UV-induced and NOS-mediated Zn elevation, translation regulation and apoptosis

描述（由申请人提供）：2005年，美国每年诊断出超过100万例非黑色素瘤皮肤癌和59,600例黑色素瘤，导致约10,600人死亡（约7,800人死于黑色素瘤）。近年来，越来越清楚的是，被紫外线损伤的皮肤患其中一种皮肤癌的几率增加，包括基底细胞癌、鳞状细胞癌和皮肤恶性黑色素瘤。对紫外线的凋亡反应是一种保护性反应，它消除了接受高剂量紫外线的细胞。虽然大多数研究都集中在DNA损伤诱导的、p53依赖的紫外线诱导细胞凋亡途径上，但膜受体介导的信号通路在诱导细胞凋亡中也起着重要作用。紫外线照射激活真核起始因子2 (eIF21) α亚基磷酸化的激酶，随后抑制蛋白质合成。翻译在细胞凋亡基因表达调控中起着重要作用。然而，导致eIF21激酶在紫外线照射下活化的上游信号通路尚不清楚。本研究的目的是阐明通过一氧化氮合酶（NOS）介导的信号通路调控紫外线诱导细胞凋亡的机制，并确定一氧化氮(NO)/过氧亚硝酸盐（ONOO）和锌（Zn2+）在紫外线诱导的翻译调控和细胞凋亡中的作用。本申请中提出的研究具有重要意义，因为了解NOS激活的调控以及这种调控如何影响紫外线照射下eIF21激酶的激活和/或凋亡，将为我们提供一个新的信号网络，用于识别靶基因和开发预防和治疗紫外线相关癌症的治疗方法。在Specific Aim I中，我们提出阐明导致eIF21磷酸化的紫外线诱导和no介导的信号通路。工作假设是NO介导紫外线诱导的eIF21激酶(s)激活，使eIF21磷酸化。在Specific Aim II中，我们提出确定NO/ONOO/产生的机制和动力学及其在紫外线诱导的细胞凋亡中的作用。工作假设是，在高NO:ONOO比下，UV具有抗凋亡作用，而在低NO:ONOO比下，UV具有促凋亡作用。在Specific Aim III中，我们提出了确定锌在紫外线诱导的内质网应激和凋亡信号通路中的作用。工作假设是[Zn2+]在紫外线照射下介导no诱导的细胞凋亡。本研究的结果不仅将增加我们对紫外线诱导和nos介导的多种信号通路的认识，而且还将进一步了解受NO和翻译抑制影响的其他生理状况（如再灌注、伤口愈合、糖尿病）诱导的调控机制和信号通路。公共卫生相关性：紫外线（UV）诱导的细胞死亡是一种消除受损细胞的保护性反应。在本研究中，我们将通过一氧化氮合酶介导的信号通路研究紫外线诱导细胞凋亡的调控机制，并确定一氧化氮/过氧亚硝酸盐和胞质锌浓度在紫外线诱导的翻译调控和细胞凋亡中的作用。这些研究的结果不仅将增加我们对紫外线诱导的多种凋亡信号通路的认识，而且还将引导我们开发新的治疗紫外线相关皮肤老化和癌症的方法。

DESCRIPTION (provided by applicant): More than 1 million cases of nonmelanoma skin cancer and 59,600 cases of melanoma are diagnosed yearly in the United States, resulting in about 10,600 deaths (about 7,800 due to melanoma) in 2005. In recent years it has become clear that UV-damaged skin has an increased chance of developing one of the forms of skin cancer, including basal cell carcinoma, squamous cell carcinoma and cutaneous malignant melanoma. The apoptotic response to UV is a protective response that eliminates cells that receive high doses of UV. While most studies have focused on DNA damage-inducible, p53-dependent pathways of UV-induced apoptosis, membrane receptor mediated signaling pathways also play an important role in inducing apoptosis. UV-irradiation activates kinases that phosphorylate the alpha subunit of eukaryotic initiation factor 2 (eIF21) and subsequently inhibit protein synthesis. Translation plays an important role in regulation of apoptotic gene expression. However, the upstream signaling pathway(s) that leads to eIF21 kinase(s) activation upon UV-irradiation is not known. The objective of this application is to elucidate the mechanisms that regulate UV-induced apoptosis via nitric oxide synthase (NOS) mediated signaling pathways and to determine the roles of nitric oxide (NO)/peroxynitrite (ONOO) and zinc (Zn2+) in UV-induced translation regulation and apoptosis. The research proposed in this application is significant because understanding the regulation of NOS activation and how this regulation affects eIF21 kinase(s) activation and/or apoptosis upon UV-irradiation will lead us to a new signaling network for identification of target genes and development of therapeutics in the prevention and treatment of UV-related cancers. In Specific Aim I, we proposed to elucidate the UV-induced and NO-mediated signaling pathway(s) that leads to eIF21 phosphorylation. The working hypothesis is that NO mediates UV-induced activations of eIF21 kinase(s), which phosphorylate eIF21. In Specific Aim II: we proposed to determine the mechanism and kinetics of NO/ONOO/ production and their role in UV-induced apoptosis. The working hypothesis is that at a high ratio of NO:ONOO, the effect of UV can be anti-apoptotic, while at a low ratio this effect can be pro-apoptotic. In Specific Aim III, we proposed to determine the role(s) of Zn in UV-induced ER-stress and apoptotic signaling pathways. The working hypothesis is that [Zn2+] mediates NO-induced apoptosis upon UV- irradiation. The outcomes from this research will not only increase our knowledge of UV- induced and NOS-mediated multiple signaling pathways, but will also lead to a further understanding of regulatory mechanisms and signaling pathways induced by other physiological conditions (e.g., reperfusion, wound healing, diabetes) that are affected by NO and translation inhibition. PUBLIC HEALTH RELEVANCE: Cell death induced by ultraviolet light (UV) is a protective response that eliminates damaged cells. In the proposal, we will study the mechanisms that regulate UV-induced apoptosis via nitric oxide synthase mediated signaling pathways and to determine the roles of nitric oxide/peroxynitrite and cytosolic zinc concentration in UV-induced translation regulation and apoptosis. The outcomes from these studies will not only increase our knowledge of UV- induced multiple apoptotic signaling pathways, but will also lead us to the development of new therapeutics for treatment of UV-related skin aging and cancers.