Sustained activation of Rac1 in hepatic stellate cells promotes liver injury and fibrosis in mice.

Published

Journal Article

Rac, a small, GTP-binding protein in the Rho family, regulates several cellular functions, including the activation of NADPH oxidase, a major intracellular producer of reactive oxygen species (ROS). Hepatic stellate cells (HSCs) isolated from mice that are genetically deficient in NADPH oxidase produce less ROS, and their activation during chronic liver injury is abrogated, resulting in decreased liver fibrosis. Therefore, we hypothesized that HSC ROS production and activation would be enhanced, and fibrosis worsened, by increasing Rac expression in HSCs. To achieve this, we used transgenic mice that express constitutively active human Rac1 under the control of the alpha-smooth muscle actin (alpha-sma) promoter, because alpha-sma expression is induced spontaneously during HSC activation. Transgene expression was upregulated progressively during culture of primary Rac-transgenic HSCs, and this increased HSC ROS production as well as expression of activation markers and collagen. Similarly, Rac mice treated with carbon tetrachloride (CCl(4)) accumulated greater numbers of activated HSCs and had more liver damage, hepatocyte apoptosis, and liver fibrosis-as well as higher mortality-than CCl(4)-treated wild-type mice. In conclusion, sustained activation of Rac in HSCs perpetuates their activation and exacerbates toxin-induced liver injury and fibrosis, prompting speculation that Rac may be a therapeutic target in patients with cirrhosis.

Full Text

Duke Authors

Cited Authors

  • Choi, SS; Sicklick, JK; Ma, Q; Yang, L; Huang, J; Qi, Y; Chen, W; Li, Y-X; Goldschmidt-Clermont, PJ; Diehl, AM

Published Date

  • November 2006

Published In

Volume / Issue

  • 44 / 5

Start / End Page

  • 1267 - 1277

PubMed ID

  • 17058265

Pubmed Central ID

  • 17058265

International Standard Serial Number (ISSN)

  • 0270-9139

Digital Object Identifier (DOI)

  • 10.1002/hep.21375

Language

  • eng

Conference Location

  • United States