Kinesin-1 mediates translocation of the meiotic spindle to the oocyte cortex through KCA-1, a novel cargo adapter.
In animals, female meiotic spindles are attached to the egg cortex in a perpendicular orientation at anaphase to allow the selective disposal of three haploid chromosome sets into polar bodies. We have identified a complex of interacting Caenorhabditis elegans proteins that are involved in the earliest step in asymmetric positioning of anastral meiotic spindles, translocation to the cortex. This complex is composed of the kinesin-1 heavy chain orthologue, UNC-116, the kinesin light chain orthologues, KLC-1 and -2, and a novel cargo adaptor, KCA-1. Depletion of any of these subunits by RNA interference resulted in meiosis I metaphase spindles that remained stationary at a position several micrometers from the cell cortex during the time when wild-type spindles translocated to the cortex. After this prolonged stationary period, unc-116(RNAi) spindles moved to the cortex through a partially redundant mechanism that is dependent on the anaphase-promoting complex. This study thus reveals two sequential mechanisms for translocating anastral spindles to the oocyte cortex.
Yang
Hsin-ya
HY
Section of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA.
Mains
Paul E
PE
McNally
Francis J
FJ
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D005260:Female; D016547:Kinesins / Q000378:metabolism*; D008540:Meiosis / Q000502:physiology*; D008677:Metaphase / Q000502:physiology; D018715:Microscopy, Video; D009865:Oocytes / Q000166:cytology / Q000378:metabolism*; D021122:Protein Subunits / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology; D034741:RNA, Small Interfering / Q000378:metabolism; D008941:Spindle Apparatus / Q000378:metabolism* / Q000648:ultrastructure
D048868:Adaptor Proteins, Signal Transducing; D029742:Caenorhabditis elegans Proteins; D018797:Cell Cycle Proteins; C502664:KCA-1 protein, C elegans; D021122:Protein Subunits; D034741:RNA, Small Interfering; C502663:UNC-116 protein, C elegans; C502665:klc-1 protein, C elegans; D016547:Kinesins