MC1R variant allele effects on UVR-induced phosphorylation of p38, p53, and DDB2 repair protein responses in melanocytic cells in culture

J Invest Dermatol. 2012 May;132(5):1452-61. doi: 10.1038/jid.2011.473. Epub 2012 Feb 16.

Abstract

Variant alleles of the human melanocortin 1 receptor (MC1R) reduce the ability of melanocytes to produce the dark pigment eumelanin, with R alleles being most deficient. Cultured melanocytes of MC1R R/R variant genotype give reduced responses to [Nle(4), D-Phe(7)]α-melanocyte-stimulating hormone (NDP-MSH) ligand stimulation and lower levels of DNA repair than MC1R wild-type strains. p38 controls xeroderma pigmentosum (XP)-C recruitment to DNA damage sites through regulating ubiquitylation of the DNA damage-binding protein 2 (DDB2) protein, and p53 is implicated in the nuclear excision repair process through its regulation of XP-C and DDB2 protein expression. We report the effects of MC1R ligand treatment and UVR exposure on phosphorylation of p38 and p53, and DDB2 protein expression in MC1R variant strains. Wild-type MC1R melanocyte strains grown together with keratinocytes in coculture, when treated with NDP-MSH and exposed to UVR, gave synergistic activation of p38 and p53 phosphorylation, and were not replicated by R/R variant melanocytes, which have lower basal levels of phosphorylated forms of p38. Minor increases in p38 phosphorylation status in R/R variant melanocyte cocultures could be attributed to the keratinocytes alone. We also found that MC1R wild-type strains regulate DDB2 protein levels through p38, but MC1R R/R variant melanocytes do not. This work confirms the important functional role that the MC1R receptor plays in UVR stress-induced DNA repair.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles*
  • Cells, Cultured
  • Coculture Techniques
  • DNA Repair / genetics
  • DNA-Binding Proteins / drug effects
  • DNA-Binding Proteins / metabolism*
  • DNA-Binding Proteins / radiation effects
  • Humans
  • Keratinocytes
  • Melanocytes / drug effects
  • Melanocytes / radiation effects
  • Phosphorylation / drug effects
  • Phosphorylation / genetics
  • Phosphorylation / radiation effects
  • Receptor, Melanocortin, Type 1 / genetics*
  • Signal Transduction
  • Tumor Suppressor Protein p53 / drug effects
  • Tumor Suppressor Protein p53 / metabolism*
  • Tumor Suppressor Protein p53 / radiation effects
  • Ultraviolet Rays
  • alpha-MSH / analogs & derivatives*
  • alpha-MSH / pharmacology
  • p38 Mitogen-Activated Protein Kinases / drug effects
  • p38 Mitogen-Activated Protein Kinases / metabolism*
  • p38 Mitogen-Activated Protein Kinases / radiation effects

Substances

  • DDB2 protein, human
  • DNA-Binding Proteins
  • Receptor, Melanocortin, Type 1
  • Tumor Suppressor Protein p53
  • alpha-MSH
  • MSH, 4-Nle-7-Phe-alpha-
  • p38 Mitogen-Activated Protein Kinases