title: Actin cross-linking proteins cortexillin I and II are required for cAMP signaling during Dictyostelium chemotaxis and development.
abstract: Starvation induces Dictyostelium amoebae to secrete cAMP, toward which other amoebae stream, forming multicellular mounds that differentiate and develop into fruiting bodies containing spores. We find that the double deletion of cortexillin (ctx) I and II alters the actin cytoskeleton and substantially inhibits all molecular responses to extracellular cAMP. Synthesis of cAMP receptor and adenylyl cyclase A (ACA) is inhibited, and activation of ACA, RasC, and RasG, phosphorylation of extracellular signal regulated kinase 2, activation of TORC2, and stimulation of actin polymerization and myosin assembly are greatly reduced. As a consequence, cell streaming and development are completely blocked. Expression of ACA-yellow fluorescent protein in the ctxI/ctxII-null cells significantly rescues the wild-type phenotype, indicating that the primary chemotaxis and development defect is the inhibition of ACA synthesis and cAMP production. These results demonstrate the critical importance of a properly organized actin cytoskeleton for cAMP-signaling pathways, chemotaxis, and development in Dictyostelium.
authors: Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, Bethesda, MD 20892, USA.
authors: Shi
authors: S
authors: Shu
authors: Xiong
authors: X
authors: Liu
authors: Paul W
authors: PW
authors: Kriebel
authors: Mathew P
authors: MP
authors: Daniels
authors: Edward D
authors: ED
authors: Korn
mesh_terms: D000199:Actins / Q000378:metabolism*; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D002633:Chemotaxis / Q000235:genetics / Q000502:physiology*; D000242:Cyclic AMP; D004023:Dictyostelium / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D017353:Gene Deletion; D055786:Gene Knockout Techniques; D008164:Luminescent Proteins / Q000096:biosynthesis / Q000235:genetics; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D011953:Receptors, Cyclic AMP / Q000096:biosynthesis / Q000235:genetics; D015398:Signal Transduction
chemical_list: D000199:Actins; D001426:Bacterial Proteins; D008164:Luminescent Proteins; D008840:Microfilament Proteins; D015800:Protozoan Proteins; D011953:Receptors, Cyclic AMP; C101109:ctxA protein, Dictyostelium discoideum; C101110:ctxB protein, Dictyostelium discoideum; C068125:cyclic AMP receptor cAR1; C054562:yellow fluorescent protein, Bacteria; D000242:Cyclic AMP