Despite the fact that both electrochemical experiments and density functional theory calculations have testified to the superior electrocatalytic activity and CO-poisoning tolerance of platinum-ruthenium (PtRu) alloy nanoparticles toward the methanol oxidation reaction (MOR), the facet-dependent electrocatalytic properties of PtRu nanoparticles are scarcely revealed because it is extremely difficult to synthesize well-defined facets-enclosed PtRu nanocrystals. Herein, we for the first time report a general synthesis of ultrathin PtRu nanocrystals with tunable morphologies (nanowires, nanorods, and nanocubes) through a one-step solvothermal approach and a systematic investigation of the structure-directing effects of different surfactants and the formation mechanism by control experiments and time-dependent studies. In addition, we utilize these {100} and {111} facets-enclosed PtRu nanocrystals as model catalysts to evaluate the electrocatalytic characteristics of the MOR on different facets. Remarkably, {111}-terminated PtRu nanowires exhibit much higher stability and electrocatalytic mass activity toward MOR, which are 2.28 and 4.32 times higher than those of {100}-terminated PtRu nanocubes and commercial Pt/C, respectively, indicating that PtRu {111} facets possess superior methanol oxidation activity and CO-poisoning resistance relative to {100} facets. Our present work provides a series of well-defined PtRu nanocrystals with tunable facets which would be ideal model electrocatalysts for fundamental research in fuel cell electrocatalysis.

Modification by acetylation occurs at -amino lysine residues of histones and transcription factors. Unlike phosphorylation, a direct link between transcription factor acetylation and cellular growth or apoptosis has not been established. We show that the nuclear androgen receptor (

The cyclin D1 gene encodes the labile serum-inducible regulatory subunit of a holoenzyme that phosphorylates and inactivates the retinoblastoma protein. Overexpression of cyclin D1 promotes cellular proliferation and normal physiological levels of cyclin D1 function to inhibit adipocyte differentiation in vivo. We have previously shown that cyclin D1 inhibits peroxisome proliferator-activated receptor (PPAR)␥-dependent activity through a cyclin-dependent kinase-and retinoblastoma protein-binding-independent mechanism. In this study, we determined the molecular mechanism by which cyclin D1 regulated PPAR␥ function. Herein, murine embryonic fibroblast (MEF) differentiation by PPAR␥ ligand was associated with a reduction in histone deacetylase (HDAC1) activity. Cyclin D1 ؊/؊ MEFs showed an increased propensity to undergo differentiation into adipocytes. Genetic deletion of cyclin D1 reduced HDAC1 activity. Reconstitution of cyclin D1 into the cyclin D1 ؊/؊ MEFs increased HDAC1 activity and blocked PPAR␥-mediated adipogenesis. PPAR␥ activity was enhanced in cyclin D1؊/؊ cells. Reintroduction of cyclin D1 inhibited basal and ligand-induced PPAR␥ activity and enhanced HDAC repression of PPAR␥ activity. Cyclin D1 bound HDAC in vivo and preferentially physically associated with HDAC1, HDAC2, HDAC3, and HDAC5. Chromatin immunoprecipitation assay demonstrated that cyclin D1 enhanced recruitment of HDAC1 and HDAC3 and histone methyltransferase SUV39H1 to the PPAR response element of the lipoprotein lipase promoter and decreased acetylation of total histone H3 and histone H3 lysine 9. Collectively, these studies suggest an important role of cyclin D1 in regulation of PPAR␥-mediated adipocyte differentiation through recruitment of HDACs to regulate PPAR response element local chromatin structure and PPAR␥ function.The cyclin D1 gene was cloned as a breakpoint rearrangement in parathyroid adenoma (1) and as a macrophage colonystimulating factor-1-responsive gene in the mouse (2). Cyclin D1 encodes a labile growth factor-inducible regulatory subunit of the holoenzyme that phosphorylates and inactivates the retinoblastoma protein (Rb).1 Cyclin D1 overexpression promotes G 1 phase progression in cultured cells and immunoneutralizing experiments have shown a requirement for cyclin D1 in fibroblast, mammary, and epithelial cell proliferation (3, 4). Furthermore, cyclin D1 overexpression was shown to induce mammary tumorigenesis and to collaborate with the c-myc oncogene to induce lymphomagenesis (6). Deletion of the cyclin D1 gene in mice has demonstrated a key role for cyclin D1 in several distinct processes, including retinal and mammary gland development (7), cellular migration (8), cellular proliferation and survival (9), angiogenesis (10), and adipocyte differentiation (5). Cyclin D1 Ϫ/Ϫ MEFs have enhanced adipocyte differentiation in response to PPAR␥ ligands, which is reversed by cyclin D1 reintroduction (5).In addition to promoting DNA synthesis and cellular proliferation, cyclin D1 has been shown to inhibit the activity o...

The NAD-dependent histone deacetylase Sir2 plays a key role in connecting cellular metabolism with gene silencing and aging. The androgen receptor (AR) is a ligand-regulated modular nuclear receptor governing prostate cancer cellular proliferation, differentiation, and apoptosis in response to androgens, including dihydrotestosterone (DHT). Here, SIRT1 antagonists induce endogenous AR expression and enhance DHTmediated AR expression. SIRT1 binds and deacetylates the AR at a conserved lysine motif. Human SIRT1 (hSIRT1) repression of DHT-induced AR signaling requires the NAD-dependent catalytic function of hSIRT1 and the AR lysine residues deacetylated by SIRT1. SIRT1 inhibited coactivator-induced interactions between the AR amino and carboxyl termini. DHT-induced prostate cancer cellular contact-independent growth is also blocked by SIRT1, providing a direct functional link between the AR, which is a critical determinant of progression of human prostate cancer, and the sirtuins.