Optimization of compounds to improve mRNA splicing in familial dysautonomia

描述（申请人提供）：家族性自主神经功能障碍（FD）是一种遗传性感觉和自主神经病变，由IKBKAP基因剪接突变引起。该突变导致IKBKAP mRNA中外显子20的可变跳跃，这导致IKAP蛋白的组织特异性减少。对FD患者组织的分析显示，神经元组织中的外显子跳跃显著更多，因此IKAP水平较低。IKAP是人类延伸子复合体的成员，其是基因子集的有效转录延伸所需的。尽管FD是隐性的，但我们已经证明患者保留了制造正常mRNA和蛋白质的能力。这一发现为开发旨在通过剪接修饰增加细胞IKAP水平的疗法提供了一种令人兴奋的直接方法。作为NINDS赞助的神经变性药物筛选联盟的一部分，我们发现用激动素（一种植物细胞分裂素）处理培养的FD细胞，可增强FD细胞中20号外显子的包含，并显著增加野生型IKBKAP mRNA和IKAP蛋白的量。该化合物具有显著的功效，并且可以在培养的一周内恢复患者细胞中正常的IKAP蛋白水平。我们已经证明了激动素的能力，改变IKBKAP剪接在各种细胞类型，以及在人类细胞中使用小基因测定。最近，我们已经在转基因小鼠和人FD携带者中显示了体内功效。尽管Dysautonomia基金会在开发激动素作为FD的潜在治疗方法方面进行了大量投资，但通往临床的道路一直很缓慢，我们仍在研究最初确定的化合物。我们最近已经产生了一些有前途的SAR（结构和活性关系）的数据显示，可以提高活性的先导化合物激动素。为了提高激动素的效力和活性，进行化学优化是至关重要的，并且时间至关重要。尽管FD是一种发育障碍，但患者一生中仍受到持续、剧烈的神经元变性的困扰。在生命早期有效地增加IKAP水平可以支持神经元存活， 预防或延缓患者随着年龄增长而出现的虚弱步态以及感觉和认知能力下降。Blueprint Neurotherapeutics Network为药物开发提供了一个独特的机会，可以获得目前无法获得的资源。

DESCRIPTION (provided by applicant): Familial dysautonomia (FD) is a hereditary sensory and autonomic neuropathy that is caused by a splice mutation in the IKBKAP gene. The mutation results in variable skipping of exon 20 in IKBKAP mRNA, which leads to a tissue-specific reduction of IKAP protein. Analysis of tissues from FD patients shows significantly more exon-skipping in neuronal tissue, and therefore lower IKAP levels. IKAP is a member of the human Elongator complex, which is required for efficient transcriptional elongation of a subset of genes. Despite the fact that FD is recessive, we have shown that patients retain the capacity to make both normal mRNA and protein. This discovery offers an exciting, direct approach towards the development of therapies aimed at increasing levels of cellular IKAP via splicing modification. As part of the NINDS-sponsored Neurodegeneration Drug Screening Consortium, we found that treatment of cultured FD cells with kinetin, a plant cytokinin, enhances exon-20-inclusion and dramatically increases the amount of wild-type IKBKAP mRNA and IKAP protein in FD cells. This compound has remarkable efficacy and can restore normal IKAP protein levels in patient cells within one week in culture. We have demonstrated kinetin's ability to alter IKBKAP splicing using minigene assays in a variety of cell types, as well as in human cells. More recently, we have shown in vivo efficacy in both transgenic mice and in human FD carriers. Despite substantial investment by the Dysautonomia Foundation in developing kinetin as a potential treatment for FD, the road to the clinic has been slow, and we are still working with the originally identified compound. We have recently generated some promising SAR (structure and activity relationship) data showing that the activity of the lead compound kinetin can be improved. It is crucial that chemical optimization be performed in order to improve the potency and activity of kinetin, and time is of the essence. Despite the fact that FD is a developmental disorder, patients are plagued by continued, drastic neuronal degeneration throughout life. Effectively increasing IKAP levels early in life may support neuronal survival and prevent or delay the debilitating gait and sensory and cognitive decline seen in patients as they age. The Blueprint Neurotherapeutics Network offers a unique opportunity for drug development that will provide access to resources that are currently out of reach.