Cell Biology Laboratories, School of Biochemistry, Medical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK.
Eur J Cell Biol. 2011 Oct;90(10):865-71. doi: 10.1016/j.ejcb.2011.05.003. Epub 2011 Jun 22.
The microtubule motor complex cytoplasmic dynein is known to be involved in multiple processes including endomembrane organization and trafficking, mitosis, and microtubule organization. The majority of studies of cytoplasmic dynein have focused on the form of the motor that is built around the dynein-1 heavy chain. A second isoform, dynein heavy chain-2, and its specifically associated light intermediate chain, LIC3 (D2LIC), are known to be involved in the formation and function of primary cilia. We have used RNAi in human epithelial cells to define the cytoplasmic dynein subunits that function with dynein heavy chain 2 in primary cilia. We identify the dynein light chain Tctex-1 as a key modulator of cilia length control; depletion of Tctex-1 results in longer cilia as defined by both acetylated tubulin labeling of the axoneme and Rab8a labeling of the cilia membrane. Suppression of dynein heavy chain-2 causes concomitant loss of Tctex-1 and this correlates with an increase in cilia length. Compared to individual depletions, double siRNA depletion of DHC2 and Tctex-1 causes an even greater increase in cilia length. Our data show that Tctex-1 is a key regulator of cilia length and most likely functions as part of dynein-2.
细胞质动力蛋白复合物微管动力蛋白已知参与多种过程，包括内膜组织和运输、有丝分裂和微管组织。大多数细胞质动力蛋白的研究都集中在围绕动力蛋白-1 重链构建的动力蛋白形式上。第二种同工型，动力蛋白重链-2 及其特定相关的轻中间链 LIC3（D2LIC），已知参与初级纤毛的形成和功能。我们使用人类上皮细胞中的 RNAi 来确定与初级纤毛中的动力蛋白重链 2 一起起作用的细胞质动力蛋白亚基。我们确定动力蛋白轻链 Tctex-1 是纤毛长度控制的关键调节剂；Tctex-1 的耗竭导致纤毛长度更长，这可以通过轴突的乙酰化微管标记和纤毛膜的 Rab8a 标记来定义。动力蛋白重链-2 的抑制导致 Tctex-1 的同时丢失，这与纤毛长度的增加相关。与单独耗竭相比，DHC2 和 Tctex-1 的双 siRNA 耗竭导致纤毛长度甚至更大的增加。我们的数据表明，Tctex-1 是纤毛长度的关键调节剂，很可能作为动力蛋白-2 的一部分发挥作用。
