title: Direct binding of Lgl2 to LGN during mitosis and its requirement for normal cell division.
abstract: The Drosophila tumor suppressor protein lethal (2) giant larvae (l(2)gl) is involved in asymmetric cell division during development and epithelial cell polarity through interaction with the aPKC.Par-6 complex. We showed here that Lgl2, a mammalian homolog of l(2)gl, directly bound to LGN, a mammalian homolog of Partner of inscuteable in HEK293 cells. The C-terminal tail of Lgl2 bound to LGN with a K(d) value of about 56 nm. Endogenous Lgl2 formed a complex with aPKC, Par-6, and LGN. This complex formation was enhanced in metaphase of the synchronized cells by treatment with thymidine and nocodazole. Immunofluorescence staining of the complex was the strongest at the cell periphery of the metaphase cells. Overexpression of the C-terminal tail of Lgl2 induced mis-localization of the nuclear mitotic apparatus protein NuMA and disorganization of the mitotic spindle during mitosis, eventually causing formation of multiple micronuclei. Knockdown of endogenous Lgl (Lgl1 and Lgl2) also induced disorganization of the mitotic spindle, thereby causing formation of multiple micronuclei. The binding between Lgl2 and LGN played a role in the mitotic spindle organization through regulating formation of the LGN.NuMA complex. These results indicate that Lgl2 forms a Lgl2.Par-6.aPKC.LGN complex, which responds to mitotic signaling to establish normal cell division.
authors.affiliation: Department of Molecular Biology and Biochemistry, Osaka University Graduate School of Medicine/Faculty of Medicine, Suita, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Yasumi
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Sakisaka
authors.forename: Takashi
authors.initials: T
authors.lastname: Hoshino
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Kimura
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Sakamoto
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Yamanaka
authors.forename: Shigeo
authors.initials: S
authors.lastname: Ohno
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Takai
mesh_terms: D034961:Antigens, Nuclear; D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism* / Q000502:physiology; D018797:Cell Cycle Proteins; D002455:Cell Division; D002460:Cell Line; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008677:Metaphase; D008938:Mitosis; D046912:Multiprotein Complexes / Q000502:physiology; D034521:Nuclear Matrix-Associated Proteins; D009687:Nuclear Proteins / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D011493:Protein Kinase C / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D008941:Spindle Apparatus / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D028961:beta Karyopherins / Q000378:metabolism* / Q000502:physiology
chemical_list: D034961:Antigens, Nuclear; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C102754:GPSM2 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D046912:Multiprotein Complexes; C050045:NUMA1 protein, human; D034521:Nuclear Matrix-Associated Proteins; D009687:Nuclear Proteins; D011506:Proteins; D025521:Tumor Suppressor Proteins; D028961:beta Karyopherins; C424163:late gestation lung 2 karyopherin; C115015:PKC-3 protein; D011493:Protein Kinase C