Objective    To construct the p300 specific siRNA vector in mice and observe its effect on cardiac transcription factor

GATA4

for further study of the effect of p300-mediated histone acetylation on heart growth.     Methods    Three recombinant plasmid vectors (p300 RNAi1，p300 RNAi2

and p300 RNAi3s)

designed and constructed according to the conservative sequence of mice p300

were respectively tansfected into in vitro cultured cardiac muscle cells of suckling mice. Expression of p300 and GATA4 at mRNA and protein levels was detected by RT-PCR and immunofluorescence

respectively.      Results    The expression level of p300 mRNA was not significantly decreased in pSOS-HUS and p300 RNAi2 groups

but significantly decreased in p300 RNAi1 and p300 RNAi3 groups (0.220 8±0.020 0 and 0.170 8±0.040 0 vs 0.509 5±0.030 0

P0.05)

with an inhibition rate of 56.7% and 66.5%

respectively. The expression level of GATA4 mRNA was significantly lower in transfected p300RNAi1 and p300RNAi3 groups than in normal and negative control groups (0.423 1±0.110 0 and 0.262 7±0.080 0 vs 0.856 4±0.070 0 and 0.841 5±0.040 0

P0.05).     Conclusion    A p300 specific siRNA vector is successfully constructed. Both p300 RNAi1 and p300 RNAi3 can effectively block the expression of p300 and GATA4. 