Anne T. Reutens

The androgen receptor (AR) is a sequence-specific DNA-binding protein that plays a key role in prostate cancer cellular proliferation by dihydrotestosterone and the induction of secondary sexual characteristics. In this study we demonstrate that the AR can be modified by acetylation in vitro and in vivo. p300 and p300/cAMP-response element-binding protein acetylated the AR at a highly conserved lysine-rich motif carboxyl-terminal to the zinc finger DNA-binding domain. [(14)C]acetate-labeling experiments demonstrated that AR acetylation by p300 in cultured cells requires the same residues identified in vitro. Point mutation of the AR acetylation site (K632A/K633A) abrogated dihydrotestosterone-dependent transactivation of the AR in cultured cells. Mutation of the p300 CH3 region or the p300/cAMP-response element-binding protein histone acetylase domain reduced ligand-dependent AR function. The identification of the AR as a direct target of histone acetyltransferase co-activators has important implications for targeting inhibitors of AR function.

I. Introduction II.Regulation of the Cell Cycle G 1 Phase A. The cyclins B. The Cdk-inhibitory proteins C. Regulation of transcription by cell cycle-control proteins III.Endocrine Regulation of Cyclin and Cdk-Regulatory Proteins A. Single-transmembrane segment receptors B. Seven-transmembrane receptors C. Steroid hormones D. Intracellular second

Regulation of nuclear receptor gene expression involves dynamic and coordinated interactions with histone acetyl transferase (HAT) and deacetylase complexes. The estrogen receptor (ERalpha) contains two transactivation domains regulating ligand-independent and -dependent gene transcription (AF-1 and AF-2 (activation functions 1 and 2)). ERalpha-regulated gene expression involves interactions with cointegrators (e.g. p300/CBP, P/CAF) that have the capacity to modify core histone acetyl groups. Here we show that the ERalpha is acetylated in vivo. p300, but not P/CAF, selectively and directly acetylated the ERalpha at lysine residues within the ERalpha hinge/ligand binding domain. Substitution of these residues with charged or polar residues dramatically enhanced ERalpha hormone sensitivity without affecting induction by MAPK signaling, suggesting that direct ERalpha acetylation normally suppresses ligand sensitivity. These ERalpha lysine residues also regulated transcriptional activation by histone deacetylase inhibitors and p300. The conservation of the ERalpha acetylation motif in a phylogenetic subset of nuclear receptors suggests that direct acetylation of nuclear receptors may contribute to additional signaling pathways involved in metabolism and development.

Diabetic nephropathy affects approximately one third of people with type 1 or type 2 diabetes mellitus. Risk factors affecting progression of kidney disease include baseline albumin excretion, age, glycemic control, blood pressure, serum cholesterol and use of renin-angiotensin system blockers. As the total number of people with diabetes is projected to increase substantially to 2050, the prevalence of diabetic nephropathy will rise dramatically, with concomitant increase in associated cardiovascular mortality and endstage renal disease. This will produce significant social and economic ramifications, particularly in the developing world.