Drosophila APC2 and Armadillo participate in tethering mitotic spindles to cortical actin.
Proper positioning of mitotic spindles ensures equal allocation of chromosomes to daughter cells. This often involves interactions between spindle and astral microtubules and cortical actin. In yeast and Caenorhabditis elegans, some of the protein machinery that connects spindles and cortex has been identified but, in most animal cells, this process remains mysterious. Here, we report that the tumour suppressor homologue APC2 and its binding partner Armadillo both play roles in spindle anchoring during the syncytial mitoses of early Drosophila embryos. Armadillo, alpha-catenin and APC2 all localize to sites of cortical spindle attachment. APC2-Armadillo complexes often localize with interphase microtubules. Zeste-white 3 kinase, which can phosphorylate Armadillo and APC, is also crucial for spindle positioning and regulates the localization of APC2-Armadillo complexes. Together, these data suggest that APC2, Armadillo and alpha-catenin provide an important link between spindles and cortical actin, and that this link is regulated by Zeste-white 3 kinase.
McCartney
B M
BM
Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3280, USA.
McEwen
D G
DG
Grevengoed
E
E
Maddox
P
P
Bejsovec
A
A
Peifer
M
M
D000199:Actins / Q000378:metabolism*; D000818:Animals; D051186:Armadillo Domain Proteins; D015820:Cadherins / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000166:cytology / Q000196:embryology* / Q000235:genetics; D015726:Giant Cells / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3; D006801:Humans; D019476:Insect Proteins / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008938:Mitosis; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D008941:Spindle Apparatus / Q000378:metabolism* / Q000648:ultrastructure; D015534:Trans-Activators; D014157:Transcription Factors; D051178:alpha Catenin
C495305:ARM protein, Drosophila; D000199:Actins; D051186:Armadillo Domain Proteins; C495273:CTNNA1 protein, human; D015820:Cadherins; D003598:Cytoskeletal Proteins; D029721:Drosophila Proteins; D019476:Insect Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C117846:adenomatous polyposis coli protein 2; D051178:alpha Catenin; D017346:Protein Serine-Threonine Kinases; C080335:Sgg protein, Drosophila; D038362:Glycogen Synthase Kinase 3