HGF/c-Met通路通过调节Smurf1表达调控肌腱祖细胞自我更新及骨性分化能力的机制

Calcification is the pathological feature of tendon injury and the main cause of hypokinesia. The cause of this is unknown. It is believed that it is associated with stem cell osteogenic differentiation. We have previously found that the use of tendon stem/progenitor cells for the treatment of tendon injury can significantly promote tendon tissue repair and recovery of exercise capacity, but it is impossible to avoid calcification in the healing site. Further studies showed that the expression level of c-Met gene in tendon stem/progenitor cells was higher than that of bone marrow/adipose-derived mesenchymal stem cells, and the activation of HGF/c-Met signaling pathway promoted the expression of Smurf1, increased the self-renewal ability of tendon stem/progenitor cells, and inhibited the ability of osteogenic differentiation. From this we hypothesized that HGF/c-Met signaling activation promotes Smurf1 expression, enhances the ability of tendon stem/progenitor cells to self-renew but inhibits their ability to differentiate into osteoblast. The aim of this study was to investigate the effects of changes in the activation level of HGF/c-Met signaling on the self-renewal and osteogenic differentiation of tendon stem/progenitor cells at the cellular and animal levels by regulating the expression of c-Met gene in rat tendon stem/progenitor cells. This project is expected to determine the self-renewal and osteogenic differentiation mechanism of tendon stem/progenitor cells from the perspective of HGF/c-Met-Smurf1 regulation, and provide a target for improving the pathological mechanism of tendon diseases and improving the outcome of tendon calcification.

钙化是肌腱损伤的病理特点也是引起运动力减退的主要病因，其发生原因不明，推测与干细胞骨性分化相关。我们前期发现，肌腱祖细胞用于肌腱损伤模型治疗可明显促进肌腱组织修复及运动能力恢复，但无法避免愈合部位发生钙化。进一步研究发现肌腱祖细胞c-Met基因表达水平高于骨髓/脂肪间充质干细胞，且HGF/c-Met通路的激活促进Smurf1表达，提高肌腱祖细胞自我更新能力，抑制其骨性分化能力。由此我们提出假说：HGF/c-Met通路激活促进Smurf1表达，提高肌腱祖细胞的自我更新能力但抑制其骨性分化能力。本研究旨在通过调控鼠肌腱祖细胞c-Met基因表达，在细胞及动物水平验证HGF/c-Met通路激活水平变化对肌腱祖细胞自我更新及骨性分化能力的影响及作用机制。本项目有望从HGF/c-Met-Smurf1调控角度明确肌腱祖细胞的自我更新及骨性分化机制，为明确肌腱疾病的病理机制，改善肌腱钙化结局提供作用靶点。

肌腱是终末分化细胞，肌腱的损伤及肌腱病是困扰运动员、劳动者的主要运动疾病。肌腱部位钙化是肌腱疾病的病理特征，多见于慢性肌腱炎或肌腱损伤患者，常常引起严重的疼痛及运动功能障碍，因其病因仍未完全揭示，尚缺乏有效的治疗方案。干细胞的发现为研究肌腱损伤的发病机制及治疗提供了新的视野。前期研究中，我们发现肌腱祖细胞在生长因子的调控下，自身增殖及分化能力发生了显著改变。在本研究中，我们进一步探究了BMP通路调控因子Smurf1及胰岛素受体通过YAP1对大鼠肌腱祖细胞，人脂肪来源干细胞，人滋养细胞的调控作用。研究发现，Smurf1主要在细胞核内表达，胰岛素受体底物1与肌腱祖细胞、脂肪干细胞自我增殖能力呈负向相关，与以上细胞分化能力呈正向相关。同时发现HIPPO通路效应因子YAP1的表达改变间接影响胰岛素受体底物1及WNT通路激活，通过调节胰岛素受体底物1表达，可逆转祖/干细胞增殖及分化功能的改变，证实葡萄糖胰岛素代谢可能在祖/干细胞增殖及分化过程中发挥调节作用。进一步发现Smurf1的表达可抑制WNT及BMP通路激活。此外，在另一类具备增殖潜力的滋养细胞中，我们发现YAP1与母源效应基因PADI6存在细胞浆及细胞核水平相互作用，可能通过影响细胞应力影响滋养细胞迁移、增殖。通过生物信息筛选及分析，初步发现脂肪基因家族2通过改变肿瘤细胞命运改变子宫内膜癌患者预后。通过以上研究结果，我们发现祖/干细胞及滋养层细胞受到葡萄糖代谢调控，YAP1对细胞命运的决定揭示了祖/干细胞及滋养细胞有可能受到细胞张力的影响，为进一步体外培养可替代肌腱、韧带组织提供了研究基础。脂肪干细胞分化及代谢在人体内发挥了广泛的作用，未来研究者将进一步对脂肪干细胞的体内代谢调节，细胞张力对祖/干细胞的影响机制进行探究。

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