The exocyst is required for melanin exocytosis from melanocytes and transfer to keratinocytes

Skin pigmentation involves the production of the pigment melanin by melanocytes, in melanosomes and subsequent transfer to keratinocytes. Within keratinocytes, melanin polarizes to the apical perinuclear region to form a protective cap, shielding the DNA from ultraviolet radiation‐induced damage. Pr...

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Bibliographic Details
Published in:Pigment cell and melanoma research 2020-03, Vol.33 (2), p.366-371
Main Authors: Moreiras, Hugo, Pereira, Francisco J. C., Neto, Matilde V., Bento‐Lopes, Liliana, Festas, Tiago C., Seabra, Miguel C., Barral, Duarte C.
Format: Article
Language:English
Subjects:
Cell Line
exocyst
Exocytosis
Gene Silencing
Humans
Immunoprecipitation
Keratinocytes
Keratinocytes - metabolism
Melanin
Melanins - metabolism
Melanocytes
Melanocytes - metabolism
Melanosomes
Phagocytosis
Pigmentation
Protein Binding
Protein Subunits - metabolism
Radiation damage
Radiation shielding
Skin pigmentation
Tethering
Ultraviolet radiation
Vesicular Transport Proteins - metabolism
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Summary:Skin pigmentation involves the production of the pigment melanin by melanocytes, in melanosomes and subsequent transfer to keratinocytes. Within keratinocytes, melanin polarizes to the apical perinuclear region to form a protective cap, shielding the DNA from ultraviolet radiation‐induced damage. Previously, we found evidence to support the exocytosis by melanocytes of the melanin core, termed melanocore, followed by endo/phagocytosis by keratinocytes as a main form of transfer, with Rab11b playing a key role in the process. Here, we report the requirement for the exocyst tethering complex in melanocore exocytosis and transfer to keratinocytes. We observed that the silencing of the exocyst subunits Sec8 or Exo70 impairs melanocore exocytosis from melanocytes, without affecting melanin synthesis. Moreover, we confirmed by immunoprecipitation that Rab11b interacts with Sec8 in melanocytes. Furthermore, we found that the silencing of Sec8 or Exo70 in melanocytes impairs melanin transfer to keratinocytes. These results support our model as melanocore exocytosis from melanocytes is essential for melanin transfer to keratinocytes and skin pigmentation and suggest that the role of Rab11b in melanocore exocytosis is mediated by the exocyst.
ISSN:1755-1471
1755-148X
DOI:10.1111/pcmr.12840