIRT5 in PC-3M, a highly aggressive PC-3 cell variant. MATERIALS AND METHODS: We characterized the differentially expressed proteins between parental and SIRT5 KO PC-3 cells using quantitative proteomics analysis. RESULTS: A significant increase in expression of interleukin-1ß (IL-1ß) in SIRT5 KO cells was observed, and the PI3K/AKT/NF-ĸB signaling pathway was found significantly elevated in SIRT5 KO cells by the Gene Ontology annotation and KEGG pathway functional enrichment analysis. Moreover, we confirmed that SIRT5 can bind PI3K by immunoprecipitation analysis. CONCLUSION: This study is the first to demonstrate a relationship between SIRT5 and PCa metastasis, suggesting that SIRT5-mediated inhibition of the PI3K/AKT/NK-kB pathway is reduced for secondary metastasis from bone to other tissues.
Assuntos
Epigênese Genética , Regulação Neoplásica da Expressão Gênica , Neoplasias da Próstata/genética , Sirtuínas/metabolismo , Acetilação , Apoptose/genética , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células/genética , Técnicas de Inativação de Genes , Humanos , Masculino , Fosfatidilinositol 3-Quinases/metabolismo , Neoplasias da Próstata/patologia , Proteômica , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais/genética , Sirtuínas/genéticaRESUMO
Intermittent fasting (IF) is gaining popularity for its effectiveness in improving overall health, including its effectiveness in achieving weight loss and euglycemia. The molecular mechanisms of IF, however, are not well understood. This study investigated the relationship between adipocyte sirtuin 6 (Sirt6) and the metabolic benefits of IF. Adipocyte-specific Sirt6-knockout (aS6KO) mice and wild-type littermates were fed a high-fat diet (HFD) ad libitum for four weeks and then subjected to 12 weeks on a 2:1 IF regimen consisting of two days of feeding followed by one day of fasting. Compared with wild-type mice, aS6KO mice subjected to HFD + IF exhibited a diminished response, as reflected by their glucose and insulin intolerance, reduced energy expenditure and adipose tissue browning, and increased inflammation of white adipose tissue. Sirt6 deficiency in hepatocytes or in myeloid cells did not impair adaptation to IF. Finally, the results indicated that the impaired adipose tissue browning and reduced expression of UCP1 in aS6KO mice were accompanied by downregulation of p38 MAPK/ATF2 signaling. Our findings indicate that Sirt6 in adipocytes is critical to obtaining the improved glucose metabolism and metabolic profiles conferred by IF and that maintaining high levels of Sirt6 in adipocytes may mimic the health benefits of IF.