CELL SIGNALING LEADING TO UV-INDUCED CELL INJURY

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。我们的初步数据表明，紫外线辐射上调了HIFIa和DEC1，这两个基因都参与了细胞的生存和增殖。导致HIFIa和DEC1表达的信号通路尚不清楚。本研究拟验证的假设是，EGFR/rac1/P13K/AKT介导紫外线诱导的HIF1a表达，DEC1和HIF1a是相互调节的。本项目的具体目的是：1)明确EGFR在紫外线诱导HIF1a表达中的作用。(A)EGFR抑制剂和(B)EGFR的强制表达(例如，EGFR的过度表达、EGFR的敲除、RNAi)将被用来确定EGFR的调节是否会影响HIF1a及其靶基因的表达；2)研究Rac1/P13K/AKT信号通路在紫外线诱导HIF1a表达中的作用：(A)Rac1和P13激酶抑制因子的表达以及(B)Rac1和P13激酶的强迫表达(如P13激酶亚基和rac1的过度表达，或P13激酶和rac1的显性负亚单位的过度表达)将被用来确定Rac1/P13激酶信号的调节是否会影响HIF1a的表达；3)研究DEC1和HIF1a在紫外线照射下是否相互调节。(A)强制表达DEC1(例如，DEC1基因敲除或RNAi，过表达DEC1)将用于确定紫外线诱导的HIF1a表达是否依赖于DEC1。(B)强制表达HIFIa将被用来确定DEC1依赖的HIF1a表达是否也反式激活DEC1。我们的期望是，在本项目结束时，我们将：(A)描述一种新的细胞信号通路，以响应紫外线照射导致HIF1a的表达；以及(B)一种新的机制，即HIF1a和DEC1对紫外线辐射的相互调节。总之，所概述的实验将有助于我们了解紫外线诱导的皮肤光老化和皮肤癌的分子机制，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.