UV-induced reduction in Polycomb repression promotes epidermal pigmentation

Meng Yen Li, Pooja Flora, Hong Pu, Carmit Bar, Jose Silva, Idan Cohen, Phillip M. Galbo, Hequn Liu, Xufen Yu, Jian Jin, Haruhiko Koseki, John A. D'Orazio, Deyou Zheng, Elena Ezhkova

Research output: Contribution to journalArticlepeer-review


Ultraviolet (UV) radiation is a prime environmental stressor that our epidermis is exposed to on a daily basis. To avert UV-induced damage, epidermal stem cells (EpSCs) become pigmented via a process of heterotypic interaction between melanocytes and EpSCs; however, the molecular mechanisms of this interaction are not well understood. In this study, we show that the function of a key chromatin regulator, the Polycomb complex, was reduced upon UV exposure in human and mouse epidermis. Genetic ablation of key Polycomb subunits in murine EpSCs, mimicking depletion upon UV exposure, results in an increased number of epidermal melanocytes and subsequent epidermal pigmentation. Genome-wide transcriptional and chromatin studies show that Polycomb regulates the expression of UV-responsive genes and identifies type II collagen (COL2A1) as a critical secreted regulator of melanogenesis and epidermal pigmentation. Together, our findings show how UV exposure induces Polycomb-mediated changes in EpSCs to affect melanocyte behavior and promote epidermal pigmentation.

Original languageAmerican English
Pages (from-to)2547-2561.e8
JournalDevelopmental Cell
Issue number18
StatePublished - 27 Sep 2021


  • Polycomb
  • UV
  • epidermis
  • melanocyte
  • pigmentation
  • stem cell
  • type II collagen

All Science Journal Classification (ASJC) codes

  • General Biochemistry,Genetics and Molecular Biology
  • Molecular Biology
  • Cell Biology
  • Developmental Biology


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