Lgl (lethal giant larvae) plays an important role in cell polarity. Atypical protein kinase C (aPKC) binds to and phosphorylates Lgl, and the phosphorylation negatively regulates Lgl activity. In this study, we identify p32 as a novel Lgl binding protein that directly binds to a domain on mammalian Lgl2 (mLgl2), which contains the aPKC phosphorylation site. p32 also binds to PKCζ, and the three proteins form a transient ternary complex. When p32 is bound, PKCζ is stimulated to phosphorylate mLgl2 more efficiently. p32 overexpression in Madin–Darby canine kidney cells cultured in a 3D matrix induces an expansion of the actin-enriched apical membrane domain and disrupts cell polarity. Addition of PKCζ inhibitor blocks apical actin accumulation, which is rescued by p32 overexpression. p32 knockdown by short hairpin RNA also induces cell polarity defects. Collectively, our data indicate that p32 is a novel regulator of cell polarity that forms a complex with mLgl2 and aPKC and enhances aPKC activity.
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13 August 2007
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August 06 2007
p32 is a novel mammalian Lgl binding protein that enhances the activity of protein kinase Cζ and regulates cell polarity
Carl U. Bialucha,
Carl U. Bialucha
1Medical Research Council Laboratory for Molecular Cell Biology and Cell Biology Unit
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Emma C. Ferber,
Emma C. Ferber
1Medical Research Council Laboratory for Molecular Cell Biology and Cell Biology Unit
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Franck Pichaud,
Franck Pichaud
1Medical Research Council Laboratory for Molecular Cell Biology and Cell Biology Unit
2Department of Anatomy and Developmental Biology,
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Sew Y. Peak-Chew,
Sew Y. Peak-Chew
4Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 2QH, England, UK
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Yasuyuki Fujita
Yasuyuki Fujita
1Medical Research Council Laboratory for Molecular Cell Biology and Cell Biology Unit
3Department of Biology, University College London, London WC1E 6BT, England, UK
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Carl U. Bialucha
1Medical Research Council Laboratory for Molecular Cell Biology and Cell Biology Unit
Emma C. Ferber
1Medical Research Council Laboratory for Molecular Cell Biology and Cell Biology Unit
Franck Pichaud
1Medical Research Council Laboratory for Molecular Cell Biology and Cell Biology Unit
2Department of Anatomy and Developmental Biology,
Sew Y. Peak-Chew
4Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 2QH, England, UK
Yasuyuki Fujita
1Medical Research Council Laboratory for Molecular Cell Biology and Cell Biology Unit
3Department of Biology, University College London, London WC1E 6BT, England, UK
Correspondence to Yasuyuki Fujita: [email protected]
Abbreviations used in this paper: aPKC, atypical PKC; HEK, human embryonic kidney; Lgl, lethal giant larvae; MBP, maltose binding protein; mLgl, mammalian Lgl; shRNA, short hairpin RNA; WT, wild type; ZO-1, zonula occludens-1.
Received:
December 04 2006
Accepted:
July 11 2007
Online ISSN: 1540-8140
Print ISSN: 0021-9525
The Rockefeller University Press
2007
J Cell Biol (2007) 178 (4): 575–581.
Article history
Received:
December 04 2006
Accepted:
July 11 2007
Citation
Carl U. Bialucha, Emma C. Ferber, Franck Pichaud, Sew Y. Peak-Chew, Yasuyuki Fujita; p32 is a novel mammalian Lgl binding protein that enhances the activity of protein kinase Cζ and regulates cell polarity . J Cell Biol 13 August 2007; 178 (4): 575–581. doi: https://doi.org/10.1083/jcb.200612022
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