作者: Pan, Mingyu ; Tang, Xiyang ; Li, Ling ; Tang, Ziling ; Meng, Xiangbo ; Qiu, Zuocheng ; Liu, Chunxia ; Wang, Xinluan ; Gao, Hao ; Hu, Xueling ; Zou, Jian ; Liu, Yanzhi ; Fang, Ailing

BACKGROUNDCathepsin K (CTSK) is a key enzyme in bone resorption, making it a promising target for osteoporosis treatment. Active-site inhibitors of CTSK are effective but have undesirable side effects, while ectosteric inhibitors may provide a safer alternative.PURPOSEThis study investigates whether Sophoraflavanone G (SG), derived from Rhizoma Drynariae, can act as an ectosteric CTSK inhibitor to attenuate osteoporotic bone loss and explores its underlying mechanisms.STUDY DESIGNSG's effects were evaluated in an ovariectomized (OVX) osteoporotic mice model, with in vitro experiments assessing SG's interaction and binding affinity with CTSK.METHODSMicro-CT, histology, and mechanical testing were used to evaluate bone density and strength. CTSK activity and expression were assessed by immunohistochemistry and western blotting. Cell thermal shift assays, isothermal titration calorimetry, CTSK site-specific degradation assays, molecular docking and dynamic simulation were performed to study SG's binding affinity and inhibitory effects. Biosafety, including body weight, uterine histomorphometry, and toxicity of the heart and lung, was also assessed.RESULTSSG improved bone mineral density, microarchitecture, and strength, primarily by inhibiting bone resorption. It inhibited CTSK's enzymatic activity with a strong binding affinity (KD: 8.49 μM) and effectively inhibited osteoclast function. CTSK site-specific assays showed SG inhibited CTSK-mediated degradation of type I collagen. Unlike odanacatib, SG did not affect gelatin or TGF-β1 degradation in fibroblasts. Biosafety assessments revealed no adverse effects.CONCLUSIONSG acts as an ectosteric CTSK inhibitor, offering a safer alternative for postmenopausal osteoporosis treatment by selectively inhibiting bone resorption without the side effects associated with active-site inhibitors.

2025-03-24·JACS Au

Development and Application of Small Molecule–Peptide Conjugates as Cathepsin K-Specific Covalent Irreversible Inhibitors in Human Osteoclast and Lung Cancer

Article

作者: Sridharan, Nikhila ; Yona, Simon ; Merquiol, Emmanuelle ; Yakobovich, Evalyn ; Turk, Dusan ; Levaot, Noam ; Turk, Boris ; Abramovitch-Dahan, Chen ; Wald, Ori ; Itzhak, Gal ; Sinai-Turyansky, Reut ; Blum, Galia ; Loboda, Jure ; Dey, Gourab

Cathepsin K (CTSK), a proteolytic enzyme that degrades the extracellular matrix, is recognized as a significant therapeutic target for osteoporosis, osteoarthritis, and rheumatoid arthritis. Due to adverse effects, no clinically approved drugs exist for CTSK. In order to develop safer therapeutics, highly selective CTSK inhibitors are required to elucidate the origins of side effects. Here, we developed various hybrid inhibitors by combining peptide sequences with small organic molecules. An acyloxymethyl ketone electrophile was incorporated as a bioisostere of the glycine-glycine cleavage site and inverse peptide sequences to enhance prime site interactions, as seen in the crystal structure. Additionally, a diphenyl group was incorporated to improve nonprime site interactions, culminating in highly selective and potent irreversible CTSK inhibitors with negligible off-target binding by closely related cathepsins. These novel inhibitors were also designed to attach to targeting moieties, further reducing off-target effects in vivo. Our findings demonstrate that these highly selective inhibitors are nontoxic, effectively inhibit bone resorption by human osteoclasts, block CTSK activity in cells and their nuclei, and inhibit activity in human lung cancer tissue. This study highlights significant advancements in designing CTSK inhibitors with potential clinical applications for lung cancer and osteoclast-related conditions.

2024-05-01·Matrix Biology

Heparan sulfate selectively inhibits the collagenase activity of cathepsin K

Article

作者: Liu, Jian ; Xu, Yongmei ; Hao, Huanmeng ; Pedersen, Lars C ; Xu, Ding ; Krahn, Juno M ; Luo, Yin ; Dutcher, Robert ; Zhang, Xiaoxiao ; Su, Guowei

Cathepsin K (CtsK) is a cysteine protease with potent collagenase activity. CtsK is highly expressed by bone-resorbing osteoclasts and plays an essential role in resorption of bone matrix. Although CtsK is known to bind heparan sulfate (HS), the structural details of the interaction, and how HS regulates the biological functions of CtsK, remains largely unknown. In this report, we discovered that HS is a multifaceted regulator of the structure and function of CtsK. Structurally, HS forms a highly stable complex with CtsK and induces its dimerization. Co-crystal structures of CtsK with bound HS oligosaccharides reveal the location of the HS binding site and suggest how HS may support dimerization. Functionally, HS plays a dual role in regulating the enzymatic activity of CtsK. While it preserves the peptidase activity of CtsK by stabilizing its active conformation, it inhibits the collagenase activity of CtsK in a sulfation level-dependent manner. These opposing effects can be explained by our finding that the HS binding site is remote from the active site, which allows HS to specifically inhibit the collagenase activity without affecting the peptidase activity. At last, we show that structurally defined HS oligosaccharides effectively block osteoclast resorption of bone in vitro without inhibiting osteoclast differentiation, which suggests that HS-based oligosaccharide might be explored as a new class of selective CtsK inhibitor for many diseases involving exaggerated bone resorption.

100 项与 CTSK inhibitors(Merck) 相关的药物交易

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