The Function Of P85 In The Development Of Mouse Cerebral Cortex

The mammalian cerebral cortex is a highly organized structure composed of billions of neurons and glial cells with different morphological functions.It is an important organ for the advanced cognition and regulation of movement.The development of the cerebral cortex begins with the proliferation and differentiation of neural progenitor cells,which determines the number of different types of neurons.Then,the projection neurons migrate along the radial fibers of the glial cells towards the surface of the pia mater.After the "inside-out" migration,the six-layer structure of the cerebral cortex is gradually formed.The neurons eventually acquire layer-specificity at specific locations and form precise synaptic connections and neural networks.Accurate coordination and proper connection of this series of biological processes are necessary for the normal function of the cerebral cortex.With the development of science and technology such as genome sequencing analysis and transcriptome analysis,more and more factors controlling the development of the cerebral cortex or causing neurological diseases have been discovered,one of which is PI3 K and its signaling pathway.Studies have shown that the excessive activation of the PI3K/AKT/mTOR signal pathway is closely related to hemihemopathy.PI3Ks are Classified into three categories,according to the subunits structure and different functions,among which Class I PI3 Ks have the most complex structure and function,including a catalytic subunit and a regulatory subunit.These PI3 Ks,in vivo,can be activated by receptor tyrosine kinases,G protein-coupled receptors,and certain oncogenes,such as Ras,and then use PtdIns(4,5)P2 to generate PIP3 to further produce PtdIns(3,4)P2.These processes will mobilize a series of biological activities,such as cell growth,entering and exiting the cell cycle,cell migration,and cell survival.Interestingly,regulation subunit P85 can regulate the production of PIP3 through different pathways.Therefore,P85?,which contains most complete domains,was selected in this study to investigate its function in the development of the mouse cerebral cortex.In this study,an overexpression plasmid of P85 was constructed.The gene was transfected into late-born neurons or neural progenitor cells by in utero electroporation.Through BrdU labeling,immunofluorescence staining,and laser confocal imaging,we analyzed the function of P85 during mouse cerebral cortex development.We mainly obtained the following results:1.The P85 overexpression plasmid was successfully constructed,and it was transfected into PC12 cells to confirm that the fluorescent protein can be normally expressed.This plasmid can be used for in utero electroporation;2.Overexpression of P85 inhibited the late-born neurons radial migration and had effect on the morphology of migrating neurons.Primary neuron culture showed that overexpression of P85 altered neuronal morphology;neurons that overexpressed P85 in vivo showed significant migration disturbances,and the number of nurites and branches increased significantly,but the growth of the leading processes was affected;3.Overexpression of P85 affected the final layer location of neurons without alternation of the fate of neurons.The neurons overexpressed P85 failed to migrate to the location where the neurons arrived at in the control group on the 7th day after birth,but neurons staying in deep layers of the cerebral cortex can still be labeled by specific markers of neurons,suggesting that the neurons fate decision was not influenced;4.Overexpression of P85 extended the cell cycle of neural progenitor cells and inhibited their proliferation.Using BrdU labeling at different time points,cells at different cell cycle stages were marked.The duration of cell cycle of overexpressed P85 neural progenitor cells was found to be longer than that of control cells,and the number of proliferating cells was markedly reduced.5.Overexpression of P85 inhibited neuronal differentiation.At E18.5,the sections of cerebral cortex were staining with a newborn neurons marker,Brn2,and the results showed that the proportion of newborn neurons within overexpressed P85 neurons was significantly less than the proportion in the control group.In summary,P85 was involved in the regulation of neural cell proliferation,neuronal migration,differentiation and other processes in the development of mouse cerebral cortex.