ENVIROMENTAL STRESS APOPTOSIS AND SYSTEMIC AUTOIMMUNITY

我们实验室最近的观察表明，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相互作用对自身免疫的控制至关重要，正如lpr和gld突变小鼠株所表明的那样，我们假设自身免疫性疾病可能依赖于Fas的有效调节和损伤细胞的有效诱导凋亡。在本提案中，我们将使用正常细胞研究损伤后Fas上调的生物学，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缺乏的小鼠会产生更高滴度的自身抗体。我们假设p53可能通过Fas诱导受损细胞凋亡，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。我们将确定在p53-/-小鼠中负责诱导自身免疫的细胞。我们将通过将正常和突变小鼠暴露于电离和UV-B辐射中来测试Fas和p53在介导局部病理和系统性自身免疫性疾病中的作用。最后，我们将利用fas结合的M13噬菌体克隆扩展我们的初步数据，以开发修饰fas介导的细胞凋亡的试剂，包括激动剂和拮抗剂。我们将根据从噬菌体展示文库中鉴定出的fas结合噬菌体序列，合成激动和拮抗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。总的来说，拟议的研究应该有助于阐明Fas在免疫损伤和系统性自身免疫性疾病中的作用，以及它作为对环境应激作出反应的前哨分子的参与。

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.