Tensin is potentially involved in extracellular matrix production in mesangial cells
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Tensin, a focal adhesion protein, is expressed in renal tubular epithelial cells (TECs). Tensin-null mice develop multiple large cysts in the renal proximal tubules. However, the role of tensin in human glomeruli remains unclear. In this study, we assessed tensin localization in human kidney and interaction between tensin and other adhesion components. In human mesangial cells (MCs) and TECs, we confirmed mRNA and protein expressions of tensin by RT-PCR and immunoprecipitation. In normal kidney, immunohistochemistry revealed that tensin was localized in MCs and parietal epithelial cells as well as TECs. In biopsy specimens, the expression of tensin was significantly increased in areas of mesangial expansion in patients with IgA nephropathy and diabetic nephropathy. These results suggest that the expression of tensin is associated with extracellular matrix (ECM) production. In vitro, immunocytochemistry revealed that MCs express tensin mainly at the ends of actin stress fibers and apparently in the focal adhesion areas. Integrin α5, but not α1 and α3, colocalized with tensin. Vinculin and focal adhesion kinase (FAK) were coprecipitated by tensin, suggesting that tensin can mediate signal transduction between cell and ECM through these molecules. Tensin may play important roles in mesangial ECM production through an adhesion complex with integrin α5, FAK, and vinculin.
KeywordsFocal adhesion Integrin FAK Vinculin
The authors thank Dr. Yusuke Suzuki for critical reading of the manuscript, Dr. Tsutomu Fujimura for preparation of the illustrations, and Ms Terumi Shibata and Dr. Yukihiko Takeda for technical support. This work was supported, in part, by grants-in-aid for the Special Study Group on Progressive Glomerular Disease from the Ministry of Health, Labor and Welfare of Japan.
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