Rac Inhibition Reverses the Phenotype of Fibrotic Fibroblasts

Background: Fibrosis, the excessive deposition of scar tissue by fibroblasts, is one of the largest groups of diseases for which there is no therapy. Fibroblasts from lesional areas of scleroderma patients possess elevated abilities to contract matrix and produce alpha-smooth muscle actin (alpha-SMA), type I collagen and CCN2 (connective tissue growth factor, CTGF). The basis for this phenomenon is poorly understood, and is a necessary prerequisite for developing novel, rational anti-fibrotic strategies.Methods and Findings: Compared to healthy skin fibroblasts, dermal fibroblasts cultured from lesional areas of scleroderma (SSc) patients possess elevated Rac activity. NSC23766, a Rac inhibitor, suppressed the persistent fibrotic phenotype of lesional SSc fibroblasts. NSC23766 caused a decrease in migration on and contraction of matrix, and alpha-SMA, type I collagen and CCN2 mRNA and protein expression. SSc fibroblasts possessed elevated Akt phosphorylation, which was also blocked by NSC23766. Overexpression of rac1 in normal fibroblasts induced matrix contraction and alpha-SMA, type I collagen and CCN2 mRNA and protein expression. Rac1 activity was blocked by PI3kinase/Akt inhibition. Basal fibroblast activity was not affected by NSC23766.Conclusion: Rac inhibition may be considered as a novel treatment for the fibrosis observed in SSc

Serine phosphorylation regulates paxillin turnover during cell migration

BACKGROUND: Paxillin acts as an adaptor protein that localizes to focal adhesion. This protein is regulated during cell migration by phosphorylation on tyrosine, serine and threonine residues. Most of these phosphorylations have been implicated in the regulation of different steps of cell migration. The two major phosphorylation sites of paxillin in response to adhesion to an extracellular matrix are serines 188 and 190. However, the function of this phosphorylation event remains unknown. The purpose of this work was to determine the role of paxillin phosphorylation on residues S188 and S190 in the regulation of cell migration. RESULTS: We used NBT-II epithelial cells that can be induced to migrate when plated on collagen. To examine the role of paxillin serines 188/190 in cell migration, we constructed an EGFP-tagged paxillin mutant in which S188/S190 were mutated into unphosphorylatable alanine residues. We provide evidence that paxillin is regulated by proteasomal degradation following polyubiquitylation of the protein. During active cell migration on collagen, paxillin is protected from proteasome-dependent degradation. We demonstrate that phosphorylation of serines 188/190 is necessary for the protective effect of collagen. In an effort to understand the physiological relevance of paxillin protection from degradation, we show that cells expressing the paxillin S188/190A interfering mutant spread less, have reduced protrusive activity but migrate more actively. CONCLUSION: Our data demonstrate for the first time that serine-regulated degradation of paxillin plays a key role in the modulation of membrane dynamics and consequently, in the control of cell motility

Cigarette smoking, genetic polymorphisms and colorectal cancer risk: the Fukuoka Colorectal Cancer Study

Background: It is uncertain whether smoking is related to colorectal cancer risk. Cytochrome P-450 CYP1A1, glutathione-S-transferase (GST) and NAD(P)H:quinone oxidoreductase 1 (NQO1) are important enzymes in the metabolism of tobacco carcinogens, and functional genetic polymorphisms are known for these enzymes. We investigated the relation of cigarette smoking and related genetic polymorphisms to colorectal cancer risk, with special reference to the interaction between smoking and genetic polymorphism. Methods: We used data from the Fukuoka Colorectal Cancer Study, a population-based case-control study, including 685 cases and 778 controls who gave informed consent to genetic analysis. Interview was conducted to assess lifestyle factors, and DNA was extracted from buffy coat. Results: In comparison with lifelong nonsmokers, the odds ratios (OR) of colorectal cancer for <400, 400-799 and ≥800 cigarette-years were 0.65 (95 % confidence interval [CI], 0.45-0.89), 1.16 (0.83-1.62) and 1.14 (0.73-1.77), respectively. A decreased risk associated with light smoking was observed only for colon cancer, and rectal cancer showed an increased risk among those with ≥400 cigarette-years (OR 1.60, 95 % CI 1.04-2.45). None of the polymorphisms under study was singly associated with colorectal cancer risk. Of the gene-gene interactions studied, the composite genotype of CYP1A1*2A or CYP1A1*2C and GSTT1 polymorphisms was associated with a decreased risk of colorecta