ROLE OF AHR/ARNT SIGNALING ON MATRIX REMODELING IN SKIN

描述 （摘自《候选人摘要》） 接触TCDD会导致严重的皮肤损伤，称为氯痤疮。 这些病变 以过度增殖、过度分化和异常增殖为特征。 角质形成细胞在复层鳞状上皮中的迁移。 是 不清楚TCDD暴露如何导致皮肤病理学。 大多数关于 TCDD功能的分子机制主要集中在配体激活的 转录因子AhR/Arnt。 TCDD与AhR的结合启动 与Arnt异源二聚化，并最终通过 该复合物与AhR的5'区域中的特异性位点（XRES）的结合 反应基因 已确定的TCDD靶基因包括I期和II期 II解毒酶，以及细胞因子（TGF-β，IL-1B），转录 因子（Fos，Jun）和细胞外基质重塑抑制蛋白 （派-2）。 细胞外基质的代谢是必要的， 需要组织重塑或细胞迁移，如伤口愈合。 的 大部分基质降解是通过以下活性完成的： 基质金属蛋白酶（MMP）家族的成员。 转录因子 数据库搜索在MMP-1的5 ′区域鉴定了两个潜在的XRE位点， 初步结果表明，MMP-1 mRNA水平在TCDD后增加， 角质形成细胞的治疗。 这一数据表明TCDD/AhR/Arnt之间存在联系 和基质重塑。 该候选人目前是博士后研究员， B博士的实验室L.威斯康星州大学的艾伦-霍夫曼 麦迪逊，她的项目是产生一个组织特异性敲除小鼠， AhR在复层鳞状上皮中的表达，以研究AhR缺失对皮肤的影响 结构和分化。 这项提案的目标是研究皮肤 病理所造成的TCDD暴露在完整的组织，并确定 AhR/Arnt通路对MMPs及其抑制剂TIMPS的作用， 受影响的皮肤 因此，本提案的具体目标是：（1）建立 使用噬菌体P1的Cre/loxP重组系统， 有条件地敲除复制角质形成细胞中的Arnt基因， 鼠皮 使用该小鼠模型，沿着AhR组织特异性 敲除，研究AhR和Arnt缺失对MMP/TIMP表达的影响， TCDD皮肤病理学。 (2)在器官型细胞培养中使用角质形成细胞 系统研究TCDD对组织结构和基因表达的影响 MMPs/TIMPs

DESCRIPTION (Adapted from the Candidate's Abstract) TCDD exposure leads to severe skin lesions known as chloracne. These lesions are characterized by hyperproliferation, hyperdifferentiation, and abnormal migration of keratinocytes in the stratified squamous epithelia. It is unclear how TCDD exposure leads to the skin pathology. Most of the studies on the molecular mechanisms of TCDD function have focused on the ligand-activated transcription factor AhR/Arnt. Binding of TCDD to AhR initiates heterodimerization with Arnt, and ultimately alters transcription through binding of this complex to specific sites (XRES) in the 5' regions of AhR responsive genes. TCDD target genes identified include the Phase I and Phase II detoxifying enzymes, as well as cytokines (TGF-B, IL-1B), transcription factors (Fos, Jun), and an extracellular matrix remodeling inhibitory proteins (PAI-2). Metabolism of the extracellular matrix is required in situations that require tissue remodeling or cell migration, such as wound healing. The majority of the matrix degradation is accomplished through the activity of members of the matrix metalloproteinase (MMP) family. A transcription factor database search identified two potential XRE sites in the 5' region of MMP-1, and preliminary results demonstrate that MMP-1 MRNA levels increase upon TCDD treatment of keratinocytes. This data suggests a link between TCDD/AhR/Arnt and matrix remodeling. The candidate is currently a post-doctoral fellow in the laboratory of Dr. B. L. Allen-Hoffmann at the University of Wisconsin- Madison, where her project is to generate a tissue specific knockout mouse of AhR in stratified squamous epithelia to study the effects of AhR loss on skin structure and differentiation. The goal of this proposal is to study the skin pathology resulting from TCDD exposure in intact tissue, and determine the role of the AhR/Arnt pathway on MMPs and their inhibitors, the TIMPS, into the affected skin. Therefore the specific aims of this proposal are: (1) create a mouse model, using the Cre/loxP recombination system of bacteriophage P1, to conditionally knock out the Arnt gene in the replicating keratinocytes of murine skin. Use this mouse model, along with the AhR tissue specific knockout, to study the effect of AhR and Arnt loss on MMP/TIMP expression and TCDD skin pathologies. (2) Use keratinocytes in an organotypic cell culture system to study the effect of TCDD on tissue architecture and gene expression of MMPs/TIMPS.