Department of Medical Sciences, Section of Dermatology and Venereology, Uppsala University, Sweden.
J Dermatol Sci. 2010 Mar;57(3):207-13. doi: 10.1016/j.jdermsci.2009.12.013. Epub 2010 Jan 15.
Retinoids influence keratinocyte proliferation and differentiation via binding to nuclear retinoic acid receptors (RARalpha, -gamma) and retinoid X receptor alpha (RXRalpha). The effect of keratinocyte differentiation on expression of nuclear retinoid receptors and on the conversion of retinol into retinoic acid has not been examined earlier in depth.
Our aim was to examine the expression of retinoid receptors and a retinoid-regulated gene CRABPII, as well as the metabolism of exogenous [(3)H]retinol in cultured human keratinocytes induced to differentiate by exposure to either calcium, phorbol 12-myristate 13-acetate (PMA), or interferon-gamma (IFNgamma).
Normal human keratinocytes were cultured and exposed to differentiation-inducing agents. The mRNA and protein expression of retinoid receptors were examined using real-time PCR and Western blot. [(3)H]Retinol uptake and metabolism was monitored by HPLC with on-line radioactivity detection.
In calcium-exposed cells, increased expression of RARgamma and RXRalpha, enhanced metabolism of [(3)H]retinol to 3,4-didehydro-RA (ddRA), and an induction of CRABPII mRNA and protein was noted. In contrast, treatment with PMA and IFNgamma reduced the RARgamma and RXRalpha protein expression (preventable by the proteasome inhibitor MG132), increased the accumulation of [(3)H]RA and/or [(3)H]ddRA in the cells, and changed the CRABPII transcription.
Retinoid signalling is profoundly altered upon differentiation of keratinocytes and the effects depend on how cellular differentiation is initiated.
视黄酸通过与核视黄酸受体（RARα、-γ）和视黄醛 X 受体α（RXRα）结合，影响角质形成细胞的增殖和分化。角质形成细胞分化对核视黄酸受体表达和视黄醇转化为视黄酸的影响尚未进行深入研究。
我们的目的是研究培养的人角质形成细胞中视黄酸受体和视黄酸调节基因 CRABPII 的表达，以及外源性[(3)H]视黄醇在暴露于钙、佛波醇 12-肉豆蔻酸 13-醋酸盐（PMA）或干扰素-γ（IFNγ）诱导分化的细胞中的代谢情况。
培养正常的人角质形成细胞并使其暴露于诱导分化的试剂中。使用实时 PCR 和 Western blot 检测视黄酸受体的 mRNA 和蛋白表达。通过 HPLC 结合在线放射性检测监测[(3)H]视黄醇的摄取和代谢。
在暴露于钙的细胞中，RARγ和 RXRα的表达增加，[(3)H]视黄醇代谢为 3,4-二脱氢视黄醛（ddRA）增强，CRABPII mRNA 和蛋白诱导。相比之下，用 PMA 和 IFNγ处理会降低 RARγ和 RXRα蛋白表达（可被蛋白酶体抑制剂 MG132 预防），增加细胞内[(3)H]RA 和/或[(3)H]ddRA 的积累，并改变 CRABPII 转录。
角质形成细胞分化时视黄酸信号显著改变，其影响取决于细胞分化的启动方式。
