RESUMEN
Basal bodies (BBs) are macromolecular complexes required for the formation and cortical positioning of cilia. Both BB assembly and DNA replication are tightly coordinated with the cell cycle to ensure their accurate segregation and propagation to daughter cells, but the mechanisms ensuring coordination are unclear. The Tetrahymena Sas4/CPAP protein is enriched at assembling BBs, localizing to the core BB structure and to the base of BB-appendage microtubules and striated fiber. Sas4 is necessary for BB assembly and cortical microtubule organization, and Sas4 loss disrupts cell division furrow positioning and DNA segregation. The Hippo signaling pathway is known to regulate cell division furrow position, and Hippo molecules localize to BBs and BB-appendages. We find that Sas4 loss disrupts localization of the Hippo activator, Mob1, suggesting that Sas4 mediates Hippo activity by promoting scaffolds for Mob1 localization to the cell cortex. Thus, Sas4 links BBs with an ancient signaling pathway known to promote the accurate and symmetric segregation of the genome.
Asunto(s)
Cuerpos Basales/metabolismo , División Celular , Centriolos/metabolismo , Proteínas Asociadas a Microtúbulos/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Protozoarias/metabolismo , Tetrahymena thermophila/metabolismo , Cuerpos Basales/ultraestructura , Centriolos/genética , Centriolos/ultraestructura , Proteínas Asociadas a Microtúbulos/genética , Proteínas Serina-Treonina Quinasas/genética , Proteínas Protozoarias/genética , Transducción de Señal , Tetrahymena thermophila/genética , Tetrahymena thermophila/ultraestructura , Factores de TiempoRESUMEN
Multi-ciliary arrays promote fluid flow and cellular motility using the polarized and coordinated beating of hundreds of motile cilia. Tetrahymena basal bodies (BBs) nucleate and position cilia, whereby BB-associated striated fibers (SFs) promote BB anchorage and orientation into ciliary rows. Mutants that shorten SFs cause disoriented BBs. In contrast to the cytotaxis model, we show that disoriented BBs with short SFs can regain normal orientation if SF length is restored. In addition, SFs adopt unique lengths by their shrinkage and growth to establish and maintain BB connections and cortical interactions in a ciliary force-dependent mechanism. Tetrahymena SFs comprise at least eight uniquely localizing proteins belonging to the SF-assemblin family. Loss of different proteins that localize to the SF base disrupts either SF steady-state length or ciliary force-induced SF elongation. Thus, the dynamic regulation of SFs promotes BB connections and cortical interactions to organize ciliary arrays.
Asunto(s)
Cuerpos Basales/fisiología , Cilios/fisiología , Proteínas Asociadas a Microtúbulos/metabolismo , Microtúbulos/metabolismo , Proteínas Protozoarias/metabolismo , Tetrahymena thermophila/crecimiento & desarrollo , Tetrahymena thermophila/metabolismo , Fenómenos Mecánicos , Proteínas Asociadas a Microtúbulos/genética , Proteínas Protozoarias/genética , Tetrahymena thermophila/genéticaRESUMEN
Idiopathic scoliosis (IS) is a structural lateral spinal curvature of ≥10° that affects up to 3% of otherwise healthy children and can lead to life-long problems in severe cases. It is well-established that IS is a genetic disorder. Previous studies have identified genes that may contribute to the IS phenotype, but the overall genetic etiology of IS is not well understood. We used exome sequencing to study five multigenerational families with IS. Bioinformatic analyses identified unique and low frequency variants (minor allele frequency ≤5%) that were present in all sequenced members of the family. Across the five families, we identified a total of 270 variants with predicted functional consequences in 246 genes, and found that eight genes were shared by two families. We performed GO term enrichment analyses, with the hypothesis that certain functional annotations or pathways would be enriched in the 246 genes identified in our IS families. Using three complementary programs to complete these analyses, we identified enriched categories that include stereocilia and other actin-based cellular projections, cilia and other microtubule-based cellular projections, and the extracellular matrix (ECM). Our results suggest that there are multiple paths to IS and provide a foundation for future studies of IS pathogenesis.