Protein Kinase C δ Increases Kruppel-like Factor 4 Protein, which Drives Involucrin Gene Transcription in Differentiating Keratinocytes
Protein Kinase C δ Increases Kruppel-like Factor 4 Protein, which Drives Involucrin Gene Transcription in Differentiating Keratinocytes
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DOI：
10.1074/jbc.m113.477133
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发表时间：
2013-06-14
影响因子：
4.8
通讯作者：
Eckert, Richard L.
中科院分区：
文献类型：
--
作者：
Chew, Yap Ching;Adhikary, Gautam;Eckert, Richard L.
KLF4是Kruppel样转录因子家族的成员。已显示KLF4是角质形成细胞正常终末分化所需的，但KLF4调节与分化过程相关的基因的分子机制尚未研究。在本研究中，我们探讨了KLF4对外皮蛋白表达的影响，外皮蛋白是一种在分化的角质形成细胞中特异性表达的基因。KLF4过表达和敲低研究表明，外皮蛋白mRNA和蛋白水平与KLF4水平直接相关。此外，突变KLF4蛋白的研究表明，转录失活形式不增加外皮蛋白的表达。PKC δ是角质形成细胞分化的调节因子，其增加分化相关靶基因的表达，包括外皮蛋白。KLF4的过表达增强了PKC δ依赖的外皮蛋白表达的增加，而KLF4敲低则减弱了这种反应。KLF4对人外皮蛋白（hINV）启动子活性的诱导是通过KLF4与位于hINV启动子远端调控区（体内外皮蛋白表达所需的启动子区域）的富含GC的元件结合来介导的。富含GC的元件、邻近的AP1因子结合位点或这两个位点的突变严重减弱了反应。此外，在分化的表皮等效模型中KLF4的损失导致hINV表达的损失。这些研究表明，KLF4是多蛋白复合物的一部分，该复合物与hINV启动子远端调控区相互作用，以驱动表皮中的分化依赖性hINV基因表达。
KLF4 is a member of the Kruppel-like factor family of transcriptional regulators. KLF4 has been shown to be required for normal terminal differentiation of keratinocytes, but the molecular mechanism whereby KLF4 regulates genes associated with the differentiation process has not been studied. In the present study, we explore the impact of KLF4 on expression of involucrin, a gene that is specifically expressed in differentiated keratinocytes. KLF4 overexpression and knockdown studies show that involucrin mRNA and protein level correlates directly with KLF4 level. Moreover, studies of mutant KLF4 proteins indicate that transcriptionally inactive forms do not increase involucrin expression. PKC delta is a regulator of keratinocyte differentiation that increases expression of differentiation-associated target genes, including involucrin. Overexpression of KLF4 augments the PKC delta-dependent increase in involucrin expression, whereas KLF4 knockdown attenuates this response. The KLF4 induction of human involucrin (hINV) promoter activity is mediated via KLF4 binding to a GC-rich element located in the hINV promoter distal regulatory region, a region of the promoter required for in vivo involucrin expression. Mutation of the GC-rich element, an adjacent AP1 factor binding site, or both sites severely attenuates the response. Moreover, loss of KLF4 in an epidermal equivalent model of differentiation results in loss of hINV expression. These studies suggest that KLF4 is part of a multiprotein complex that interacts that the hINV promoter distal regulatory region to drive differentiation-dependent hINV gene expression in epidermis.