Histone Acetyltransferase Activity of p300 Is Required for Transcriptional Repression by the Promyelocytic Leukemia Zinc Finger Protein

Abstract

Histone acetyltransferase (HAT) activities of proteins such as p300, CBP, and P/CAF play important roles in activation of gene expression. We now show that the HAT activity of p300 can also be required for down-regulation of transcription by a DNA binding repressor protein. Promyelocytic leukemia zinc finger (PLZF), originally identified as a fusion with retinoic acid receptor alpha in rare cases of all-trans-retinoic acid-resistant acute promyelocytic leukemia, is a transcriptional repressor that recruits histone deacetylase-containing corepressor complexes to specific DNA binding sites. PLZF associates with p300 in vivo, and its ability to repress transcription is specifically dependent on HAT activity of p300 and acetylation of lysines in its C-terminal C₂-H₂ zinc finger motif. An acetylation site mutant of PLZF does not repress transcription and is functionally deficient in a colony suppression assay despite retaining its abilities to interact with corepressor/histone deacetylase complexes. This is due to the fact that acetylation of PLZF activates its ability to bind specific DNA sequences both in vitro and in vivo. Taken together, our results indicate that a histone deacetylase-dependent transcriptional repressor can be positively regulated through acetylation and point to an unexpected role of a coactivator protein in transcriptional repression.

ACKNOWLEDGMENTS

We are grateful to Masashi Suzuki, Sam Waxman, Ari Melnik, and Joan Boyes for comments. We also thank Joan Boyes for providing us with p300 and p300ΔHAT expression vectors, Kevin Petrie for help with the figures, and M. K. Devlin for experimental assistance. We are grateful to Alan Ashworth and the BreakThrough Breast Cancer Research Center for the use of confocal microscope facility.

This work was supported by a program grant from the Leukemia Research Fund of Great Britain (A.Z.), a studentship from the Medical Research Council of Great Britain (S.I.), International Research Fellowship from the Wellcome Trust, United Kingdom (M.I.), Kay Kendall Leukemia Fund (F.G.), FAMRI Foundation and NCI-SPORE Program in Cervical Cancer at Johns Hopkins (R.M.A.), and National Institutes of Health grants CA59936 (A.Z. and J.D.L.) and GM62437 (P.A.C.).