Up-regulation of skeletal muscle LIM protein 1 gene by 25-hydroxycholesterol may mediate morphological changes of rat aortic smooth muscle cells

15-Deoxy-Δ-12,14-prostaglandin J2 effects in vascular smooth muscle cells: Implications in vascular smooth muscle cell proliferation and contractility

15-Deoxy-Δ-12,14-prostaglandin J2 (15d-PGJ2) is an endogenous agonist of the ligand dependent transcriptional factor, peroxisome proliferator-activated receptor -gamma (PPAR-γ). Although PPAR-γ mediates some actions of 15d-PGJ2, many actions of 15d-PGJ2 are independent of PPAR-γ. The PPAR-γ signaling pathway has beneficial effects on tumor progression, inflammation, oxidative stress, and angiogenesis in numerous studies. In this review, various studies were analyzed to understand the effects of 15d-PGJ2 in vascular smooth muscle cells (VSMC)s. 15d-PGJ2 inhibits proliferation of VSMCs during vascular remodeling and it alters the expression of contractile proteins and inflammatory components within these cells as well. However, the effects of 15d-PGJ2 as well as its ability to induce PPAR-γ activation remains controversial as contradictory effects of this prostaglandin in VSMCs exist. Understanding the mechanisms by which 15d-PGJ2 elicit beneficial actions whether by PPAR-γ activation or independently, will aid in developing new therapeutic strategies for diseases such as hypertension with an inflammatory component. Although great advances are being made, more research is needed to reach definitive conclusions.

Liver x receptor signaling pathways and atherosclerosis

First discovered as orphan receptors, liver X receptors (LXRs) were subsequently identified as the nuclear receptor target of the cholesterol metabolites, oxysterols. There are 2 LXR receptors encoded by distinct genes: LXRalpha is most highly expressed in the liver, adipose, kidney, adrenal tissues, and macrophages and LXRbeta is ubiquitously expressed. Despite differential tissue distribution, these isoforms have 78% homology in their ligand-binding domain and appear to respond to the same endogenous ligands. Work over the past 10 years has shown that the LXR pathway regulates lipid metabolism and inflammation via both the induction and repression of target genes. Given the importance of cholesterol regulation and inflammation in the development of cardiovascular disease, it is not surprising that activation of the LXR pathway attenuates various mechanisms underlying atherosclerotic plaque development. In this brief review, we will discuss the impact of the LXR pathway on both cholesterol metabolism and atherosclerosis.

Perfusion of veins at arterial pressure increases the expression of KLF5 and cell cycle genes in smooth muscle cells

Vascular smooth muscle cell (VSMC) proliferation remains a major cause of veno-arterial graft failure. We hypothesised that exposure of venous SMCs to arterial pressure would increase KLF5 expression and that of cell cycle genes. Porcine jugular veins were perfused at arterial or venous pressure in the absence of growth factors. The KLF5, c-myc, cyclin-D and cyclin-E expression were elevated within 24h of perfusion at arterial pressure but not at venous pressure. Arterial pressure also reduced the decline in SM-myosin heavy chain expression. These data suggest a role for KLF5 in initiating venous SMCs proliferation in response to arterial pressure.