| Tbr1 is a transcription factor of T-box brain protein family which is encoded by TBR1.It is a key factor protein affect vertebrate fetal development,especially in embryonic cerebral cortex.It regulates the development of neurons after mitosis in the cerebral cortex.The cerebral cortex is an important organ of central nervous system during evolution.The lamellar structures with a specific neurons distribution is one of the most significant features of cerebral cortex.Neurons in cerebral cortex originate from neural progenitor cells of ependyma.The neural proliferation,differentiation and migration can be carried out in developing cerebral cortex smoothly.The neuronal migration and specialization are influenced by cell's interactions,molecular regulation and gene expression.Tbr1 is also playing an important role in the process.Tbr1 has an important relationship with axon path finding and the development of cortical lamination.Therefore,scientists want to explore the functions of Tbr1 in the process of brain development.PC12 cells may differentiate into neuron-like cells under the action of inducible factors.Therefore,it would be good model for us to understand Tbr1 how to express in PC12 cells and regulate cell differentiation.Finally,iPSCs(induced pluripotent stem cells)are the pluripotent stem cells,which are similar to embryonic stem cells.Recently,iPSCs can be 3D-cultured into cerebral organoid,therefore,they provided us opportunity to study Tbr1 ex-vivo without ethic problems.Objective Our aim is to explore the function of Tbr1 gene in cell differentiation and neural development through animal experiments,cell cultures and cerebral organoid cultures.Methods(1)The brains of Kunming mice from embryonic day 16.5(E16.5)to postnatal day(P14)were used for immunofluorescent staining to visualize the expression of Tbr1 in neocortex,entorhinal cortex and hippocampus.(2)PC12 cells were induced to differentiate into neuron like cells by RA,and then the expression of Tbr1 in cells was detected by immunocytochemical method during the whole process of cell differentiation.(3)iPSCs was used as experimental materials to 3D-culture cerebral organoid,and immunofluorescent staining was used to detect the expression of Tbr1 in cerebral organoid.Results(1)Tbr1's expression was mainly located in cortical plate of neocortex and entorhinal cortex,especially in the cortical subplate or layer ? of cortices above.(2)In dentate gyrus,Tbr1 positive cells were also located in granular layer,and finally were found inner-granular layer after P7.According to their location and histogenesis,these Tbr1 positive cells should be the migrating neurons and newborn neurons in the cortical plate.(3)During the differentiation of PC12 cells,the expression of Tbr1 gradually weakened.With MAP2 expression in the cells strongly,Tbr1 did not expressed anymore.(4)MAP2 positive cells and Tbr1 positive cells were sequentially arranged in the neuroepithelium at cerebral organoid,which shows that the migration of Tbr1 positive neurons in the process of migration is accompanied by the differentiation and maturation of the cells.Conclusion(1)Tbr1 is expressed in newborn neurons specifically,and it plays a key role in cell migration and neural differentiation during cerebral development.(2)Tbr1 is involved in the cortical lamination and affects the processes of cell migration and neural differentiation obviously.(3)During cell differentiation,the expression of Tbr1 decreased,suggesting Tbr1 was closely related to the process of cell differentiation.(4)Tbr1 may guide the differentiation of newborn neurons,and Tbr1 is a key factor which affecting the neural induction culture process of cerebral organoid. |
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