title: Mechanisms of bradykinin-induced expression of connective tissue growth factor and nephrin in podocytes.
abstract: Diabetic nephropathy (DN) is the main cause of morbidity and mortality in diabetes and is characterized by mesangial matrix deposition and podocytopathy, including podocyte loss. The risk factors and mechanisms involved in the pathogenesis of DN are still not completely defined. In the present study, we aimed to understand the cellular mechanisms through which activation of B2 kinin receptors contribute to the initiation and progression of DN. Stimulation of cultured rat podocytes with bradykinin (BK) resulted in a significant increase in ROS generation, and this was associated with a significant increase in NADPH oxidase (NOX)1 and NOX4 protein and mRNA levels. BK stimulation also resulted in a signicant increase in the phosphorylation of ERK1/2 and Akt, and this effect was inhibited in the presence of NOX1 and Nox4 small interfering (si)RNA. Furthermore, podocytes stimulated with BK resulted in a significant increase in protein and mRNA levels of connective tissue growth factor (CTGF) and, at the same time, a significant decrease in protein and mRNA levels of nephrin. siRNA targeted against NOX1 and NOX4 significantly inhibited the BK-induced increase in CTGF. Nephrin expression was increased in response to BK in the presence of NOX1 and NOX4 siRNA, thus implicating a role for NOXs in modulating the BK response in podocytes. Moreover, nephrin expression in response to BK was also significantly increased in the presence of siRNA targeted against CTGF. These findings provide novel aspects of BK signal transduction pathways in pathogenesis of DN and identify novel targets for interventional strategies.
authors.affiliation: Biochemistry and Molecular Genetics Department, Faculty of Medicine, American University of Beirut, Beirut, Lebanon;
authors.forename: J
authors.initials: J
authors.lastname: Abou Msallem
authors.affiliation: Biochemistry and Molecular Genetics Department, Faculty of Medicine, American University of Beirut, Beirut, Lebanon;
authors.forename: H
authors.initials: H
authors.lastname: Chalhoub
authors.affiliation: Biochemistry and Molecular Genetics Department, Faculty of Medicine, American University of Beirut, Beirut, Lebanon;
authors.forename: M
authors.initials: M
authors.lastname: Al-Hariri
authors.affiliation: Biochemistry and Molecular Genetics Department, Faculty of Medicine, American University of Beirut, Beirut, Lebanon;
authors.forename: L
authors.initials: L
authors.lastname: Saad
authors.affiliation: Epidemiology and Population Health Department, Faculty of Health Sciences, American University of Beirut, Beirut, Lebanon; and.
authors.forename: M A
authors.initials: MA
authors.lastname: Jaffa
authors.affiliation: Biochemistry and Molecular Genetics Department, Faculty of Medicine, American University of Beirut, Beirut, Lebanon;
authors.forename: F N
authors.initials: FN
authors.lastname: Ziyadeh
authors.affiliation: Biochemistry and Molecular Genetics Department, Faculty of Medicine, American University of Beirut, Beirut, Lebanon; Department of Medicine, Medical University of South Carolina, Charleston, South Carolina aj24@aub.edu.lb.
authors.forename: A A
authors.initials: AA
authors.lastname: Jaffa
mesh_terms: D000818:Animals; D001920:Bradykinin / Q000494:pharmacology*; D002478:Cells, Cultured; D055513:Connective Tissue Growth Factor / Q000235:genetics / Q000378:metabolism*; D003928:Diabetic Nephropathies / Q000235:genetics / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics / Q000378:metabolism; D000074624:NADPH Oxidase 1; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010766:Phosphorylation; D050199:Podocytes / Q000187:drug effects* / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D043782:Receptor, Bradykinin B2 / Q000819:agonists / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014162:Transfection; D015854:Up-Regulation
chemical_list: C526316:CCN2 protein, rat; D008565:Membrane Proteins; D012333:RNA, Messenger; D043782:Receptor, Bradykinin B2; C113267:nephrin; D055513:Connective Tissue Growth Factor; D009247:NADH, NADPH Oxidoreductases; D000074624:NADPH Oxidase 1; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C000614712:NOX1 protein, rat; C498911:Nox4 protein, rat; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D001920:Bradykinin
keywords: connective tissue growth factor; diabetic nephropathy; kinin receptors; nephrin; oxidative stress; podocytes