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Updated: Nov 5, 2025

Spatial and Temporal Control of Murine Melanoma Initiation from Mutant Melanocyte Stem Cells
Published on: June 7, 2019
Transcriptional co-activator regulates melanocyte differentiation and oncogenesis by integrating cAMP and MAPK/ERK
Jelena Ostojić1, Young-Sil Yoon1, Tim Sonntag1
1Clayton Foundation Laboratories for Peptide Biology, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
Abstract:
The cyclic AMP pathway promotes melanocyte differentiation by activating CREB and the cAMP-regulated transcription co-activators 1-3 (CRTC1-3). Differentiation is dysregulated in melanomas, although the contributions of CRTC proteins is unclear. We report a selective differentiation impairment in CRTC3 KO melanocytes and melanoma cells, due to downregulation of oculo-cutaneous albinism II (OCA2) and block of melanosome maturation. CRTC3 stimulates OCA2 expression by binding to CREB on a conserved enhancer, a regulatory site for pigmentation and melanoma risk. CRTC3 is uniquely activated by ERK1/2-mediated phosphorylation at Ser391 and by low levels of cAMP. Phosphorylation at Ser391 is constitutively elevated in human melanoma cells with hyperactivated ERK1/2 signaling; knockout of CRTC3 in this setting impairs anchorage-independent growth, migration, and invasiveness, whereas CRTC3 overexpression supports cell survival in response to the mitogen-activated protein kinase (MAPK) inhibitor vemurafenib. As melanomas expressing gain-of-function mutations in CRTC3 are associated with reduced survival, our results suggest that CRTC3 inhibition may provide therapeutic benefit in this setting.
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