Glycogen synthase kinase-3 (GSK3) is a highly conserved protein kinase that is involved in several important cell signaling pathways and is associated with a range of medical conditions. Previous studies indicated a major role of the Dictyostelium homologue of GSK3 (gskA) in cell fate determination during morphogenesis of the fruiting body; however, transcriptomic and proteomic studies have sug...

Aspects of innate immunity derive from characteristics inherent to phagocytes, including chemotaxis toward and engulfment of unicellular organisms or cell debris. Ligand chemotaxis has been biochemically investigated using mammalian and model systems, but precision of chemotaxis towards ligands being actively secreted by live bacteria is not well studied, nor has there been systematic analyses ...

Phosphoinositide 3-kinase (PI3K), PTEN and localized phosphatidylinositol (3,4,5)-trisphosphate [PtdIns(3,4,5)P3] play key roles in chemotaxis, regulating cell motility by controlling the actin cytoskeleton in Dictyostelium and mammalian cells. PtdIns(3,4,5)P3, produced by PI3K, acts via diverse downstream signaling components, including the GTPase Rac, Arf-GTPases and the kinase Akt (PKB). It ...

Mycobacterium marinum, a close relative of Mycobacterium tuberculosis, provides a useful model to study the pathogenesis of tuberculosis in genetically tractable model organisms. Using the amoeba Dictyostelium discoideum as a host, we show that expression of the M. marinum protein MAG24-1 is crucial to interfere with phagosome maturation. We find that two host proteins - the flotillin homologue...

The ability of cells to sense external chemical cues and respond by directionally migrating towards them is a fundamental process called chemotaxis. This phenomenon is essential for many biological responses in the human body, including the invasion of neutrophils to sites of inflammation. Remarkably, many of the molecular mechanisms involved in controlling neutrophils chemotaxis arose millions...

The life cycle of Dictyostelium discoideum consists of many cellular and developmental aspects. By virtue of its relatively high transformation efficiency and a small haploid genome, this organism has proven to be advantageous for characterizing gene functions. However, a much higher transformation efficiency is required as one of the prerequisites for unraveling gene function on a genome-wide ...

Predation of bacteria by phagocytic cells was first developed during evolution by environmental amoebae. Many of the core mechanisms used by amoebae to sense, ingest and kill bacteria have also been conserved in specialized phagocytic cells in mammalian organisms. Here we focus on recent results revealing how Dictyostelium discoideum senses and kills non-pathogenic bacteria. In this model, gene...

Micro-organisms, whether the prokaryotic Myxococcus or the eukaryotic amoeba Dictyostelium, can achieve an impressive level of multicellular cooperativity and it is revealing to ask how this came to be and how it differs from the cooperativity found in animal development. This is not a sterile exercise that begins and ends with speculation – there is a usefulness, a utility to evolutionary theo...

Cross-linking of actin filaments (F-actin) into bundles and networks was investigated with three different isoforms of the dumbbell-shaped alpha-actinin homodimer under identical reaction conditions. These were isolated from chicken gizzard smooth muscle, Acanthamoeba, and Dictyostelium, respectively. Examination in the electron microscope revealed that each isoform was able to cross-link F-act...