Centre for Auditory Research, UCL Ear Institute, University College London, 332 Gray's Inn Road, London, WC1X 8EE, UK.
J Assoc Res Otolaryngol. 2012 Aug;13(4):473-84. doi: 10.1007/s10162-012-0322-7. Epub 2012 Apr 5.
The cochlear spiral ligament is a connective tissue that plays diverse roles in normal hearing. Spiral ligament fibrocytes are classified into functional sub-types that are proposed to carry out specialized roles in fluid homeostasis, the mediation of inflammatory responses to trauma, and the fine tuning of cochlear mechanics. We derived a secondary sub-culture from guinea pig spiral ligament, in which the cells expressed protein markers of type III or "tension" fibrocytes, including non-muscle myosin II (nmII), α-smooth muscle actin (αsma), vimentin, connexin43 (cx43), and aquaporin-1. The cells formed extensive stress fibers containing αsma, which were also associated intimately with nmII expression, and the cells displayed the mechanically contractile phenotype predicted by earlier modeling studies. cx43 immunofluorescence was evident within intercellular plaques, and the cells were coupled via dye-permeable gap junctions. Coupling was blocked by meclofenamic acid (MFA), an inhibitor of cx43-containing channels. The contraction of collagen lattice gels mediated by the cells could be prevented reversibly by blebbistatin, an inhibitor of nmII function. MFA also reduced the gel contraction, suggesting that intercellular coupling modulates contractility. The results demonstrate that these cells can impart nmII-dependent contractile force on a collagenous substrate, and support the hypothesis that type III fibrocytes regulate tension in the spiral ligament-basilar membrane complex, thereby determining auditory sensitivity.
耳蜗螺旋韧带是一种结缔组织，在正常听力中发挥着多种作用。螺旋韧带成纤维细胞可分为功能亚型，这些亚型被认为在液稳态调节、创伤性炎症反应的介导以及耳蜗力学的精细调节中发挥专门作用。我们从小鼠螺旋韧带中衍生出一个二级亚培养物，其中的细胞表达 III 型或“张力”成纤维细胞的蛋白标志物，包括非肌肉肌球蛋白 II（nmII）、α-平滑肌肌动蛋白（αsma）、波形蛋白、连接蛋白 43（cx43）和水通道蛋白 1。细胞形成了含有αsma 的广泛张力纤维，这些纤维与 nmII 表达密切相关，并且细胞表现出与早期建模研究预测的机械收缩表型一致。细胞间斑块中存在明显的 cx43 免疫荧光，并且细胞通过可渗透染料的间隙连接进行偶联。cx43 包含的通道抑制剂 meclofenamic acid（MFA）可阻断偶联。细胞介导的胶原格子凝胶收缩可被 nmII 功能抑制剂 blebbistatin 可逆地阻止。MFA 还降低了凝胶收缩，表明细胞间偶联可调节收缩性。结果表明，这些细胞可以将依赖 nmII 的收缩力施加到胶原蛋白基质上，并支持 III 型成纤维细胞调节螺旋韧带-基底膜复合物张力的假说，从而决定听觉敏感性。
