Optimization of Small Molecule GPR17 Antagonists for Multiple Sclerosis

项目总结：R03提案的目标是为孤儿开发有效的、选择性的拮抗剂 受体GPR17。最终，在此应用程序下开发的配体将用作探测信号的工具 机制和体内功能，并有可能加速疾病新疗法的开发 由GPR17介导，如多发性硬化症(MS)。多发性硬化症是一种严重的神经系统疾病，特点是 自身免疫介导的神经元脱髓鞘和少突胶质细胞损伤。由此产生的轴突 变性会损害快速神经传导，如果不及时修复，会导致神经功能障碍。 重新髓鞘形成。再髓鞘形成过程需要少突胶质前体细胞的增殖和成熟。 (OPC)转化为髓鞘，产生成熟的少突胶质细胞。Gpr17是一种孤立的gpr，已被鉴定为 是少突胶质细胞成熟的负调控因子，主要在OPC中表达。Gpr17-/-小鼠有 中枢神经系统髓鞘形成增加和GPR17过表达的小鼠表现出缺乏髓鞘形成 中枢神经系统，类似于髓鞘疾病。GPR17激动剂探针MDL29,951加入培养物中 从GPR17+/-小鼠身上提取的蛋白质导致少突胶质细胞分化减少，髓鞘碱性减少 蛋白质(MBP)和树枝晶形成。此外，使用MS小鼠模型(实验性自身免疫)的研究 脑脊髓炎(EAE)表现为中枢神经系统脱髓鞘区域GPR17表达上调。 总体而言，这些数据表明GPR17参与了中枢神经系统激活后的脱髓鞘过程。因此，小说 能够选择性调节GPR17功能的小分子拮抗剂将是研究的宝贵工具 Gpr17生物学并导致治疗严重的脱髓鞘疾病的新药发现机会，如 女士。 到目前为止，小分子拮抗剂在文献和药理学方面的报道很少。 对现有的非选择性和效力较低的拮抗剂的研究一直具有挑战性。我们的前期工作 鉴定了一种新的小分子铅化合物SN-50(GPR17IC50=1701 nm，CysLT1，IC50 =6580 nM)通过非选择性GPR17拮抗剂Pranlukast的结构修饰(GPR17 IC50=588 NM，CysLT1 IC50=4 NM)。SN-50在GPR17和CysLT1的效价分别降低约3倍和1600倍 对GPR17的选择性是CysLT1的~4倍。此外，SN-50的性能提高了~6倍 与我们之前的引线SN-23(GPR17 IC50=1035 NM，CysLT1，IC50=590 NM)相比，选择性 在大鼠OPC分化实验中评价促进少突胶质细胞分化。因此，SN-50 作为一个优秀的线索，以确定强有力的和选择性的GPR17拮抗剂。在拟议的具体目标1中 R03项目，我们将通过一系列迭代支架合成至少100个新型SN-50类似物 修改。在具体目标2中，我们将评估合成的化合物的GPR17活性和选择性 通过CysLT1。两种具有良好拮抗活性的先导化合物的初步ADME性质 还将评估选择性(GPR17 IC50&lt；100 nm，&gt；50倍于CysLT1的选择性)。这些目标将是 通过化学和体外药理学的合作完成。

Project Summary: The goal of this R03 proposal is to develop potent, selective antagonists for the orphan receptor GPR17. Ultimately, ligands developed under this application will serve as tools to probe signaling mechanisms and in vivo functions, and could expedite development of novel therapies for diseases potentially mediated by GPR17, such as Multiple Sclerosis (MS). MS is a severe neurological disease characterized by autoimmune-mediated demyelination of neurons and oligodendrocyte damage. The resulting axonal degeneration impairs rapid nerve conduction, which leads to neurological disability if not repaired through remyelination. The remyelination process requires proliferation and maturation of oligodendrocyte precursor cells (OPCs) into myelin producing mature oligodendrocytes. GPR17 is an orphan GPCR that has been identified as a negative regulator of oligodendrocyte maturation and is predominantly expressed in OPCs. GPR17-/- mice have increased CNS myelination and GPR17 overexpressing mice showed lack of myelin sheath formation in the CNS, similar to that seen in myelinating disorders. Addition of the GPR17 agonist probe MDL29,951 to cultures from GPR17+/- mice resulted in reduced differentiation of oligodendrocytes, along with a decrease in myelin basic protein (MBP) and dendrite formation. In addition, studies using an MS mouse model (experimental autoimmune encephalomyelitis, EAE) showed an upregulation of GPR17 in CNS regions where demyelination was occurring. Collectively, these data suggest the involvement of GPR17 in CNS demyelination upon activation. Hence, novel small molecule antagonists that can selectively modulate GPR17 functions will be invaluable tools to study GPR17 biology and lead to new drug discovery opportunities to treat severe demyelinating diseases such as MS. To date, very few small molecule antagonists have been reported in the literature and pharmacological studies with the existing non-selective and less potent antagonists have been challenging. Our preliminary work led to the identification of a novel small molecule lead compound SN-50 (GPR17 IC50 = 1701 nM, CysLT1, IC50 = 6580 nM) through structural modification of Pranlukast, a non-selective GPR17 antagonist (GPR17 IC50 = 588 nM, CysLT1 IC50 = 4 nM). SN-50 exhibited ~3- and 1600-fold reduced potency at GPR17 and CysLT1 respectively, and is ~4-fold selective for GPR17 over CysLT1. Moreover, SN-50 exhibits ~6-fold improved selectivity compared to our previous lead SN-23 (GPR17 IC50 = 1035 nM, CysLT1, IC50 = 590 nM), which promoted oligodendrocyte differentiation upon evaluation in a rat OPC differentiation assay. SN-50 therefore serves as an excellent lead to identify potent and selective GPR17 antagonists. In Specific Aim 1 of the proposed R03 project, we will synthesize at least 100 novel SN-50 analogs through a series of iterative scaffold modifications. In Specific Aim 2, we will evaluate the synthesized compounds for GPR17 potency and selectivity over CysLT1. Preliminary ADME properties of two lead compounds with favorable antagonist potency and selectivity (GPR17 IC50 < 100 nM, >50-fold selectivity over CysLT1) will also be evaluated. These Aims will be accomplished through a collaboration of chemistry and in vitro pharmacology.