ENVIROMENTAL STRESS APOPTOSIS AND SYSTEMIC AUTOIMMUNITY

我们实验室最近的观察结果表明，Fas/FasL系统是UV-B和γ辐射以及热休克损伤后细胞凋亡的关键介质。 由于Fas/FasL相互作用是控制自身免疫性的关键，如lpr和gld突变小鼠品系所示，我们假设自身免疫性疾病可能依赖于有效的Fas调节和有效诱导受损细胞的凋亡。 在这个建议中，我们将研究Fas上调损伤后使用正常细胞的生物学，特别强调p53分子的作用。 我们对p53在自身免疫中的作用特别感兴趣，因为我们惊人的初步数据表明，p53缺陷的小鼠产生更高滴度的自身抗体。 我们假设p53可能通过Fas诱导损伤细胞凋亡，并且p53-/-小鼠可能无法消除这些细胞，并可能保留潜在的自身免疫原性细胞。 我们将定义负责诱导p53-/-小鼠自身免疫的细胞。 我们将测试Fas和p53在介导局部病理和全身性自身免疫性疾病中的作用，通过将正常和突变小鼠暴露于电离和UV-B辐射。 最后，我们将扩展我们的初步数据使用Fas结合M13噬菌体克隆开发试剂，以修改Fas介导的细胞凋亡，无论是作为激动剂和拮抗剂。我们将根据从噬菌体展示文库中鉴定的Fas结合肽序列合成激动性和拮抗性Fas结合肽，并评估它们在体内和体外诱导和阻断细胞死亡的能力。总体而言，拟议的研究应有助于澄清Fas在免疫损伤和系统性自身免疫性疾病中的作用，以及其作为响应环境应激的哨兵分子的参与。

Recent observations in our laboratory have implicated the Fas/FasL system as a key mediator of apoptosis following injury by UV-B and gamma irradiation, as well as heat shock. Because Fas/FasL interactions are critical to the control of autoimmnuity, as illustrated by the lpr and gld mutant mouse strains, we hypotheisze that autoimmune disease may depend on effective Fas regulation and the efficient induction of apoptosis in injured cells. In this proposal, we will study the biology of Fas upregulation after injury using normal cells, with particular emphasis on the role of the p53 molecule. We are particularly interested in p53's role in autoimmunity because of our striking preliminary data that mice deficient in p53 develop higher-titer auto-antibodies. We hypothesize that p53 may act via Fas to induce apoptosis of injured cells, and that the p53-/-mice may be unable to eliminate such cells and may retain potentially autoimmunogenic cells. We will define the cells responsible for induction of autoimmunity in p53-/- mice. We will test the role of both Fas and p53 in mediating local pathology and in systemic autoimmune disease by exposing normal and mutant mice to ionizing and UV-B radiation. Finally, we will extend our preliminary data using Fas-binding M13 bacteriophage clones to develop reagents to modify Fas-mediated apoptosis, both as agonists and antagonists. We will synthesize agonistic and antagonistic Fas-binding peptides based on sequences of Fas-binding phages we have identified from a phage display library, and will assess their ability to induce and to block cell death in vivo and in vitro. Overall, the proposed studies should help clarify the role of Fas in immune injury and systemic autoimmune disease, and its participation as a sentinel molecule which responds to environmental stress.