Objective: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.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 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).Results: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).Accordingly

ChIP analysis revealed there exist difference on levels of histoneH3 acetylation of these heart-specific TFs promtor 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 suggests 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.