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Human genetic studies show that loss of function mutations in 17-Beta hydroxysteroid dehydrogenase (HSD17ß13) are associated with protection from non-alcoholic steatohepatitis (NASH). As a result, therapies which reduce HSD17ß13 are being pursued for the treatment of NASH. However, inconsistent effects on steatosis, inflammation and fibrosis pathogenesis have been reported in murine Hsd17b13 knockdown or knockout models. To clarify whether murine Hsd17b13 loss regulates liver damage and fibrosis, we characterized Hsd17b13 knockout mice subjected to pro-NASH diets or pro-inflammatory chemical-induced liver injury. There were no effects of Hsd17b13 loss on liver injury, inflammation, fibrosis or lipids after 28 weeks on the Gubra-Amylin NASH (GAN) diet or 12 weeks on a 45% choline deficient high fat diet (CDAHFD). However, AAV-mediated re-expression of murine Hsd17b13 in KO mice increased liver macrophage abundance in both sexes fed the 45% CDAHFD. In contrast, there was a modest reduction in liver fibrosis, but not lipids or inflammation within Hsd17b13 null female, but not male, mice after 12 weeks of a 60% CDAHFD compared to WT littermates. Fibrosis and the abundance of liver macrophages were increased in Hsd17b13 KO females upon adenoviral re-expression of mouse HSD17ß13, but this was not reflected in inflammatory markers. Additionally, we found minimal differences in liver injury, lipids, or inflammatory and fibrotic markers 48 hours after acute CCl4 exposure. In summary, murine Hsd17b13 loss has modest diet- and sex-specific effects on liver fibrosis which contrasts with human genetic studies. This suggests a disconnect between the biological function of HSD17ß13 in mice and humans.
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Impaired wound healing in elderly individuals increases infection risk and prolongs surgical recovery, but current treatment options are limited. Low doses of interleukin-15 (IL-15) that mimic exercise responses in the circulation improve skin structure and increase mitochondria in uninjured aged skin, suggesting that IL-15 is an essential mitochondrial signal for healing that is lost during aging. Here we used gene microarray analysis of old and young murine epidermal stem cells and demonstrate that aging results in a gene signature characteristic of bioenergetic dysfunction. Intravenous IL-15 treatment rescued chronological aging-induced healing defects and restored youthful wound closure in old, sedentary mice. Additionally, exercise-mediated improvements in the healing of aged skin depend upon circulating IL-15. We show that IL-15 induces signal transducer and activator of transcription 3 (STAT3) signaling characteristic of young animals, reduces markers of growth arrest, and increases keratinocyte and fibroblast growth. Moreover, exercise or exercise-mimicking IL-15 treatment rescued the age-associated decrease in epidermal mitochondrial complex IV activity. Overall, these results indicate that IL-15 or its analogs represent promising therapies for treating impaired wound healing in elderly patients.
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Envelhecimento , Interleucina-15/farmacologia , Condicionamento Físico Animal , Cicatrização/efeitos dos fármacos , Animais , Anticorpos Neutralizantes/imunologia , Anticorpos Neutralizantes/farmacologia , Células Cultivadas , Senescência Celular/efeitos dos fármacos , Derme/citologia , Feminino , Fibroblastos/citologia , Fibroblastos/metabolismo , Interleucina-15/sangue , Interleucina-15/genética , Interleucina-15/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias/metabolismo , Fosforilação/efeitos dos fármacos , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/farmacologia , Fator de Transcrição STAT3/metabolismo , Comportamento Sedentário , Transdução de Sinais , Pele/patologiaRESUMO
Metformin is the mainstay therapy for type 2 diabetes (T2D) and many patients also take salicylate-based drugs [i.e., aspirin (ASA)] for cardioprotection. Metformin and salicylate both increase AMP-activated protein kinase (AMPK) activity but by distinct mechanisms, with metformin altering cellular adenylate charge (increasing AMP) and salicylate interacting directly at the AMPK ß1 drug-binding site. AMPK activation by both drugs results in phosphorylation of ACC (acetyl-CoA carboxylase; P-ACC) and inhibition of acetyl-CoA carboxylase (ACC), the rate limiting enzyme controlling fatty acid synthesis (lipogenesis). We find doses of metformin and salicylate used clinically synergistically activate AMPK in vitro and in vivo, resulting in reduced liver lipogenesis, lower liver lipid levels and improved insulin sensitivity in mice. Synergism occurs in cell-free assays and is specific for the AMPK ß1 subunit. These effects are also observed in primary human hepatocytes and patients with dysglycaemia exhibit additional improvements in a marker of insulin resistance (proinsulin) when treated with ASA and metformin compared with either drug alone. These data indicate that metformin-salicylate combination therapy may be efficacious for the treatment of non-alcoholic fatty liver disease (NAFLD) and T2D.
Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Aspirina/administração & dosagem , Fígado/efeitos dos fármacos , Fígado/metabolismo , Metformina/administração & dosagem , Animais , Cardiotônicos/administração & dosagem , Células Cultivadas , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/metabolismo , Dieta Hiperlipídica/efeitos adversos , Sinergismo Farmacológico , Ativação Enzimática/efeitos dos fármacos , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Humanos , Hipoglicemiantes/administração & dosagem , Resistência à Insulina , Lipogênese/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Mitochondrial dysfunction may contribute to age-associated muscle atrophy. Previous data has shown that resistance exercise (RE) increases mitochondrial gene expression and enzyme activity in older adults; however, the acute response to RE has not been well characterized. To characterize the acute mitochondrial response to unaccustomed RE, healthy young (21 ± 3 yr) and older (70 ± 4 yr) men performed a unilateral RE bout for the knee extensors. Muscle biopsies were taken at rest and 3, 24, and 48 h following leg press and knee extension exercise. The expression of the mitochondrial transcriptional regulator proliferator-activated receptor γ coactivator 1-α (PGC-1α) mRNA was increased at 3 h postexercise; however, all other mitochondrial variables decreased over the postexercise period, irrespective of age. ND1, ND4, and citrate synthase (CS) mRNA were all lower at 48 h postexercise, along with specific protein subunits of complex II, III, IV, and ATP synthase. Mitochondrial DNA (mtDNA) copy number decreased by 48 h postexercise, and mtDNA deletions were higher in the older adults and remained unaffected by acute exercise. Elevated mitophagy could not explain the reduction in mitochondrial proteins and DNA, because there was no increase in ubiquitinated voltage-dependent anion channel (VDAC) or its association with PTEN-induced putative kinase 1 (Pink1) or Parkin, and elevated p62 content indicated an impairment or reduction in autophagocytic flux. In conclusion, age did not influence the response of specific mitochondrial transcripts, proteins, and DNA to a bout of RE.
Assuntos
Envelhecimento/metabolismo , Mitocôndrias Musculares/metabolismo , Proteínas Mitocondriais/metabolismo , Músculo Esquelético/metabolismo , RNA Mensageiro/metabolismo , Treinamento Resistido , Adolescente , Fatores Etários , Idoso , Envelhecimento/genética , Envelhecimento/patologia , Autofagia , Biópsia , DNA Mitocondrial/metabolismo , Regulação da Expressão Gênica , Humanos , Masculino , Mitocôndrias Musculares/patologia , Proteínas Mitocondriais/genética , Músculo Esquelético/patologia , Fatores de Tempo , Transcrição Gênica , Adulto JovemRESUMO
Endoplasmic reticulum (ER) stress results from an imbalance between the abundance of synthesized proteins and the folding capacity of the ER. In response, the unfolded protein response (UPR) attempts to restore ER function by attenuating protein synthesis and inducing chaperone expression. Resistance exercise (RE) stimulates protein synthesis; however, a postexercise accumulation of unfolded proteins may activate the UPR. Aging may impair protein folding, and the accumulation of oxidized and misfolded proteins may stimulate the UPR at rest in aged muscle. Eighteen younger (n = 9; 21 ± 3 yr) and older (n = 9; 70 ± 4 yr) untrained men completed a single, unilateral bout of RE using the knee extensors (four sets of 10 repetitions at 75% of one repetition maximum on the leg press and leg extension) to determine whether the UPR is increased in resting, aged muscle and whether RE stimulates the UPR. Muscle biopsies were taken from the nonexercised and exercised vastus lateralis at 3, 24, and 48 h postexercise. Age did not affect any of the proteins and transcripts related to the UPR. Glucose-regulated protein 78 (GRP78) and protein kinase R-like ER protein kinase (PERK) proteins were increased at 48 h postexercise, whereas inositol-requiring enzyme 1 alpha (IRE1α) was elevated at 24 h and 48 h. Despite elevated protein, GRP78 and PERK mRNA was unchanged; however, IRE1α mRNA was increased at 24 h postexercise. Activating transcription factor 6 (ATF6) mRNA increased at 24 h and 48 h, whereas ATF4, CCAAT/enhancer-binding protein homologous protein (CHOP), and growth arrest and DNA damage protein 34 mRNA were unchanged. These data suggest that RE activates specific pathways of the UPR (ATF6/IRE1α), whereas PERK/eukaryotic initiation factor 2 alpha/CHOP does not. In conclusion, acute RE results in UPR activation, irrespective of age.
Assuntos
Estresse do Retículo Endoplasmático , Retículo Endoplasmático/metabolismo , Contração Muscular , Músculo Quadríceps/metabolismo , Treinamento Resistido , Resposta a Proteínas não Dobradas , Fator 4 Ativador da Transcrição/genética , Fator 4 Ativador da Transcrição/metabolismo , Fator 6 Ativador da Transcrição/genética , Fator 6 Ativador da Transcrição/metabolismo , Adolescente , Fatores Etários , Idoso , Chaperona BiP do Retículo Endoplasmático , Endorribonucleases/genética , Endorribonucleases/metabolismo , Proteínas de Choque Térmico/genética , Proteínas de Choque Térmico/metabolismo , Humanos , Masculino , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , RNA Mensageiro/metabolismo , Transdução de Sinais , Fatores de Tempo , Fator de Transcrição CHOP/genética , Fator de Transcrição CHOP/metabolismo , Adulto Jovem , eIF-2 Quinase/genética , eIF-2 Quinase/metabolismoRESUMO
AMP-activated protein kinase (AMPK) ß1 or ß2 subunits are required for assembling of AMPK heterotrimers and are important for regulating enzyme activity and cellular localization. In skeletal muscle, α2ß2γ3-containing heterotrimers predominate. However, compensatory up-regulation and redundancy of AMPK subunits in whole-body AMPK α2, ß2, and γ3 null mice has made it difficult to determine the physiological importance of AMPK in regulating muscle metabolism, because these models have normal mitochondrial content, contraction-stimulated glucose uptake, and insulin sensitivity. In the current study, we generated mice lacking both AMPK ß1 and ß2 isoforms in skeletal muscle (ß1ß2M-KO). ß1ß2M-KO mice are physically inactive and have a drastically impaired capacity for treadmill running that is associated with reductions in skeletal muscle mitochondrial content but not a fiber-type switch. Interestingly, young ß1ß2M-KO mice fed a control chow diet are not obese or insulin resistant but do have impaired contraction-stimulated glucose uptake. These data demonstrate an obligatory role for skeletal muscle AMPK in maintaining mitochondrial capacity and contraction-stimulated glucose uptake, findings that were not apparent in mice with single mutations or deletions in muscle α, ß, or γ subunits.
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Proteínas Quinases Ativadas por AMP/metabolismo , Glucose/metabolismo , Mitocôndrias Musculares/metabolismo , Músculo Esquelético/metabolismo , Condicionamento Físico Animal , Proteínas Quinases Ativadas por AMP/genética , Animais , DNA Mitocondrial/genética , Feminino , Glucose/farmacocinética , Hipoglicemiantes/farmacologia , Immunoblotting , Insulina/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microscopia Eletrônica de Transmissão , Mitocôndrias Musculares/genética , Mitocôndrias Musculares/ultraestrutura , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Contração Muscular , Músculo Esquelético/efeitos dos fármacos , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Idiopathic pulmonary fibrosis (IPF) is an age-related disease with poor prognosis and limited therapeutic options. Activation of lung fibroblasts and differentiation to myofibroblasts are the principal effectors of disease pathology, but damage and senescence of alveolar epithelial cells, specifically type II (ATII) cells, has recently been identified as a potential trigger event for the progressive disease cycle. Targeting ATII senescence and the senescence-associated secretory phenotype (SASP) is an attractive therapeutic strategy; however, translatable primary human cell models that enable mechanistic studies and drug development are lacking. Here, we describe a novel system of conditioned medium (CM) transfer from bleomycin-induced senescent primary alveolar epithelial cells (AEC) onto normal human lung fibroblasts (NHLF) that demonstrates an enhanced fibrotic transcriptional and secretory phenotype compared to non-senescent AEC CM treatment or direct bleomycin damage of the NHLFs. In this system, the bleomycin-treated AECs exhibit classical hallmarks of cellular senescence, including SASP and a gene expression profile that resembles aberrant epithelial cells of the IPF lung. Fibroblast activation by CM transfer is attenuated by pre-treatment of senescent AECs with the senolytic Navitoclax and AD80, but not with the standard of care agent Nintedanib or senomorphic JAK-targeting drugs (e.g., ABT-317, ruxolitinib). This model provides a relevant human system for profiling novel senescence-targeting therapeutics for IPF drug development.
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Células Epiteliais Alveolares , Bleomicina , Senescência Celular , Fibroblastos , Fibrose Pulmonar Idiopática , Humanos , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Bleomicina/toxicidade , Bleomicina/farmacologia , Senescência Celular/efeitos dos fármacos , Células Epiteliais Alveolares/efeitos dos fármacos , Células Epiteliais Alveolares/metabolismo , Células Epiteliais Alveolares/patologia , Fibrose Pulmonar Idiopática/patologia , Fibrose Pulmonar Idiopática/metabolismo , Meios de Cultivo Condicionados/farmacologia , Indóis/farmacologia , Fenótipo Secretor Associado à Senescência/efeitos dos fármacos , Pulmão/patologia , Pulmão/citologia , Pulmão/efeitos dos fármacos , Sulfonamidas/farmacologia , Senoterapia/farmacologia , Células Cultivadas , Pirimidinas/farmacologia , Pirazóis/farmacologia , Nitrilas/farmacologia , Compostos de AnilinaRESUMO
BACKGROUND: Exercise and nutritional interventions have been examined independently as countermeasures to offset the loss of skeletal muscle mass with unloading, yet a protocol to completely preserve the soleus has not been identified. Little is known regarding the combined effect of exercise and nutrition on factors regulating skeletal muscle growth. The purpose of this investigation was to evaluate the influence of amino acid (AA) infusion on myogenic (MRF-4, MyoD, and Myogenin), proteolytic (MuRF-1, Atrogin-1, FOXO3A, Calpain-1, Calpain-2, Caspase-3, Cathepsin L1), and cytokine (IL-6, IL-8, and IL-15) mRNA transcripts in two skeletal muscles that respond distinctly to microgravity unloading. METHODS: Muscle biopsies were obtained from the vastus lateralis (VL) and soleus of eight male subjects prior to and after 4 h of AA infusion for analysis of mRNA expression. All subjects performed a standardized exercise bout (45-min treadmill run) 24 h prior to the AA infusion. RESULTS: In the VL, proteolytic factors MuRF-1 and FOXO3A were reduced (44 +/- 9 and 28 +/- 6%, respectively) in response toAA infusion. In the soleus, mRNA transcripts of myogenic factor MRF-4 (91 +/- 36%) and cytokines IL-6, IL-8, and IL-15 were elevated while the proteolytic marker FOXO3A mRNA was reduced by 19 +/- 9%. DISCUSSION: These data suggest that the expression of genes related to skeletal muscle remodeling is altered during acute AA infusion 24 h post-exercise. It appears that increased amino acid availability in concert with exercise may create an intramuscular environment favorable for the prevention of muscle atrophy associated with unloading, which may be particularly beneficial for the soleus.
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Aminoácidos/farmacologia , Cisteína Endopeptidases/genética , Citocinas/genética , Expressão Gênica/efeitos dos fármacos , Proteínas Musculares/genética , Músculo Esquelético/metabolismo , Adulto , Cisteína Endopeptidases/efeitos dos fármacos , Cisteína Endopeptidases/metabolismo , Citocinas/efeitos dos fármacos , Citocinas/metabolismo , Exercício Físico/fisiologia , Humanos , Masculino , Proteínas Musculares/efeitos dos fármacos , Proteínas Musculares/metabolismo , Músculo Esquelético/efeitos dos fármacos , Fatores de Regulação Miogênica/genética , Fatores de Regulação Miogênica/metabolismo , Músculo Quadríceps/efeitos dos fármacos , Músculo Quadríceps/metabolismo , RNA Mensageiro/metabolismo , Adulto JovemRESUMO
Lactic acid or lactate, a key byproduct of anaerobic glycolysis, plays pivotal roles in routine metabolism. An increase in lactic acid is observed in various pathological conditions such as cancer, diabetes, genetic mitochondrial disease, and aging. While several groups have proposed small molecule inhibitors to reduce circulating lactic acid, there are few clinically relevant ways to manage acute or chronic elevations in lactic acid in patients. In addition, recent evidence suggests that lactic acid exchanges between the gut, blood, and peripheral tissues, and professional marathon runners harbor specific gut microbial species that more efficiently metabolize lactic acid. Inspired by these findings, this work sought to engineer probiotic B. subtilis strains to express lactate oxidase that could increase circulating lactic acid catabolism after delivery to the gut. After optimization, oral administration of engineered B. subtilis to the gut of mice reduced the elevation in blood lactic acid levels after exogenous lactic acid challenge without affecting normal gut microbiota composition, inflammation or liver enzymes. Taken together, through the oral delivery of engineered probiotics to the gastrointestinal tract, our proof-of-concept study offers a new opportunity to therapeutically target diseases where blood lactic acid is elevated, and provides a new approach to "knocking down" metabolites to help understand the roles of metabolites in host physiological and pathological processes.
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BACKGROUND: The FRG1-transgenic mouse displays muscle dysfunction and atrophy reminiscent of fascioscapulohumeral muscular dystrophy (FSHD) and could provide a model to determine potential therapeutic interventions. METHODS: To determine if FRG1 mice benefit from treatments that improve muscle mass and function, mice were treated with creatine alone (Cr) or in combination with treadmill exercise (CrEX). RESULTS: The CrEx treatment increased quadriceps weight, mitochondrial content (cytochome c oxidase (COX) activity, COX subunit one and four protein), and induced greater improvements in grip strength and rotarod fall speed. While Cr increased COX subunits one and four protein, no effect on muscle mass or performance was found. Since Cr resulted in no functional improvements, the benefits of CrEx may be mediated by exercise; however, the potential synergistic action of the combined treatment cannot be excluded. CONCLUSION: Treatment with CrEx attenuates atrophy and muscle dysfunction associated with FRG1 overexpression. These data suggest exercise and creatine supplementation may benefit individuals with FSHD.
Assuntos
Creatina/farmacologia , Músculo Esquelético/efeitos dos fármacos , Distrofia Muscular Facioescapuloumeral/tratamento farmacológico , Condicionamento Físico Animal/fisiologia , Proteínas/metabolismo , Animais , Creatina/uso terapêutico , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Força da Mão/fisiologia , Camundongos , Camundongos Transgênicos , Proteínas dos Microfilamentos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Atividade Motora/efeitos dos fármacos , Atividade Motora/fisiologia , Músculo Esquelético/metabolismo , Distrofia Muscular Facioescapuloumeral/genética , Distrofia Muscular Facioescapuloumeral/metabolismo , Proteínas/genética , Proteínas de Ligação a RNARESUMO
OBJECTIVE: The epidermal barrier is renewed by the activation, proliferation, and differentiation of keratinocyte stem cells after injury and aging impedes this repair process through undefined mechanisms. We previously identified a gene signature of metabolic dysfunction in aged murine epidermis, but the precise regulators of epidermal repair and age-related growth defects are not well established. Aged mouse models as well as mice with conditional epidermal loss of the metabolic regulator peroxisome proliferator-activated receptor gamma coactivator-1 alpha (Pgc-1α) were used to explore the cellular pathways which control skin repair after injury and stress. METHODS: Aged mice or those with epidermal Pgc-1α deletion (epiPgc-1α KO) and young or Pgc1afl/fl controls were subjected to wound injury, UVB exposure or the inflammatory agent TPA. In vivo and ex vivo analyses of wound closure, skin structure, cell growth and stem cell differentiation were used to understand changes in epidermal re-growth and repair resulting from aging or Pgc-1α loss. RESULTS: Aging impairs epidermal re-growth during wound healing and results in lower expression of Pgc-1α. Mice with conditional deletion of epidermal Pgc-1α exhibit greater inflammation- and UVB-induced cell differentiation, reduced proliferation, and slower wound healing. epiPgc-1α KO mice also displayed reduced keratinocyte NAD+ levels, shorter telomeres, and greater poly ADP-ribosylation, resulting in enhanced stress-stimulated p53 and p21 signaling. When NAD+ was reduced by Pgc-1α loss or pharmacologic inhibition of NAD+ synthesis, there was reduced stress-induced proliferation, increased differentiation, and protection against DNA damage via enhanced epidermal shedding. Similarly, aged mice exhibit disrupted epidermal NAD+ homeostasis and enhanced p53 activation, resulting in p21 growth arrest after wounding. NAD+ precursor treatment restores epidermal growth from old skin to that of young. CONCLUSIONS: Our studies identify a novel role for epidermal Pgc-1α in controlling epidermal repair via its regulation of cellular NAD+ and downstream effects on p53-driven growth arrest. We also establish that parallel mechanisms are evident in aged epidermis, showing that NAD+ signaling is an important controller of physiologic skin repair and that dysfunction of this pathway contributes to age-related wound repair defects.
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NAD , PPAR gama , Envelhecimento/metabolismo , Animais , Homeostase , Camundongos , Camundongos Endogâmicos C57BL , NAD/metabolismo , PPAR gama/metabolismo , Células-Tronco/metabolismo , Proteína Supressora de Tumor p53RESUMO
Aging results in a chronic, proinflammatory state which can promote and exacerbate age-associated diseases. In contrast, physical activity in older adults improves whole body health, protects against disease, and reduces inflammation, but the elderly are less active making it difficult to disentangle the effects of aging from a sedentary lifestyle. To interrogate this interaction, we analyzed peripheral blood collected at rest and postexercise from 68 healthy younger and older donors that were either physically active aerobic exercisers or chronically sedentary. Subjects were profiled for 44 low-abundance cytokines, chemokines, and growth factors in peripheral blood. At rest, we found that regular physical activity had no impact on the age-related elevation in circulating IL-18, eotaxin, GRO, IL-8, IP-10, PDGF-AA, or RANTES. Similarly, there was no impact of physical activity on the age-related reduction in VEGF, EGF, or IL-12 (p70). However, older exercisers had lower resting plasma fractalkine, IL-3, IL-6, and TNF-α compared to sedentary older adults. In contrast to our resting characterization, blood responses following acute exercise produced more striking difference between groups. Physically active younger and older subjects increased over 50% of the analyzed factors in their blood which resulted in both unique and overlapping exercise signatures. However, sedentary individuals, particularly the elderly, had few detectable changes in response to exercise. Overall, we show that long-term physical activity has a limited effect on age-associated changes in basal cytokines and chemokines in the healthy elderly, yet physically active individuals exhibit a broader induction of factors postexercise irrespective of age.
Assuntos
Envelhecimento/sangue , Quimiocinas/sangue , Citocinas/sangue , Exercício Físico/fisiologia , Comportamento Sedentário , Adulto , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/fisiologia , Fator de Crescimento Epidérmico/sangue , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fator de Crescimento Derivado de Plaquetas/análise , Fator A de Crescimento do Endotélio Vascular/sangue , Adulto JovemRESUMO
Epidermal keratinocytes (KCs) rapidly proliferate to repair the skin barrier, and a strict control of division is necessary for healthy tissue homeostasis. However, the pathways that restrain proliferation after epidermal stress are not known. AMPK is an important signaling mediator of energy metabolism previously associated with skin stress and cancer; yet, its explicit impact on KC growth is not known. To examine the requirement of epidermal AMPK in physiologic skin repair, we genetically deleted AMPK within all adult, keratin 14âexpressing KCs of mice. AMPK loss resulted in hyperproliferation and hyperactive mTOR signaling after acute wounding, UVB exposure, and phorbol ester application. This excessive division could be completely blocked by the mTORC1 inhibitor rapamycin. Moreover, we establish that the diabetes drug metformin depends on AMPK to suppress stress-induced KC proliferation. Collectively, these findings show that KC AMPK restrains mTORC1 to control epidermal proliferation after tissue injury.
Assuntos
Adenilato Quinase/metabolismo , Queratinócitos/metabolismo , Pele/patologia , Adenilato Quinase/genética , Animais , Proliferação de Células , Células Cultivadas , Metabolismo Energético , Queratina-14/genética , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Metformina/farmacologia , Camundongos , Camundongos Transgênicos , Sirolimo , Estresse Fisiológico , Raios UltravioletaRESUMO
OBJECTIVE: Advanced glycation end-product (AGE) accumulation is implicated in osteoarthritis (OA) pathogenesis in aging and diabetic populations. Here, we develop a representative nonenzymatic glycation-induced OA cartilage explant culture model and investigate the effectiveness of resveratrol, curcumin, and eugenol in inhibiting AGEs and the structural and biological hallmarks of cartilage degeneration. DESIGN: Bovine cartilage explants were treated with AGE-bovine serum albumin, threose, and ribose to determine the optimal conditions that induce physiological levels of AGEs while maintaining chondrocyte viability. AGE crosslinks, tissue stiffness, cell viability, metabolism and senescence, nitrite release and loss of glycosaminoglycans were assessed. Explants were cotreated with resveratrol, curcumin, or eugenol to evaluate their anti-AGE properties. Blind docking analysis was conducted to estimate binding energies of drugs with collagen II. RESULTS: Treatment with 100 mM ribose significantly increased AGE crosslink formation and tissue stiffness, resulting in reduced chondrocyte metabolism and enhanced senescence. Blind docking analysis revealed stronger binding energies of both resveratrol and curcumin than ribose, with glycation sites along a human collagen II fragment, indicating their increased likelihood of competitively inhibiting ribose activity. Resveratrol and curcumin, but not eugenol, successfully inhibited AGE crosslink formation and its associated downstream biological response. CONCLUSIONS: We establish a cartilage explant model of OA that recapitulates several aspects of aged human cartilage. We find that resveratrol and curcumin are effective anti-AGE therapeutics with the potential to decelerate age-related and diabetes-induced OA. This in vitro nonenzymatic glycation-induced model provides a tool for screening OA drugs, to simultaneously evaluate AGE-induced biological and mechanical changes.
Assuntos
Curcumina , Idoso , Cartilagem/metabolismo , Curcumina/farmacologia , Produtos Finais de Glicação Avançada/metabolismo , Produtos Finais de Glicação Avançada/farmacologia , Humanos , Resveratrol/metabolismo , Resveratrol/farmacologia , Açúcares/metabolismo , Açúcares/farmacologiaRESUMO
The study of long-lived and regenerative animal models has revealed diverse protective responses to stressors such as aging and tissue injury. Spiny mice (Acomys) are a unique mammalian model of skin wound regeneration, but their response to other types of physiological skin damage has not been investigated. In this study, we examine how spiny mouse skin responds to acute UVB damage or chronological aging compared to non-regenerative C57Bl/6 mice (M. musculus). We find that, compared to M. musculus, the skin epidermis in A. cahirinus experiences a similar UVB-induced increase in basal cell proliferation but exhibits increased epidermal turnover. Notably, A. cahirinus uniquely form a suprabasal layer co-expressing Keratin 14 and Keratin 10 after UVB exposure concomitant with reduced epidermal inflammatory signaling and reduced markers of DNA damage. In the context of aging, old M. musculus animals exhibit typical hallmarks including epidermal thinning, increased inflammatory signaling and senescence. However, these age-related changes are absent in old A. cahirinus skin. Overall, we find that A. cahirinus have evolved novel responses to skin damage that reveals new aspects of its regenerative phenotype.
Assuntos
Envelhecimento/efeitos da radiação , Camundongos/fisiologia , Pele/efeitos da radiação , Raios Ultravioleta/efeitos adversos , Animais , Proliferação de Células/efeitos da radiação , Senescência Celular/efeitos da radiação , Células Epidérmicas/citologia , Células Epidérmicas/efeitos da radiação , Epiderme/fisiologia , Epiderme/efeitos da radiação , Feminino , Masculino , Camundongos Endogâmicos C57BL , Pele/citologiaRESUMO
Obesity is linked with insulin resistance and is characterized by excessive accumulation of adipose tissue due to chronic energy imbalance. Increasing thermogenic brown and beige adipose tissue futile cycling may be an important strategy to increase energy expenditure in obesity, however, brown adipose tissue metabolic activity is lower with obesity. Herein, we report that the exposure of mice to thermoneutrality promotes the infiltration of white adipose tissue with mast cells that are highly enriched with tryptophan hydroxylase 1 (Tph1), the rate limiting enzyme regulating peripheral serotonin synthesis. Engraftment of mast cell-deficient mice with Tph1-/- mast cells or selective mast cell deletion of Tph1 enhances uncoupling protein 1 (Ucp1) expression in white adipose tissue and protects mice from developing obesity and insulin resistance. These data suggest that therapies aimed at inhibiting mast cell Tph1 may represent a therapeutic approach for the treatment of obesity and type 2 diabetes.
Assuntos
Resistência à Insulina/fisiologia , Mastócitos/metabolismo , Obesidade/etiologia , Serotonina/biossíntese , Triptofano Hidroxilase/metabolismo , Tecido Adiposo Branco/metabolismo , Tecido Adiposo Branco/patologia , Animais , Dieta Hiperlipídica/efeitos adversos , Metabolismo Energético/fisiologia , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Obesidade/prevenção & controle , Serotonina/genética , Termogênese , Triglicerídeos/metabolismo , Triptofano Hidroxilase/genética , Proteína Desacopladora 1/metabolismoRESUMO
Serotonin is a phylogenetically ancient biogenic amine that has played an integral role in maintaining energy homeostasis for billions of years. In mammals, serotonin produced within the central nervous system regulates behavior, suppresses appetite, and promotes energy expenditure by increasing sympathetic drive to brown adipose tissue. In addition to these central circuits, emerging evidence also suggests an important role for peripheral serotonin as a factor that enhances nutrient absorption and storage. Specifically, glucose and fatty acids stimulate the release of serotonin from the duodenum, promoting gut peristalsis and nutrient absorption. Serotonin also enters the bloodstream and interacts with multiple organs, priming the body for energy storage by promoting insulin secretion and de novo lipogenesis in the liver and white adipose tissue, while reducing lipolysis and the metabolic activity of brown and beige adipose tissue. Collectively, peripheral serotonin acts as an endocrine factor to promote the efficient storage of energy by upregulating lipid anabolism. Pharmacological inhibition of serotonin synthesis or signaling in key metabolic tissues are potential drug targets for obesity, type 2 diabetes, and nonalcoholic fatty liver disease (NAFLD).
Assuntos
Serotonina/metabolismo , Tecido Adiposo Marrom/metabolismo , Tecido Adiposo Branco/metabolismo , Animais , Metabolismo Energético , Humanos , Metabolismo dos Lipídeos , Serotonina/fisiologia , Transdução de SinaisRESUMO
The discovery of brown adipose tissue (BAT) in adults has sparked interest in its role as a therapeutic target in metabolic disorders. Infrared thermography is a promising way to quantify BAT; however, a standardized methodology has not been established. This study aims to establish a standardized and reproducible protocol to measure thermal response to cold in the supraclavicular area using thermographic imaging. In Phase 1, we compared the thermal response to 12 °C cold after acclimation at either 32 °C or room temperature using thermographic imaging. Repeatability of the 32 °C acclimation trial was studied in a second group in Phase 2. Phase 1 included 28 men (mean age 23.9 ± 5.9 y; mean BMI 25.2 ± 3.9 kg/m2) and Phase 2 included 14 men (mean age 20.9 ± 2.4 y; mean BMI 23.6 ± 3.1 kg/m2). The thermal response was greater after 32 °C than after room temperature acclimation (0.22 ± 0.19 vs 0.13 ± 0.17 °C, p = 0.05), was not related to outdoor temperature (r = -0.35, p = 0.07), did not correlate with supraclavicular fat (r = -0.26, p = 0.21) measured with dual-energy x-ray absorptiometry and was repeatable [ICC 0.69 (0.14-0.72)]. Acclimation at 32 °C followed by cold generates a reproducible change in supraclavicular skin temperature measurable by thermal imaging that may be indicative of BAT metabolic activity.
Assuntos
Tecido Adiposo Marrom/anatomia & histologia , Tecido Adiposo Marrom/fisiologia , Temperatura Cutânea , Termografia/métodos , Aclimatação , Adolescente , Adulto , Temperatura Baixa , Humanos , Masculino , Adulto JovemRESUMO
OBJECTIVE: Fibroblast growth factor 21 (FGF21) shows great potential for the treatment of obesity and type 2 diabetes, as its long-acting analogue reduces body weight and improves lipid profiles of participants in clinical studies; however, the intracellular mechanisms mediating these effects are poorly understood. AMP-activated protein kinase (AMPK) is an important energy sensor of the cell and a molecular target for anti-diabetic medications. This work examined the role of AMPK in mediating the glucose and lipid-lowering effects of FGF21. METHODS: Inducible adipocyte AMPK ß1ß2 knockout mice (iß1ß2AKO) and littermate controls were fed a high fat diet (HFD) and treated with native FGF21 or saline for two weeks. Additionally, HFD-fed mice with knock-in mutations on the AMPK phosphorylation sites of acetyl-CoA carboxylase (ACC)1 and ACC2 (DKI mice) along with wild-type (WT) controls received long-acting FGF21 for two weeks. RESULTS: Consistent with previous studies, FGF21 treatment significantly reduced body weight, adiposity, and liver lipids in HFD fed mice. To add, FGF21 improved circulating lipids, glycemic control, and insulin sensitivity. These effects were independent of adipocyte AMPK and were not associated with changes in browning of white (WAT) and brown adipose tissue (BAT). Lastly, we assessed whether FGF21 exerted its effects through the AMPK/ACC axis, which is critical in the therapeutic benefits of the anti-diabetic medication metformin. ACC DKI mice had improved glucose and insulin tolerance and a reduction in body weight, body fat and hepatic steatosis similar to WT mice in response to FGF21 administration. CONCLUSIONS: These data illustrate that the metabolic improvements upon FGF21 administration are independent of adipocyte AMPK, and do not require the inhibitory action of AMPK on ACC. This is in contrast to the anti-diabetic medication metformin and suggests that the treatment of obesity and diabetes with the combination of FGF21 and AMPK activators merits consideration.
Assuntos
Acetil-CoA Carboxilase/metabolismo , Fatores de Crescimento de Fibroblastos/farmacologia , Glucose/metabolismo , Proteínas Quinases/metabolismo , Quinases Proteína-Quinases Ativadas por AMP , Adipócitos/metabolismo , Animais , Homeostase , Metabolismo dos Lipídeos/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Camundongos , Proteínas Quinases/genéticaRESUMO
Premature birth in conjunction with extremely low birth weight (<1 kg, ELBW) is associated with insulin resistance and increased cardiometabolic health risk compared to birth at full term with normal birth weight (NBW). However, little is known regarding the biologic mediators of these effects. Abdominal and ectopic lipid accumulation is linked to insulin resistance and metabolic dysfunction, yet whether ELBW survivors are predisposed to aberrant lipid deposition in adulthood is unknown. We used magnetic resonance imaging in a cohort of 16 NBW and 29 ELBW participants to determine if ELBW survivors have differences in pancreatic, hepatic, subcutaneous and visceral fat distribution compared to NBW participants. ELBW individuals had a higher proportion of liver and pancreatic fat compared to NBW subjects (P < 0.05). Abdominal subcutaneous fat, but not visceral fat, area was higher in ELBW survivors compared to NBW individuals. In multivariate analyses, tissue fat measures were most highly related to BMI and sex, but not preterm birth. This work highlights that fat deposition is enhanced in adults born preterm and suggests that ectopic fat accretion driven by their relatively greater adiposity may contribute to the higher rates of metabolic dysfunction seen in ELBW survivors.