ROLE OF AHR/ARNT SIGNALING ON MATRIX REMODELING IN SKIN

描述(改编自候选人的摘要) 接触TCDD会导致严重的皮肤损害，称为氯痤疮。这些损伤 以过度增殖、高度分化和异常为特征 角质形成细胞在复层鳞状上皮中的迁移。它是 尚不清楚接触TCDD是如何导致皮肤病理的。大多数研究都是关于 TCDD作用的分子机制主要集中在配体激活 转录因子AhR/Arnt。TCDD与AhR启动子的结合 与Arnt的异源二聚作用，并最终通过 该复合体与AhR基因5‘端特定位点(XRES)的结合 反应基因。已确定的TCDD靶基因包括第一阶段和第二阶段 II解毒酶，以及细胞因子(转化生长因子-B，IL-1B)，转录 因子(Fos、Jun)和一种细胞外基质重塑抑制蛋白 (PAI-2)。在某些情况下需要细胞外基质的新陈代谢 需要组织重塑或细胞迁移，如伤口愈合。这个 大多数基质的降解是通过 基质金属蛋白酶(MMPs)家族的成员。A转录因子 数据库搜索发现在基质金属蛋白酶-1的5‘端区域有两个潜在的XRE位点， 初步结果显示，TCDD时，基质金属蛋白酶-1mRNA水平升高 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。 威斯康星大学B.L.Allen-Hoffmann博士的实验室- 在麦迪逊，她的项目是制造一种组织特异性基因敲除小鼠 AHR在复层鳞状上皮细胞中的表达研究AhR缺失对皮肤的影响 结构和分化。这项建议的目标是研究皮肤 TCDD暴露在完整组织中引起的病理变化，并确定 AhR/Arnt通路在MMPs及其抑制物TIMPs中的作用 受影响皮肤。因此，这项建议的具体目标是：(1)创造 用噬菌体P1的Cre/loxP重组系统建立小鼠模型 条件性敲除复制型角质形成细胞中的Arnt基因 小鼠皮肤。使用此小鼠模型以及AhR组织特异性 目的：研究AhR和Arnt缺失对MMPTIMP表达的影响。 TCDD皮肤病理。(2)在器官细胞培养中使用角质形成细胞 研究TCDD对组织结构和基因表达影响的系统 MMPs/TIMP。

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.