Eley Lorraine, Yates Laura M, Goodship Judith A
Institute of Human Genetics, University of Newcastle, International Centre for Life, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK.
Curr Opin Genet Dev. 2005 Jun;15(3):308-14. doi: 10.1016/j.gde.2005.04.008.
Cilia are classified according to their microtubule components as 9+2 (motile) and 9+0 (primary) cilia. Disruption of 9+2 cilia, which move mucus across respiratory epithelia, leads to rhinitis, sinusitis and bronchiectasis. Approximately half of the patients with primary ciliary dyskinesia (PCD) have situs inversus, providing a link between left-right asymmetry and cilia. 9+0 cilia at the embryonic node are also motile and involved in establishing left-right asymmetry. Most 9+0 cilia, however, act as antennae, sensing the external environment. Defective 9+0 cilia of principal cells of the nephron cause cystic diseases of the kidney. In the rods and cones of the retina, photoreceptor discs and visual pigments are synthesized in the inner segment and transported to the distal outer segment through a narrow 9+0 connecting cilium; defects in this process lead to retinitis pigmentosa. Although the function of primary cilia in some organs is being elucidated, in many other organs they have not been studied at all. It is probable that many more cilia-related disorders remain to be discovered.
纤毛根据其微管成分可分为9+2（运动性）纤毛和9+0（原发性）纤毛。9+2纤毛负责推动黏液穿过呼吸道上皮，其功能紊乱会导致鼻炎、鼻窦炎和支气管扩张。约半数原发性纤毛运动障碍（PCD）患者存在脏器反位，提示左右不对称与纤毛之间存在关联。胚胎节点处的9+0纤毛也具有运动性，并参与左右不对称的建立。然而，大多数9+0纤毛起到触角的作用，感知外部环境。肾单位主细胞的9+0纤毛功能缺陷会导致肾脏囊性疾病。在视网膜的视杆细胞和视锥细胞中，光感受器盘和视觉色素在内段合成，并通过狭窄的9+0连接纤毛运输至远端外段；这一过程中的缺陷会导致色素性视网膜炎。尽管原发性纤毛在某些器官中的功能正在逐步阐明，但在许多其他器官中，它们根本未被研究过。很可能还有更多与纤毛相关的疾病有待发现。
