Pins is not required for spindle orientation in the Drosophila wing disc.
In animal cells, mitotic spindles are oriented by the dynein/dynactin motor complex, which exerts a pulling force on astral microtubules. Dynein/dynactin localization depends on Mud/NUMA, which is typically recruited to the cortex by Pins/LGN. In Drosophila neuroblasts, the Inscuteable/Baz/Par-6/aPKC complex recruits Pins apically to induce vertical spindle orientation, whereas in epithelial cells Dlg recruits Pins laterally to orient the spindle horizontally. Here we investigate division orientation in the Drosophila imaginal wing disc epithelium. Live imaging reveals that spindle angles vary widely during prometaphase and metaphase, and therefore do not reliably predict division orientation. This finding prompted us to re-examine mutants that have been reported to disrupt division orientation in this tissue. Loss of Mud misorients divisions, but Inscuteable expression and aPKC, dlg and pins mutants have no effect. Furthermore, Mud localizes to the apical-lateral cortex of the wing epithelium independently of both Pins and cell cycle stage. Thus, Pins is not required in the wing disc because there are parallel mechanisms for Mud localization and hence spindle orientation, making it a more robust system than in other epithelia.
The Gurdon Institute and the Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK.
Dan T
0000-0003-1689-3715
DT
Bergstralh
The Gurdon Institute and the Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK.
Holly E
HE
Lovegrove
The Gurdon Institute and the Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK.
Izabela
I
Kujawiak
The Gurdon Institute and the Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK.
Nicole S
NS
Dawney
National Center for Protein Science Shanghai, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
Jinwei
J
Zhu
The Gurdon Institute and the Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK.
Samantha
S
Cooper
National Center for Protein Science Shanghai, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
Rongguang
R
Zhang
The Gurdon Institute and the Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK d.stjohnston@gurdon.cam.ac.uk.
Daniel
0000-0001-5582-3301
D
St Johnston
D000818:Animals; D018797:Cell Cycle Proteins; D002455:Cell Division; D003598:Cytoskeletal Proteins / Q000378:metabolism; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology / Q000378:metabolism*; D020730:Guanine Nucleotide Dissociation Inhibitors / Q000378:metabolism*; D060227:Imaginal Discs / Q000166:cytology / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D015398:Signal Transduction; D008941:Spindle Apparatus / Q000378:metabolism*; D014921:Wings, Animal / Q000166:cytology / Q000378:metabolism*
D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D029721:Drosophila Proteins; D020730:Guanine Nucleotide Dissociation Inhibitors; C405164:Pins protein, Drosophila; C098678:insc protein, Drosophila
Drosophila; Epithelia; Mud/NuMA; Pins/LGN; Spindle orientation