title: A novel Dictyostelium gene encoding multiple repeats of adhesion inhibitor-like domains has effects on cell-cell and cell-substrate adhesion.
abstract: The Dictyostelium protein AmpA (adhesion modulation protein A) is encoded by the gene originally identified by the D11 cDNA clone. AmpA contains repeated domains homologous to a variety of proteins that influence cell adhesion. The protein accumulates during development, reaching a maximal level at the finger stage. Much of the AmpA protein is found extracellularly during development, and in culminants, AmpA is found in association with anterior-like cells. Characterization of an ampA- strain generated by gene replacement reveals a significant increase in cell-cell clumping when cells are starved in nonnutrient buffer suspensions. Developing ampA- cells are also more adhesive to the underlying substrate and are delayed in developmental progression, with the severity of the delay increasing as cells are grown in the presence of bacteria or on tissue culture dishes rather than in suspension culture. Reintroduction of the ampA gene rescues the developmental defects of ampA- cells; however, expression of additional copies of the gene in wild-type cells results in more severe developmental delays and decreased clumping in suspension culture. We propose that the AmpA protein functions as an anti-adhesive to limit cell-cell and cell-substrate adhesion during development and thus facilitates cell migration during morphogenesis.
authors.affiliation: Department of Biological Sciences, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Varney
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Casademunt
authors.forename: Hoa N
authors.initials: HN
authors.lastname: Ho
authors.forename: Cheré
authors.initials: C
authors.lastname: Petty
authors.forename: Jayne
authors.initials: J
authors.lastname: Dolman
authors.forename: Daphne D
authors.initials: DD
authors.lastname: Blumberg
mesh_terms: D000362:Agar; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002448:Cell Adhesion / Q000235:genetics / Q000502:physiology; D015815:Cell Adhesion Molecules / Q000737:chemistry / Q000235:genetics* / Q000276:immunology / Q000502:physiology; D002633:Chemotaxis; D018920:Coculture Techniques; D018076:DNA, Complementary / Q000235:genetics; D016054:DNA, Protozoan / Q000235:genetics; D004023:Dictyostelium / Q000235:genetics* / Q000254:growth & development; D004926:Escherichia coli / Q000502:physiology; D005110:Extracellular Space / Q000737:chemistry; D017125:Genes, Protozoan; D008969:Molecular Sequence Data; D009024:Morphogenesis / Q000235:genetics; D016133:Polymerase Chain Reaction; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000276:immunology / Q000502:physiology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D015815:Cell Adhesion Molecules; D018076:DNA, Complementary; D016054:DNA, Protozoan; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; D000362:Agar