RESUMO
Increased levels of intestinal bile acids (BAs) are a risk factor for colorectal cancer (CRC). Here, we show that the convergence of dietary factors (high-fat diet) and dysregulated WNT signaling (APC mutation) alters BA profiles to drive malignant transformations in Lgr5-expressing (Lgr5+) cancer stem cells and promote an adenoma-to-adenocarcinoma progression. Mechanistically, we show that BAs that antagonize intestinal farnesoid X receptor (FXR) function, including tauro-ß-muricholic acid (T-ßMCA) and deoxycholic acid (DCA), induce proliferation and DNA damage in Lgr5+ cells. Conversely, selective activation of intestinal FXR can restrict abnormal Lgr5+ cell growth and curtail CRC progression. This unexpected role for FXR in coordinating intestinal self-renewal with BA levels implicates FXR as a potential therapeutic target for CRC.
Assuntos
Neoplasias Intestinais/metabolismo , Células-Tronco Neoplásicas/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Animais , Ácidos e Sais Biliares/metabolismo , Linhagem Celular , Proliferação de Células/genética , Neoplasias Colorretais/metabolismo , Ácido Desoxicólico/metabolismo , Regulação Neoplásica da Expressão Gênica/genética , Humanos , Neoplasias Intestinais/genética , Intestinos , Fígado , Camundongos , Camundongos Endogâmicos C57BL , Células-Tronco Neoplásicas/fisiologia , Organoides/metabolismo , Receptores Citoplasmáticos e Nucleares/genética , Fatores de Risco , Transdução de Sinais , Ácido Taurocólico/análogos & derivados , Ácido Taurocólico/metabolismo , Via de Sinalização Wnt/genética , Via de Sinalização Wnt/fisiologiaRESUMO
Islets derived from stem cells hold promise as a therapy for insulin-dependent diabetes, but there remain challenges towards achieving this goal1-6. Here we generate human islet-like organoids (HILOs) from induced pluripotent stem cells and show that non-canonical WNT4 signalling drives the metabolic maturation necessary for robust ex vivo glucose-stimulated insulin secretion. These functionally mature HILOs contain endocrine-like cell types that, upon transplantation, rapidly re-establish glucose homeostasis in diabetic NOD/SCID mice. Overexpression of the immune checkpoint protein programmed death-ligand 1 (PD-L1) protected HILO xenografts such that they were able to restore glucose homeostasis in immune-competent diabetic mice for 50 days. Furthermore, ex vivo stimulation with interferon-γ induced endogenous PD-L1 expression and restricted T cell activation and graft rejection. The generation of glucose-responsive islet-like organoids that are able to avoid immune detection provides a promising alternative to cadaveric and device-dependent therapies in the treatment of diabetes.
Assuntos
Diabetes Mellitus Experimental/imunologia , Diabetes Mellitus Experimental/patologia , Evasão da Resposta Imune , Ilhotas Pancreáticas/citologia , Ilhotas Pancreáticas/imunologia , Organoides/citologia , Organoides/imunologia , Animais , Antígeno B7-H1/genética , Antígeno B7-H1/metabolismo , Linhagem Celular , Epigênese Genética , Feminino , Glucose/metabolismo , Rejeição de Enxerto , Xenoenxertos , Homeostase , Humanos , Tolerância Imunológica , Secreção de Insulina , Transplante das Ilhotas Pancreáticas , Ativação Linfocitária , Masculino , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Organoides/transplante , Linfócitos T/citologia , Linfócitos T/imunologia , Via de Sinalização Wnt/efeitos dos fármacos , Proteína Wnt4/metabolismo , Proteína Wnt4/farmacologiaRESUMO
Inexorable increases in insulin resistance, lipolysis, and hepatic glucose production (HGP) are hallmarks of type 2 diabetes. Previously, we showed that peripheral delivery of exogenous fibroblast growth factor 1 (FGF1) has robust anti-diabetic effects mediated by the adipose FGF receptor (FGFR) 1. However, its mechanism of action is not known. Here, we report that FGF1 acutely lowers HGP by suppressing adipose lipolysis. On a molecular level, FGF1 inhibits the cAMP-protein kinase A axis by activating phosphodiesterase 4D (PDE4D), which separates it mechanistically from the inhibitory actions of insulin via PDE3B. We identify Ser44 as an FGF1-induced regulatory phosphorylation site in PDE4D that is modulated by the feed-fast cycle. These findings establish the FGF1/PDE4 pathway as an alternate regulator of the adipose-HGP axis and identify FGF1 as an unrecognized regulator of fatty acid homeostasis.
Assuntos
Diabetes Mellitus Tipo 2 , Resistência à Insulina , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/metabolismo , Fator 1 de Crescimento de Fibroblastos/metabolismo , Humanos , Insulina/metabolismo , Lipólise/fisiologiaRESUMO
A hypercaloric diet combined with a sedentary lifestyle is a major risk factor for the development of insulin resistance, type 2 diabetes mellitus (T2DM) and associated comorbidities. Standard treatment for T2DM begins with lifestyle modification, and includes oral medications and insulin therapy to compensate for progressive ß-cell failure. However, current pharmaceutical options for T2DM are limited in that they do not maintain stable, durable glucose control without the need for treatment intensification. Furthermore, each medication is associated with adverse effects, which range from hypoglycaemia to weight gain or bone loss. Unexpectedly, fibroblast growth factor 1 (FGF1) and its low mitogenic variants have emerged as potentially safe candidates for restoring euglycaemia, without causing overt adverse effects. In particular, a single peripheral injection of FGF1 can lower glucose to normal levels within hours, without the risk of hypoglycaemia. Similarly, a single intracerebroventricular injection of FGF1 can induce long-lasting remission of the diabetic phenotype. This Review discusses potential mechanisms by which centrally administered FGF1 improves central glucose-sensing and peripheral glucose uptake in a sustained manner. Specifically, we explore the potential crosstalk between FGF1 and glucose-sensing neuronal circuits, hypothalamic neural stem cells and synaptic plasticity. Finally, we highlight therapeutic considerations of FGF1 and compare its metabolic actions with FGF15 (rodents), FGF19 (humans) and FGF21.
Assuntos
Glicemia/efeitos dos fármacos , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/metabolismo , Fator 1 de Crescimento de Fibroblastos/administração & dosagem , Resistência à Insulina , Insulina/metabolismo , Animais , Glicemia/metabolismo , Diabetes Mellitus Tipo 2/diagnóstico , Modelos Animais de Doenças , Feminino , Fator 1 de Crescimento de Fibroblastos/metabolismo , Seguimentos , Humanos , Masculino , Camundongos Endogâmicos C57BL , Distribuição Aleatória , Papel (figurativo) , Resultado do TratamentoRESUMO
MicroRNAs (miRNAs) are negative modulators of gene expression that fine-tune numerous biological processes. miRNA loss-of-function rarely results in highly penetrant phenotypes, but rather, influences cellular responses to physiologic and pathophysiologic stresses. Here, we have reported that a single member of the evolutionarily conserved miR-7 family, miR-7a2, is essential for normal pituitary development and hypothalamic-pituitary-gonadal (HPG) function in adulthood. Genetic deletion of mir-7a2 causes infertility, with low levels of gonadotropic and sex steroid hormones, small testes or ovaries, impaired spermatogenesis, and lack of ovulation in male and female mice, respectively. We found that miR-7a2 is highly expressed in the pituitary, where it suppresses golgi glycoprotein 1 (GLG1) expression and downstream bone morphogenetic protein 4 (BMP4) signaling and also reduces expression of the prostaglandin F2a receptor negative regulator (PTGFRN), an inhibitor of prostaglandin signaling and follicle-stimulating hormone (FSH) and luteinizing hormone (LH) secretion. Our results reveal that miR-7a2 critically regulates sexual maturation and reproductive function by interconnecting miR-7 genomic circuits that regulate FSH and LH synthesis and secretion through their effects on pituitary prostaglandin and BMP4 signaling.
Assuntos
Hipogonadismo/metabolismo , Sistema Hipotálamo-Hipofisário/metabolismo , Infertilidade/metabolismo , MicroRNAs/metabolismo , Transdução de Sinais , Animais , Proteína Morfogenética Óssea 4/genética , Proteína Morfogenética Óssea 4/metabolismo , Feminino , Hormônio Foliculoestimulante/genética , Hormônio Foliculoestimulante/metabolismo , Hormônios Esteroides Gonadais/genética , Hormônios Esteroides Gonadais/metabolismo , Hipogonadismo/genética , Infertilidade/genética , Hormônio Luteinizante/genética , Hormônio Luteinizante/metabolismo , Masculino , Camundongos , Camundongos Knockout , MicroRNAs/genética , Ovário/metabolismo , Receptores de Fatores de Crescimento de Fibroblastos/genética , Receptores de Fatores de Crescimento de Fibroblastos/metabolismo , Sialoglicoproteínas/genética , Sialoglicoproteínas/metabolismo , Testículo/metabolismoRESUMO
Inactivation of transcription factor Foxa1 in mice results in neonatal mortality of unknown cause. Here, we report that ablation of Foxa1 causes impaired development and loss of the subthalamic nucleus (STN). Functional deficits in the STN have been implicated in the etiology of Huntington's and Parkinson's disease. We show that neuronal ablation by Synapsin1-Cre-mediated Foxa1 deletion is sufficient to induce hyperlocomotion in mice. Transcriptome profiling of STN neurons in conditional Foxa1 knockout mice revealed changes in gene expression reminiscent of those in neurodegenerative diseases. We identified Ppargc1a, a transcriptional co-activator that is implicated in neurodegeneration, as a Foxa1 target. These findings were substantiated by the observation of Foxa1-dependent demise of STN neurons in conditional models of Foxa1 mutant mice. Finally, we show that the spontaneous firing activity of Foxa1-deficient STN neurons is profoundly impaired. Our data reveal so far elusive roles of Foxa1 in the development and maintenance of STN function.
Assuntos
Fator 3-alfa Nuclear de Hepatócito/genética , Núcleo Subtalâmico/fisiologia , Animais , Regulação da Expressão Gênica , Técnicas de Inativação de Genes , Genes Essenciais , Genes Reporter , Fator 3-alfa Nuclear de Hepatócito/metabolismo , Hipercinese/genética , Masculino , Camundongos , Camundongos Transgênicos , Doenças Neurodegenerativas/genética , Doenças Neurodegenerativas/metabolismo , Neurônios/metabolismo , Especificidade de Órgãos/genética , Organogênese/genética , Núcleo Subtalâmico/embriologia , TranscriptomaRESUMO
Circulating levels of insulin and glucagon reflect the nutritional state of animals and elicit regulatory responses in the liver that maintain glucose and lipid homeostasis. The transcription factor Foxa2 activates lipid metabolism and ketogenesis during fasting and is inhibited via insulin-PI3K-Akt signaling-mediated phosphorylation at Thr156 and nuclear exclusion. Here we show that, in addition, Foxa2 is acetylated at the conserved residue Lys259 following inhibition of histone deacetylases (HDACs) class I-III and the cofactors p300 and SirT1 are involved in Foxa2 acetylation and deacetylation, respectively. Physiologically, fasting states and glucagon stimulation are sufficient to induce Foxa2 acetylation. Introduction of the acetylation-mimicking (K259Q) or -deficient (K259R) mutations promotes or inhibits Foxa2 activity, respectively, and adenoviral expression of Foxa2-K259Q augments expression of genes involved in fatty acid oxidation and ketogenesis. Our study reveals a molecular mechanism by which glucagon signaling activates a fasting response through acetylation of Foxa2.