MiR9-3/miR9-2 Deficiency Affects Hematopoietic Cell And BMM Of Mice

MicroRNA is a class of short non-coding RNA,mainly involved in the biological function of regulation of gene expression,cell proliferation,differentiation,and apoptosis.Researches showed many miRNAs paticipated in regulation of hematopoietic stem cells（HSCs）,and it had been found to take part in the occurrence and development of tumors by promoting or inhibiting in many blood diseases.However the current researches on the role of miR-9 in regulation of lymphocytes（B and T cells）in hematopoietic system is not perfect.In order to explored the effects of miR9-3 and miR9-2 in the development of HSCs and lymphocytes in hematopoietic system,this study used CRISPR/Cas9 gene editing technology to successfully construct miR9-3^-/-homozygous knockout and miR9-2^+/-heterozygote knockout mice.These two kinds of mice showed enlargement head,reduced weight,and small spleen phenotypes.FACS analysis showed that the development of B cells in spleen,bone marrow and inguinal lymph nodes of these mice were blocked,accompanied by impaired T cell development of thymus,the hematopoietic system of miR9-3^-/-mice was severely damaged and the development of HSCs was blocked.These results suggested that miR9-3 and miR9-2 were essential for the development of the HSCs and lymphatic systems.FACS analysis of WT recipient mice which were transplanted with miR9-3^-/-mice bone marrow cells showed that miR9-3 deficient HSCs and lymphocytes normally developed,indicating that the impeded development of lymphocytes in miR9-3^-/-mice was not due to an intrinsic defect of HSCs.The results of micro-c T scan showed that the relative bone volume and trabecular number of femur in miR9-3^-/-mice were significantly reduced,the degree of trabecular separation was significantly increased,suggesting that miR9-3 played an important role in bone formation.Analysis of existing database by GO（Gene Ontology）showed that Notch 2,Col9AI,Mmp16,Col18AI,Fst,Fbn1,Col27AI,Sh3pxd2B,Vcan,IFT80 and TGF-βR1 are the potential key target genes of miR-9 affecting bone development in mice.This study has important scientific significance for further understanding the role of miR9-3 in the development of hematopoietic stem cells and lymphocytes.