Toll-like receptors 2 and 3 enhance melanogenesis and melanosome transport in human melanocytes

Saaya Koike, Kenshi Yamasaki, Takeshi Yamauchi, Mai Inoue, Ryoko Shimada-Ohmori, Kenichiro Tsuchiyama, Setsuya Aiba

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


Because little is known about how the innate immune response influences skin pigmentation, we examined whether Toll-like receptor (TLR) agonists participate in melanogenesis and melanosome transportation. We observed that TLR2/2 agonist HKLM and TLR3 agonist Poly(I:C) increased the amount of extracellular melanin from primary human epidermal melanocytes. HKLM, but not Poly(I:C), increased the melanogenic genes such as tyrosinase and dopachrome tautomerase. Poly(I:C) increased the expression of Rab27A, a molecule that facilitates melanosome transport to perimembranous actin filament. UVB irradiation induced Rab27A and melanosome transportation in a similar manner of Poly(I:C). SiRNA for TLR3 or Rab27A suppressed the perimembranous accumulation of Gp100-positive vesicles in melanocytes and decreased melanin transfer to neighboring keratinocytes induced by both Poly(I:C) and UVB. These results suggest that the microenvironment in the epidermis and innate immune stimuli, such as microbiome and ultraviolet represented here by TLR2 and TLR3 agonists, could affect the melanogenesis in human melanocytes.

Original languageEnglish
Pages (from-to)570-584
Number of pages15
JournalPigment Cell and Melanoma Research
Issue number5
Publication statusPublished - 2018 Sept


  • Rab27A
  • melanogenesis
  • melanosome
  • toll-like receptor
  • ultraviolet

ASJC Scopus subject areas

  • Oncology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Dermatology


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