| Astrocytes are characteristic star-shaped glial cells in the brain and spinal cord. The proportion of astrocytes in the brain is not well defined. Depending on the counting technique used, studies have found that the astrocyte proportion 80% of all cells in CNS.They perform many functions, including biochemical support of endothelial cells that form the blood–brain barrier, provision of nutrients to the nervous tissue, maintenance of extracellular ion balance, and a role in the repair and scarring process of the brain and spinal cord following traumatic injuries.Dicer, also known as endoribonuclease Dicer or helicase with RNase motif, is an enzyme that in humans is encoded by the DICER1 gene. Being part of the RNase III family, Dicer cleaves double-stranded RNA(dsRNA) and pre-microRNA(pre-miRNA) into short double-stranded RNA fragments called small interfering RNA and microRNA respectively. These fragments are approximately 20-25 base pairs long with a two-base overhang on the 3’ end. Dicer facilitates the activation of the RNA-induced silencing complex(RISC), which is essential for RNA interference.We report that microRNAs play an essential role in the differentiation and maturation of fibrous astrocytes in the spinal cord tissues. In hGFAP /Dicer conditional mutants, the initial generation of astrocyte progenitor cells was normal in the spinal cord. However, there was a much reduced number of GFAP+ astrocyte with shorter and branched processes in the white matter of mutant tissues.In order to find out the role of GFAP+ astrocyte plays in mature CNS, we apply mGFAP/dicer conditional mutants. By observing the slide of mutants SC and brain, we find dicer in astrocytes play a significant role in CNS homeostasis. |
