Redundancy in the microfilament system: Abnormal development of dictyostelium cells lacking two F-actin cross-linking proteins

  title={Redundancy in the microfilament system: Abnormal development of dictyostelium cells lacking two F-actin cross-linking proteins},
  author={Walter Witke and Michael Schleicher and Angelika A. Noegel},

Dictyostelium discoideum cells lacking the 34,000-dalton actin-binding protein can grow, locomote, and develop, but exhibit defects in regulation of cell structure and movement: a case of partial redundancy

It is concluded that the 34-kD actin-bundling protein is not essential for growth, but plays an important role in dynamic control of cell shape and cytoplasmic structure.

Dictyostelium mutants lacking the cytoskeletal protein coronin are defective in cytokinesis and cell motility

Coronin has been localized in mitotic wild-type cells by immunofluorescence labeling and suggests that coronin functions independently of the conventional myosin in facilitating cytokinesis.

Re-expression of ABP-120 rescues cytoskeletal, motility, and phagocytosis defects of ABP-120- Dictyostelium mutants.

It is demonstrated that the severity and properties of the structural and behavioral defects of ABP-120- cell lines produced by homologous recombination are the direct result of the absence of ABp-120, which has been proposed to cross-link actin filaments in nascent pseudopods.

The Dictyostelium RasS protein is required for macropinocytosis, phagocytosis and the control of cell movement.

Dictyostelium cells lacking one member of this family, RasS, and the mutant cells are perturbed in endocytosis and cell migration, suggesting that RasS protein is likely to maintain the normal balance between these two actin-dependent processes.

A talin homologue of Dictyostelium rapidly assembles at the leading edge of cells in response to chemoattractant

Evidence for receptor-mediated accumulation was obtained by local stimulation of cells with cAMP, indicating a signal cascade in Dictyostelium responsible for assembly of the talin beneath sites of the plasma membrane where chemoattractant receptors are strongly activated.

Dictyostelium discoideum mutants with conditional defects in phagocytosis

This class of conditional phagocytosis mutant should prove to be useful for the expression cloning of the affected gene(s) and is likely to affect an early signaling event because the binding of bacteria to mutant cells in suspension was unable to trigger the localized polymerization of actin filaments required for ingestion.



A Dictyostelium mutant lacking an F-actin cross-linking protein, the 120-kD gelation factor

The results indicate that control of cell shape and motility does not require the fine-tuned interactions of all proteins that have been identified as actin-binding proteins by in vitro assays.

A Dictyostelium mutant deficient in severin, an F-actin fragmenting protein, shows normal motility and chemotaxis

Under the culture conditions used, severin proved to be neither essential for growth of D. discoideum nor for any cell function that is important for aggregation or later development.

A Dictyostelium mutant with severe defects in alpha-actinin: its characterization using cDNA probes and monoclonal antibodies.

Not only certain epitopes of alpha-actinin were altered but the entire molecule is almost completely lacking in the mutant, indicating that the fitness of mutant cells relative to wild type was determined during growth in nutrient medium, and a slight disadvantage for the mutant was indicated.

Probing an adhesion mutant of Dictyostelium discoideum with cDNA clones and monoclonal antibodies indicates a specific defect in the contact site A glycoprotein

One among 51 csA‐negative mutants, HG693, specifically lacked the capability of forming EDTA‐stable intercellular contacts, and acquired chemotactic responsiveness and developed into fruiting bodies.

Selection of Dictyostelium mutants defective in cytoskeletal proteins: use of an antibody that binds to the ends of alpha‐actinin rods.

In a mutant, HG1130, no antibody label was detected in colony blots, and by immunoblotting of mutant proteins separated by SDS‐PAGE, only trace amounts of alpha‐actinin were found, and the mutant showed normal binding of antibodies directed against the actin‐binding proteins severin and capping protein.

Disruption of the Dictyostelium myosin heavy chain gene by homologous recombination.

Data are presented demonstrating that integration of a transfected plasmid by homologous recombination occurs in the motile eukaryotic cell Dictyostelium discoideum, providing genetic proof that the intact myosin molecule is required for cytokinesis and not for karyokinesis.

Actin and actin-binding proteins in yeast.

  • D. Drubin
  • Biology
    Cell motility and the cytoskeleton
  • 1990
A number of components of the yeast actin cytoskeleton have now been identified, and genetic studies on several of these proteins are already shedding light on their in vivo functions.

DNA-mediated transformation in Dictyostelium discoideum: regulated expression of an actin gene fusion

A new vector for transformation that carries a fusion of the Dictyostelium discoideum actin 6 promoter gene and 5' flanking region with the bacterial Tn5 NeoR (KanR) gene which can confer resistance to the aminoglycoside G418 is constructed and results indicate that this system can be used to examine control of gene expression during D. discoidum development.

Homologous recombination in the Dictyostelium alpha‐actinin gene leads to an altered mRNA and lack of the protein.

The defect in alpha‐actinin production was not due to integration of the vector within the gene, but was apparently caused by errors produced during homologous recombination between the introduced alpha‐ actinin sequence and its complementary sequence in the coding region of the endogenous gene.