骨关节炎（OA）是最常见的关节疾病，在OA管理中，需要疾病修饰性OA药物（DMOADs）作为重要需求。Krüppel-like factor 4（KLF4）是促进关节组织再生和保护功能的中心转录因子。本研究旨在鉴定激活KLF4表达的小分子，并确定击中化合物的功能和机制。采用能够检测内源性KLF4激活的报告细胞系，对11,948种临床阶段化合物进行了高通量筛选（HTS）。通过HTS确定了18个化合物，并在二次筛选中得到确认。在SW1353软骨肉瘤细胞和人软骨细胞中进行测试后，选择了一种I类选择性组蛋白去乙酰化酶（HDAC）抑制剂mocetinostat作为生物活性最佳化合物。mocetinostat能够上调人软骨细胞、髁状突肌细胞和骨髓间充质干细胞的软骨标志基因，并且在这些细胞和滑膜细胞中下调肥大、炎症和分解基因。将mocetinostat经腹腔注射给小鼠后，发现其可以减轻OA相关变化的严重程度，并改善疼痛行为。全基因表达和蛋白质组学分析显示，mocetinostat的再生和保护作用依赖于过氧化物酶体增殖物激活受体γ共激活物1-α。这些发现显示了mocetinostat在OA治疗和保护方面的作用，使其有资格成为DMOAD的候选药物。

Osteoarthritis (OA) is the most common joint disorder, and disease-modifying OA drugs (DMOADs) represent a major need in OA management. Krüppel-like factor 4 (KLF4) is a central transcription factor upregulating regenerative and protective functions in joint tissues. This study was aimed to identify small molecules activating KLF4 expression and to determine functions and mechanisms of the hit compounds. High-throughput screening (HTS) with 11,948 clinical-stage compounds was performed using a reporter cell line detecting endogenous KLF4 activation. Eighteen compounds were identified through the HTS and confirmed in a secondary screen. After testing in SW1353 chondrosarcoma cells and human chondrocytes, mocetinostat - a class I selective histone deacetylase (HDAC) inhibitor - had the best profile of biological activities. Mocetinostat upregulated cartilage signature genes in human chondrocytes, meniscal cells, and BM-derived mesenchymal stem cells, and it downregulated hypertrophic, inflammatory, and catabolic genes in those cells and synoviocytes. I.p. administration of mocetinostat into mice reduced severity of OA-associated changes and improved pain behaviors. Global gene expression and proteomics analyses revealed that regenerative and protective effects of mocetinostat were dependent on peroxisome proliferator-activated receptor γ coactivator 1-α. These findings show therapeutic and protective activities of mocetinostat against OA, qualifying it as a candidate to be used as a DMOAD.