Chen Lijun, Peng Chao, Chai Lanyi, Zhang Renjie, Zhu Chenghang, Wang Hailin, Cheng Qirong, Yan Yan, Shen Cailiang, Zheng Hong, Yang Jiazhao, Fan Haitao, Kan Chen
Department of Orthopedics, The First Affiliated Hospital of Anhui Medical University, 218 Jixi Road, 230032, Hefei, China.
Department of Pathophysiology, School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, 230022, Hefei, China.
EMBO J. 2025 Sep 1. doi: 10.1038/s44318-025-00553-7.
Tendon injury promotes aberrant osteochondral differentiation of tendon stem cells (TSCs) and results in disability. However, the cellular subsets within the osteochondral lineage involved in this process and associated mechanisms remain unclear. Here, we found that, following Achilles tenotomy, murine Gli1 tendon sheath cells expanded rapidly, transitioning into tenogenic and osteochondrogenic cells. Lineage tracing, together with single-cell RNA sequencing, revealed that osteochondrogenic Gli1 tendon sheath cells originate from Scx tendon stem/progenitor cells, preferentially differentiate into osteochondral lineage tendon progenitors at 7 dpi, subsequently undergoing aberrant chondrogenesis and osteogenesis at 21dpi and 63dpi, respectively. In addition, Acvr1 robustly accelerates osteochondral differentiation in Gli1 tendon sheath progenitors. Furthermore, GNAS/PKA signaling was significantly activated in osteochondral differentiation of Gli1 tendon sheath progenitors. Alternatively, treatment with the G antagonist, NF449, or genetic inhibition of the PKA subunit, Prkaca, in Gli1 sheath progenitors significantly alleviated aberrant osteochondral differentiation. NF449 also prevented osteochondral differentiation of human tendon stem cells. These findings identify Gli1 tendon sheath progenitors with osteochondral differentiation capacity during heterotopic ossification via activation of GNAS/PKA signaling, suggesting PKA as a potentially effective therapeutic target to treat tendon ossification.
肌腱损伤会促进肌腱干细胞（TSCs）异常的骨软骨分化并导致残疾。然而，参与这一过程的骨软骨谱系中的细胞亚群及其相关机制仍不清楚。在这里，我们发现，跟腱切断术后，小鼠Gli1肌腱鞘细胞迅速扩增，转变为成腱细胞和成骨软骨细胞。谱系追踪以及单细胞RNA测序显示，成骨软骨的Gli1肌腱鞘细胞起源于Scx肌腱干/祖细胞，在损伤后7天优先分化为骨软骨谱系的肌腱祖细胞，随后分别在损伤后21天和63天经历异常的软骨生成和成骨。此外，Acvr1强烈加速Gli1肌腱鞘祖细胞的骨软骨分化。此外，GNAS/PKA信号在Gli1肌腱鞘祖细胞的骨软骨分化中显著激活。或者，用G拮抗剂NF449处理，或在Gli1鞘祖细胞中对PKA亚基Prkaca进行基因抑制，可显著减轻异常的骨软骨分化。NF449也可防止人肌腱干细胞的骨软骨分化。这些发现确定了Gli1肌腱鞘祖细胞在异位骨化过程中具有骨软骨分化能力，这是通过激活GNAS/PKA信号实现的，提示PKA作为治疗肌腱骨化的潜在有效治疗靶点。
