Aged bone marrow mesenchymal stem cells (BMSCs) exhibit aberrant self-renewal and lineage specification, which contribute to imbalanced bone-fat and progressive bone loss. In addition to known master regulators of lineage commitment, it is crucial to identify pivotal switches governing the specific differentiation fate of aged BMSCs. Here, we profiled differences in epigenetic regulation between adipogenesis and osteogenesis and identified super-enhancer associated lncRNA nuclear-enriched abundant transcript 1 (NEAT1) as a key bone-fat switch in aged BMSCs. We validated that NEAT1 with high enhancer activity was transcriptionally activated by ATF2 and directed aged BMSCs to a greater propensity to differentiate toward adipocytes than osteoblasts by mediating mitochondrial function. Furthermore, we confirmed NEAT1 as a protein-binding scaffold in which phosphorylation modification of SOX2 Ser249/250 by CDK2 impaired SOX2/OCT4 complex stability and dysregulated downstream transcription networks of pluripotency maintenance. In addition, by sponging miR-27b-3p, NEAT1 upregulated BNIP3L, BMP2K, and PPARG expression to shape mitochondrial function and osteogenic/adipogenic differentiation commitment, respectively. In extracellular communication, NEAT1 promoted CSF1 secretion from aged BMSCs and then strengthened osteoclastic differentiation by extracellular vesicle delivery. Notably, Neat1 small interfering RNA delivery induced increased bone mass in aged mice and decreased fat accumulation in the bone marrow. These findings suggest that NEAT1 regulates the lineage fates of BMSCs by orchestrating mitochondrial function and pluripotency maintenance, and might be a potential therapeutic target for skeletal aging.

衰老的骨髓间充质干细胞 (BMSC) 表现出异常的自我更新和谱系规范，导致骨脂肪失衡和进行性骨质流失。除了已知的谱系承诺主调节器外，确定控制老化 BMSC 特定分化命运的关键开关也至关重要。在这里，我们分析了脂肪生成和成骨之间表观遗传调控的差异，并将超增强子相关的 lncRNA 核富集丰富转录物 1 (NEAT1) 鉴定为老年 BMSC 中的关键骨脂肪转换。我们验证了具有高增强子活性的 NEAT1 被 ATF2 转录激活，并通过介导线粒体功能引导老化的 BMSCs 比成骨细胞更倾向于分化为脂肪细胞。此外，我们证实 NEAT1 是一种蛋白质结合支架，其中 CDK2 对 SOX2 Ser249/250 的磷酸化修饰损害了 SOX2/OCT4 复合物的稳定性，并失调了多能性维持的下游转录网络。此外，通过海绵化 miR-27b-3p，NEAT1 上调 BNIP3L、BMP2K 和 PPARG 表达，从而分别塑造线粒体功能和成骨/成脂分化承诺。在细胞外通讯中，NEAT1 促进老化 BMSCs 分泌 CSF1，然后通过细胞外囊泡递送加强破骨细胞分化。值得注意的是，Neat1 小干扰 RNA 递送诱导老年小鼠骨量增加并减少骨髓中的脂肪积累。