L-arginine stimulates fibroblast proliferation through the GPRC6A-ERK1/2 and PI3K/Akt pathway

PLoS One. 2014 Mar 20;9(3):e92168. doi: 10.1371/journal.pone.0092168. eCollection 2014.

Abstract

L-arginine is considered a conditionally essential amino acid and has been shown to enhance wound healing. However, the molecular mechanisms through which arginine stimulates cutaneous wound repair remain unknown. Here, we evaluated the effects of arginine supplementation on fibroblast proliferation, which is a key process required for new tissue formation. We also sought to elucidate the signaling pathways involved in mediating the effects of arginine on fibroblasts by evaluation of extracellular signal-related kinase (ERK) 1/2 activation, which is important for cell growth, survival, and differentiation. Our data demonstrated that addition of 6 mM arginine significantly enhanced fibroblast proliferation, while arginine deprivation increased apoptosis, as observed by enhanced DNA fragmentation. In vitro kinase assays demonstrated that arginine supplementation activated ERK1/2, Akt, PKA and its downstream target, cAMP response element binding protein (CREB). Moreover, knockdown of GPRC6A using siRNA blocked fibroblast proliferation and decreased phosphorylation of ERK1/2, Akt and CREB. The present experiments demonstrated a critical role for the GPRC6A-ERK1/2 and PI3K/Akt signaling pathway in arginine-mediated fibroblast survival. Our findings provide novel mechanistic insights into the positive effects of arginine on wound healing.

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Arginine / pharmacology*
  • Cell Proliferation / drug effects
  • Cyclic AMP Response Element-Binding Protein / metabolism
  • Cyclic AMP-Dependent Protein Kinases / antagonists & inhibitors
  • Cyclic AMP-Dependent Protein Kinases / metabolism
  • Dermis / cytology
  • Enzyme Activation / drug effects
  • Fibroblasts / cytology*
  • Fibroblasts / drug effects
  • Fibroblasts / enzymology
  • Gene Knockdown Techniques
  • Humans
  • Mice
  • Mitogen-Activated Protein Kinase 1 / metabolism*
  • Mitogen-Activated Protein Kinase 3 / metabolism*
  • NIH 3T3 Cells
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphoinositide-3 Kinase Inhibitors
  • Proto-Oncogene Proteins c-akt / antagonists & inhibitors
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Receptors, G-Protein-Coupled / metabolism*
  • Signal Transduction / drug effects

Substances

  • Cyclic AMP Response Element-Binding Protein
  • GPRC6A protein, human
  • Phosphoinositide-3 Kinase Inhibitors
  • Receptors, G-Protein-Coupled
  • Arginine
  • Proto-Oncogene Proteins c-akt
  • Cyclic AMP-Dependent Protein Kinases
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3

Associated data

  • RefSeq/NM_004379
  • RefSeq/NM_148963

Grants and funding

The authors have no support or funding to report.