Inhibition of the protein kinase MK-2 protects podocytes from nephrotic syndrome-related injury

Am J Physiol Renal Physiol. 2011 Sep;301(3):F509-19. doi: 10.1152/ajprenal.00661.2010. Epub 2011 May 25.

Abstract

While mitogen-activated protein kinase (MAPK) activation has been implicated in the pathogenesis of various glomerular diseases, including nephrotic syndrome (NS), its specific role in podocyte injury is not known. We hypothesized that MK-2, a downstream substrate of p38 MAPK, mediates the adverse effects of this pathway and that inhibition of MK-2 would protect podocytes from NS-related injury. Using cultured podocytes, we analyzed 1) the roles of MK-2 and p38 MAPK in puromycin aminonucleoside (PAN)-induced podocyte injury; 2) the ability of specific MK-2 and p38 MAPK inhibitors to protect podocytes against injury; 3) the role of serum albumin, known to induce podocyte injury, in activating p38 MAPK/MK-2 signaling; and 4) the role of p38 MAPK/MK-2 signaling in the expression of Cox-2, an enzyme associated with podocyte injury. Treatment with protein kinase inhibitors specific for both MK-2 (C23, a pyrrolopyridine-type compound) or p38 MAPK (SB203580) reduced PAN-induced podocyte injury and actin cytoskeletal disruption. Both inhibitors reduced baseline podocyte p38 MAPK/MK-2 signaling, as measured by the degree of phosphorylation of HSPB1, a downstream substrate of MK-2, but exhibited disparate effects on upstream signaling. Serum albumin activated p38 MAPK/MK-2 signaling and induced Cox-2 expression, and these responses were blocked by both inhibitors. Given the critical importance of podocyte injury to both NS and other progressive glomerular diseases, these data suggest an important role for p38 MAPK/MK-2 signaling in podocyte injury and identify MK-2 inhibition as a promising potential therapeutic strategy to protect podocytes in various glomerular diseases.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cell Line
  • Disease Models, Animal
  • Heat-Shock Proteins / metabolism
  • Imidazoles / pharmacology
  • Intracellular Signaling Peptides and Proteins / antagonists & inhibitors*
  • Intracellular Signaling Peptides and Proteins / drug effects
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Mice
  • Molecular Chaperones
  • Neoplasm Proteins / metabolism
  • Nephrotic Syndrome / metabolism*
  • Nephrotic Syndrome / pathology*
  • Nephrotic Syndrome / physiopathology
  • Podocytes / drug effects
  • Podocytes / metabolism*
  • Podocytes / pathology*
  • Protein Kinase Inhibitors / pharmacology
  • Protein Serine-Threonine Kinases / antagonists & inhibitors*
  • Protein Serine-Threonine Kinases / drug effects
  • Protein Serine-Threonine Kinases / metabolism
  • Puromycin Aminonucleoside / pharmacology
  • Pyridines / pharmacology
  • Serum Albumin / pharmacology
  • Signal Transduction / drug effects
  • Signal Transduction / physiology
  • p38 Mitogen-Activated Protein Kinases / antagonists & inhibitors
  • p38 Mitogen-Activated Protein Kinases / drug effects
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • Heat-Shock Proteins
  • Hsbp1 protein, mouse
  • Imidazoles
  • Intracellular Signaling Peptides and Proteins
  • Molecular Chaperones
  • Neoplasm Proteins
  • Protein Kinase Inhibitors
  • Pyridines
  • Serum Albumin
  • Puromycin Aminonucleoside
  • MAP-kinase-activated kinase 2
  • Protein Serine-Threonine Kinases
  • p38 Mitogen-Activated Protein Kinases
  • SB 203580