title: Quantitative mass spectrometry of diabetic kidney tubules identifies GRAP as a novel regulator of TGF-beta signaling.
abstract: The aim of this study was to define novel mediators of tubule injury in diabetic kidney disease. For this, we used state-of-the-art proteomic methods combined with a label-free quantitative strategy to define protein expression differences in kidney tubules from transgenic OVE26 type 1 diabetic and control mice. The analysis was performed with diabetic samples that displayed a pro-fibrotic phenotype. We have identified 476 differentially expressed proteins. Bioinformatic analysis indicated several clusters of regulated proteins in relevant functional groups such as TGF-beta signaling, tight junction maintenance, oxidative stress, and glucose metabolism. Mass spectrometry detected expression changes of four physiologically relevant proteins were confirmed by immunoblot analysis. Of these, the Grb2-related adaptor protein (GRAP) was up-regulated in kidney tubules from diabetic mice and fibrotic kidneys from diabetic patients, and subsequently confirmed as a novel component of TGF-beta signaling in cultured human renal tubule cells. Thus, indicating a potential novel role for GRAP in TGF-beta-induced tubule injury in diabetic kidney disease. Although we targeted a specific disease, this approach offers a robust, high-sensitivity methodology that can be applied to the discovery of novel mediators for any experimental or disease condition.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, KY, USA.
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Cummins
authors.forename: Michelle T
authors.initials: MT
authors.lastname: Barati
authors.forename: Susan C
authors.initials: SC
authors.lastname: Coventry
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Salyer
authors.forename: Jon B
authors.initials: JB
authors.lastname: Klein
authors.forename: David W
authors.initials: DW
authors.lastname: Powell
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D003922:Diabetes Mellitus, Type 1 / Q000378:metabolism*; D003928:Diabetic Nephropathies / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007684:Kidney Tubules / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D040901:Proteomics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D053719:Tandem Mass Spectrometry; D016212:Transforming Growth Factor beta / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C510602:Grap protein, human; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta