CELL SIGNALING LEADING TO UV-INDUCED CELL INJURY

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。我们的初步数据表明，紫外线辐射上调HIFIa和DEC 1，两者都参与细胞的存活和增殖。导致HIFIa和DEC 1表达的信号通路尚不清楚。在这个拟议的项目中要检验的假设是，EGFR/Rac 1/P13 K/AKT介导UV诱导的HIF 1a表达，而DEC 1和HIF 1a是受UV调控的。本课题的具体目的是：1）明确EGFR在紫外线诱导HIF 1a表达中的作用。(a)EGFR抑制剂和（B）EGFR的强制表达（例如EGFR的过表达、EGFR的敲除、RNAi）将用于确定EGFR的调节是否会影响HIF 1a及其靶基因的表达; 2）确定Rac 1/P13 K/AKT通路在UV诱导的HIF 1a表达中的作用（a）Rac 1和P13激酶抑制剂和（B）Rac 1和P13激酶的强制表达（例如P13激酶亚基和Rac 1的过表达，或P13激酶和Rac 1的显性失活亚基）将用于确定Rac 1/P13激酶信号的调节是否会影响HIF 1a的表达; 3）研究DEC 1和HIF 1a在紫外线照射下是否受到调控。(a)DEC 1的强制表达（例如DEC 1敲除或RNAi，DEC 1的过表达）将用于确定UV诱导的HIF 1a表达是否为DEC 1依赖性。(b)HIFIa的强制表达将用于确定HIF 1a的DEC 1依赖性表达是否也反式激活DEC 1。我们的期望是，在本项目结束时，我们将：（a）描绘一个新的细胞信号通路，响应于UV辐射导致HIF 1a的表达;和（B）一个新的机制，相互调节HIF 1a和DEC 1响应于UV辐射。总之，所概述的实验将有助于我们对紫外线诱导的皮肤光老化和皮肤癌的分子机制的基本理解，并为制定预防和治疗策略提供分子基础。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Our preliminary data indicate that UV radiation up-regulates HIFIa and DEC1, both are involved in cell survival and proliferation. The signaling pathway leading to HIFIa and DEC1 expression is unknown. The hypotheses to be tested in this proposed project are that EGFR/Rac1/P13K/AKT mediates UV-induced HIF1a expression, and DEC1 and HIF1a are reciprocally regulated. The specific aims of this project are: 1) To define the role of EGFR in UV-induced expression of HIF1a. (a) EGFR inhibitors and (b) Forced expression of EGFR (e.g. over-expression of EGFR, knockout of EGFR, RNAi) will be utilized to determine whether modulation of EGFR would affect the expression HIF1a and its target genes; 2) To determine the role of Rac1/P13K/AKT pathway in UV-induced expression of HIF1a (a) Rac1 and P13 kinase inhibitors and (b) Forced expression of Rac1 and P13 kinase (e.g. over-expression of P13 kinase subunits and Rac1, or dominant negative subunits of P13 kinase and Rac1) will be utilized to determine whether modulation of Rac1/P13 kinase signal would affect the expression of HIF1a; 3) To investigate whether DEC1 and HIF1a are reciprocally regulated in response to UV irradiation. (a) Forced expression of DEC1 (e.g. DEC1 knockout or RNAi, over-expression of DEC1) will be used to determine whether UV-induced HIF1a expression is DEC1-dependent. (b) Forced expression of HIFIa will be used to determine whether DEC1-dependent expression of HIF1a also transactivates DEC1. Our expectations are that, at the conclusion of this project, we will have: (a) delineated a novel cell signaling pathway in response to UV irradiation leading to the expression of HIF1a; and (b) a novel mechanism of reciprocal regulation of HIF1a and DEC1 in response to UV radiation. Overall, the experiments outlined will contribute significantly to our basic understanding of molecular mechanism of UV-induced skin photoaging and skin cancer, and provide molecular basis for developing preventive and therapeutic strategies.