CELL ADHESION DURING THE MIGRATORY SLUG STAGE OF DICTYOSTELIUM DISCOIDEUM

Abstract

Prespore-specific Antigen (PsA) is selectively expressed on the surface of prespore cells at the multicellular migratory slug stage of Dictyostelium discoideum development. It is a developmentally regulated glycoprotein that is anchored to the cell membrane through a glycosyl phosphatidylinositol (GPI) anchor. We present the results of an in vitro immunological investigation of the hypothesis that PsA functions as a cell adhesion molecule (CAM), and of a ligand-binding assay indicating that PsA has cell membrane binding partner(s). This is the first evidence to implicate a direct role for a putative CAM in cell-cell adhesion during the multicellular migratory slug stage of D. discoideum development. Cell-cell adhesion assays were carried out in the presence or absence of the monoclonal antibody (mAb) MUD1 that has a single antigenic determinant: a peptide epitope on PsA. These assays showed specific inhibition of cell-cell adhesion by MUD1. Further, it was found that a purified recombinant form of PsA (rPsA), can neutralize the inhibitory effect of MUD1; the inhibitory effect on cell-cell adhesion is primarily due to the blocking of PsA by the mAb. The resistance of aggregates to dissociation in the presence of 10 mM EDTA (ethylenediamintetraacetic acid) indicates that PsA mediates EDTA-stable cell-cell contacts, and that PsA-mediated cell adhesion is likely to be independent of divalent cations such as Ca(2+) or Mg(2+).

Initiation of Mucin-type O-Glycosylation in Dictyostelium Is Homologous to the Corresponding Step in Animals and Is Important for Spore Coat Function

“…DL118(H) is an axenic, spontaneously haploidized derivative of the original diploid strain DL118, which carries the chemically mutagenized modB mutant allele from HL220 (16,17). HU2421 is a non-axenic strain also carrying the HL220 modB allele (28). HW11 is an axenic strain that carries a modB mutant allele, which appears to partially retain function (29).…”

Dictyostelium discoideum Paxillin Regulates Actin-Based Processes

“…D. discoideum is a simple eukaryote with a well defined life cycle that displays many of the features of animal embryogenesis (Bowers-Morrow et al 2002; Siu et al 2004; Wong et al 2002). It feeds on bacteria and grows as single amoeboid cells, but multicellular development is triggered subsequently by starvation.…”

“…The tipped mound or slug shows a much more compact, tissue-like structure than aggregates from the aggregation stage. In addition, prestalk and prespore cell populations within the slug display different degrees of adhesiveness (Bowers-Morrow et al 2002). It is not known whether the differences between prestalk and prespore cells result from the expression of new cell type-specific adhesion molecules or from quantitative differences in adhesion molecules common to both cell types.…”

Interplay of mesoscale physics and agent-like behaviors in the parallel evolution of aggregative multicellularity

“…Analogously to Ca 2+ -dependent and Ca 2+ -independent mechanisms for cell-cell adhesion seen in vertebrate development, Dictyostelium development relies on the appearance of EDTA-sensitive and EDTA-insensitive contact sites [56]. At least one EDTA-insensitive adhesion protein, PsA, appears concomitantly with the formation of the multicellular slug [57].…”