title: A functional interaction between CD46 and DLG4: a role for DLG4 in epithelial polarization.
abstract: Using a yeast two-hybrid screen, we identified a physical interaction between CD46 and DLG4. CD46 is a ubiquitous human cell-surface receptor for the complement components C3b and C4b and for measles virus and human herpesvirus 6. DLG4 is a scaffold protein important for neuronal signaling and is homologous to the Drosophila tumor suppressor DLG. We show that an interaction between CD46 and DLG4 is important for polarization in epithelial cells. Specifically, we show (i) biochemical evidence for an interaction between CD46 and DLG4, (ii) that this interaction is specific for the Cyt1 (but not Cyt2) domain of CD46, (iii) that both CD46 and an alternatively spliced isoform of DLG4 are polarized in normal human epithelial cells, and (iv) that the polarized expression of CD46 in epithelial cells requires the DLG4-binding domain and alters with expression of a truncated form of DLG4. This is the first identification of a direct and cytoplasmic domain-specific interaction between CD46 and an intracellular signaling molecule and provides a molecular mechanism for the polarization of CD46. These data also indicate that, in addition to the known role for DLG4 in neuronal cells, DLG4 may be important for polarization in epithelial cells.
authors.affiliation: Peter MacCallum Cancer Institute, Trescowthick Research Laboratories, St. Andrew's Place, East Melbourne, Victoria 3002, Australia.
authors.forename: Mandy J
authors.initials: MJ
authors.lastname: Ludford-Menting
authors.forename: Suzanne J
authors.initials: SJ
authors.lastname: Thomas
authors.forename: Blessing
authors.initials: B
authors.lastname: Crimeen
authors.forename: Lisa J
authors.initials: LJ
authors.lastname: Harris
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Loveland
authors.forename: Margaret
authors.initials: M
authors.lastname: Bills
authors.forename: Sarah
authors.initials: S
authors.lastname: Ellis
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Russell
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000737:chemistry / Q000378:metabolism*; D001483:Base Sequence; D002460:Cell Line; D016764:Cell Polarity; D017931:DNA Primers; D000076122:Disks Large Homolog 4 Protein; D004285:Dogs; D004847:Epithelial Cells / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D051916:Membrane Cofactor Protein; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000378:metabolism*; D008565:Membrane Proteins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation
chemical_list: D015703:Antigens, CD; C497857:CD46 protein, human; C501444:DLG4 protein, human; D017931:DNA Primers; D000076122:Disks Large Homolog 4 Protein; D047908:Intracellular Signaling Peptides and Proteins; D051916:Membrane Cofactor Protein; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C033652:postsynaptic density proteins