title: LET-99, GOA-1/GPA-16, and GPR-1/2 are required for aster-positioned cytokinesis.
abstract: At anaphase, the mitotic spindle positions the cytokinesis furrow [1]. Two populations of spindle microtubules are implicated in cytokinesis: radial microtubule arrays called asters and bundled nonkinetochore microtubules called the spindle midzone [2-4]. In C. elegans embryos, these two populations of microtubules provide two consecutive signals that position the cytokinesis furrow: The first signal is positioned midway between the microtubule asters; the second signal is positioned over the spindle midzone [5]. Evidence for two cytokinesis signals came from the identification of molecules that block midzone-positioned cytokinesis [5-7]. However, no molecules that are only required for, and thus define, the molecular pathway of aster-positioned cytokinesis have been identified. With RNAi screening, we identify LET-99 and the heterotrimeric G proteins GOA-1/GPA-16 and their regulator GPR-1/2 [10-12] in aster-positioned cytokinesis. By using mechanical spindle displacement, we show that the anaphase spindle positions cortical LET-99, at the site of the presumptive cytokinesis furrow. LET-99 enrichment at the furrow depends on the G proteins. GPR-1 is locally reduced at the site of cytokinesis-furrow formation by LET-99, which prevents accumulation of GPR-1 at this site. We conclude that LET-99 and the G proteins define a molecular pathway required for aster-positioned cytokinesis.
authors.affiliation: Max Planck Institute for Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany. bringman@mpi-cbg.de
authors.forename: Henrik
authors.initials: H
authors.lastname: Bringmann
authors.forename: Carrie R
authors.initials: CR
authors.lastname: Cowan
authors.forename: Jun
authors.initials: J
authors.lastname: Kong
authors.forename: Anthony A
authors.initials: AA
authors.lastname: Hyman
mesh_terms: D000705:Anaphase / Q000502:physiology; D000818:Animals; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism*; D048749:Cytokinesis / Q000235:genetics / Q000502:physiology*; D004625:Embryo, Nonmammalian; D044385:GTP-Binding Protein alpha Subunits / Q000378:metabolism; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D019204:GTP-Binding Proteins / Q000378:metabolism; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism*; D034622:RNA Interference; D008941:Spindle Apparatus / Q000378:metabolism; D013997:Time Factors
chemical_list: D029742:Caenorhabditis elegans Proteins; C475458:G protein regulator 1, C elegans; C475459:G protein regulator 2, C elegans; C516620:GOA-1 protein, C elegans; D044385:GTP-Binding Protein alpha Subunits; C467518:LET-99 protein, C elegans; D019204:GTP-Binding Proteins; C480838:GPA-16 protein, C elegans; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D020962:Heterotrimeric GTP-Binding Proteins