ABSTRACT
Objective:To investigate the influence of miR-7 knock down on the development of CD 4+SP cells in the thymus in mice,and preliminary explore its possible mechanism.Methods:The changes of volume ,weight and total cell counts of thymus in miR-7 knock down (miR-7KD) mice were observed compared with Wild-type(WT)mice;the pathological changes of thymus were observed by HE staining.FACS analysis was performed on the proportion ,as well as the expression level of CD44 and CD62L,of thymus CD4+single positive (SP) cells.Meanwhile,the proliferation percentage of CD4+SP cells was measured by Ki-67 staining.The apoptosis percentage of CD4+SP cells was analyzed by FACS.The changes on the transduction of ERK 1/2 pathways were determined by Western blot.Results:Compared with WT mice ,the size,weight and total cell number of thymus were marked reduced in miR-7KD mice( P<0.05 );moreover ,pathological change also was presented.The proportion and total cell number of thymus CD 4+SP cells were marked decreased ( P<0.05 ).Furthermore ,the expression level of CD 44 and proliferation percentage ,as well as apoptosis percentage ,of CD4+SP cells were obviously increased (P<0.05),however,the expression level of CD62L of CD4+SP cells were decreased (P<0.05). Finally,the level of total ERK1/2 and phosphor-ERK1/2 was decreased obviously ( P<0.05 ).Conclusion: miR-7 knock down can affect the development of CD 4+SP cells in the thymus , which might be closely related to the cell activation state and altered the transduction of ERK1/2 pathways.