| The cerebral cortex orderly development is essential for mammals advanced features establishment.To explore the molecular regulation mechanism in the cortical neurogenesis is significant.Expecially in understanding the process of brain function establishment and neurological disease.DICER is a key enzyme for microRNAs(miRNAs)processing,can be used to clarify the role of miRNAs during neurogenesis progresses.Here,we report Dicer is necessary for the development.Dicer specifically deletion in dorsal cortex by Emx1IRES-Cre,D6-Cre and hGFAP-Cre.The Dicer conditional knockout mice referred t as ED?DD?HD.Genetically removing Dicer caused smaller telencephalon,thinner cortex,and abnormal hippocampus.We use immunofluorescence to test the cortical layer formation by layerspecific makers.Cux1+ late-born neurons and Sox5+ early-born neurons occupied the reversed positions,part of neurons inappropriately expressed lamina fate,or failed to express the appropriately fate.The spatiotemporal specificity of Cre lines determine the specificity phenotype of ED?DD?HD.Firstly,layer I structure was absent only can be detected in ED mice;Then,large of stem-cells apoptosis in ED mice at E14.5 causes neocortical neurons completely to form the layer;Next,neuronal projection was significantly abnormal in ED mice,slightly abnormal in DD.Moreover,Aldh111+ astrocytes increased in DD and HD,severely lost in ED.Finally,hippocampal structure formation failure in ED,DD and HD mice had defective hippocampal structure.Ctip2+ granulosa cells in CA1-CA3 region and GFAP+astrocyte like neural progenitor cells were signicicantly decreased in DD and HD.In summary,we further explored the specific phenotypic differences between ED?DD?HD and analyzed the causes.Cre recombinant enzyme spatiotemporal specificity determine the phenotype specificity.Additional,miRNAs effect the cortical neuron and glia laminar determination during the neurogenesis independent of stem-cells. |
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