Cooperative Activation By GATA4 And STAT3 Of The EGF Promoter

The heart is the first functional organ formed in a human embryo. Coronary heart diseases will occur if there is any dysfunction during the heart embryonic development. GATA4 is an important transcription factor which regulates the cardiac development and differention. GATA4 mutations are associated with the occurrence of coronary heart diseases. EGF (epidermal growth factor) promotes proliferation and inhibits differentiation of ventricular cardiac myocytes. EGF plays very important role in the development and maintains the function of cardiac. However the mechanism underlying the regulation of EGF expression in cardiac remains unknown. In order to clarify the transcription factors regulating the expression of EGF in convenience, we constructed the EGF promoter-reporter gene. This research is mean to find the transcription cofactors interaction with GATA4, and to explore the effection of the interaction on GATA4 transcription activity.In this research, Immunoprecipitation-immunoblotting experiments were conducted to prove STAT3 could interact with GATA4 in vivo. In order to examine whether the interaction between GATA4 and STAT3 is directly or indirectly, GST pull-down and immunoblotting experiments were conducted and the results proved that GATA4 can physically interact with STAT3 directly in vitro. GATA4 interacts with STAT3 independent of the C-Zinc finger, and the SH2 in STAT3 is necessary for their interaction by GATA4 and STAT3 various truncated mutants assay. Then EGF promoter was cloned from rat genomic and cloned into the pGL3-basic vector which contains the gene coding luciferase without promoter. Luciferase reporter assays were conducted and found that GATA4 and STAT3 activate the transcription of EGF promoter in combination.In conclusion, we found GATA4 interact with STAT3 directly in vivo and in vitro. The interaction between GATA4 and STAT3 is dependent on the SH2 within STAT3. Unlike other transcriptional cofactors, STAT3 interact with GATA4 independent of the C-Zinc finger of GATA4. We constructed the EGF promoter-report gene for analysis the transcription activity of EGF promoter. GATA4 and STAT3 activate the transcriptional activity of EGF promoter in cooperation.