Retinoblastoma 1 (RB1) modulates the proliferation of chicken preadipocytes.

1. The objective of this study was to reveal the role of chicken RB1 (Gallus gallus RB1, gRB1) in the proliferation of preadipocytes. 2. To measure gene expression of gRB1 in the proliferation of chicken preadipocyte, quantitative real-time PCR was used. The expression levels of gRB1 transiently increased during this process. 3. To detect the effect of gRB1 on the proliferation of chicken preadipocyte, MTT assay and cell-cycle analysis were performed. MTT assay showed that overexpression of gRB1 significantly suppressed (P<0.05) the proliferation of chicken preadipocytes, and knockdown of gRB1 promoted the proliferation of chicken preadipocytes. Cell-cycle analysis showed that the proportion of preadipocytes in the G1 and G2 phases significantly increased (P<0.05), and the proportion of preadipocytes in the S phase significantly decreased (P<.05) after up-regulation of the expression of gRB1. The proportion of preadipocytes in the S phase significantly increased (P<0.05) after down-regulation of gRB1. 4. Quantitative real-time PCR was used to detect the effect of gRB1 on the expression of genes related to proliferation of chicken preadipocytes. Gene expression analysis showed that gRB1 knockdown promoted markers indicating proliferation of Ki-67 (MKi67) expression at 96 h (P<0.05), and overexpression of gRB1 reduced MKi67 expression at 72 h (P<0.05). 5. This study demonstrated that gRB1 inhibited preadipocyte proliferation at least in part by inhibiting the G1 to S phase transition.