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A Novel Concept for Origin and Treatment of Diabetic Nephropathy
Author(s) -
Svensson Daniel,
Zhang Liang,
Panizza Elena,
Nilsson Linnéa,
Fontana Jacopo Maria,
Moruzzi Noah,
Scott Lena,
Brismar Hjalmar,
Aperia Anita
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.567.4
Subject(s) - ouabain , apoptosis , microbiology and biotechnology , tunel assay , phosphorylation , chemistry , biology , medicine , biochemistry , sodium , organic chemistry
Objectives Diabetic nephropathy (DN) is the most common cause of end‐stage renal failure and affects around 40% of all diabetic patients. This project aims to investigate the loss of proximal tubular cells (PTCs) in DN which are epithelial cells of the nephron leading away from the Bowman's capsule. Hyperglycemia induced damage to PTCs is attenuated by the Na/K‐ATPase ligand ouabain. Our second objective was thus to investigated the underlying mechanisms of ouabain in vitro and the function of Na/K‐ATPase as a signaling transducer. Methods PTCs were isolated from mouse and rat kidney cortex and cultured for up to a week. COS‐7 kidney cells were used for some experiments. Protein expression and phosphorylation was studied by Western blotting and proteomics/phosphoproteomics. Gene ontology analysis was performed to find distinct cellular processes regulated by ouabain in the phopshoproteomic analysis. Seahorse was used for metabolic studies. Gene expression was analyzed by qPCR and apoptosis assessed by the TUNEL assay. Key results High glucose (HG, 15 mM) triggers apoptosis in PTC due to their expression of sodium dependent glucose transporter 2 (SGLT2), SGLT2 siRNA abolishes HG induced apoptosis. Apoptosis does not appear to coincide with a switch in glucose metabolism. Low concentrations of ouabain (10 nM) completely inhibits the apoptosis. Phosphoproteomic analysis revealed 2580 ouabain‐regulated phosphorylation sites, many of which were associated with cell adhesion and proliferation. Out of these, CaMK2γ were shown to be involved in the anti‐apoptotic effect of ouabain, siRNA silencing of CaMK2γ eliminates the protective effect of ouabain. Conclusions Loss of tubular cells in DN might be driven by hyperglycemia due to the PTC expression of SGLT2. Low concentrations of ouabain protects from the detrimental hyperglycemic effects through an anti‐apoptotic mechanism involving CaMK2γ. Support or Funding Information The study was funded by the Swedish Research Council and Erling‐Persson Family Foundation. D.S. and N.M. is supported by a Novo Nordisk postdoctoral fellowship run in partnership with Karolinska Institutet. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .