Cilia are found on nearly every cell in our bodies, and many genetic multi-system diseases are caused by defects in cilia formation and function. A recent paper describes the roles for several ciliary proteins, with fantastic images of cilia cross-sections to help tell the story.
Cilia are long microtubule-based organelles that project from cells, and nearly every cell has one single primary cilium that is important for sensory processes. Mutations that disrupt the formation and function of these primary cilia affect nearly all cell types and can cause a variety of different diseases. Despite the importance of primary cilia, the functions of many proteins involved weren’t completely understood. Thankfully, a recent paper describes the functions of eight cilia disease proteins that function at the cilia’s transition zone, a site adjacent to the cilia’s organizing center (called the basal body). Images above show cross sections of the transition zone of cilia from different genetic backgrounds. The wild-type (left) cilium has an ordered structure, with the important Y-links connecting microtubules and membrane. These Y-links are still present when one cilia disease gene called mks-6 is mutated (middle), but these Y-links are not present when two cilia disease genes, mks-6 and nphp-4, are mutated at the same time (right).
Williams, C., Li, C., Kida, K., Inglis, P., Mohan, S., Semenec, L., Bialas, N., Stupay, R., Chen, N., Blacque, O., Yoder, B., & Leroux, M. (2011). MKS and NPHP modules cooperate to establish basal body/transition zone membrane associations and ciliary gate function during ciliogenesis originally published in The Journal of Cell Biology, 192 (6), 1023-1041 DOI: 10.1083/jcb.201012116