TY - JOUR
T1 - TLR3 stimulation induces melanosome endo/phagocytosis through RHOA and CDC42 in human epidermal keratinocyte
AU - Koike, Saaya
AU - Yamasaki, Kenshi
AU - Yamauchi, Takeshi
AU - Shimada-Omori, Ryoko
AU - Tsuchiyama, Kenichiro
AU - Ando, Hideya
AU - Aiba, Setsuya
N1 - Funding Information:
This work was supported in part by Grant-in-Aid for Challenging Exploratory Research16K15542 (K.Y.) and a Grant-in-aid for Scientific ResearchC 24591622 (K.Y.) and 25893012 (K.T) from the Ministry of Education, Culture, Sports, Science and Technology, Japan, by Novartis Pharma Research Grants (K.Y.), and by research grant from Kao Melanin Workshop (K.Y.).
Funding Information:
This work was supported in part by Grant-in-Aid for Challenging Exploratory Research 16K15542 (K.Y.) and a Grant-in-aid for Scientific Research C 24591622 (K.Y.) and 25893012 (K.T) from the Ministry of Education, Culture, Sports, Science and Technology, Japan , by Novartis Pharma Research Grants (K.Y.) , and by research grant from Kao Melanin Workshop (K.Y.) .
Publisher Copyright:
© 2019 Japanese Society for Investigative Dermatology
PY - 2019/12
Y1 - 2019/12
N2 - Background: Keratinocytes and melanocytes in human epidermis express Toll-like receptors (TLR) and induce immune responses. We previously reported that TLR3 stimulation increases melanosome transport from perinuclear to cell membrane in melanocytes and enhanced release of melanosome from melanocytes, which were followed by increase in melanosome uptake into keratinocytes. Objective: In this study, we investigated whether TLR3 stimuli directly affect keratinocytes to enhance melanosome uptake. Methods: To observe keratinocyte's melanosome uptake ability precisely without melanocytes influences, we isolated melanosomes from human melanocytes and applied isolated melanosomes to keratinocytes stimulated by Poly(I:C). Results: Poly(I:C)-stimulated keratinocytes enhanced uptake of isolated melanosome-rich globules five-times as much as control. Poly(I:C) increases the RNA and protein expressions of RHOA and CDC42, which are small GTP-binding proteins inducing the endocytosis. Pull-down assay showed that Poly(I:C) increased the GTP-binding RHOA and CDC42, suggesting TLR3 stimulation activated RHOA and CDC42. The knockdown of TLR3 suppressed RHOA and CDC42 induction by Poly(I:C). Consistently, the knockdown of RHOA and CDC42 significantly suppressed the melanosome-rich globules uptake by Poly(I:C)-stimulated keratinocytes. Conclusion: Because RHOA and CDC42 activation induces endocytosis by modification of actin stress fiber and filopodia formation, respectively, these results suggested that TLR3 stimulation enhances melanosome uptake into keratinocytes through endocytosis mechanisms. Combining with the data of our previous publications, TLR3, which signal is activated by sensing viral molecules, enhance pigmentation by controlling both melanin transport system by RAB GTPases induction in melanocytes and uptake system by RHOA and CDC42 in keratinocytes.
AB - Background: Keratinocytes and melanocytes in human epidermis express Toll-like receptors (TLR) and induce immune responses. We previously reported that TLR3 stimulation increases melanosome transport from perinuclear to cell membrane in melanocytes and enhanced release of melanosome from melanocytes, which were followed by increase in melanosome uptake into keratinocytes. Objective: In this study, we investigated whether TLR3 stimuli directly affect keratinocytes to enhance melanosome uptake. Methods: To observe keratinocyte's melanosome uptake ability precisely without melanocytes influences, we isolated melanosomes from human melanocytes and applied isolated melanosomes to keratinocytes stimulated by Poly(I:C). Results: Poly(I:C)-stimulated keratinocytes enhanced uptake of isolated melanosome-rich globules five-times as much as control. Poly(I:C) increases the RNA and protein expressions of RHOA and CDC42, which are small GTP-binding proteins inducing the endocytosis. Pull-down assay showed that Poly(I:C) increased the GTP-binding RHOA and CDC42, suggesting TLR3 stimulation activated RHOA and CDC42. The knockdown of TLR3 suppressed RHOA and CDC42 induction by Poly(I:C). Consistently, the knockdown of RHOA and CDC42 significantly suppressed the melanosome-rich globules uptake by Poly(I:C)-stimulated keratinocytes. Conclusion: Because RHOA and CDC42 activation induces endocytosis by modification of actin stress fiber and filopodia formation, respectively, these results suggested that TLR3 stimulation enhances melanosome uptake into keratinocytes through endocytosis mechanisms. Combining with the data of our previous publications, TLR3, which signal is activated by sensing viral molecules, enhance pigmentation by controlling both melanin transport system by RAB GTPases induction in melanocytes and uptake system by RHOA and CDC42 in keratinocytes.
KW - CDC42
KW - Endo/phagocytosis
KW - Keratinocytes
KW - Melanin
KW - Melanosome
KW - PAR2
KW - RHOA
KW - Toll-like receptor 3
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UR - http://www.scopus.com/inward/citedby.url?scp=85076312125&partnerID=8YFLogxK
U2 - 10.1016/j.jdermsci.2019.11.005
DO - 10.1016/j.jdermsci.2019.11.005
M3 - Article
C2 - 31776046
AN - SCOPUS:85076312125
VL - 96
SP - 168
EP - 177
JO - Journal of Dermatological Science
JF - Journal of Dermatological Science
SN - 0923-1811
IS - 3
ER -