PARP-1 suppresses adiponectin expression through poly(ADP-ribosyl)ation of PPAR gamma in cardiac fibroblasts

Regulatory role of mitochondria in oxidative stress and atherosclerosis

Mitochondrial physiology and biogenesis play a crucial role in the initiation and progression of cardiovascular disease following oxidative stress-induced damage such as atherosclerosis (AST). Dysfunctional mitochondria caused by an increase in mitochondrial reactive oxygen species (ROS) production, accumulation of mitochondrial DNA damage, and respiratory chain deficiency induces death of endothelial/smooth muscle cells and favors plaque formation/rupture via the regulation of mitochondrial biogenesis-related genes such as peroxisome proliferator-activated receptor γ coactivator (PGC-1), although more detailed mechanisms still need further study. Based on the effect of healthy mitochondria produced by mitochondrial biogenesis on decreasing ROS-mediated cell death and the recent finding that the regulation of PGC-1 involves mitochondrial fusion-related protein (mitofusin), we thus infer the regulatory role of mitochondrial fusion/fission balance in AST pathophysiology. In this review, the first section discusses the possible association between AST-inducing factors and the molecular regulatory mechanisms of mitochondrial biogenesis and dynamics, and explains the role of mitochondria-dependent regulation in cell apoptosis during AST development. Furthermore, nitric oxide has the Janus-faced effect by protecting vascular damage caused by AST while being a reactive nitrogen species (RNS) which act together with ROS to damage cells. Therefore, in the second section we discuss mitochondrial ATP-sensitive K(+) channels, which regulate mitochondrial ion transport to maintain mitochondrial physiology, involved in the regulation of ROS/RNS production and their influence on AST/cardiovascular diseases (CVD). Through this review, we can further appreciate the multi-regulatory functions of the mitochondria involved in AST development. The understanding of these related mechanisms will benefit drug development in treating AST/CVD through targeted biofunctions of mitochondria.

Biochemical analyses of nuclear receptor-dependent transcription with chromatin templates

Chromatin, the physiological template for transcription, plays important roles in gene regulation by nuclear receptors (NRs). It can (1) restrict the binding of NRs or the transcriptional machinery to their genomic targets, (2) serve as a target of regulatory posttranslational modifications by NR coregulator proteins with histone-directed enzymatic activities, and (3) function as a binding scaffold for a variety of transcription-related proteins. The advent of in vitro or "cell-free" systems that accurately recapitulate ligand-dependent transcription by NRs with chromatin templates has allowed detailed analyses of these processes. Biochemical studies have advanced our understanding of the mechanisms of gene regulation, including the role of ligands, coregulators, and nucleosome remodeling. In addition, they have provided new insights about the dynamics of NR-mediated transcription. This chapter reviews the current methodologies for assembling, transcribing, and analyzing chromatin in vitro, as well as the new information that has been gained from these studies.

Angiotensin II promotes poly(ADP-ribosyl)ation of c-Jun/c-Fos in cardiac fibroblasts

Although c-Jun/c-Fos (activator protein 1, AP1) contributes importantly to Ang II-induced cardiac fibrosis through induction of extracellular matrix protein over-expression in cardiac fibroblasts, the mechanism by which Ang II promotes c-Jun/c-Fos transactivation remains unclear. In this study, we demonstrated that c-Fos and c-Jun were poly(ADP-ribosyl)ated in cultured cardiac fibroblasts. Southwestern blot and EMSA assays showed that incubation of nuclear extracts with NAD(+) and active DNA increased the basal DNA binding activities of c-Jun (31.0+/-1.0%, P<0.01) and AP1 (14.2+/-3.1%, P<0.01); incubation of recombinant c-Fos or/and c-Jun with PARP-1, NAD(+) and active DNA increased the basal DNA binding activities of c-Jun (48.3+/-4.2%, P<0.01) and AP1 (21.2+/-1.5%, P<0.01). Treatment with Ang II promoted PARP-1 activation and enhanced poly(ADP-ribosyl)ation of c-Fos (14.1+1.1%, P<0.01) and c-Jun (15.5+/-5.6%, P<0.01). Ang II also increased the basal DNA binding activities of c-Jun (13.5+/-2.4%, P<0.01) and AP1 (18.7+/-3.5%, P<0.01) in cultured cells. Inhibition of PARP-1 by PJ34 or siRNA effectively prevented Ang II-induced increases in the DNA binding of c-Jun and AP1, and decreased AP1-driven transcription (including collagen Ialpha1 and IIIalpha1, MMP-9 and TIMP-1). This study illustrated that c-Jun and c-Fos were poly(ADP-ribosyl)ated by PARP-1, and poly(ADP-ribosyl)ation enhanced the DNA binding of AP1. Ang II promoted poly(ADP-ribosyl)ation of c-Jun and c-Fos through activation of PARP-1 and, subsequently, enhanced AP1-driven transcription in cardiac fibroblasts.