Thrombin is a novel regulator of hexokinase activity in mesangial cells

Kidney Int. 2000 Jun;57(6):2308-18. doi: 10.1046/j.1523-1755.2000.00091.x.

Abstract

Background: Hexokinase (HK) activity is fundamentally important to cellular glucose uptake and metabolism. Phorbol esters increase both HK activity and glucose utilization in cultured mesangial cells via a protein kinase C (PKC)- and extracellular signal-regulated kinases 1 and 2 (ERK1/2)-dependent mechanism. In adult kidneys, increased HK activity has been reported in both glomerular injury and in diabetes, but the mechanisms responsible for these changes are unknown. Thrombin, a known activator of both PKC and ERK1/2, is increased in the settings of renal injury and diabetes. Thus, thrombin may contribute to the observed changes in HK activity in vivo.

Methods: Thrombin and thrombin receptor agonists were tested for the ability to increase HK activity and glucose metabolism in murine mesangial (SV40 MES 13) cells. ERK1/2 activation was also evaluated in parallel. Thrombin inhibition (hirudins), PKC depletion, Ser-Thr kinase inhibition (H-7), MEK1/2 inhibition (PD98059), pertussis toxin (PTX), and general inhibitors of transcription or translation were then tested for the ability to attenuate these effects.

Results: Thrombin (>/=0.01 U/mL) mimicked the effect of phorbol esters, increasing HK activity> 50% within 12 to 24 hours (P < 0.05). This effect was inhibited by hirudins, mimicked by thrombin receptor agonists, and accompanied by increased Glc utilization. H-7, PD98059, and general inhibitors of transcription or translation-but not PTX-prevented thrombin-induced HK activity at 24 hours. PKC depletion and PD98059 also blocked the associated phosphorylation and activation of ERK1/2.

Conclusions: Thrombin increases mesangial cell HK activity via a PTX-insensitive mechanism involving thrombin receptor activation, PKC-dependent activation of ERK1/2, and both ongoing gene transcription and de novo protein synthesis. As such, thrombin is a novel regulator of HK activity in mesangial cells and may play a role in coupling renal injury to metabolism.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Dose-Response Relationship, Drug
  • Drug Resistance
  • Enzyme Inhibitors / pharmacology
  • Glomerular Mesangium / cytology
  • Glomerular Mesangium / drug effects
  • Glomerular Mesangium / enzymology*
  • Glucose / metabolism
  • Hexokinase / antagonists & inhibitors
  • Hexokinase / metabolism*
  • Hirudins / pharmacology
  • Mice
  • Mitogen-Activated Protein Kinases / metabolism
  • Pertussis Toxin
  • Protein-Serine-Threonine Kinases / antagonists & inhibitors
  • Receptor, PAR-1
  • Receptors, Thrombin / agonists
  • Thrombin / pharmacology*
  • Transcription, Genetic / physiology
  • Virulence Factors, Bordetella / pharmacology

Substances

  • Enzyme Inhibitors
  • Hirudins
  • Receptor, PAR-1
  • Receptors, Thrombin
  • Virulence Factors, Bordetella
  • Pertussis Toxin
  • Hexokinase
  • Protein-Serine-Threonine Kinases
  • Mitogen-Activated Protein Kinases
  • Thrombin
  • Glucose