One of the most fascinating and terrifying things about human health is how a single mutation in a single gene can cause such dramatic disorders and diseases. A person may have a lifetime of adjustments that their disorder or handicap requires, a constant looking-over-your-shoulder for that increased cancer risk (BRCA, I’m looking at you), or far worse. One mutation can affect one small part of a cell that, in no small way, affects everything. Today’s image is from a paper on primary cilia, and discusses applications of the research into understanding human ciliopathies.
Cilia are microtubule-based protrusions that function in sweeping material across a tissue (motile cilia) or as sensory orgnanelles (primary cilia). The link between several disorders and ciliary defects has driven more research towards understanding how cilia are formed and how they function. Specifically, certain disorders that cause blindness result from defective or dying photoreceptor cells in the retina, which have the largest primary cilia found in mammals—rod and cone photoreceptors. In a recent paper, Zhang and colleagues identified the roles of a novel protein, Ttc26, in ciliogenesis. Zebrafish with reduced levels of Ttc26 had ciliary defects both in kidneys and photoreceptor cells. Without Ttc26, cells produced cilia that were short and defective. In the images above of rat photoreceptor cells (green), Ttc26 (red) is seen in the transition zone of cilia. Zhang and colleagues suggest that based on the importance of Ttc26 in ciliogenesis, patients with ciliary disorders should be screened for ttc26 gene mutations.
Zhang Q, Liu Q, Austin C, Drummond I, & Pierce EA (2012). Knockdown of ttc26 disrupts ciliogenesis of the photoreceptor cells and the pronephros in zebrafish. Molecular biology of the cell, 23 (16), 3069-78 PMID: 22718903