过氧化物酶体增殖物激活受体γ是1α,25 - 二羟基维生素D3诱导的内聚蛋白表达中的一种重要转录因子。

PPAR gamma is an important transcription factor in 1 alpha,25-dihydroxyvitamin D3-induced involucrin expression.

作者信息

Dai Xiuju, Sayama Koji, Shirakata Yuji, Tokumaru Sho, Yang Lujun, Tohyama Mikiko, Hirakawa Satoshi, Hanakawa Yasushi, Hashimoto Koji

机构信息

Department of Dermatology, Ehime University School of Medicine, Ehime, Japan.

出版信息

J Dermatol Sci. 2008 Apr;50(1):53-60. doi: 10.1016/j.jdermsci.2007.10.011.

DOI:10.1016/j.jdermsci.2007.10.011

PMID:18077140

Abstract

BACKGROUND

1 alpha,25-Dihydroxyvitamin D3 (1 alpha,25(OH)2D3), the active form of vitamin D, suppresses keratinocyte proliferation, promotes keratinocyte differentiation, and induces involucrin expression. Peroxisome proliferation-activated receptors (PPARs) are ligand-activated transcription factors. It has been reported that PPARs stimulate keratinocyte differentiation and regulate the expression of differentiation molecules.

OBJECTIVE

Keratinocytes treated with 1 alpha,25(OH)2D3 induced PPAR gamma, which was followed by increased involucrin expression. In this study, we investigated whether PPAR gamma is involved in the 1 alpha,25(OH)2D3-induced involucrin expression in human keratinocytes.

METHODS

Subconfluent keratinocytes were treated with 10(-7)M 1 alpha,25(OH)2D3 for the indicated times, and PPAR and involucrin mRNA expression were determined by real-time RT-PCR. The levels of PPARs, involucrin, p38, and phospho-p38 proteins were assayed by Western blotting, and the DNA binding activities of PPAR gamma and AP-1 were investigated by electrophoretic mobility shift assays (EMSA). To examine the role of PPAR gamma in 1 alpha,25(OH)2D3 responses, recombinant adenovirus carrying a dominant-negative form of PPAR gamma (Axdn-PPAR gamma) was constructed and transfected into keratinocytes. The p38 inhibitor SB203580 was added to the cultures to evaluate the involvement of p38 in involucrin expression.

RESULTS

1 alpha,25(OH)2D3 induced PPAR gamma expression and stimulated PPAR gamma activity. The introduction of dn-PPAR gamma inhibited the expression of involucrin mRNA and protein induced by 1 alpha,25(OH)2D3, and suppressed AP-1 DNA binding activity. 1 alpha,25(OH)2D3 also triggered the phosphorylation of p38, which contributes to involucrin induction. Moreover, dn-PPAR gamma prevented the 1 alpha,25(OH)2D3-induced phosphorylation of p38.

CONCLUSIONS

These results suggest that PPAR gamma regulates involucrin expression by controlling the AP-1 signal and p38 activation in 1 alpha,25(OH)2D3-induced keratinocyte differentiation.

摘要

背景

1α,25 - 二羟基维生素D3（1α,25(OH)2D3）是维生素D的活性形式，可抑制角质形成细胞增殖，促进角质形成细胞分化，并诱导兜甲蛋白表达。过氧化物酶体增殖物激活受体（PPARs）是配体激活的转录因子。据报道，PPARs可刺激角质形成细胞分化并调节分化分子的表达。

目的

用1α,25(OH)2D3处理角质形成细胞可诱导PPARγ表达，随后兜甲蛋白表达增加。在本研究中，我们调查了PPARγ是否参与1α,25(OH)2D3诱导的人角质形成细胞中兜甲蛋白的表达。

方法

将亚汇合的角质形成细胞用10(-7)M 1α,25(OH)2D3处理指定时间，通过实时RT-PCR测定PPAR和兜甲蛋白mRNA表达。通过蛋白质印迹法检测PPARs、兜甲蛋白、p38和磷酸化p38蛋白的水平，并通过电泳迁移率变动分析（EMSA）研究PPARγ和AP-1的DNA结合活性。为了研究PPARγ在1α,25(OH)2D3反应中的作用，构建携带PPARγ显性负性形式的重组腺病毒（Axdn-PPARγ）并转染到角质形成细胞中。向培养物中加入p38抑制剂SB203580以评估p38在兜甲蛋白表达中的作用。

结果

1α,25(OH)2D3诱导PPARγ表达并刺激PPARγ活性。导入显性负性PPARγ可抑制1α,25(OH)2D3诱导的兜甲蛋白mRNA和蛋白表达，并抑制AP-1 DNA结合活性。1α,25(OH)2D3还可触发p38的磷酸化，这有助于兜甲蛋白的诱导。此外，显性负性PPARγ可阻止1α,25(OH)2D3诱导的p38磷酸化。