The Acetylation Modification Mediated By P300 And Cardiac Development-related Genes Expression

Objectives Cardiogenesis is a precise process controlled by sequential gene regulatory steps. Heart-specific transcription factors (TFs) GATA4, Nkx2.5, MEF2C and Tbx5 play critical roles in controlling heart development. But the genetic basis for the temporal expression of genes during heart development still remains unclear. Substantial studies displayed gene regulation partly attributes to histone acetylation. However, the functions of individual histone acetyltransferases (HATs) in specific developmental transcription programs are not well elucidated. P300, a histone acetyltransferase and coactivator, plays key role in many physiological processes, moreover our previous study suggests that expression of p300 is developmentally regulated during mouse cardiogenesis, but the underlying molecular mechanism remains elusive. This study was to observe temporal expression of heart-specific transcription factors (TFs) GATA4, Nkx2.5, MEF2c and Tbx5 and the changes of histone acetylation on these genes promoter region during mouse embryonic heart development. And this study was also to investigate if histone acetyltransferase p300 directly controlled dynamic expression of heart-specific transcription factors. These lay the foundations to further clarify the relations between them and congenital heart diseases.Material and Methods The whole hearts from embryonic mice on embryonic days(E)10.5 and 16.5 were collected accordingly, and then total RNA was extracted. Heart-specific transcription factors (TFs) GATA4, Nkx2.5, MEF2C and Tbx5 mRNA from mouse myocardium at differential embryonic days during cardiac development were analyzed by quantitative (Q)-PCR. The levels of histone H3 acetylation on these heart-specific TFs promoter and transcription factor binding sites of p300 to these genes were identified by chromatin immunoprecipitation assays (ChIP).Results1. The present study furnishes a comparative temporal expression map of cardiac transcriptional factors, during murine heart development (E10.5 and E16.5). The mRNA levels of these genes present dynamic change. On E10.5, the expressions of GATA4 and MEF2C were remarkable lower than those on E16.5 (P<0.01). While Nkx2.5 and Tbx5 gene expression levels were remarkable higher on E10.5(P<0.05).2. Chromatin immunoprecipitation (ChIP) analysis revealed there exist obviously difference on levels of histone H3 acetylation of these heart-specific TFs promtor between E10.5 and E16.5. The changing trend of Nkx2.5,MEF2C and Tbx5 was consistent with that of heart-specific TFs mRNA expression between E10.5 and E16.5. Meanwhile, binding of p300 to GATA4, Nkx2.5, MEF2C and Tbx5 promoter was detected by ChIP assay.Conclusion Data suggest that heart-specific TFs expression could be regulated by promoter activation through histone H3 acetylation activation, which might be dependent on the cooperation with co-activator p300. These results implicate p300 is an important component of heart development and provides an insight into the mechanisms of the dynamic expression of cardiac transcriptional factors during mouse cardiogenesis.