RESUMEN
Cellular reprogramming using chemically defined conditions, without genetic manipulation, is a promising approach for generating clinically relevant cell types for regenerative medicine and drug discovery. However, small-molecule approaches for inducing lineage-specific stem cells from somatic cells across lineage boundaries have been challenging. Here, we report highly efficient reprogramming of mouse fibroblasts into induced neural stem cell-like cells (ciNSLCs) using a cocktail of nine components (M9). The resulting ciNSLCs closely resemble primary neural stem cells molecularly and functionally. Transcriptome analysis revealed that M9 induces a gradual and specific conversion of fibroblasts toward a neural fate. During reprogramming specific transcription factors such as Elk1 and Gli2 that are downstream of M9-induced signaling pathways bind and activate endogenous master neural genes to specify neural identity. Our study provides an effective chemical approach for generating neural stem cells from mouse fibroblasts and reveals mechanistic insights into underlying reprogramming processes.
Asunto(s)
Reprogramación Celular/genética , Medios de Cultivo/farmacología , Fibroblastos/citología , Células-Madre Neurales/citología , Transducción de Señal/genética , Activación Transcripcional/genética , Animales , Linaje de la Célula/efectos de los fármacos , Reprogramación Celular/efectos de los fármacos , Embrión de Mamíferos/citología , Factor 2 de Crecimiento de Fibroblastos/metabolismo , Fibroblastos/efectos de los fármacos , Fibroblastos/metabolismo , Proteínas Hedgehog/metabolismo , Ratones , Células Madre Multipotentes/citología , Células Madre Multipotentes/efectos de los fármacos , Células Madre Multipotentes/metabolismo , Células-Madre Neurales/efectos de los fármacos , Células-Madre Neurales/metabolismo , Neuronas/citología , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Transducción de Señal/efectos de los fármacos , Activación Transcripcional/efectos de los fármacosRESUMEN
Apolipoprotein (apo) E4 is the major genetic risk factor for Alzheimer's disease (AD), but the mechanism by which it causes cognitive decline is unclear. In knockin (KI) mice, human apoE4 causes age-dependent learning and memory impairments and degeneration of GABAergic interneurons in the hippocampal dentate gyrus. Here we report two functional apoE4-KI phenotypes involving sharp-wave ripples (SWRs), hippocampal network events critical for memory processes. Aged apoE4-KI mice had fewer SWRs than apoE3-KI mice and significantly reduced slow gamma activity during SWRs. Elimination of apoE4 in GABAergic interneurons, which prevents learning and memory impairments, rescued SWR-associated slow gamma activity but not SWR abundance in aged mice. SWR abundance was reduced similarly in young and aged apoE4-KI mice; however, the full SWR-associated slow gamma deficit emerged only in aged apoE4-KI mice. These results suggest that progressive decline of interneuron-enabled slow gamma activity during SWRs critically contributes to apoE4-mediated learning and memory impairments. VIDEO ABSTRACT.