The Identification Of The Promoter And Enhancer Of Rb1 Gene

The retinoblastoma susceptibility gene(Rb1)is an important tumor suppressor gene during the tumorigeneses,which is also involved in the multiple physiological processes,including cell cycle,cellular apoptosis,and cell differentiation.The interaction between Rb1 and E2F1/DP1 plays a pivotal role in the cell cycle regulation and cellular apoptosis,while the association between Rb1 and myogenic transcription factor(MRF)is required for the skeletal muscle development.Rb1 can inhibit cell cycle progression and promote differentiation,which is also required for the muscle differentiation program and myogenic transcription.In the early study,murine Rb1 6 kb promoter directed the transgenic reporter expression exclusively to the central and peripheral nervous system.However,it was unable to recapitulate Rb1 transcription in murine embryonic somite.It is still not well understood the mechanisms of the transcriptional regulation of Rb1 during skeletal muscle development.In the present studies,we have utilized a number of techniques,including bioinformatic analysis,transgenic mice model,transcriptional assays,and mutagenic analysis.In summary,we have made several discoveries:(1)we have identified the promoter and enhancer of the Rb1 gene through bioinformatics analysis,and then analyzed the function of these two regulatory elements through C2C12 cells.We have observed a significant synergistic effect between the promoter and enhancer;(2)we have successfully constructed the transgenic vector promoter-Hsp68-LacZ-enhancer,generated transgenic Rb1-LacZ murine model,and characterized the LacZ reporter expression in the embryonic somite and adult skeletal muscle;(3)the transcriptional assays have shown that the mutation of the E-box sites in the promoter and enhancer resulted in the significant decrease of the reporter activity;(4)MRFs can transactivate the Rb1 reporter containing the promoter and enhancer.Our discoveries will provide new insights into the comprehensive understanding of the transcription regulation of Rb1 gene.