title: Signaling and regulatory mechanisms of integrinalpha3beta1 on the apoptosis of cultured rat podocytes.
abstract: Integrin is the major adhesion molecule for the attachment of podocytes to the glomerular basement membrane, and integrins have been shown to play a major role in the regulation of cell survival. In this study, the authors investigated the apoptosis and its related signal pathways to integrin in cultured rat podocytes. Apoptosis was detected with the terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) technique. Cytochrome c was examined by immunohistochemical stain, and Fas, Fas ligand, Bax, Bcl-2, and ERK activation (p-ERK/ERK) were analyzed by Western blotting analysis. The results demonstrated that the integrin antagonist, Gly-Arg-Gly-Asp (GRGD), increased the percentage of cells with apoptosis (from 0.9+/-0.5% to 27.2+/-9.9%, P < 0.01). Inhibition of protein tyrosine kinase with genistein also caused apoptosis of podocytes (from 0.9+/-0.5% to 26.0+/-8.7%, P < 0.01). In GRGD-treated cells, cytochrome c was found released into cytoplasm by immunohistochemical study and the Bax expression was upregulated, whereas Bcl-2 expression was not changed. Fas was not expressed in both control and GRGD-treated podocytes, although Fas ligand was upregulated in GRGD-treated cells. ERK activation was also found to be increased in GRGD-treated cells. The results indicated that alpha3beta1integrin is necessary for the prevention of the apoptosis of cultured rat podocytes, and that the signaling involves the Bax, Bcl-2, and cytochrome c pathways.
authors.affiliation: Graduate Institute of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Chien-An
authors.initials: CA
authors.lastname: Chen
authors.forename: Jer-Chia
authors.initials: JC
authors.lastname: Tsai
authors.forename: Pin-Wen
authors.initials: PW
authors.lastname: Su
authors.forename: Yung-Hsiung
authors.initials: YH
authors.lastname: Lai
authors.forename: Hung-Chun
authors.initials: HC
authors.lastname: Chen
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002448:Cell Adhesion / Q000502:physiology; D002478:Cells, Cultured; D045304:Cytochromes c / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D053222:Fas Ligand Protein; D020287:In Situ Nick-End Labeling; D039201:Integrin alpha3beta1 / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000378:metabolism; D050199:Podocytes / Q000166:cytology* / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000502:physiology*; D048069:Tumor Necrosis Factors / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D019014:fas Receptor / Q000378:metabolism
chemical_list: D053222:Fas Ligand Protein; C505662:Faslg protein, rat; D039201:Integrin alpha3beta1; D008562:Membrane Glycoproteins; D019253:Proto-Oncogene Proteins c-bcl-2; D048069:Tumor Necrosis Factors; D051028:bcl-2-Associated X Protein; D019014:fas Receptor; D045304:Cytochromes c; D048049:Extracellular Signal-Regulated MAP Kinases