L-Proline transport into renal OK epithelial cells: a second renal proline transport system is induced by amino acid deprivation

Amino Acids. 2010 Mar;38(3):753-61. doi: 10.1007/s00726-009-0280-5. Epub 2009 Mar 31.

Abstract

Influx of [(3)H]-L-proline into renal OK cells revealed that basal transport was mediated by the transporter SIT1. When cells were submitted for 8 h to amino acid deprivation, uptake of L-proline was now dominated by a low-affinity system with an apparent K (m) of 4.4 +/- 0.6 mM and a V (max) of 10.2 +/- 0.6 nmol/mg of protein/min operating in addition to the high-affinity SIT1 system with a K (m) of 0.12 +/- 0.01 mM and a V (max) of 0.28 +/- 0.04 nmol/mg of protein/min. The low- and high-affinity proline transporting systems were sensitive to inhibitors of JNK and PI-3 kinases, whereas a GSK-3 inhibitor affected only the upregulated transport system. Ion-replacement studies and experiments assessing substrate specificities for both systems provided strong evidence that SNAT2, that showed two- to threefold increased mRNA levels, is the responsible transporter mediating the increased proline influx under conditions of amino acid deprivation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Transport System A / genetics
  • Amino Acid Transport System A / metabolism
  • Amino Acid Transport Systems, Neutral / antagonists & inhibitors
  • Amino Acid Transport Systems, Neutral / classification*
  • Amino Acid Transport Systems, Neutral / genetics
  • Amino Acid Transport Systems, Neutral / metabolism*
  • Amino Acids / deficiency*
  • Amino Acids / metabolism
  • Animals
  • Cell Line
  • Cell Membrane Permeability / drug effects
  • Cell Membrane Permeability / genetics
  • Epithelial Cells / drug effects
  • Epithelial Cells / metabolism*
  • Glycogen Synthase Kinase 3 / antagonists & inhibitors
  • Ions / metabolism
  • JNK Mitogen-Activated Protein Kinases / antagonists & inhibitors
  • Kidney / drug effects
  • Kidney / metabolism*
  • Kinetics
  • Opossums
  • Phosphoinositide-3 Kinase Inhibitors
  • Proline / metabolism*
  • Protein Biosynthesis / drug effects
  • Protein Kinase Inhibitors / pharmacology
  • RNA, Messenger / metabolism
  • Substrate Specificity
  • Up-Regulation / drug effects

Substances

  • Amino Acid Transport System A
  • Amino Acid Transport Systems, Neutral
  • Amino Acids
  • Ions
  • Phosphoinositide-3 Kinase Inhibitors
  • Protein Kinase Inhibitors
  • RNA, Messenger
  • Proline
  • JNK Mitogen-Activated Protein Kinases
  • Glycogen Synthase Kinase 3