Adjei-Sowah Emmanuela, Lecaj Elsa, Adhikari Neeta, Sensini Clara, Nichols Anne E C, Buckley Mark R, Loiselle Alayna E
Department of Biomedical Engineering, University of Rochester; Rochester, NY 14623, USA.
Center for Musculoskeletal Research, University of Rochester Medical Center; Rochester, NY 14642, USA.
bioRxiv. 2024 Nov 14:2024.11.14.623674. doi: 10.1101/2024.11.14.623674.
Aging tendons undergo disruptions in homeostasis, increased susceptibility to injury, and reduced capacity for healing. Exploring the mechanisms behind this disruption in homeostasis is essential for developing therapeutics aimed at maintaining tendon health through the lifespan. We have previously identified that the extracellular matrix protein, , which is highly expressed in healthy flexor tendon, is consistently lost during both natural aging and upon depletion of Scleraxis-lineage cells in young animals, which recapitulates many aging-associated homeostatic disruptions. Therefore, we hypothesized that loss of Cochlin would disrupt tendon homeostasis, including alterations in collagen fibril organization, and impaired tendon mechanics. By 3-months of age, flexor tendons exhibited altered collagen structure, with these changes persisting through at least 9-months. In addition, Cochlin tendons demonstrated significant declines in structural and material properties at 6-months, and structural properties at 9-months. While did not drastically change the overall tendon proteome, consistent decreases in proteins associated with RNA metabolism, extracellular matrix production and the cytoskeleton were observed in . Interestingly, homeostatic disruption via did not impair the tendon healing process. Taken together, these data define a critical role for in maintaining tendon homeostasis and suggest retention or restoration of as a potential therapeutic approach to retain tendon structure and function through the lifespan.
衰老的肌腱会出现内环境稳态破坏、受伤易感性增加以及愈合能力下降的情况。探究这种内环境稳态破坏背后的机制对于开发旨在在整个生命周期维持肌腱健康的治疗方法至关重要。我们之前已经确定,细胞外基质蛋白,在健康的屈肌腱中高度表达,在自然衰老过程以及幼年动物中硬骨素谱系细胞耗竭时会持续丢失,这概括了许多与衰老相关的内环境稳态破坏。因此,我们假设耳蜗素的缺失会破坏肌腱内环境稳态,包括胶原纤维组织的改变以及肌腱力学受损。到3个月大时,屈肌腱表现出胶原结构改变,这些变化至少持续到9个月。此外,耳蜗素缺陷的肌腱在6个月时结构和材料特性显著下降,在9个月时结构特性下降。虽然耳蜗素并没有大幅改变整体肌腱蛋白质组,但在耳蜗素缺陷的肌腱中观察到与RNA代谢、细胞外基质产生和细胞骨架相关的蛋白质持续减少。有趣的是,通过耳蜗素缺失造成的内环境稳态破坏并没有损害肌腱愈合过程。综上所述,这些数据确定了耳蜗素在维持肌腱内环境稳态中的关键作用,并表明保留或恢复耳蜗素作为一种潜在的治疗方法,以在整个生命周期维持肌腱结构和功能。
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