RESUMO
We generated human iPS derived neural stem cells and differentiated cells from healthy control individuals and an individual with autism spectrum disorder carrying bi-allelic NRXN1-alpha deletion. We investigated the expression of NRXN1-alpha during neural induction and neural differentiation and observed a pivotal role for NRXN1-alpha during early neural induction and neuronal differentiation. Single cell RNA-seq pinpointed neural stem cells carrying NRXN1-alpha deletion shifting towards radial glia-like cell identity and revealed higher proportion of differentiated astroglia. Furthermore, neuronal cells carrying NRXN1-alpha deletion were identified as immature by single cell RNA-seq analysis, displayed significant depression in calcium signaling activity and presented impaired maturation action potential profile in neurons investigated with electrophysiology. Our observations propose NRXN1-alpha plays an important role for the efficient establishment of neural stem cells, in neuronal differentiation and in maturation of functional excitatory neuronal cells.
Assuntos
Transtorno Autístico/patologia , Proteínas de Ligação ao Cálcio/genética , Deleção de Genes , Células-Tronco Pluripotentes Induzidas/patologia , Proteínas do Tecido Nervoso/genética , Moléculas de Adesão de Célula Nervosa/genética , Células-Tronco Neurais/patologia , Análise de Célula Única/métodos , Potenciais de Ação , Alelos , Transtorno Autístico/genética , Diferenciação Celular , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Células-Tronco Neurais/metabolismo , Neurogênese/genéticaRESUMO
Hyperactive Notch signalling is frequently observed in breast cancer and correlates with poor prognosis. However, relatively few mutations in the core Notch signalling pathway have been identified in breast cancer, suggesting that as yet unknown mechanisms increase Notch activity. Here we show that increased expression levels of GIT1 correlate with high relapse-free survival in oestrogen receptor-negative (ER(-)) breast cancer patients and that GIT1 mediates negative regulation of Notch. GIT1 knockdown in ER(-) breast tumour cells increased signalling downstream of Notch and activity of aldehyde dehydrogenase, a predictor of poor clinical outcome. GIT1 interacts with the Notch intracellular domain (ICD) and influences signalling by inhibiting the cytoplasm-to-nucleus transport of the Notch ICD. In xenograft experiments, overexpression of GIT1 in ER(-) cells prevented or reduced Notch-driven tumour formation. These results identify GIT1 as a modulator of Notch signalling and a guardian against breast cancer growth.