Expression of membrane-bound NPP-type ecto-phosphodiesterases in rat podocytes cultured at normal and high glucose concentrations

Biochem Biophys Res Commun. 2011 Dec 9;416(1-2):64-9. doi: 10.1016/j.bbrc.2011.10.144. Epub 2011 Nov 6.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Membrane / enzymology*
  • Cells, Cultured
  • Female
  • Glucose / metabolism*
  • Glucose / pharmacology
  • Insulin / metabolism
  • Insulin / pharmacology
  • Phosphoric Diester Hydrolases / biosynthesis*
  • Phosphoric Diester Hydrolases / genetics
  • Podocytes / drug effects
  • Podocytes / enzymology*
  • Pyrophosphatases / biosynthesis*
  • Pyrophosphatases / genetics
  • Rats
  • Rats, Wistar


  • Insulin
  • Phosphoric Diester Hydrolases
  • Enpp3 protein, rat
  • Pyrophosphatases
  • nucleotide pyrophosphatase - phosphodiesterase I
  • Glucose