title: Expression of membrane-bound NPP-type ecto-phosphodiesterases in rat podocytes cultured at normal and high glucose concentrations.
abstract: The ecto-nucleotide pyrophosphatase/phosphodiesterase family (E-NPPs) contains two membrane-bound members: E-NPP1 and E-NPP3. These enzymes mediate hydrolysis of extracellular nucleotides and their abnormal expression may affect intracellular signal transduction pathways, leading to cellular dysfunction, e.g., insulin resistance. Podocytes are insulin-dependent glomerular epithelial cells that regulate the glomerular filtration rate. Pathology of podocytes is a hallmark of diabetic nephropathy. Here, we investigated the expressions of E-NPP1 and E-NPP3 and activity of E-NPP enzymes in rat podocytes cultured with 5mM (NG) or 30 mM glucose (HG). Insulin resistance was determined by measuring changes in [1,2-(3)H]-deoxy-D-glucose uptake in response to insulin. mRNAs of E-NPP1 and E-NPP3 were detected within podocytes. The E-NPP expressions were confirmed at the protein level using western blot and immunofluorescence techniques. At NG, insulin (300 nM, 3 min) increased glucose uptake 1.5-fold; however, this effect was abolished at HG. The protein expressions of E-NPP1 and E-NPP3 were not affected at HG. The E-NPP activities were 24.68±0.72 and 26.51±1.55 nmol/min/mg protein at NG and HG, respectively. In conclusion, ecto-nucleotide pyrophosphatase/phosphodiesterase 1 and 3 are expressed on podocytes, but changes in expression of these enzymes are most likely not involved in etiology of insulin resistance in podocytes.
authors.affiliation: Laboratory of Molecular and Cellular Nephrology, M. Mossakowski Medical Research Centre, Polish Academy of Science, Medical University of Gdańsk, Poland. majank@gumed.edu.pl
authors.forename: Maciej
authors.initials: M
authors.lastname: Jankowski
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Piwkowska
authors.forename: Dorota
authors.initials: D
authors.lastname: Rogacka
authors.forename: Irena
authors.initials: I
authors.lastname: Audzeyenka
authors.forename: Anna
authors.initials: A
authors.lastname: Janaszak-Jasiecka
authors.forename: Stefan
authors.initials: S
authors.lastname: Angielski
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000201:enzymology*; D002478:Cells, Cultured; D005260:Female; D005947:Glucose / Q000378:metabolism* / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology; D010727:Phosphoric Diester Hydrolases / Q000096:biosynthesis* / Q000235:genetics; D050199:Podocytes / Q000187:drug effects / Q000201:enzymology*; D011755:Pyrophosphatases / Q000096:biosynthesis* / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar
chemical_list: D007328:Insulin; D010727:Phosphoric Diester Hydrolases; C524442:Enpp3 protein, rat; D011755:Pyrophosphatases; C405782:nucleotide pyrophosphatase - phosphodiesterase I; D005947:Glucose