1. Academic Validation
  2. mTORC1 coordinates NF-κB signaling pathway to promote chondrogenic differentiation of tendon cells in heterotopic ossification

mTORC1 coordinates NF-κB signaling pathway to promote chondrogenic differentiation of tendon cells in heterotopic ossification

  • Bone. 2022 Oct;163:116507. doi: 10.1016/j.bone.2022.116507.
Jiaming Fu 1 Jie Zhang 2 Tao Jiang 1 Xiang Ao 1 Peng Li 1 Zhengnan Lian 2 Chenglong Li 1 Xibing Zhang 2 Jie Liu 2 Minjun Huang 2 Zhongmin Zhang 3 Liang Wang 4
Affiliations

Affiliations

  • 1 Division of Spine Surgery, Department of Orthopedics, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China.
  • 2 Department of Orthopedics, The Third Affiliated Hospital, Southern Medical University, Guangzhou 510630, China; Academy of Orthopaedics, Guangdong Province, Guangzhou 510630, China.
  • 3 Division of Spine Surgery, Department of Orthopedics, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China. Electronic address: nfzzm@163.com.
  • 4 Department of Orthopedics, The Third Affiliated Hospital, Southern Medical University, Guangzhou 510630, China; Academy of Orthopaedics, Guangdong Province, Guangzhou 510630, China. Electronic address: liang091@aliyun.com.
Abstract

Heterotopic ossification (HO) is a pathological bone formation based on endochondral ossification distinguished by ossification within muscles, tendons, or other soft tissues. There has been growing studies focusing on the treatment with rapamycin to inhibit HO, but the mechanism of mTORC1 on HO remains unclear. Tendon cells (TDs) are the first cells to form during tendon heterotopic ossification. Here, we used an in vivo model of HO and an in vitro model of chondrogenesis induction to elucidate the effect and underlying mechanism of mTORC1 in HO. The current study highlights the effect of rapamycin on murine Achilles tenotomy-induced HO and the role of mTORC1 signaling pathway on TDs. Our result showed that mTORC1 was activation in the early stage of HO, whereas the mTORC1 maintained low expression in the mature ectopic cartilage tissue and the ectopic bone formation sites. The use of mTORC1-specific inhibitor (rapamycin) immediately after Achilles tendon injury could suppress the formation of HO; once ectopic cartilage and bone had formed, treatment with rapamycin could not significantly inhibit the progression of HO. Mechanistically, mTORC1 stimulation by silencing of TSC1 promoted the expression of the chondrogenic markers in TDs. In TDs, treated with mTORC1 stimulation by silencing of TSC1, mTORC1 increased the activation of the NF-κB signaling pathway. NF-κB selective inhibitor BAY11-7082 significantly suppressed the chondrogenesis of TDs that treated with mTORC1 stimulation by silencing of TSC1. Together, our findings demonstrated that mTORC1 promoted HO by regulating TDs chondrogenesis partly through the NF-κB signaling pathway; and rapamycin could be a viable HO therapeutic regimen.

Keywords

Chondrogenic differentiation; Heterotopic ossification; NF-κB signaling pathway; TSC1; Tendon cells; mTORC1 signaling pathway.

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