Radnai Laszlo, Young Erica J, Kikuti Carlos, Hafenbreidel Madalyn, Stremel Rebecca F, Lin Li, Toth Katalin, Pasetto Paolo, Jin Xiaomin, Patel Aagam, Conlon Michael, Briggs Sherri, Heidsieck Leïla, Sweeney H Lee, Sellers James, Krieger-Burke Teresa, Martin William H, Sisco Jay, Young Steven, Pearson Paul, Rumbaugh Gavin, Araldi Gian Luca, Duddy Steven K, Cameron Michael D, Surman Matthew, Houdusse Anne, Griffin Patrick R, Kamenecka Theodore M, Miller Courtney A
bioRxiv. 2024 Oct 12:2024.10.07.617018. doi: 10.1101/2024.10.07.617018.
Non-muscle myosin II (NMII), a molecular motor that regulates critical processes such as cytokinesis and neuronal synaptic plasticity, has substantial therapeutic potential. However, translating this potential to use has been hampered by the lack of selective tools. The most prototypical non-selective inhibitor, blebbistatin inactivates both NMII and cardiac myosin II (CMII), a key regulator of heart function. Using rational drug design, we developed a series of NMII inhibitors that improve tolerability by selectively targeting NMII over CMII, including MT-228, which has excellent properties such as high brain penetration and efficacy in preclinical models of stimulant use disorder, which has no current FDA-approved therapies. The structure of MT-228 bound to myosin II provides insight into its 17-fold selectivity for NMII over CMII. MT-228's broad therapeutic window opens the door to new disease treatments and provides valuable tools for the scientific community, along with promising leads for future medication development.
Research suggests numerous indications, from axon regeneration and cancer, would benefit from a small molecule inhibitor of non-muscle myosin II, a molecular motor that regulates the actin cytoskeleton. Current chemical probe options are very limited and lack sufficient safety for studies, which we show is primarily due to potent inhibition of cardiac myosin II.Rational design that focused on improving target selectivity over the pan-myosin II inhibitor, blebbistatin, led to the identification of MT-228, a small molecule inhibitor with a wide therapeutic window.High-resolution structure of MT-228 bound to myosin II reveals that selectivity results from a different positioning compared to blebbistatin and an important sequence difference between cardiac and non-muscle myosin II in the inhibitor binding pocket.A single administration of MT-228 shows long-lasting efficacy in animal models of stimulant use disorder, a current unmet and rapidly escalating need with no FDA-approved treatments.
非肌肉肌球蛋白II（NMII）是一种调节细胞分裂和神经元突触可塑性等关键过程的分子马达，具有巨大的治疗潜力。然而，由于缺乏选择性工具，将这种潜力转化为实际应用受到了阻碍。最典型的非选择性抑制剂blebbistatin会使NMII和心脏肌球蛋白II（CMII，心脏功能的关键调节因子）都失活。通过合理的药物设计，我们开发了一系列NMII抑制剂，这些抑制剂通过选择性地靶向NMII而非CMII来提高耐受性，包括MT - 228，它具有诸如高脑渗透性以及在目前尚无FDA批准疗法的兴奋剂使用障碍临床前模型中有效的优异特性。与肌球蛋白II结合的MT - 228的结构揭示了其对NMII的选择性比对CMII高17倍的原因。MT - 228广泛的治疗窗口为新疾病治疗打开了大门，为科学界提供了有价值的工具，也为未来药物开发提供了有前景的线索。
研究表明，从轴突再生到癌症等众多适应症，都将受益于一种非肌肉肌球蛋白II的小分子抑制剂，这种分子马达调节肌动蛋白细胞骨架。目前的化学探针选择非常有限，且缺乏足够的安全性用于研究，我们发现这主要是由于对心脏肌球蛋白II的强效抑制。专注于提高对泛肌球蛋白II抑制剂blebbistatin的靶标选择性的合理设计，导致了MT - 228的鉴定，这是一种具有广泛治疗窗口的小分子抑制剂。与肌球蛋白II结合的MT - 228的高分辨率结构表明，选择性源于与blebbistatin不同的定位以及抑制剂结合口袋中心脏和非肌肉肌球蛋白II之间重要的序列差异。单次给药MT - 228在兴奋剂使用障碍动物模型中显示出持久的疗效，这是目前未满足且需求迅速增加的领域，尚无FDA批准的治疗方法。
