Allosteric Costimulatory Blockade

蛋白质-蛋白质相互作用（PPI）是所有蛋白质功能的最终决定因素，很少能被小分子调节，因为相应的蛋白质界面没有足够的结合口袋。最近，一个有趣的替代方案已被确认为组成型多聚体蛋白，如那些在重要的TNF超家族（TNFSF）通过变构机制，扭曲的结合伙伴之一。由于我们最近已经确定了第一个小分子抑制剂的CD 40 <$CD154共刺激相互作用，这是这个家庭的成员，我们建议利用可能的优势，可以从这样的机制和（1）确认的可行性，变构，三聚体扭曲机制干扰CD 40 <$CD154共刺激相互作用，CD 154共刺激蛋白-蛋白相互作用，TNFSF的一个成员，在免疫应答的激活中起重要作用，（2）利用这些信息，设计改进的小-适合于治疗应用的分子抑制剂和为了证实最有希望的抑制剂的免疫抑制活性，以及（3）研究是否可以在TNF超家族的其他成员中发现类似的机制（特别是OX 40 <$OX40 L、BAFF-R <$BAFF、RANK <$RANKL、4-1BB <$4 - 1BBL）以及是否可用于鉴定特异性抑制剂。TNFSF共刺激相互作用在有效免疫反应的发展中起着关键作用，但直到最近，它们和大多数其他PPI一样，被认为是不可用的。现在已经表明，这种对CD 40、CD 154和TNFSF家族其他成员的抑制可能通过独特的变构机制发生，其中破坏分子不是插入在受体配体界面之间，而是插入在三聚体配体（或受体）的单体单元之间。这可以允许更有效的结合，使得这些相互作用特别可被小分子靶向。然而，类毒品现在已经认识到，通常用于高通量筛选的化学文库不太适合PPI抑制，但是我们的抑制剂的化学空间可以允许快速探索组成型同源三聚体细胞因子的这种新机制，并且可以导致用于涉及TNF超家族相互作用的许多疾病领域的新的药理学工具和新的创新药物。对小分子抑制CD 40、CD 154和TNF超家族其他可能的受体-配体对的详细机制理解的发展可以导致开发新的临床可行方法，以解决T-、B-和APC细胞中共刺激分子功能失调引起的治疗需求，如自身免疫性疾病和移植排斥。因此，拟议的工作应导致阐明一个有趣的新机制，可以使小分子共刺激阻断以及新的药理学工具和新的创新药物的一些疾病领域，其中涉及TNF超家族的相互作用。由于其在小分子药理学、药物化学、分子生物学、细胞移植和免疫生物学方面的专业知识的独特组合，我们相信我们的团队非常有能力在这些方面取得沿着进展。

Protein-protein interactions (PPI), which are the ultimate determinants of the function of all proteins, can rarely be modulated by small molecules because the corresponding protein interfaces do not have adequate binding pockets. Recently, an intriguing alternative has been recognized for constitutively multimeric proteins such as those in the important TNF superfamily (TNFSF) via an allosteric mechanism that distorts one of the binding partners. Since we have recently identified the first small-molecule inhibitors of the CD40¿CD154 costimulatory interaction, which is a member of this family, we propose to exploit the possible advantages that can be derived from such a mechanism and (1) confirm the feasibility of an allosteric, trimer-distorting mechanism in interfering with the CD40¿CD154 costimulatory proteinprotein interaction, a member of the TNFSF that plays an important role in the activation of immune responses, (2) use this information and design improved small-molecule inhibitors suitable for therapeutic applications and to confirm the immunosuppressive activity of the most promising inhibitors, and (3) investigate whether similar mechanism can be found for other members of the TNF superfamily (in particular, OX40¿OX40L, BAFF-R¿BAFF, RANK¿RANKL, 4-1BB¿4- 1BBL) and whether it can be used to identify specific inhibitors. TNFSF costimulatory interactions play key roles in the development of effective immune responses, but until relatively recently, they, just as most other PPIs, were considered ¿undruggable¿. It has now been suggested that such inhibitions for CD40¿CD154 and other members of the TNFSF family might occur via a unique allosteric mechanism whereby the disruptor molecule intercalates not between the receptorligand interface, but between monomeric units of the trimeric ligand (or receptor). This can allow more efficient binding making these interactions particularly targetable by small molecule. Whereas ¿drug-like¿ chemical libraries commonly used for high-throughput screening are now recognized to not be well-suited for PPI inhibition, the chemical space of our inhibitors can allow quick exploration of this novel mechanism for constitutively homotrimeric cytokines, and can lead to novel pharmacological tools and new innovative drugs for the many disease areas where TNF superfamily interactions are involved. Development of a detailed mechanistic understanding of the small-molecule inhibition of CD40¿CD154 and possibly other receptor-ligand pairs of the TNF superfamily can lead to the development of novel, clinically feasible approaches addressing therapeutic needs arising from dysregulated functions of costimulatory molecules in T-, B-, and APC cells such as autoimmune diseases and transplant rejection. Accordingly, the proposed work should lead to the elucidation of an intriguing new mechanism that can make possible small-molecule costimulatory blockade as well as to novel pharmacological tools and new innovative drugs for a number of disease areas where TNF superfamily interactions are involved. Because of its unique combination of expertise in small molecule pharmacology, medicinal chemistry, molecular biology, cell transplant, and immunobiology, we believe that our team is very well positioned to achieve considerable progress along these lines.