title: Novel kelch-like protein, KLEIP, is involved in actin assembly at cell-cell contact sites of Madin-Darby canine kidney cells.
abstract: Dynamic rearrangements of cell-cell adhesion underlie a diverse range of physiological processes, but their precise molecular mechanisms are still obscure. Thus, identification of novel players that are involved in cell-cell adhesion would be important. We isolated a human kelch-related protein, Kelch-like ECT2 interacting protein (KLEIP), which contains the broad-complex, tramtrack, bric-a-brac (BTB)/poxvirus, zinc finger (POZ) motif and six-tandem kelch repeats. KLEIP interacted with F-actin and was concentrated at cell-cell contact sites of Madin-Darby canine kidney cells, where it colocalized with F-actin. Interestingly, this localization took place transiently during the induction of cell-cell contact and was not seen at mature junctions. KLEIP recruitment and actin assembly were induced around E-cadherin-coated beads placed on cell surfaces. The actin depolymerizing agent cytochalasin B inhibited this KLEIP recruitment around E-cadherin-coated beads. Moreover, constitutively active Rac1 enhanced the recruitment of KLEIP as well as F-actin to the adhesion sites. These observations strongly suggest that KLEIP is localized on actin filaments at the contact sites. We also found that N-terminal half of KLEIP, which lacks the actin-binding site and contains the sufficient sequence for the localization at the cell-cell contact sites, inhibited constitutively active Rac1-induced actin assembly at the contact sites. We propose that KLEIP is involved in Rac1-induced actin organization during cell-cell contact in Madin-Darby canine kidney cells.
authors.affiliation: Molecular Tumor Biology Section, Basic Research Laboratory, National Cancer Institute, Bethesda, Maryland, 20892-4255, USA.
authors.forename: Takahiko
authors.initials: T
authors.lastname: Hara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ishida
authors.forename: Razi
authors.initials: R
authors.lastname: Raziuddin
authors.forename: Stephan
authors.initials: S
authors.lastname: Dorkhom
authors.forename: Keiju
authors.initials: K
authors.lastname: Kamijo
authors.forename: Toru
authors.initials: T
authors.lastname: Miki
mesh_terms: D000199:Actins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D015820:Cadherins / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D003001:Cloning, Molecular; D003571:Cytochalasin B / Q000494:pharmacology; D004285:Dogs; D007365:Intercellular Junctions / Q000378:metabolism*; D008969:Molecular Sequence Data; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
chemical_list: D000199:Actins; D015820:Cadherins; D002352:Carrier Proteins; D003571:Cytochalasin B; D020830:rac1 GTP-Binding Protein