Fu Jiaxin, Liu Zhi, Zhang Guangxin, Zhang Chun
Department of Orthopedics, The Third Central Hospital of Tianjin, Tianjin, 300170, China.
Tianjin Key Laboratory of Extracorporeal Life Support for Critical Diseases, Tianjin, 300170, China.
BMC Musculoskelet Disord. 2025 Mar 17;26(1):268. doi: 10.1186/s12891-025-08505-2.
Osteoporosis (OP), a systemic bone disease, is characterized by degeneration of bone microstructure and susceptibility to fracture. Teriparatide (TPD) is an active fragment of human endogenous parathyroid hormone which has been revealed to promote osteogenesis of mesenchymal stem cells (hMSCs) to alleviate osteoporosis. Currently, the underlying cellular and molecular mechanisms of TPD in treating OP were not fully understood. This study aimed to investigate the roles of non-coding RNA-regulated osteogenic differentiation of hMSCs under TPD treatments. Circular RNA FNDC3B was significantly downregulated, and miRNA-125a-5p was upregulated in primary hMSCs of osteoporosis patients. Moreover, during osteogenesis, expression of circFNDC3B and glutamine metabolism were gradually elevated and miR-125a-5p was suppressed. Silencing circFNDC3B or overexpression of miR-125a-5p remarkedly suppressed the TPD-induced osteogenic differentiation-related genes (ALP, RUNX2, osteocalcin, osteonectin) activity or expression and calcium deposition of hMSCs. Results from RNA pull-down, RNA IP and luciferase assays demonstrated that circFNDC3B sponged miR-125a-5p, which further targeted 3'UTR of glutaminase (GLS), a key enzyme in glutamine metabolism to form a ceRNA regulator network. Rescue experiments demonstrated under TPD treatment, silencing of circFNDC3B significantly upregulated miR-125a-5p expression, blocked GLS expression and inhibited osteogenic differentiation evidenced by the suppressed ALP activity and expressions of osteocalcin, osteonectin and RUNX2. These regulatory phenotypes were further overridden by miR-125a-5p inhibition. In summary, our study demonstrated that TPD treatment promoted osteogenic differentiation of hMSCs by regulating the circFNDC3B-miR-125a-5p-GLS pathway.
骨质疏松症（OP）是一种全身性骨病，其特征在于骨微结构退变和易骨折性。特立帕肽（TPD）是人类内源性甲状旁腺激素的活性片段，已被证实可促进间充质干细胞（hMSCs）的成骨作用以缓解骨质疏松症。目前，TPD治疗OP的潜在细胞和分子机制尚未完全阐明。本研究旨在探讨在TPD治疗下非编码RNA调控hMSCs成骨分化的作用。在骨质疏松症患者的原代hMSCs中，环状RNA FNDC3B显著下调，而miRNA-125a-5p上调。此外，在成骨过程中，circFNDC3B的表达和谷氨酰胺代谢逐渐升高，而miR-125a-5p受到抑制。沉默circFNDC3B或过表达miR-125a-5p显著抑制了TPD诱导的hMSCs成骨分化相关基因（碱性磷酸酶、RUNX2、骨钙素、骨连接蛋白）的活性或表达以及钙沉积。RNA下拉、RNA免疫沉淀和荧光素酶测定结果表明，circFNDC3B可吸附miR-125a-5p，后者进一步靶向谷氨酰胺代谢中的关键酶谷氨酰胺酶（GLS）的3'非翻译区，从而形成一个竞争性内源RNA调控网络。挽救实验表明，在TPD治疗下，沉默circFNDC3B显著上调miR-125a-5p表达，阻断GLS表达并抑制成骨分化，表现为碱性磷酸酶活性以及骨钙素、骨连接蛋白和RUNX2表达受到抑制。这些调控表型可被miR-125a-5p抑制进一步逆转。总之，我们的研究表明，TPD治疗通过调节circFNDC3B-miR-125a-5p-GLS通路促进hMSCs的成骨分化。
