The melanocortin 1 receptor (MC1R), a G S -coupled receptor that signals through cAMP and protein kinase A (PKA), regulates pigmentation, adaptive tanning, and melanoma resistance. MC1R-cAMP signaling promotes PKA-mediated phosphorylation of ataxia telangiectasia and rad3-related (ATR) at Ser435 (ATR-pS435), a modification that enhances nucleotide excision repair (NER) by facilitating recruitment of the XPA protein to sites of UV-induced DNA damage. High-throughput methods were developed to quantify ATR-pS435, measure XPA-photodamage interactions, and assess NER function. We report that melanocyte-stimulating hormone (α-MSH) or ACTH induce ATR-pS435, enhance XPA's association with UV-damaged DNA and optimize melanocytic NER. In contrast, MC1R antagonists agouti signaling protein (ASIP) or human β-defensin 3 (HBD3) interfere with ATR-pS435 generation, impair the XPA-DNA interaction, and reduce DNA repair. Although ASIP and HBD3 each blocked α-MSH-mediated induction of the signaling pathway, only ASIP depleted basal ATR-pS435. Our findings confirm that ASIP diminishes agonist-independent MC1R basal signaling whereas HBD3 is a neutral MC1R antagonist that blocks activation by melanocortins. Furthermore, our data suggest that ATR-pS435 may be a useful biomarker for the DNA repair-deficient MC1R phenotype.
|Number of pages||10|
|Journal||Journal of Investigative Dermatology|
|State||Published - Dec 1 2015|
Bibliographical noteFunding Information:
We thank S. Iwai for the generous gift of the CPD-containing substrate. This work was supported by the following NIH grants: R01 CA131075 and T32CA165990. We thank the Drury Pediatric Research Endowed Chair Fund, Melanoma Research Alliance, Wendy Will Case Cancer Research Fund, Markey Cancer Foundation, Children’s Miracle Network, and Jennifer and David Dickens Melanoma Research Foundation.
© 2015 The Society for Investigative Dermatology.
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology