An unconventional myosin required for cell polarization and chemotaxis.
MyTH/FERM (myosin tail homology 4/band 4.1, ezrin, radixin, and moesin) myosins have roles in cellular adhesion, extension of actin-filled projections such as filopodia and stereocilia, and directional migration. The amoeba Dictyostelium discoideum expresses a simple complement of MyTH/FERM myosins, a class VII (M7) myosin required for cell-substrate adhesion and a unique myosin named MyoG. Mutants lacking MyoG exhibit a wide range of normal actin-based behaviors, including chemotaxis to folic acid, but have a striking defect in polarization and chemotaxis to cAMP. Although the myoG mutants respond to cAMP stimulation by increasing persistence and weakly increasing levels of cortical F-actin, they do not polarize; instead, they maintain a round shape and move slowly and randomly when exposed to a chemotactic gradient. The mutants also fail to activate and localize PI3K to the membrane closest to the source of chemoattractant. These data reveal a role for a MyTH/FERM myosin in mediating early chemotactic signaling and suggest that MyTH/FERM proteins have conserved roles in signaling and the generation of cell polarity.
Breshears
Laura M
LM
Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA.
Wessels
Deborah
D
Soll
David R
DR
Titus
Margaret A
MA
D000199:Actins / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D002465:Cell Movement; D002633:Chemotaxis; D003599:Cytoskeleton / Q000378:metabolism; D004023:Dictyostelium / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008954:Models, Biological; D018008:Myogenin / Q000235:genetics / Q000502:physiology*; D009218:Myosins / Q000502:physiology*; D010641:Phenotype; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D015398:Signal Transduction
D000199:Actins; D018008:Myogenin; D049452:Green Fluorescent Proteins; D019869:Phosphatidylinositol 3-Kinases; D009218:Myosins