INFLAMMATORY RESPONSES IN THE TOXICITY OF RICIN

描述（由申请人提供）：鉴于蓖麻毒素的广泛可用性和易于净化，它已被极权主义政权用作有毒和致命的毒剂，最近也被恐怖组织使用。蓖麻毒素是核糖体导向毒素家族的一员，其毒性源于28S核糖体RNA （28S rRNA）“sarcin/ Ricin”环内单个腺嘌呤的去嘌呤化。28S rRNA的去嘌呤化不仅会抑制蛋白质翻译，还会导致应激激活的蛋白激酶如JNK和p38 MAPK的强烈和扩展激活。这些激酶被认为是炎症反应的中心介质，负责诱导促炎细胞因子和趋化因子的转录。蓖麻毒素和其他核糖体导向毒素中毒病例的介入治疗的发展将主要取决于我们对受影响的主要靶组织和驱动促炎和细胞毒性反应的机制的进一步了解。当给予培养细胞或小鼠时，蓖麻毒素能有效地诱导编码促炎细胞因子和趋化因子的基因的激活，以及已知驱动其表达的转录因子。同时，蓖麻毒素激活凋亡途径，通过参与顶端半胱天冬酶8和9，导致细胞死亡。我们的初步研究支持这样一种观点，即伴随蓖麻毒素中毒的健康风险源于蓖麻毒素激活炎症和凋亡途径。在这项应用中，我们建议在培养细胞和野生型和“敲除”小鼠中使用蓖麻毒素，以阐明作用的初始靶点、细胞毒性后果以及蓖麻毒素中毒的细胞和分子机制。在本应用中，我们建议：1)在蓖麻毒素中毒小鼠模型中鉴定受蓖麻毒素影响的靶组织和细胞类型；2)鉴定蓖麻毒素在特定细胞和组织类型中诱导表达的基因；3)明确蓖麻毒素引发细胞凋亡的机制及细胞凋亡在蓖麻毒素诱导炎症过程中的作用；4)通过小鼠“敲除”模型阐明特异性炎症或促凋亡基因在介导蓖麻毒素中毒反应中的作用。

DESCRIPTION (provided by applicant): In view of its wide availability and ease of purification, ricin has been employed as a toxic and lethal agent by totalitarian regimes and, recently, by terrorist groups. Ricin is a member of a family of ribosome-directed toxins whose toxicity stems from the depurination of a single adenine within the "sarcin/ricin" loop of 28S ribosomal RNA (28S rRNA). The depurination of 28S rRNA results not only in the inhibition of protein translation, but also the intense and extended activation of the stress-activated protein kinases such as JNK and p38 MAPK. These kinases are thought to be central mediators of inflammatory responses that are responsible for inducing the transcription of proinflammatory cytokines and chemokines. The development of interventional remedies in cases of poisoning by ricin and other ribosome-directed toxins will depend critically on our improved understanding of the primary target tissues affected and the mechanisms that drive the proinflammatory and cytotoxic responses. When administered to cultured cells or to mice, ricin potently induces the activation of genes that encode proinflammatory cytokines and chemokines and the transcription factors that are known to drive their expression. Simultaneously, ricin activates apoptotic pathways, via engagement of apical caspases 8 and 9, which lead to cell death. Our preliminary studies support the notion that the health risks that accompany ricin intoxication stem from ricin' s activation of inflammatory and apoptotic pathways. In this application we propose to employ ricin in both cultured cells and in wild-type and "knockout" mice to elucidate the initial targets of action, the cytotoxic consequences, and the cellular and molecular mechanisms that are pursuant to intoxication by ricin. In this application we propose to: 1) identify target tissues and cell types affected by ricin in a mouse model of ricin intoxication; 2) identify genes whose expression is induced by ricin in specific cell and tissue types; 3) determine the mechanisms of apoptosis triggered by ricin and the roles of apoptosis in the course of ricin-induced inflammation; and 4) elucidate the roles of specific inflammatory or pro-apoptotic genes in mediating the response to ricin intoxication by employing mouse "knock out" models.