RRC ID 53323
Author Wolff ID, Tran MV, Mullen TJ, Villeneuve AM, Wignall SM.
Title Assembly of Caenorhabditis elegans acentrosomal spindles occurs without evident microtubule-organizing centers and requires microtubule sorting by KLP-18/kinesin-12 and MESP-1.
Journal Mol Biol Cell
Abstract Although centrosomes contribute to spindle formation in most cell types, oocytes of many species are acentrosomal and must organize spindles in their absence. Here we investigate this process in Caenorhabditis elegans, detailing how acentrosomal spindles form and revealing mechanisms required to establish bipolarity. Using high-resolution imaging, we find that in meiosis I, microtubules initially form a "cage-like" structure inside the disassembling nuclear envelope. This structure reorganizes so that minus ends are sorted to the periphery of the array, forming multiple nascent poles that then coalesce until bipolarity is achieved. In meiosis II, microtubules nucleate in the vicinity of chromosomes but then undergo similar sorting and pole formation events. We further show that KLP-18/kinesin-12 and MESP-1, previously shown to be required for spindle bipolarity, likely contribute to bipolarity by sorting microtubules. After their depletion, minus ends are not sorted outward at the early stages of spindle assembly and instead converge. These proteins colocalize on microtubules, are interdependent for localization, and can interact, suggesting that they work together. We propose that KLP-18/kinesin-12 and MESP-1 form a complex that functions to sort microtubules of mixed polarity into a configuration in which minus ends are away from the chromosomes, enabling formation of nascent poles.
Volume 27(20)
Pages 3122-3131
Published 2016-10-15
DOI 10.1091/mbc.E16-05-0291
PII mbc.E16-05-0291
PMID 27559133
PMC PMC5063619
MeSH Animals Caenorhabditis elegans / metabolism Caenorhabditis elegans Proteins / metabolism* Cell Polarity / physiology Centrosome / metabolism Chromosomes / metabolism Kinesins / metabolism* Meiosis / physiology Microtubule-Organizing Center / metabolism Microtubules / metabolism Oocytes / metabolism Spindle Apparatus / metabolism* Spindle Poles / metabolism Spindle Poles / physiology
IF 3.791
Times Cited 12
C.elegans tm2841