Quantitative control of adaptive cardiac hypertrophy by acetyltransferase p300.
BACKGROUND
Acetyltransferase p300 is essential for cardiac development and is thought to be involved in cardiac myocyte growth through MEF2- and GATA4-dependent transcription. However, the importance of p300 in the modulation of cardiac growth in vivo is unknown.


RESULTS
Pressure overload induced by transverse aortic coarctation, postnatal physiological growth, and human heart failure were associated with large increases in p300. Minimal transgenic overexpression of p300 (1.5- to 3.5-fold) induced striking myocyte and cardiac hypertrophy. Both mortality and cardiac mass were directly related to p300 protein dosage. Heterozygous loss of a single p300 allele reduced pressure overload-induced hypertrophy by approximately 50% and rescued the hypertrophic phenotype of p300 overexpressers. Increased p300 expression had no effect on total histone deacetylase activity but was associated with proportional increases in p300 acetyltransferase activity and acetylation of the p300 substrates histone 3 and GATA-4. Remarkably, a doubling of p300 levels was associated with the de novo acetylation of MEF2. Consistent with this, genes specifically upregulated in p300 transgenic hearts were highly enriched for MEF2 binding sites.


CONCLUSIONS
Small increments in p300 are necessary and sufficient to drive myocardial hypertrophy, possibly through acetylation of MEF2 and upstream of signals promoting phosphorylation or nuclear export of histone deacetylases. We propose that induction of myocardial p300 content is a primary rate-limiting event in the response to hemodynamic loading in vivo and that p300 availability drives and constrains adaptive myocardial growth. Specific reduction of p300 content or activity may diminish stress-induced hypertrophy and forestall the development of heart failure.
Wei
Jian Qin
JQ
University of Miami School of Medicine, Department of Molecular and Cellular Pharmacology, Miami, FL, USA.
Shehadeh
Lina A
LA
Mitrani
James M
JM
Pessanha
Monica
M
Slepak
Tatiana I
TI
Webster
Keith A
KA
Bishopric
Nanette H
NH
D000107:Acetylation; D000818:Animals; D001017:Aortic Coarctation / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D006332:Cardiomegaly / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D002455:Cell Division / Q000502:physiology; D002478:Cells, Cultured; D044127:Epigenesis, Genetic / Q000502:physiology; D006333:Heart Failure / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D026161:MADS Domain Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D032383:Myocytes, Cardiac / Q000166:cytology / Q000201:enzymology*; D018006:Myogenic Regulatory Factors / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014158:Transcription, Genetic / Q000502:physiology; D014162:Transfection; D050880:p300-CBP Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D000099224:p300-CBP-Associated Factor
D026161:MADS Domain Proteins; D018006:Myogenic Regulatory Factors; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor