INFLAMMATORY RESPONSES IN THE TOXICITY OF RICIN

描述(申请人提供)：鉴于蓖麻毒素的广泛可获得性和易于提纯，它已被极权政权和最近的恐怖组织用作有毒和致命的毒剂。蓖麻毒素是核糖体定向毒素家族中的一员，其毒性源于28S核糖体RNA(28S RRNA)的sarcin/ricin环中单个腺嘌呤的脱嘌呤作用。28S rRNA的脱氢不仅导致蛋白质翻译的抑制，而且还导致JNK和p38MAPK等应激激活蛋白激酶的强烈和广泛的激活。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。在蓖麻毒素和其他核糖体导向毒素中毒的情况下，介入治疗的发展将关键取决于我们对受影响的主要靶组织以及驱动促炎和细胞毒反应的机制的了解。当给培养的细胞或小鼠注射时，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以及已知驱动它们表达的转录因子的激活。同时，蓖麻毒素通过激活顶端caspase8和9激活细胞凋亡途径，从而导致细胞死亡。我们的初步研究支持这一观点，即伴随着蓖麻毒素中毒的健康风险源于蓖麻毒素S激活炎症和凋亡途径。在这一应用中，我们建议在培养细胞以及野生型和“基因敲除”小鼠中使用蓖麻毒素，以阐明蓖麻毒素中毒的初始作用靶点、细胞毒性后果以及细胞和分子机制。在这一应用中，我们建议：1)在蓖麻毒素中毒的小鼠模型中识别受蓖麻毒素影响的靶组织和细胞类型；2)识别在特定细胞和组织类型中由蓖麻毒素诱导表达的基因；3)确定蓖麻毒素引发的细胞凋亡的机制和细胞凋亡在蓖麻毒素诱导的炎症过程中的作用；以及4)利用小鼠的“敲除”模型阐明特定的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.