AMPHIREGULIN PROCESSING IN HUMAN KERATINOCYTES

两性调节素(AR)是表皮生长因子受体的一员 (EGFR)配体家族。在培养的人角质形成细胞中，双调节蛋白 主要是自分泌是主要的增长因素。此外， 相互作用可增强角质形成细胞对AR的丝裂原作用 与CD9等其他蛋白质结合，并被肝素抑制。虽然 AR在正常成人表皮中的作用尚不完全清楚， 成人表皮分析不完全了解，AR分析 蛋白质和信使核糖核酸水平提供了对其功能的一些见解。Ar 在正常成人表皮角质形成细胞中弱表达，但 在几种增生性疾病中上调，如银屑病 以及在肿瘤中。AR水平升高和高血压之间可能的因果联系 最近的一项研究发现，转基因小鼠可能患有牛皮癣 人AR基因在K14角蛋白启动子下的高表达 银屑病表型。结果与效果形成了直接对比。 TGFAlpha的过度表达，表明这两种基因的作用截然不同 配基。此外，AR，但不是TGFα，被戏剧性地诱导(10-30 折叠)在几个创伤模型中。 两亲性调节素作为糖基膜锚定的合成 前体(ProAR)。在极化的上皮细胞中，我们研究了 ProAR和演示复合序列的生物合成和加工 加工ProAR胞外结构域生产多种细胞和可溶性蛋白 AR表格。一种主要的43kD可溶性AR形式是新的，含有N- 末端前区域，并具有c-末端延伸。生物学的 多个AR物种的意义尚不清楚。这样做的目的是 资助计划是为了确定AR的细胞和可溶性形式 在正常角质形成细胞中产生。这些研究将是第一次 在正常情况下全面检查proAR的生物合成和加工 原代上皮细胞类型。参与调控的机制(S) 角质形成细胞中的proAR胞外结构域的切割也将提供基础 了解金属蛋白酶在这一过程中的作用以及更多 一般在膜脱落的过程中。最后，这些研究 应加强我们对各种AR表格的作用的了解 在不同的环境条件下表达(例如，紫外线照射) 在不同的皮肤病状态下。

Amphiregulin (AR) is a member of the epidermal growth factor receptor (EGFR) family of ligands. In cultured human keratinocytes, amphiregulin is the major is the major autocrine growth factor. Additionally, the mitogenic effects on AR on keratinocytes can be enhanced by interaction with other proteins such as CD9 and are inhibited by heparin. Although the role of AR in normal adult epidermis is not completely understood, analysis adult epidermis is not completed understood, analysis of AR protein and mRNA levels has provided some insights into its function. AR is weakly expressed in keratinocytes in normal adult epidermis but is up-regulated in several hyperproliferative disorders such as psoriasis and in tumors. A possible causal link between elevated AR levels and psoriasis has been suggested by the recent finding that transgenic mice over-expressing human AR cDNA under the K14 keratin promoter display a psoriatic phenotype. The result stands in direct contrast to the effects of TGFalpha over-expression, suggesting distinct roles for these two ligands. Moreover, AR, but not TGFalpha, is dramatically induced (10-30 fold) in several wounding models. Amphiregulin is synthesized as a glycosylated membrane-anchored precursor (proAR). In polarized epithelial cells, we have examined the biosynthesis and processing of proAR and demonstrated complex sequential processing of proAR ectodomain to produce multiple cellular and soluble AR forms. A predominant 43 kD soluble AR form is novel, contains the N- terminal pro-region and has a c-terminal extension. The biological significance of multiple AR species is not known. The goals of this grant proposal are to identify the cellular and soluble forms of AR produced in normal keratinocytes. These studies will be the first to comprehensively examine proAR biosynthesis and processing in a normal primary epithelial cell type. The mechanism(s) involved in regulating proAR ectodomain cleavage in keratinocytes will also provide the basis for understanding the role of metalloproteases in this process and more generally in the process of membrane shedding. Finally, these studies should enhance our understanding of the role of the various AR forms expressed under different environmental conditions (e.g., UV exposure) and in different skin disease states.