Max-Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany.
Curr Biol. 2013 May 6;23(9):755-63. doi: 10.1016/j.cub.2013.03.065. Epub 2013 Apr 11.
Mechanoreceptors contain compliant elements, termed "gating springs," that transfer macroscopic stimuli impinging on the cells into microscopic stimuli that open the mechanosensitive channels. Evidence for gating springs comes from mechanical experiments; they have not been identified molecularly or ultrastructurally.
We show that the filamentous structures that connect the plasma membrane to the microtubules are compliant structural elements in the mechanoreceptive organelle of fly campaniform receptors. These filaments colocalize with the ankyrin-repeat domain of the transient receptor potential (TRP) channel NOMPC. In addition, they resemble the purified ankyrin-repeat domain in size and shape. Most importantly, these filaments are nearly absent in nompC mutants and can be rescued by the nompC gene. Finally, mechanical modeling suggests that the filaments provide most of the compliance in the distal tip of the cell, thought to be the site of mechanotransduction.
Our results provide strong evidence that the ankyrin-repeat domains of NOMPC structurally contribute to the membrane-microtubule connecting filaments. These filaments, as the most compliant element in the distal tip, are therefore good candidates for the gating springs.
机械感受器包含顺应性元件，称为“门控弹簧”，它将作用于细胞的宏观刺激转化为打开机械敏感通道的微观刺激。门控弹簧的证据来自于力学实验；它们尚未在分子或超微结构上被识别。
我们表明，连接质膜和微管的丝状结构是果蝇杯状感受器机械感受器器官中的顺应性结构元件。这些细丝与瞬时受体电位（TRP）通道 NOMPC 的锚蛋白重复域共定位。此外，它们在大小和形状上与纯化的锚蛋白重复域相似。最重要的是，这些细丝在 nompC 突变体中几乎不存在，并且可以由 nompC 基因拯救。最后，力学模型表明，这些细丝提供了细胞远端尖端的大部分顺应性，被认为是机械转导的部位。
我们的结果提供了强有力的证据，表明 NOMPC 的锚蛋白重复域在结构上有助于连接膜和微管的丝状结构。这些细丝作为远端尖端最顺应的元件，因此是门控弹簧的良好候选者。
