Department of Orthopedics, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China.
Orthopaedic Department, The 4th Medical Center of Chinese PLA General Hospital, Beijing, China.
FASEB J. 2024 May 15;38(9):e23657. doi: 10.1096/fj.202302508R.
The pathogenesis of osteoporosis (OP) is closely associated with the disrupted balance between osteogenesis and adipogenesis in bone marrow-derived mesenchymal stem cells (BMSCs). We analyzed published single-cell RNA sequencing (scRNA-seq) data to dissect the transcriptomic profiles of bone marrow-derived cells in OP, reviewing 56 377 cells across eight scRNA-seq datasets from femoral heads (osteoporosis or osteopenia n = 5, osteoarthritis n = 3). Seventeen genes, including carboxypeptidase M (CPM), were identified as key osteogenesis-adipogenesis regulators through comprehensive gene set enrichment, differential expression, regulon activity, and pseudotime analyses. In vitro, CPM knockdown reduced osteogenesis and promoted adipogenesis in BMSCs, while adenovirus-mediated CPM overexpression had the reverse effects. In vivo, intraosseous injection of CPM-overexpressing BMSCs mitigated bone loss in ovariectomized mice. Integrated scRNA-seq and bulk RNA sequencing analyses provided insight into the MAPK/ERK pathway's role in the CPM-mediated regulation of BMSC osteogenesis and adipogenesis; specifically, CPM overexpression enhanced MAPK/ERK signaling and osteogenesis. In contrast, the ERK1/2 inhibitor binimetinib negated the effects of CPM overexpression. Overall, our findings identify CPM as a pivotal regulator of BMSC differentiation, which provides new clues for the mechanistic study of OP.
骨质疏松症（OP）的发病机制与骨髓间充质干细胞（BMSCs）中成骨和脂肪生成之间平衡的破坏密切相关。我们分析了已发表的单细胞 RNA 测序（scRNA-seq）数据，以剖析 OP 中骨髓细胞的转录组谱，共对来自股骨头的八个 scRNA-seq 数据集（骨质疏松症或骨量减少 n = 5，骨关节炎 n = 3）中的 56377 个细胞进行了综述。通过全面的基因集富集、差异表达、调控子活性和伪时间分析，确定了包括羧肽酶 M（CPM）在内的 17 个关键成骨-脂肪生成调节基因。体外实验中，CPM 敲低可减少 BMSCs 的成骨并促进其脂肪生成，而腺病毒介导的 CPM 过表达则具有相反的效果。在体内，过表达 CPM 的 BMSCs 经骨内注射可减轻去卵巢小鼠的骨丢失。单细胞 RNA-seq 和批量 RNA 测序分析为 MAPK/ERK 通路在 CPM 介导的 BMSC 成骨和脂肪生成调节中的作用提供了新的见解；具体来说，CPM 过表达增强了 MAPK/ERK 信号和成骨作用。相比之下，ERK1/2 抑制剂 binimetinib 否定了 CPM 过表达的作用。总之，我们的研究结果确定 CPM 是 BMSC 分化的关键调节因子，为 OP 的机制研究提供了新线索。
