UVB-dependent changes in the expression of fast-responding early genes is modulated by huCOP1 in keratinocytes

Abstract

Ultraviolet (UV) B is the most prominent physical carcinogen in the environment leading to the development of various skin cancers. We have previously demonstrated that the human ortholog of the Arabidopsis thaliana constitutive photomorphogenesis 1 (COP1) protein, huCOP1, is expressed in keratinocytes in a UVB-regulated manner and is a negative regulator of p53 as a posttranslational modifier. However, it was not known whether huCOP1 plays a role in mediating the UVB-induced early transcriptional responses of human keratinocytes. In this study, we report that stable siRNA-mediated silencing of huCOP1 affects the UVB response of several genes within 2 h of irradiation, indicating that altered huCOP1 expression sensitizes the cells toward UVB.Pathway analysis identified a molecular network in which 13 of the 30 examined UVB-regulated genes were organized around three central proteins. Since the expression of the investigated genes was upregulated by UVB in the siCOP1 cell line, we hypothesize that huCOP1 is a repressor of the identified pathway. Several members of the network have been implicated previously in the pathogenesis of non-melanoma skin cancers; therefore, clarifying the role of huCOP1 in these skin diseases may have clinical relevance in the future.

HuCOP1 contributes to the regulation of DNA repair in keratinocytes

“…We have previously demonstrated that huCOP1 is expressed in human keratinocytes, regulates p53, and potentially plays a pathogenic role in basal cell carcinoma and/or in squamous cell carcinoma [6,7]. These data collectively suggest that huCOP1 may have a role in DNA damage repair, and deciphering its role in these processes may bring us closer to understanding the DNA repair mechanism in keratinocytes.…”

“…The keratinocyte cell lines used in the experiments-control and siCOP1, in which the expression level of huCOP1 was stably decreased-have been described previously [7]. HPV-KER cells were maintained in keratinocyte serumfree medium (GibcoÒ Keratinocyte SFM Kit; Life Technologies, Copenhagen, Denmark) supplemented with 1% antibiotic/antimycotic solution (PAA, Pasching, Austria) and 1% L-glutamine (PAA) at 37°C in a humidified atmosphere containing 5% CO 2 .…”

“…Immunocytochemistry was carried out using a previously described procedure [7]. As primary antibody, the mouse monoclonal anti-human MSH2 antibody was used at a dilution of 1:50 (product no.…”

“…Our first goal was to reveal whether huCOP1 affects MSH2 protein abundance in human keratinocytes. For this purpose, we used a well-characterized cell line in which the expression level of huCOP1 was stably decreased (siCOP1) [7]. The MSH2 protein in siCOP1 and control cells was visualized by immunocytochemical staining.…”

Effect of Zanthoxylum piperitum Extract on Human Skin Protection from UVB by Regulation of COP1 and PPAR-α

“…사람의 경우에서 는 COP1은 E3 ligase 기능을 가지고 있으며, human de-etiolated-1 (DET1)와 복합으로 p53이나 c-Jun 단백질 의 분해에 관여한다 [6,7]. 자외선에 의하여 각질형성세 포 및 섬유세포에서 COP1과 DET1 발현이 자외선에 의하여 감소하였으며 [6,8,9], 결과적으로 p53과 c-Jun 단백질을 세포 내에 축적시킬 수 있음이 보고되었다 [5].…”