Mechanistic Study Of The Regulatory Effect Of TEAD1 On Embryonic Cardiovascular Development Through Targeting Pitx2c And Myocardin

Background and aims:The heart is the first functional organ formed during mammalian development.Vasculogenesis and angiogenesis are the critical steps in cardiovascular development.Blood and nutrients are pumped through the cardiovascular system to the whole body,which is very important for embryonic development.Cardiomyocytes(CMCs)and vascular smooth muscle cells(VSMCs)are the major components of the cardiovascular system.The impaired proliferation and differentiation of CMCs and VSMCs could lead to kinds of cardiovascular diseases.TEAD1 specifically binds to the MCAT element in CMCs and VSMCs to promote muscle-specific gene expression under the synergistic action of SRF and Myocardin.Pitx2 is the determination factors of left-right asymmetry during cardiovascular development.Pitx2c and myocardin have been shown to play critical roles in CMCs/VSMCs differentiation.However,the mechanisms that regulate the expression of these two critical transcription cofactors,and the functional relationship between Pitx2 and myocardin in the regulation of smooth muscle-specific gene expression remain elusive.The role of TEAD1 in vascular development and the relationship between TEAD1 and Pitx2c is unknown.In this study,CMCs/VSMCs-specific deletion of TEAD1 as directed by SM22-Cre transgene are used to reveal the role of TEAD1 in cardiovascular development,especially in VSMCs differentiation.The illumination of this mechanisms is expected to provide new idea for prevention and treatment of cardiovascular disease.Methods:1.In vivo,To investigate cell specific roles of TEAD1,we generated TEAD1 floxed mice and ablated TEAD1 in CMCs and VSMCs by crossing SM22a-Cre +,TEAD1F/W mice with TEAD1F/F,mTmG+/+ mice.2.In vitro,To demonstrate the mechanisms of TEAD1 in VSMCs differentiation.Luciferase reporter assay and ChIP assay were performed using TEAD1 deficient VSMCs and MEFs.Results:1.CMCs/VSMCs-specific deletion of TEAD1 led to embryonic lethality by E14.5 in mice due to cardiovascular defects including severe hypoplastic cardiac and vascular walls.,as a result of impaired CMCs/VSMCs proliferation.Whole RNA-seq data revealed that deletion of TEAD1 in CMCs and VSMCs significantly down-regulated expression of contractile muscle genes and key transcription factors including myocardin and Pitx2c,which have been shown critical for differentiation of CMCs and VSMCs.2.In vitro studies demonstrated that myocardin and Pitx2c rescued TEAD1-dependent defects in VSMCs differentiation.We further identified Pitx2c as a novel transcriptional target of TEAD1,and the function of Pitx2c exhibited synergy with myocardin in promoting the differentiation of VSMCs.Conclusion:Our study not only reveals a novel and critical role of the Hippo signaling effector,TEAD1,in embryonic cardiovascular development in mice,but we have identified a novel regulatory mechanism.TEAD1 directly regulate the critical transcription factors Pitx2c and myocardin to promote the expression of contractile muscle genes,...