RESUMO
OBJECTIVE: Obesity represents a significant global health challenge characterized by chronic low-grade inflammation and metabolic dysregulation. The hypothalamus, a key regulator of energy homeostasis, is particularly susceptible to obesity's deleterious effects. This study investigated the role of the immunoproteasome, a specialized proteasomal complex implicated in inflammation and cellular homeostasis, during metabolic diseases. METHODS: The levels of the immunoproteasome ß5i subunit were analyzed by immunostaining, western blotting, and proteasome activity assay in mice fed with either a high-fat diet (HFD) or a regular diet (CHOW). We also characterized the impact of autophagy inhibition on the levels of the immunoproteasome ß5i subunit and the activation of the AKT pathway. Finally, through confocal microscopy, we analyzed the contribution of ß5i subunit inhibition on mitochondrial function by flow cytometry and mitophagy assay. RESULTS: Using an HFD-fed obese mouse model, we found increased immunoproteasome levels in hypothalamic POMC neurons. Furthermore, we observed that palmitic acid (PA), a major component of saturated fats found in HFD, increased the levels of the ß5i subunit of the immunoproteasome in hypothalamic neuronal cells. Notably, the increase in immunoproteasome expression was associated with decreased autophagy, a critical cellular process in maintaining homeostasis and suppressing inflammation. Functionally, PA disrupted the insulin-glucose axis, leading to reduced AKT phosphorylation and increased intracellular glucose levels in response to insulin due to the upregulation of the immunoproteasome. Mechanistically, we identified that the protein PTEN, a key regulator of insulin signaling, was reduced in an immunoproteasome-dependent manner. To further investigate the potential therapeutic implications of these findings, we used ONX-0914, a specific immunoproteasome inhibitor. We demonstrated that this inhibitor prevents PA-induced insulin-glucose axis imbalance. Given the interplay between mitochondrial dysfunction and metabolic disturbances, we explored the impact of ONX-0914 on mitochondrial function. Notably, ONX-0914 preserved mitochondrial membrane potential and attenuated mitochondrial ROS production in the presence of PA. Moreover, we found that ONX-0914 reduced mitophagy in the presence of PA. CONCLUSIONS: Our findings strongly support the pathogenic involvement of the immunoproteasome in hypothalamic neurons in the context of HFD-induced obesity and metabolic disturbances. Targeting the immunoproteasome highlights a promising therapeutic strategy to mitigate the detrimental effects of obesity on the insulin-glucose axis and cellular homeostasis. This study provides valuable insights into the mechanisms driving obesity-related metabolic diseases and offers potential avenues for developing novel therapeutic interventions.
Assuntos
Dieta Hiperlipídica , Hipotálamo , Camundongos Endogâmicos C57BL , Neurônios , Obesidade , Complexo de Endopeptidases do Proteassoma , Animais , Dieta Hiperlipídica/efeitos adversos , Camundongos , Hipotálamo/metabolismo , Obesidade/metabolismo , Neurônios/metabolismo , Neurônios/efeitos dos fármacos , Complexo de Endopeptidases do Proteassoma/metabolismo , Masculino , Doenças Metabólicas/metabolismo , Doenças Metabólicas/etiologia , OligopeptídeosRESUMO
Obesity, a global health crisis, disrupts multiple systemic processes, contributing to a cascade of metabolic dysfunctions by promoting the pathological expansion of visceral adipose tissue (VAT). This expansion is characterized by impaired differentiation of pre-adipocytes and an increase in senescent cells, leading to a pro-inflammatory state and exacerbated oxidative stress. Particularly, the senescence-associated secretory phenotype (SASP) and adipose tissue hypoxia further impair cellular function, promoting chronic disease development. This review delves into the potential of autophagy modulation and the therapeutic application of senolytics and senomorphics as novel strategies to mitigate adipose tissue senescence. By exploring the intricate mechanisms underlying adipocyte dysfunction and the emerging role of natural compounds in senescence modulation, we underscore the promising horizon of senotherapeutics in restoring adipose health. This approach not only offers a pathway to combat the metabolic complications of obesity, but also opens new avenues for enhancing life quality and managing the global burden of obesity-related conditions. Our analysis aims to bridge the gap between current scientific progress and clinical application, offering new perspectives on preventing and treating obesity-induced adipose dysfunction.
Assuntos
Tecido Adiposo , Autofagia , Senescência Celular , Obesidade , Senoterapia , Humanos , Obesidade/tratamento farmacológico , Senescência Celular/fisiologia , Senescência Celular/efeitos dos fármacos , Autofagia/fisiologia , Autofagia/efeitos dos fármacos , Senoterapia/farmacologia , Animais , AdipócitosRESUMO
The endocannabinoid system (ECS) regulates energy metabolism, has been implicated in the pathogenesis of metabolic diseases and exerts its actions mainly through the type 1 cannabinoid receptor (CB1). Likewise, autophagy is involved in several cellular processes. It is required for the normal development of muscle mass and metabolism, and its deregulation is associated with diseases. It is known that the CB1 regulates signaling pathways that control autophagy, however, it is currently unknown whether the ECS could regulate autophagy in the skeletal muscle of obese mice. This study aimed to investigate the role of the CB1 in regulating autophagy in skeletal muscle. We found concomitant deregulation in the ECS and autophagy markers in high-fat diet-induced obesity. In obese CB1-KO mice, the autophagy-associated protein LC3 II does not accumulate when mTOR and AMPK phosphorylation levels do not change. Acute inhibition of the CB1 with JD-5037 decreased LC3 II protein accumulation and autophagic flux. Our results suggest that the CB1 regulates autophagy in the tibialis anterior skeletal muscle in both lean and obese mice.
Assuntos
Canabinoides , Camundongos , Animais , Canabinoides/metabolismo , Receptor CB1 de Canabinoide/metabolismo , Camundongos Obesos , Músculo Esquelético/metabolismo , Autofagia/fisiologia , Camundongos Endogâmicos C57BLRESUMO
Acetyl-coenzyme A (AcCoA) is a major integrator of the nutritional status at the crossroads of fat, sugar, and protein catabolism. Here we show that nutrient starvation causes rapid depletion of AcCoA. AcCoA depletion entailed the commensurate reduction in the overall acetylation of cytoplasmic proteins, as well as the induction of autophagy, a homeostatic process of self-digestion. Multiple distinct manipulations designed to increase or reduce cytosolic AcCoA led to the suppression or induction of autophagy, respectively, both in cultured human cells and in mice. Moreover, maintenance of high AcCoA levels inhibited maladaptive autophagy in a model of cardiac pressure overload. Depletion of AcCoA reduced the activity of the acetyltransferase EP300, and EP300 was required for the suppression of autophagy by high AcCoA levels. Altogether, our results indicate that cytosolic AcCoA functions as a central metabolic regulator of autophagy, thus delineating AcCoA-centered pharmacological strategies that allow for the therapeutic manipulation of autophagy.
Assuntos
Acetilcoenzima A/química , Autofagia , Citosol/enzimologia , Regulação Enzimológica da Expressão Gênica , Trifosfato de Adenosina/química , Animais , Linhagem Celular Tumoral , Núcleo Celular/metabolismo , Citoplasma/metabolismo , Citosol/metabolismo , Proteína p300 Associada a E1A/química , Proteínas de Fluorescência Verde/metabolismo , Células HCT116 , Células HeLa , Humanos , Ácidos Cetoglutáricos/química , Camundongos , Camundongos Endogâmicos C57BL , Microscopia de Fluorescência , Mitocôndrias/metabolismo , RNA Interferente Pequeno/metabolismoRESUMO
A crucial etiological component in fetal programming is early nutrition. Indeed, early undernutrition may cause a chronic increase in blood pressure and cardiovascular diseases, including stroke and heart failure. In this regard, current evidence has sustained several pathological mechanisms involving changes in central and peripheral targets. In the present review, we summarize the neuroendocrine and neuroplastic modifications that underlie maladaptive mechanisms related to chronic hypertension programming after early undernutrition. First, we analyzed the role of glucocorticoids on the mechanism of long-term programming of hypertension. Secondly, we discussed the pathological plastic changes at the paraventricular nucleus of the hypothalamus that contribute to the development of chronic hypertension in animal models of prenatal undernutrition, dissecting the neural network that reciprocally communicates this nucleus with the locus coeruleus. Finally, we propose an integrated and updated view of the main neuroendocrine and central circuital alterations that support the occurrence of chronic increases of blood pressure in prenatally undernourished animals.
Assuntos
Hipertensão , Desnutrição , Efeitos Tardios da Exposição Pré-Natal , Animais , Pressão Sanguínea , Feminino , Glucocorticoides/fisiologia , Humanos , Desnutrição/patologia , Núcleo Hipotalâmico Paraventricular , Gravidez , Efeitos Tardios da Exposição Pré-Natal/patologiaRESUMO
BACKGROUND: The primary cilium is a singular cellular structure that extends from the surface of many cell types and plays crucial roles in vertebrate development, including that of the heart. Whereas ciliated cells have been described in developing heart, a role for primary cilia in adult heart has not been reported. This, coupled with the fact that mutations in genes coding for multiple ciliary proteins underlie polycystic kidney disease, a disorder with numerous cardiovascular manifestations, prompted us to identify cells in adult heart harboring a primary cilium and to determine whether primary cilia play a role in disease-related remodeling. METHODS: Histological analysis of cardiac tissues from C57BL/6 mouse embryos, neonatal mice, and adult mice was performed to evaluate for primary cilia. Three injury models (apical resection, ischemia/reperfusion, and myocardial infarction) were used to identify the location and cell type of ciliated cells with the use of antibodies specific for cilia (acetylated tubulin, γ-tubulin, polycystin [PC] 1, PC2, and KIF3A), fibroblasts (vimentin, α-smooth muscle actin, and fibroblast-specific protein-1), and cardiomyocytes (α-actinin and troponin I). A similar approach was used to assess for primary cilia in infarcted human myocardial tissue. We studied mice silenced exclusively in myofibroblasts for PC1 and evaluated the role of PC1 in fibrogenesis in adult rat fibroblasts and myofibroblasts. RESULTS: We identified primary cilia in mouse, rat, and human heart, specifically and exclusively in cardiac fibroblasts. Ciliated fibroblasts are enriched in areas of myocardial injury. Transforming growth factor ß-1 signaling and SMAD3 activation were impaired in fibroblasts depleted of the primary cilium. Extracellular matrix protein levels and contractile function were also impaired. In vivo, depletion of PC1 in activated fibroblasts after myocardial infarction impaired the remodeling response. CONCLUSIONS: Fibroblasts in the neonatal and adult heart harbor a primary cilium. This organelle and its requisite signaling protein, PC1, are required for critical elements of fibrogenesis, including transforming growth factor ß-1-SMAD3 activation, production of extracellular matrix proteins, and cell contractility. Together, these findings point to a pivotal role of this organelle, and PC1, in disease-related pathological cardiac remodeling and suggest that some of the cardiovascular manifestations of autosomal dominant polycystic kidney disease derive directly from myocardium-autonomous abnormalities.
Assuntos
Fibroblastos/ultraestrutura , Miocárdio/patologia , Rim Policístico Autossômico Dominante/patologia , Células 3T3/ultraestrutura , Animais , Animais Recém-Nascidos , Remodelamento Atrial , Cílios , Coração Fetal/citologia , Fibrose , Traumatismos Cardíacos/patologia , Humanos , Cinesinas/deficiência , Cinesinas/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Infarto do Miocárdio/patologia , Traumatismo por Reperfusão Miocárdica/patologia , Rim Policístico Autossômico Dominante/genética , Ratos , Transdução de Sinais , Proteína Smad3/fisiologia , Canais de Cátion TRPP/deficiência , Canais de Cátion TRPP/fisiologia , Fator de Crescimento Transformador beta1/fisiologia , Remodelação VentricularRESUMO
AIMS: Considerable evidence points to critical roles of intracellular Ca2+ homeostasis in the modulation and control of autophagic activity. Yet, underlying molecular mechanisms remain unknown. Mutations in the gene (pkd2) encoding polycystin-2 (PC2) are associated with autosomal dominant polycystic kidney disease (ADPKD), the most common inherited nephropathy. PC2 has been associated with impaired Ca2+ handling in cardiomyocytes and indirect evidence suggests that this protein may be involved in autophagic control. Here, we investigated the role for PC2 as an essential regulator of Ca2+ homeostasis and autophagy. METHODS AND RESULTS: Activation of autophagic flux triggered by mTOR inhibition either pharmacologically (rapamycin) or by means of nutrient depletion was suppressed in cells depleted of PC2. Moreover, cardiomyocyte-specific PC2 knockout mice (αMhc-cre;Pkd2F/F mice) manifested impaired autophagic flux in the setting of nutrient deprivation. Stress-induced autophagy was blunted by intracellular Ca2+ chelation using BAPTA-AM, whereas removal of extracellular Ca2+ had no effect, pointing to a role of intracellular Ca2+ homeostasis in stress-induced cardiomyocyte autophagy. To determine the link between stress-induced autophagy and PC2-induced Ca2+ mobilization, we over-expressed either wild-type PC2 (WT) or a Ca2+-channel deficient PC2 mutant (PC2-D509V). PC2 over-expression increased autophagic flux, whereas PC2-D509V expression did not. Importantly, autophagy induction triggered by PC2 over-expression was attenuated by BAPTA-AM, supporting a model of PC2-dependent control of autophagy through intracellular Ca2+. Furthermore, PC2 ablation was associated with impaired Ca2+ handling in cardiomyocytes marked by partial depletion of sarcoplasmic reticulum Ca2+ stores. Finally, we provide evidence that Ca2+-mediated autophagy elicited by PC2 is a mechanism conserved across multiple cell types. CONCLUSION: Together, this study unveils PC2 as a novel regulator of autophagy acting through control of intracellular Ca2+ homeostasis.
Assuntos
Autofagia , Miócitos Cardíacos/metabolismo , Canais de Cátion TRPP/metabolismo , Animais , Autofagia/efeitos dos fármacos , Proteínas Relacionadas à Autofagia/genética , Proteínas Relacionadas à Autofagia/metabolismo , Cálcio/metabolismo , Células HeLa , Humanos , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Camundongos Knockout , Miócitos Cardíacos/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Retículo Sarcoplasmático/efeitos dos fármacos , Retículo Sarcoplasmático/metabolismo , Transdução de Sinais/efeitos dos fármacos , Sirolimo/farmacologia , Estresse MecânicoRESUMO
Estrogens and their receptors play key roles in regulating body weight, energy expenditure, and metabolic homeostasis. It is known that lack of estrogens promotes increased food intake and induces the expansion of adipose tissues, for which much is known. An area of estrogenic research that has received less attention is the role of estrogens and their receptors in influencing intermediary lipid metabolism in organs such as the brain. In this review, we highlight the actions of estrogens and their receptors in regulating their impact on modulating fatty acid content, utilization, and oxidation through their direct impact on intracellular signaling cascades within the central nervous system.
Assuntos
Química Encefálica/fisiologia , Receptor alfa de Estrogênio/fisiologia , Estrogênios/fisiologia , Metabolismo dos Lipídeos/fisiologia , Animais , Química Encefálica/efeitos dos fármacos , Metabolismo Energético/efeitos dos fármacos , Metabolismo Energético/fisiologia , Receptor alfa de Estrogênio/efeitos dos fármacos , Receptor alfa de Estrogênio/metabolismo , Estrogênios/farmacologia , Humanos , Metabolismo dos Lipídeos/efeitos dos fármacosRESUMO
Calcium signaling plays a crucial role in a multitude of events within the cardiomyocyte, including cell cycle control, growth, apoptosis, and autophagy. With respect to calcium-dependent regulation of autophagy, ion channels and exchangers, receptors, and intracellular mediators play fundamental roles. In this review, we discuss calcium-dependent regulation of cardiomyocyte autophagy, a lysosomal mechanism that is often cytoprotective, serving to defend against disease-related stress and nutrient insufficiency. We also highlight the importance of the subcellular distribution of calcium and related proteins, interorganelle communication, and other key signaling events that govern cardiomyocyte autophagy.
Assuntos
Autofagia , Sinalização do Cálcio , Cálcio/metabolismo , Miócitos Cardíacos/metabolismo , Animais , Humanos , Fator de Crescimento Insulin-Like I/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismoRESUMO
Maternal nutrition has a profound long-term impact on infant health. Poor maternal nutrition influences placental development and fetal growth, resulting in low birth weight, which is strongly associated with the risk of developing chronic diseases, including heart disease, hypertension, asthma, and type 2 diabetes, later in life. Few studies have delineated the mechanisms by which maternal nutrition affects fetal lung development. Here, we report that maternal exposure to a diet high in fat (HFD) causes placental inflammation, resulting in placental insufficiency, fetal growth restriction (FGR), and inhibition of fetal lung development. Notably, pre- and postnatal exposure to maternal HFD also results in persistent alveolar simplification in the postnatal period. Our novel findings provide a strong association between maternal diet and fetal lung development.
Assuntos
Dieta Hiperlipídica/efeitos adversos , Retardo do Crescimento Fetal/etiologia , Pulmão/embriologia , Animais , Glicemia , Feminino , Retardo do Crescimento Fetal/sangue , Inflamação/metabolismo , Insulina/sangue , Pulmão/crescimento & desenvolvimento , Pulmão/patologia , Masculino , Camundongos Endogâmicos C57BL , Placenta/imunologia , Gravidez , Aumento de PesoRESUMO
Autophagic responses are coupled to the activation of the inhibitor of NF-κB kinase (IKK). Here, we report that the essential autophagy mediator Beclin 1 and TGFß-activated kinase 1 (TAK1)-binding proteins 2 and 3 (TAB2 and TAB3), two upstream activators of the TAK1-IKK signalling axis, constitutively interact with each other via their coiled-coil domains (CCDs). Upon autophagy induction, TAB2 and TAB3 dissociate from Beclin 1 and bind TAK1. Moreover, overexpression of TAB2 and TAB3 suppresses, while their depletion triggers, autophagy. The expression of the C-terminal domain of TAB2 or TAB3 or that of the CCD of Beclin 1 competitively disrupts the interaction between endogenous Beclin 1, TAB2 and TAB3, hence stimulating autophagy through a pathway that requires endogenous Beclin 1, TAK1 and IKK to be optimally efficient. These results point to the existence of an autophagy-stimulatory 'switch' whereby TAB2 and TAB3 abandon inhibitory interactions with Beclin 1 to engage in a stimulatory liaison with TAK1.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas Reguladoras de Apoptose/metabolismo , Autofagia , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas de Membrana/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Reguladoras de Apoptose/genética , Proteína Beclina-1 , Células HeLa , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Proteínas de Membrana/genética , Estrutura Terciária de Proteína , Técnicas do Sistema de Duplo-HíbridoRESUMO
AIMS: Mutations in 1-acylglycerol-3-phosphate O-acyltransferase 2 (AGPAT2) result in lipodystrophy, insulin resistance and diabetes. Autophagy is required for normal adipogenesis and adipose tissue development. The aim of this study was to determine whether impaired autophagy or excessive cell death underlie the adipogenic inability of Agpat2(-/-) mice preadipocytes. METHODS: Preadipocytes were isolated from interscapular brown adipose tissue (BAT) of Agpat2(-/-) and Agpat2(+/+) newborn mice and cultured/differentiated in vitro. Intracellular lipids were quantified by oil red O staining. Cell death was assessed by lactate dehydrogenase (LDH) activity. Apoptosis and autophagy regulatory factors were determined at the mRNA and protein level with Real-time PCR, immunoblot and immunofluorescence. RESULTS: Adipogenically induced Agpat2(-/-) preadipocytes had fewer lipid-loaded cells and lower levels of adipocyte markers than wild type preadipocytes. Before adipogenic differentiation, autophagy-related proteins (ATGs) ATG3, ATG5-ATG12 complex, ATG7 and LC3II were increased but autophagic flux was reduced, as suggested by increased p62 levels, in Agpat2(-/-) preadipocytes. Adipogenic induction increased LDH levels in the culture media in Agpat2(-/-) preadipocytes but no differences were observed in the activation of Caspase 3 or in markers of autophagic flux. CONCLUSIONS: AGPAT2 is required for in vitro adipogenesis of mouse preadipocytes. Autophagy defects or apoptosis are not involved in the adipogenic failure of Agpat2(-/-) preadipocytes.
Assuntos
Aciltransferases/deficiência , Adipócitos Marrons/citologia , Adipócitos Marrons/enzimologia , Adipogenia/fisiologia , Aciltransferases/genética , Adipogenia/genética , Animais , Apoptose , Autofagia , Diferenciação Celular , Células Cultivadas , Metabolismo dos Lipídeos , Camundongos , Camundongos Knockout , Células-Tronco/citologia , Células-Tronco/metabolismoRESUMO
In response to stress, cells start transcriptional and transcription-independent programs that can lead to adaptation or death. Here, we show that multiple inducers of autophagy, including nutrient depletion, trigger the activation of the IKK (IkappaB kinase) complex that is best known for its essential role in the activation of the transcription factor NF-kappaB by stress. Constitutively active IKK subunits stimulated autophagy and transduced multiple signals that operate in starvation-induced autophagy, including the phosphorylation of AMPK and JNK1. Genetic inhibition of the nuclear translocation of NF-kappaB or ablation of the p65/RelA NF-kappaB subunit failed to suppress IKK-induced autophagy, indicating that IKK can promote the autophagic pathway in an NF-kappaB-independent manner. In murine and human cells, knockout and/or knockdown of IKK subunits (but not that of p65) prevented the induction of autophagy in response to multiple stimuli. Moreover, the knockout of IKK-beta suppressed the activation of autophagy by food deprivation or rapamycin injections in vivo, in mice. Altogether, these results indicate that IKK has a cardinal role in the stimulation of autophagy by physiological and pharmacological stimuli.
Assuntos
Autofagia/fisiologia , Quinase I-kappa B/fisiologia , Animais , Autofagia/genética , Células Cultivadas , Células HeLa , Humanos , Quinase I-kappa B/genética , Quinase I-kappa B/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Complexos Multiproteicos/genética , Complexos Multiproteicos/metabolismo , Complexos Multiproteicos/fisiologia , NF-kappa B/genética , NF-kappa B/metabolismo , Células NIH 3T3 , Transdução de Sinais/fisiologiaRESUMO
The primary cilium, hereafter cilium, is an antenna-like organelle that modulates intracellular responses, including autophagy, a lysosomal degradation process essential for cell homeostasis. Dysfunction of the cilium is associated with impairment of autophagy and diseases known as "ciliopathies". The discovery of autophagy-related proteins at the base of the cilium suggests its potential role in coordinating autophagy initiation in response to physiopathological stimuli. One of these proteins, beclin-1 (BECN1), it which is necessary for autophagosome biogenesis. Additionally, polycystin-2 (PKD2), a calcium channel enriched at the cilium, is required and sufficient to induce autophagy in renal and cancer cells. We previously demonstrated that PKD2 and BECN1 form a protein complex at the endoplasmic reticulum in non-ciliated cells, where it initiates autophagy, but whether this protein complex is present at the cilium remains unknown. Anorexigenic pro-opiomelanocortin (POMC) neurons are ciliated cells that require autophagy to maintain intracellular homeostasis. POMC neurons are sensitive to metabolic changes, modulating signaling pathways crucial for controlling food intake. Exposure to the saturated fatty acid palmitic acid (PA) reduces ciliogenesis and inhibits autophagy in these cells. Here, we show that PKD2 and BECN1 form a protein complex in N43/5 cells, an in vitro model of POMC neurons, and that both PKD2 and BECN1 locate at the cilium. In addition, our data show that the cilium is required for PKD2-BECN1 protein complex formation and that PA disrupts the PKD2-BECN1 complex, suppressing autophagy. Our findings provide new insights into the mechanisms by which the cilium controls autophagy in hypothalamic neuronal cells.
Assuntos
Autofagia , Proteína Beclina-1 , Cílios , Hipotálamo , Neurônios , Canais de Cátion TRPP , Animais , Camundongos , Proteína Beclina-1/metabolismo , Cílios/metabolismo , Hipotálamo/metabolismo , Hipotálamo/citologia , Neurônios/metabolismo , Canais de Cátion TRPP/metabolismo , Canais de Cátion TRPP/genéticaRESUMO
AIM: The present study aimed to investigate the effects of a single bout of resistance exercise on mitophagy in human skeletal muscle (SkM). METHODS: Eight healthy men were recruited to complete an acute bout of one-leg resistance exercise. SkM biopsies were obtained one hour after exercise in the resting leg (Rest-leg) and the contracting leg (Ex-leg). Mitophagy was assessed using protein-related abundance, transmission electron microscopy (TEM), and fluorescence microscopy. RESULTS: Our results show that acute resistance exercise increased pro-fission protein phosphorylation (DRP1Ser616) and decreased mitophagy markers such as PARKIN and BNIP3L/NIX protein abundance in the Ex-leg. Additionally, mitochondrial complex IV decreased in the Ex-leg when compared to the Rest-leg. In the Ex-leg, TEM and immunofluorescence images showed mitochondrial cristae abnormalities, a mitochondrial fission phenotype, and increased mitophagosome-like structures in both subsarcolemmal and intermyofibrillar mitochondria. We also observed increased mitophagosome-like structures on the subsarcolemmal cleft and mitochondria in the extracellular space of SkM in the Ex-leg. We stimulated human primary myotubes with CCCP, which mimics mitophagy induction in the Ex-leg, and found that BNIP3L/NIX protein abundance decreased independently of lysosomal degradation. Finally, in another human cohort, we found a negative association between BNIP3L/NIX protein abundance with both mitophagosome-like structures and mitochondrial cristae density in the SkM. CONCLUSION: The findings suggest that a single bout of resistance exercise can initiate mitophagy, potentially involving mitochondrial ejection, in human skeletal muscle. BNIP3L/NIX is proposed as a sensitive marker for assessing mitophagy flux in SkM.
Assuntos
Mitofagia , Músculo Esquelético , Humanos , Mitofagia/fisiologia , Masculino , Músculo Esquelético/metabolismo , Músculo Esquelético/fisiologia , Adulto , Mitocôndrias Musculares/metabolismo , Mitocôndrias Musculares/ultraestrutura , Treinamento Resistido , Adulto Jovem , Proteínas de Membrana/metabolismoRESUMO
PSMD14/POH1/Rpn11 plays a crucial role in cellular homeostasis. PSMD14 is a structural subunit of the lid subcomplex of the proteasome 19S regulatory particle with constitutive deubiquitinase activity. Canonically, PSMD14 removes the full ubiquitin chains with K48-linkages by hydrolyzing the isopeptide bond between the substrate and the C-terminus of the first ubiquitin, a crucial step for the entry of substrates into the catalytic barrel of the 20S proteasome and their subsequent degradation, all in context of the 26S proteasome. However, more recent discoveries indicate PSMD14 DUB activity is not only coupled to the translocation of substrates into the core of 20S proteasome. During the assembly of the lid, activity of PSMD14 has been detected in the context of the heterodimer with PSMD7. Additionally, assembly of the lid subcomplex occurs as an independent event of the base subcomplex and 20S proteasome. This feature opens the possibility that the regulatory particle, free lid subcomplex or the heterodimer PSMD14-PSMD7 might play other physiological roles including a positive function on protein stability through deubiquitination. Here we discuss scenarios that could enhance this PSMD14 non-canonical pathway, the potential impact in preventing degradation of substrates by autophagy highlighting the main findings that support this hypothesis. Finally, we discuss why this information should be investigated in biomedicine specifically with focus on cancer progression to design new therapeutic strategies against the lid subcomplex and the heterodimer PSMD14-PSMD7, highlighting PSMD14 as a druggable target for cancer therapy.
Assuntos
Neoplasias , Complexo de Endopeptidases do Proteassoma , Humanos , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteostase , Ubiquitina/metabolismo , Transativadores/metabolismoRESUMO
[This corrects the article DOI: 10.3389/fendo.2023.1164047.].
RESUMO
Introduction: The modern food environment facilitates excessive calorie intake, a major driver of obesity. Glucagon-like peptide 1 (GLP1) is a neuroendocrine peptide that has been the basis for developing new pharmacotherapies against obesity. The GLP1 receptor (GLP1R) is expressed in central and peripheral tissues, and activation of GLP1R reduces food intake, increases the expression of thermogenic proteins in brown adipose tissue (BAT), and enhances lipolysis in white adipose tissue (WAT). Obesity decreases the efficiency of GLP1R agonists in reducing food intake and body weight. Still, whether palatable food intake before or during the early development of obesity reduces the effects of GLP1R agonists on food intake and adipose tissue metabolism remains undetermined. Further, whether GLP1R expressed in WAT contributes to these effects is unclear. Methods: Food intake, expression of thermogenic BAT proteins, and WAT lipolysis were measured after central or peripheral administration of Exendin-4 (EX4), a GLP1R agonist, to mice under intermittent-short exposure to CAF diet (3 h/d for 8 days) or a longer-continuous exposure to CAF diet (24 h/d for 15 days). Ex-vivo lipolysis was measured after EX4 exposure to WAT samples from mice fed CAF or control diet for 12 weeks. . Results: During intermittent-short exposure to CAF diet (3 h/d for 8 days), third ventricle injection (ICV) and intra-peritoneal administration of EX4 reduced palatable food intake. Yet, during a longer-continuous exposure to CAF diet (24 h/d for 15 days), only ICV EX4 administration reduced food intake and body weight. However, this exposure to CAF diet blocked the increase in uncoupling protein 1 (UCP1) caused by ICV EX4 administration in mice fed control diet. Finally, GLP1R expression in WAT was minimal, and EX4 failed to increase lipolysis ex-vivo in WAT tissue samples from mice fed CAF or control diet for 12 weeks. . Discussion: Exposure to a CAF diet during the early stages of obesity reduces the effects of peripheral and central GLP1R agonists, and WAT does not express a functional GLP1 receptor. These data support that exposure to the obesogenic food environment, without the development or manifestation of obesity, can alter the response to GLP1R agonists. .
Assuntos
Receptor do Peptídeo Semelhante ao Glucagon 1 , Lipólise , Camundongos , Animais , Receptor do Peptídeo Semelhante ao Glucagon 1/agonistas , Dieta , Obesidade/etiologia , Obesidade/metabolismo , Exenatida/farmacologia , Exenatida/metabolismo , Peso Corporal , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Tecido Adiposo Branco/metabolismo , Ingestão de AlimentosRESUMO
Cardiovascular diseases are the leading cause of death and disability worldwide. After heart injury triggered by myocardial ischemia or myocardial infarction, extensive zones of tissue are damaged and some of the tissue dies by necrosis and/or apoptosis. The loss of contractile mass activates a series of biochemical mechanisms that allow, through cardiac remodeling, the replacement of the dysfunctional heart tissue by fibrotic material. Our previous studies have shown that primary cilia, non-motile antenna-like structures at the cell surface required for the activation of specific signaling pathways, are present in cardiac fibroblasts and required for cardiac fibrosis induced by ischemia/reperfusion (I/R) in mice. I/R-induced myocardial fibrosis promotes the enrichment of ciliated cardiac fibroblasts where the myocardial injury occurs. Given discussions about the existence of cilia in specific cardiac cell types, as well as the functional relevance of studying cilia-dependent signaling in cardiac fibrosis after I/R, here we describe our methods to evaluate the presence and roles of primary cilia in cardiac fibrosis after I/R in mice.
Assuntos
Infarto do Miocárdio , Traumatismo por Reperfusão Miocárdica , Camundongos , Animais , Cílios/metabolismo , Traumatismo por Reperfusão Miocárdica/metabolismo , Traumatismo por Reperfusão Miocárdica/patologia , Coração , Fibrose , Miócitos Cardíacos/metabolismo , MiocárdioRESUMO
Cells are exposed and respond to various mechanical forces and physical cues stemming from their environment. This interaction has been seen to differentially regulate various cellular processes for maintenance of homeostasis, of which autophagy represents one of the major players. In addition, autophagy has been suggested to regulate mechanical functions of the cells including their interaction with the environment. In this minireview, we summarize the state of the art of the fascinating interplay between autophagy and the mechanotransduction machinery associated with cell adhesions, that we name ¨Mechanoautophagy¨.