title: Metformin reduces NAD(P)H oxidase activity in mouse cultured podocytes through purinergic dependent mechanism by increasing extracellular ATP concentration.
abstract: Hyperglycemia affects the functioning numbers of podocytes and leads to a gradual decline of renal function. The normalization of glucose level is a principle therapeutic goal in diabetic patients and metformin is a popular hypoglycemic drug used in type 2 diabetes mellitus. Metformin activates AMP-activated kinase (AMPK) and decreases NAD(P)H oxidase activity in podocytes leading to reduction of free radical generation. Similar effects are observed after activation of P2 receptors. Therefore, we investigated whether metformin increases extracellular ATP concentration and affects the activities of NAD(P)H oxidase and AMPK through P2 receptors. Experiments were performed on cultured mouse podocytes. NAD(P)H oxidase activity was measured by chemiluminescence and changes in AMPK activity were estimated by immunoblotting against AMPKα-Thr(172)-P. Metformin increased extracellular ATP concentration by reduction of ecto-ATPase activity, decreased NAD(P)H oxidase activity and increased AMPK phosphorylation. A P2 receptor antagonist, suramin (300 µM), prevented metformin action on NAD(P)H oxidase and AMPK phosphorylation. The data suggests a novel mechanism of metformin action, at least in podocytes. Metformin, which increases extracellular ATP concentration leads to activation of P2 receptors and consequent modulation of the podocytes' metabolism through AMPK and NAD(P)H oxidase which, in turn, may affect podocyte functioning.
authors.affiliation: Mossakowski Medical Research Centre Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Piwkowska
authors.affiliation: Mossakowski Medical Research Centre Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland.
authors.forename: Dorota
authors.initials: D
authors.lastname: Rogacka
authors.affiliation: Mossakowski Medical Research Centre Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland; Medical University of Gdańsk, Department of Therapy Monitoring and Pharmacogenetics, Poland.
authors.forename: Maciej
authors.initials: M
authors.lastname: Jankowski
authors.affiliation: Mossakowski Medical Research Centre Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Angielski
mesh_terms: D000091162:AMP-Activated Protein Kinase Kinases; D000255:Adenosine Triphosphate / Q000096:biosynthesis*; D000818:Animals; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism; D005609:Free Radicals / Q000633:toxicity; D006801:Humans; D008687:Metformin / Q000008:administration & dosage*; D051379:Mice; D019255:NADPH Oxidases / Q000096:biosynthesis*; D010084:Oxidation-Reduction; D050199:Podocytes / Q000187:drug effects / Q000201:enzymology; D011494:Protein Kinases / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000096:biosynthesis; D015398:Signal Transduction
chemical_list: D005609:Free Radicals; D018048:Receptors, Purinergic P2; D000255:Adenosine Triphosphate; D008687:Metformin; D019255:NADPH Oxidases; D011494:Protein Kinases; D000091162:AMP-Activated Protein Kinase Kinases