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Primary cilia, mechanical forces, and cell synchrony
Homologous recombination depends on chromosomes first finding and pairing with their homolog via protein-bridging complexes called synaptonemal complexes. In pairing, telomeres execute a unique meiotic function. Telomeres tether to the nuclear envelope (NE) and associate with perinuclear microtubules through Sun/Kash complexes on the NE (see figure below). Telomere association with microtubules facilitates their rotations around the NE (figure), which in turn shuffle chromosomes allowing them to search for homologs. Telomeres ultimately cluster at one pole on the NE, while the free looping ends of their chromosomes face the other way, a configuration called the zygotene chromosomal bouquet (figure). Telomere clustering stabilizes proper pairing between homolog chromosomes, and is required for their synapse, meiotic recombination, and fertility.
While we now know much about the nuclear mechanisms of pairing, bouquet formation likely involves dramatic mechanical forces in the cytoplasm. How are these forces generated and regulated is unknown. Furthermore, oocytes are thought to develop synchronously in the cyst, but how cell synchrony is achieved and regulated in the cyst is unknown. We discovered novel cytoskeletal features in the oocyte that resemble a primary cilia (figure below) and could regulate both bouquet mechanical forces and synchrony.
We are using genetics in vivo, experiments in culture, and proteomics to investigate this new structure and its potential roles in regulating mechanical forces and cell synchrony in the early oocyte.
