PPAR gamma is an important transcription factor in 1 alpha,25-dihydroxyvitamin D3-induced involucrin expression.
PPAR gamma is an important transcription factor in 1 alpha,25-dihydroxyvitamin D3-induced involucrin expression.
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DOI：
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发表时间：
2008
影响因子：
4.6
通讯作者：
X. Dai;K. Sayama;Y. Shirakata;S. Tokumaru;Lujun Yang;M. Tohyama;S. Hirakawa;Y. Hanakawa;K. Hashimoto
中科院分区：
文献类型：
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作者：
X. Dai;K. Sayama;Y. Shirakata;S. Tokumaru;Lujun Yang;M. Tohyama;S. Hirakawa;Y. Hanakawa;K. Hashimoto
1 α，25-二羟基维生素D3（1 α，25（OH）2D 3），维生素D的活性形式，抑制角质形成细胞增殖，促进角质形成细胞分化，并诱导外皮蛋白表达。过氧化物酶体增殖激活受体（PPARs）是配体激活的转录因子。已有报道PPARs刺激角质形成细胞分化并调节分化分子的表达。目的角质形成细胞经1 α，25（OH）2D 3诱导后，其外皮蛋白表达增加。在这项研究中，我们调查是否参与了1 α，25（OH）2D 3诱导的外皮蛋白在人角质形成细胞的表达。方法用10（-7）M 1 α，25（OH）2D 3处理角质形成细胞，用实时荧光定量RT-PCR法检测细胞内过氧化物酶体增殖物激活受体（PPAR）和外皮蛋白（involucrin）mRNA的表达。Western印迹法检测PPARs、外皮蛋白、p38和磷酸化p38蛋白水平，电泳迁移率变动分析（EMSA）检测PPARgamma和AP-1的DNA结合活性。为了检测PPAR γ在1 α，25（OH）2D 3应答中的作用，构建携带显性阴性形式的PPAR γ的重组腺病毒（Axdn-PPAR γ）并转染到角质形成细胞中。将p38抑制剂SB 203580添加到培养物中以评估p38在外皮蛋白表达中的参与。结果1 α，25（OH）2D 3诱导了PPAR γ的表达，并刺激了PPAR γ的活性。dn-PPARgamma的引入抑制了1 α，25（OH）2D 3诱导的外皮蛋白mRNA和蛋白的表达，并抑制了AP-1 DNA结合活性。1 α，25（OH）2D 3也触发了p38的磷酸化，这有助于外皮蛋白的诱导。此外，dn-PPAR γ阻止1 α，25（OH）2D 3诱导的p38磷酸化。结论：这些结果表明，在1 α，25（OH）2D 3诱导的角质形成细胞分化中，PPAR γ通过控制AP-1信号和p38激活来调节外皮蛋白的表达。
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.