RESUMEN
During brain morphogenesis, the mechanisms through which the cell cycle machinery integrates with differentiation signals remain elusive. Here we show that the Rb/E2F pathway regulates key aspects of differentiation and migration through direct control of the Dlx1 and Dlx2 homeodomain proteins, required for interneuron specification. Rb deficiency results in a dramatic reduction of Dlx1 and Dlx2 gene expression manifested by loss of interneuron subtypes and severe migration defects in the mouse brain. The Rb/E2F pathway modulates Dlx1/Dlx2 regulation through direct interaction with a Dlx forebrain-specific enhancer, I12b, and the Dlx1/Dlx2 proximal promoter regions, through repressor E2F sites both in vitro and in vivo. In the absence of Rb, we demonstrate that repressor E2Fs inhibit Dlx transcription at the Dlx1/Dlx2 promoters and Dlx1/2-I12b enhancer to suppress differentiation. Our findings support a model whereby the cell cycle machinery not only controls cell division but also modulates neuronal differentiation and migration through direct regulation of the Dlx1/Dlx2 bigene cluster during embryonic development.
Asunto(s)
Factores de Transcripción E2F/fisiología , Regulación del Desarrollo de la Expresión Génica/fisiología , Proteínas de Homeodominio/biosíntesis , Neurogénesis/fisiología , Proteína de Retinoblastoma/fisiología , Factores de Transcripción/biosíntesis , Animales , Encéfalo/crecimiento & desarrollo , Encéfalo/fisiología , Recuento de Células/métodos , Femenino , Interneuronas/fisiología , Masculino , Ratones , Ratones Noqueados , Ratones Transgénicos , Embarazo , Transducción de Señal/fisiologíaRESUMEN
This study focuses on the impact of aliskiren and (or) glucagon-like peptide-1 analogue on the binding affinity/regulation of endothelin-1 (ET-1) to its receptor subtypes A (ETAR) and B (ETBR) at the level of the coronary endothelium and the cardiomyocytes in a type-1 diabetic rat model. Seven groups were used: (i) normal rats, (ii) rats with induced diabetes, (iii) rats with induced diabetes that were treated with insulin, (iv) rats with induced diabetes that were treated with exendin-4, (v) rats with induced diabetes that were treated with aliskiren, (vi) rats with induced diabetes that were co-treated with insulin plus aliskiren, and (vii) rats with induced diabetes that were co-treated with exendin-4 plus aliskiren. Heart perfusion with [(125)I]-ET-1 was employed to estimate ET-1 binding affinity (τ = 1/K-n) to ETAR and ETBR at the level of the coronary endothelium and the cardiomyocytes. Plasma ET-1 levels were measured using enzyme immunoassay, whereas densities of ETAR and ETBR were detected using Western blot. No significance differences were detected in the τ of ETAR and ETBR between normal and diabetic in cardiomyocytes and the coronary endothelium. Exendin-4 normalized the τ value for ETAR and ETBR on coronary endothelium, while aliskiren normalized it on cardiomyocytes. Furthermore, ETAR and ETBR densities were normalized with monotreatments of aliskiren and exendin-4, compared with up-regulated ETAR and down-regulated ETBR band densities in the diabetic animals. Our data indicate that aliskiren alleviates diabetes-associated hypertrophy in type 1 diabetes mellitus.
Asunto(s)
Amidas/farmacología , Vasos Coronarios/efectos de los fármacos , Diabetes Mellitus Experimental/tratamiento farmacológico , Diabetes Mellitus Tipo 1/tratamiento farmacológico , Endotelina-1/metabolismo , Fumaratos/farmacología , Hipoglucemiantes/farmacología , Insulina/farmacología , Miocitos Cardíacos/efectos de los fármacos , Péptidos/farmacología , Receptor de Endotelina A/efectos de los fármacos , Receptor de Endotelina B/efectos de los fármacos , Ponzoñas/farmacología , Animales , Cardiomegalia/etiología , Cardiomegalia/metabolismo , Cardiomegalia/prevención & control , Vasos Coronarios/metabolismo , Diabetes Mellitus Experimental/inducido químicamente , Diabetes Mellitus Experimental/complicaciones , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Tipo 1/inducido químicamente , Diabetes Mellitus Tipo 1/complicaciones , Diabetes Mellitus Tipo 1/metabolismo , Endotelio Vascular/efectos de los fármacos , Endotelio Vascular/metabolismo , Exenatida , Masculino , Miocitos Cardíacos/metabolismo , Ratas , Ratas Sprague-Dawley , Receptor de Endotelina A/metabolismo , Receptor de Endotelina B/metabolismo , Estreptozocina , Factores de TiempoRESUMEN
This study focuses on the effects of long-term renin-angiotensin system suppression and/or incretin mimetic therapies on the regulation and binding affinity of GLP-1 to its receptor in the coronary endothelium (CE) and cardiomyocytes (CMs) of type 1 diabetic male Sprague-Dawley rats. The groups assessed are normal (N), streptozotocin-induced diabetic (D), Insulin treated (DI), Exendin-4 treated (DE), Aliskiren treated (DA), cotreated with Insulin and Aliskiren (DIA) and cotreated with exendin-4 and Aliskiren (DEA). Heart perfusion with (125)I-GLP-1 was performed to estimate GLP-1 binding affinity (τ = 1/k-n) to its receptor in the heart. Western Blotting was assessed to determine the expression variation of GLP-1 receptor in the heart. Plasma GLP-1 levels were measured using Enzyme-Linked Immunosorbent Assay (ELISA). Diabetes decreased the τ value on CE and increased it on CMs compared to normal. The combination of Exendin-4 with Aliskiren showed a normalizing effect on the binding affinity of GLP-1 at the coronary endothelium, while at the cardiomyocyte level Exendin-4 treatment alone was the most effective.