TRPV6 is a Ca2+ entry channel essential for Ca2+-induced differentiation of human keratinocytes.
Ca(2+) is an essential factor inducing keratinocyte differentiation due to the natural Ca(2+) gradient in the skin. However, the membrane mechanisms that mediate calcium entry and trigger keratinocyte differentiation had not previously been elucidated. In this study we demonstrate that Ca(2+)-induced differentiation up-regulates both mRNA and protein expression of a transient receptor potential highly Ca(2+)-selective channel, TRPV6. The latter mediates Ca(2+) uptake and accounts for the basal [Ca(2+)](i) in human keratinocytes. Our results show that TRPV6 is a prerequisite for keratinocyte entry into differentiation, because the silencing of TRPV6 in human primary keratinocytes led to the development of impaired differentiated phenotype triggered by Ca(2+). The expression of such differentiation markers as involucrin, transglutaminase-1, and cytokeratin-10 was significantly inhibited by small interfering RNA-TRPV6 as compared with differentiated control cells. TRPV6 silencing affected cell morphology and the development of intercellular contacts, as well as the ability of cells to stratify. 1,25-Dihydroxyvitamin D3, a cofactor of differentiation, dose-dependently increased TRPV6 mRNA and protein expression in human keratinocytes. This TRPV6 up-regulation led to a significant increase in Ca(2+) uptake in both undifferentiated and differentiated keratinocytes. We conclude that TRPV6 mediates, at least in part, the pro-differentiating effects of 1,25-dihydroxyvitamin D3 by increasing Ca(2+) entry, thereby promoting differentiation. Taken together, these data suggest that the TRPV6 channel is a key element in Ca(2+)/1,25-dihydroxyvitamin D3-induced differentiation of human keratinocytes.
Lehen'kyi
V'yacheslav
V
Inserm, U-800, Equipe Labellisée par la Ligue Nationale Contre le Cancer, Université des Sciences et Technologies de Lille, F-59655 Villeneuve d'Ascq, France.
Beck
Benjamin
B
Polakowska
Renata
R
Charveron
Maria
M
Bordat
Pascal
P
Skryma
Roman
R
Prevarskaya
Natalia
N
D002117:Calcitriol / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism* / Q000502:physiology; D002454:Cell Differentiation; D002460:Cell Line; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D006801:Humans; D015603:Keratinocytes / Q000166:cytology* / Q000378:metabolism; D010641:Phenotype; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D050916:TRPV Cation Channels / Q000378:metabolism / Q000502:physiology*; D013997:Time Factors
D015220:Calcium Channels; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D050916:TRPV Cation Channels; C422827:TRPV6 protein, human; D002117:Calcitriol; D002118:Calcium