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 carboxylterminal to the zinc finger DNA-binding domain.

Regulation of nuclear receptor gene expression involves dynamic and coordinated interactions with histone acetyl transferase (HAT) and deacetylase complexes. The estrogen receptor (ER␣) contains two transactivation domains regulating ligand-independent and -dependent gene transcription (AF-1 and AF-2 (activation functions 1 and 2)). ER␣-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 ER␣ is acetylated in vivo. p300, but not P/CAF, selectively and directly acetylated the ER␣ at lysine residues within the ER␣ hinge/ligand binding domain. Substitution of these residues with charged or polar residues dramatically enhanced ER␣ hormone sensitivity without affecting induction by MAPK signaling, suggesting that direct ER␣ acetylation normally suppresses ligand sensitivity. These ER␣ lysine residues also regulated transcriptional activation by histone deacetylase inhibitors and p300. The conservation of the ER␣ 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.

Coordinated interactions between cyclin-dependent kinases (Cdks), their target "pocket proteins" (the retinoblastoma protein [pRB], p107, and p130), the pocket protein binding E2F-DP complexes, and the Cdk inhibitors regulate orderly cell cycle progression. The cyclin D1 gene encodes a regulatory subunit of the Cdk holoenzymes, which phosphorylate the tumor suppressor pRB, leading to the release of free E2F-1. Overexpression of E2F-1 can induce apoptosis and may either promote or inhibit cellular proliferation, depending upon the cell type. In these studies overexpression of E2F-1 inhibited cyclin D1-dependent kinase activity, cyclin D1 protein levels, and promoter activity. The DNA binding domain, the pRB pocket binding region, and the amino-terminal Sp1 binding domain of E2F-1 were required for full repression of cyclin D1. Overexpression of pRB activated the cyclin D1 promoter, and a dominant interfering pRB mutant was defective in cyclin D1 promoter activation. Two regions of the cyclin D1 promoter were required for full E2F-1-dependent repression. The region proximal to the transcription initiation site at ؊127 bound Sp1, Sp3, and Sp4, and the distal region at ؊143 bound E2F-4-DP-1-p107. In contrast with E2F-1, E2F-4 induced cyclin D1 promoter activity. Differential regulation of the cyclin D1 promoter by E2F-1 and E2F-4 suggests that E2Fs may serve distinguishable functions during cell cycle progression. Inhibition of cyclin D1 abundance by E2F-1 may contribute to an autoregulatory feedback loop to reduce pRB phosphorylation and E2F-1 levels in the cell.

The adenovirus E1A protein interferes with regulators of apoptosis and growth by physically interacting with cell cycle regulatory proteins including the retinoblastoma tumor suppressor protein and the coactivator proteins p300/CBP (where CBP is the CREB-binding protein). The p300/CBP proteins occupy a pivotal role in regulating mitogenic signaling and apoptosis. The mechanisms by which cell cycle control genes are directly regulated by p300 remain to be determined. The cyclin D1 gene, which is overexpressed in many different tumor types, encodes a regulatory subunit of a holoenzyme that phosphorylates and inactivates PRB. In the present study E1A12S inhibited the cyclin D1 promoter via the amino-terminal p300/CBP binding domain in human choriocarcinoma JEG-3 cells. p300 induced cyclin D1 protein abundance, and p300, but not CBP, induced the cyclin D1 promoter. cyclin D1 or p300 overexpression inhibited apoptosis in JEG-3 cells. The CH3 region of p300, which was required for induction of cyclin D1, was also required for the inhibition of apoptosis. p300 activated the cyclin D1 promoter through an activator protein-1 (AP-1) site at ؊954 and was identified within a DNA-bound complex with c-Jun at the AP-1 site. Apoptosis rates of embryonic fibroblasts derived from mice homozygously deleted of the cyclin D1 gene (cyclin D1 ؊/؊ ) were increased compared with wild type control on several distinct matrices. p300 inhibited apoptosis in cyclin D1 ؉/؉ fibroblasts but increased apoptosis in cyclin D1؊/؊ cells. The anti-apoptotic function of cyclin D1, demonstrated by sub-G 1 analysis and annexin V staining, may contribute to its cellular transforming and cooperative oncogenic properties.

Sulodexide, a mixture of naturally occurring glycosaminoglycan polysaccharide components, has been reported to reduce albuminuria in patients with diabetes, but it is unknown whether it is renoprotective. This study reports the results from the randomized, double-blind, placebo-controlled, sulodexide macroalbuminuria (Sun-MACRO) trial, which evaluated the renoprotective effects of sulodexide in patients with type 2 diabetes, renal impairment, and significant proteinuria (.900 mg/d) already receiving maximal therapy with angiotensin II receptor blockers. The primary end point was a composite of a doubling of baseline serum creatinine, development of ESRD, or serum creatinine $6.0 mg/dl. We planned to enroll 2240 patients over approximately 24 months but terminated the study after enrolling 1248 patients. After 1029 person-years of follow-up, we did not detect any significant differences between sulodexide and placebo; the primary composite end point occurred in 26 and 30 patients in the sulodexide and placebo groups, respectively. Side effect profiles were similar for both groups. In conclusion, these data do not suggest a renoprotective benefit of sulodexide in patients with type 2 diabetes, renal impairment, and macroalbuminuria.