RESUMEN
Nrf2 is a master regulator of oxidative stresses through the induction of anti-oxidative genes. Nrf2 plays roles in maintaining murine hematopoietic stem cells and fly intestinal stem cells. The canonical Notch signaling pathway is also crucial for maintaining several types of adult stem cells including muscle stem cells (satellite cells). Here, we show that Dll1 induced Nrf2 expression in myogenic cells. In addition, primary targets of Notch signaling, Hesr1 and Hesr3, were involved in the up-regulation of Nrf2 mRNA and expression of its target genes. In vitro, Nrf2 had anti-myogenic and anti-proliferative effects on primary myoblasts. In vivo, although Nrf2-knockout mice showed decreased expression of its target genes in muscle stem cells, adult muscle stem cells of Nrf2-knockout mice did not exhibit the phenotype. Taken together, in muscle stem cells, the Notch-Hesr-Nrf2 axis is a pathway potentially inducing anti-oxidative genes, but muscle stem cells either do not require Nrf2-mediated anti-oxidative gene expression or they have a complementary system compensating for the loss of Nrf2.
Asunto(s)
Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Proteínas de Ciclo Celular/genética , Factor 2 Relacionado con NF-E2/genética , Receptores Notch/metabolismo , Células Satélite del Músculo Esquelético/citología , Células Madre Adultas/citología , Animales , Antioxidantes/metabolismo , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Células CHO , Proteínas de Unión al Calcio , Proteínas de Ciclo Celular/metabolismo , Diferenciación Celular/genética , Línea Celular , Cricetulus , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Ratones , Ratones Noqueados , Células Musculares/citología , Células Musculares/metabolismo , Desarrollo de Músculos/genética , Factor 2 Relacionado con NF-E2/metabolismo , Células Satélite del Músculo Esquelético/metabolismo , Transducción de SeñalRESUMEN
Leukocyte common antigen-related molecule (LAR) is a receptor-like protein tyrosine phosphatase (PTPase) with two PTPase domains. In the present study, we detected the expression of LAR in the brain, kidney, and thymus of mice using anti-LAR PTPase domain subunit monoclonal antibody (mAb) YU1. In the thymus, LAR was expressed on CD4(-)CD8(-) and CD4(-)CD8(low) thymocytes. The development of thymocytes in CD45 knockout mice is blocked partially in the maturation of CD4(-)CD8(-) to CD4(+)CD8(+). We postulated that LAR regulates Lck and Fyn in the immature thymocytes. Transfection of wild-type LAR activated extracellular signal-regulated kinase signal transduction pathway in CD45-deficient Jurkat cells stimulated with anti-CD3 mAb. LAR mutants, with Cys to Ser mutation in the catalytic center of PTPase D1, bound to tyrosine-phosphorylated Lck and Fyn, and LAR PTPase domain 2 was tyrosine phosphorylated by Fyn tyrosine kinase. The phosphorylated LAR was associated with Fyn Src homology 2 domain. Moreover, LAR dephosphorylated phosphorylated tyrosine residues in both the COOH terminus and kinase domain of Fyn in vitro. Our results indicate that Lck and Fyn would be substrates of LAR in immature thymocytes and that each LAR PTPase domain plays distinct functional roles in phosphorylation and dephosphorylation.