Violet light down-regulates the expression of specific differentiation markers through Rhodopsin in normal human epidermal keratinocytes.
Several recent reports have demonstrated that photoreceptors are expressed in human skin. The rod and cone photoreceptor-like proteins are expressed in human skin and rhodopsin, long wavelength-opsin, and short wavelength-opsin are also present in cultured murine melanocytes. Furthermore, the photopigment rhodopsin is expressed in human melanocytes and is involved in ultraviolet A phototransduction which induces early melanin synthesis. In this study, we investigated whether rhodopsin is expressed and plays any physiological roles in the normal human epidermal keratinocytes (NHEKs). We found that rhodopsin was expressed and localized on the plasma membrane in NHEKs, and only violet light among several wavelengths within the visible range significantly increased the expression of rhodopsin mRNA. We further found that rhodopsin over-expression decreased the mRNA expression levels of keratinocyte differentiation markers, such as keratin-1 and keratin-10, and violet light also decreased the mRNA expression levels of keratinocyte differentiation markers and these decreased expression levels were recovered by a rhodopsin-directed siRNA. Moreover, we further demonstrated that violet light significantly decreased the phosphorylation levels of cAMP responsive element-binding protein (CREB) and that it more effectively decreased the phosphorylation of CREB when rhodopsin was over-expressed. In addition, we observed that pertussis toxin, a Gαi protein inhibitor, restored the rhodopsin-induced decrease in the differentiation markers in NHEKs. Taken together, these results suggest that rhodopsin down-regulates the expression levels of specific keratinocyte differentiation markers via the Gαi signaling pathway in NHEKs.
Bioscience Research Institute, Amorepacific Corporation R&D Center, Yongin-city, Gyeonggi-do, Republic of Korea ; Department of Biological Sciences, Sungkyunkwan University, Suwon-city, Republic of Korea.
Hyoung-June
HJ
Kim
Eui Dong
ED
Son
Ji-Yong
JY
Jung
Hyun
H
Choi
Tae Ryong
TR
Lee
Dong Wook
DW
Shin
D015153:Blotting, Western; D002470:Cell Survival; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D015603:Keratinocytes / Q000378:metabolism* / Q000528:radiation effects; D008027:Light; D060888:Real-Time Polymerase Chain Reaction; D012243:Rhodopsin / Q000378:metabolism*; D017299:Rod Opsins / Q000378:metabolism
D017362:Cyclic AMP Response Element-Binding Protein; D017299:Rod Opsins; C095855:long-wavelength opsin; C095853:short-wavelength opsin; D012243:Rhodopsin