Functional metabotropic glutamate receptors 1 and 5 are expressed in murine podocytes

Kidney Int. 2012 Mar;81(5):458-68. doi: 10.1038/ki.2011.406. Epub 2011 Dec 14.

Abstract

In non-neuronal cells, glutamate is an extracellular signaling mediator. Since podocytes have glutamate-containing vesicles, we sought to determine glutamate receptor presence and action in glomerular cells. The metabotropic glutamate receptors (mGluR) 1, 5, 6, and 8 were found to be expressed in mouse brain and glomeruli; predominantly in podocytes. In two models of proteinuria (BalB/C mice with puromycin aminonucleoside- and doxorubicin-induced podocyte injury) we found that the selective mGluR1/5 agonist (S)-3,5-dihydroxyphenylglycine (DHPG) attenuated albuminuria and improved the expression of the podocyte marker WT-1. TUNEL staining showed that the number of podocytes undergoing apoptosis was inversely correlated with the number of WT-1-positive cells in glomeruli. When podocytes were treated with DHPG in vitro, they generated cyclic AMP and activated CREB (cyclic AMP response element binding protein). The selective mGluR1/5 antagonist (RS)-1-aminoindan-1,5-dicarboxylic acid, the adenylate cyclase inhibitor SQ22536, and RNA interference knockdown of mGluR1 or mGluR5 all prevented DHPG-induced cAMP generation and CREB activation. DHPG inhibited apoptosis and the decrease of aminonucleoside-induced mitochondrial membrane potential in podocytes but had no effect in the presence of SQ22536 with knockdown mGluR1 or mGluR5. Thus, functional mGluR1 and mGluR5 are expressed in podocytes and their activation protects against albuminuria and podocyte apoptosis, processes that are, at least in part, dependent on cAMP.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Cells, Cultured
  • Cyclic AMP / metabolism
  • Cyclic AMP Response Element-Binding Protein / metabolism
  • Doxorubicin / adverse effects
  • Doxorubicin / pharmacology
  • Glycine / analogs & derivatives
  • Glycine / pharmacology
  • In Vitro Techniques
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Models, Animal
  • Podocytes / drug effects
  • Podocytes / metabolism*
  • Podocytes / pathology*
  • Proteinuria / chemically induced
  • Proteinuria / metabolism*
  • Proteinuria / pathology*
  • Puromycin Aminonucleoside / adverse effects
  • Puromycin Aminonucleoside / pharmacology
  • Receptor, Metabotropic Glutamate 5
  • Receptors, Metabotropic Glutamate / metabolism*
  • Resorcinols / pharmacology

Substances

  • Cyclic AMP Response Element-Binding Protein
  • Grm5 protein, mouse
  • Receptor, Metabotropic Glutamate 5
  • Receptors, Metabotropic Glutamate
  • Resorcinols
  • metabotropic glutamate receptor type 1
  • Puromycin Aminonucleoside
  • 3,5-dihydroxyphenylglycine
  • Doxorubicin
  • Cyclic AMP
  • Glycine