Hormones – Cytokines – Signalling
Kidney International (2003) 64, 431–440; doi:10.1046/j.1523-1755.2003.00122.x
Integrins induce expression of monocyte chemoattractant protein-1 via focal adhesion kinase in mesangial cells
Yujiro Watanabe, Masahito Tamura, Akihiko Osajima, Hirofumi Anai, Narutoshi Kabashima, Ryota Serino and Yasuhide Nakashima
Second Department of Internal Medicine, University of Occupational and Environmental Health, School of Medicine, Kitakyushu, Japan
Correspondence: Masahito Tamura, M.D., Ph.D., Second Department of Internal Medicine, University of Occupational and Environmental Health, School of Medicine, 1-1 Iseigaoka, Yahatanishi, Kitakyushu 807-8555, Japan. E-mail: mtamura@med.uoeh-u.ac.jp
Received 30 September 2002; Revised 7 February 2003; Accepted 28 March 2003.
Abstract
Integrins induce expression of monocyte chemoattractant protein-1 via focal adhesion kinase in mesangial cells.
Background
Integrins are major adhesion receptors that not only regulate cytoskeletal organization, but also trigger a variety of intracellular signal transduction pathways. We examined the effects of increased extracellular matrix (ECM) accumulation on monocyte chemoattractant protein-1 (MCP-1) expression, which is known to play an important role in the progression of various glomerular diseases.
Methods
MCP-1 mRNA and protein expression in cultured rat mesangial cells (MC) attached to ECM proteins were examined by reverse transcription (RT)-polymerase chain reaction (PCR) and Western blotting, respectively. Phosphorylation of focal adhesion kinase (FAK) was measured by Western blotting. Effects of wild-type and dominant-negative FAK on MCP-1 expression were examined by a transient transfection assay.
Results
Cell adhesion to fibronectin-induced phosphorylation of FAK and MCP-1 mRNA expression in time- and dose-dependent manners followed by increased MCP-1 protein expression. All integrin-interacting substrates (laminin and types I, III, and IV collagens) also increased levels of FAK phosphorylation and MCP-1 expression, whereas nonspecific adhesive substrates (polylysine and concanavalin A) had no significant effects. Overexpression of wild-type FAK increased phosphorylation of FAK and expression of MCP-1 mRNA and protein, whereas transfection of dominant-negative FAK abolished adhesion-induced MCP-1 expression. Adhesion-induced expression of MCP-1 mRNA was inhibited by genistein and tosyl phenylalanyl chloromethylketone (TPCK), suggesting that tyrosine kinases [e.g., FAK, and nuclear factor kappa B (NF-
B)] are necessary in this signaling.
Conclusion
Our results indicate that integrin-mediated cell adhesion to the ECM can induce MCP-1 expression through activation of FAK, and suggest a role for altered ECM deposition in the progression of glomerular diseases by affecting gene expression.
Keywords:
focal adhesion kinase, integrin, extracellular matrix, gene expression, glomerulonephritis
