Hook Vivian, Podvin Sonia, Yoon Michael C, Phan Von V, Florio Jazmin, Spencer Brian, Mosier Charles, Cheng Adeline, Ahuett Sarah, Almaliti Jehad, Gerwick William H, Rissman Robert A, O'Donoghue Anthony J
Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, La Jolla, San Diego, California 92093, United States.
Department of Neurosciences and Department of Pharmacology, School of Medicine, University of California, La Jolla, San Diego, California 92093, United States.
ACS Chem Biol. 2025 Aug 15;20(8):1841-1848. doi: 10.1021/acschembio.5c00463. Epub 2025 Jul 23.
Cathepsin B contributes to the behavioral deficits and neuropathology that occur in traumatic brain injury (TBI) and Alzheimer's disease (AD). TBI and AD patients display elevated levels of cathepsin B that correlate with the severity of injury or cognitive deficits, respectively. In animal models of TBI and AD, cathepsin B gene knockout ameliorates behavioral deficits and improves neuropathology. While cathepsin B is normally located in acidic lysosomes, during TBI and AD, lysosomal leakage results in the translocation of cathepsin B to the neutral pH environment of the cytosol, thereby initiating neurodegeneration. Neutral pH-selective inhibitors are hypothesized to specifically target the pathogenic cytosolic cathepsin B without affecting its normal lysosomal form. Therefore, this review focuses on a novel strategy to utilize pH-dependent substrate cleavage properties of cathepsin B for the design of a neutral pH-selective inhibitor. Investigation of the enzymatic properties of cathepsin B at different pH conditions led to the development of Z-Arg-Lys-AOMK, a neutral pH-selective inhibitor that does not affect the enzyme's activity at normal lysosomal acidic pH. Z-Arg-Lys-AOMK potently inhibits cathepsin B at nM concentrations and effectively inhibits cellular cathepsin B in neuronal cell cultures at similar levels. In mice subjected to controlled cortical impact (CCI) brain injury, a model of TBI, cytosolic cathepsin B activity was significantly elevated in the brain. Treatment of the CCI-TBI mice with Z-Arg-Lys-AOMK reduced cytosolic cathepsin B activity and resulted in less motor dysfunction. These findings show that pH-dependent cleavage properties of cathepsin B can be utilized for the development of selective inhibitors to target the neutral cytosolic form of cathepsin B. The new concept of pH-selective inhibitors of cathepsin B reveals novel opportunities for targeting pathogenic, cytosolic cathepsin B involved in brain disorders.
组织蛋白酶B与创伤性脑损伤（TBI）和阿尔茨海默病（AD）中出现的行为缺陷及神经病理学改变有关。TBI和AD患者体内组织蛋白酶B水平升高，分别与损伤严重程度或认知缺陷相关。在TBI和AD的动物模型中，组织蛋白酶B基因敲除可改善行为缺陷并改善神经病理学状况。虽然组织蛋白酶B通常位于酸性溶酶体中，但在TBI和AD期间，溶酶体渗漏导致组织蛋白酶B转移至胞质溶胶的中性pH环境，从而引发神经变性。据推测，中性pH选择性抑制剂可特异性靶向致病性胞质组织蛋白酶B，而不影响其正常的溶酶体形式。因此，本综述重点关注一种利用组织蛋白酶B的pH依赖性底物切割特性来设计中性pH选择性抑制剂的新策略。对组织蛋白酶B在不同pH条件下的酶学性质进行研究后，开发出了Z-Arg-Lys-AOMK，一种中性pH选择性抑制剂，它在正常溶酶体酸性pH下不影响该酶的活性。Z-Arg-Lys-AOMK在纳摩尔浓度下能有效抑制组织蛋白酶B，并在神经元细胞培养物中以相似水平有效抑制细胞内的组织蛋白酶B。在创伤性脑损伤模型——控制性皮质撞击（CCI）脑损伤的小鼠中，脑中胞质组织蛋白酶B的活性显著升高。用Z-Arg-Lys-AOMK治疗CCI-TBI小鼠可降低胞质组织蛋白酶B的活性，并减少运动功能障碍。这些发现表明，组织蛋白酶B的pH依赖性切割特性可用于开发选择性抑制剂，以靶向组织蛋白酶B的中性胞质形式。组织蛋白酶B的pH选择性抑制剂这一新概念为靶向参与脑部疾病的致病性胞质组织蛋白酶B带来了新机遇。
