title: TOR complex 2 integrates cell movement during chemotaxis and signal relay in Dictyostelium.
abstract: Dictyostelium cells form a multicellular organism through the aggregation of independent cells. This process requires both chemotaxis and signal relay in which the chemoattractant cAMP activates adenylyl cyclase through the G protein-coupled cAMP receptor cAR1. cAMP is produced and secreted and it activates receptors on neighboring cells, thereby relaying the chemoattractant signal to distant cells. Using coimmunoprecipitation and mass spectrometric analyses, we have identified a TOR-containing complex in Dictyostelium that is related to the TORC2 complex of Saccharomyces cerevisiae and regulates both chemotaxis and signal relay. We demonstrate that mutations in Dictyostelium LST8, RIP3, and Pia, orthologues of the yeast TORC2 components LST8, AVO1, and AVO3, exhibit a common set of phenotypes including reduced cell polarity, chemotaxis speed and directionality, phosphorylation of Akt/PKB and the related PKBR1, and activation of adenylyl cyclase. Further, we provide evidence for a role of Ras in the regulation of TORC2. We propose that, through the regulation of chemotaxis and signal relay, TORC2 plays an essential role in controlling aggregation by coordinating the two essential arms of the developmental pathway that leads to multicellularity in Dictyostelium.
authors.affiliation: Section of Cell and Developmental Biology, Division of Biological Sciences and Center for Molecular Genetics, University of California, San Diego, La Jolla, CA 92093-0380, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Lee
authors.forename: Frank I
authors.initials: FI
authors.lastname: Comer
authors.forename: Atsuo
authors.initials: A
authors.lastname: Sasaki
authors.forename: Ian X
authors.initials: IX
authors.lastname: McLeod
authors.forename: Yung
authors.initials: Y
authors.lastname: Duong
authors.forename: Koichi
authors.initials: K
authors.lastname: Okumura
authors.forename: John R
authors.initials: JR
authors.lastname: Yates
authors.forename: Carole A
authors.initials: CA
authors.lastname: Parent
authors.forename: Richard A
authors.initials: RA
authors.lastname: Firtel
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics; D016764:Cell Polarity; D002633:Chemotaxis; D000242:Cyclic AMP / Q000378:metabolism; D004023:Dictyostelium / Q000235:genetics / Q000502:physiology*; D004789:Enzyme Activation; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism; D011953:Receptors, Cyclic AMP; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
chemical_list: C503706:Avo1 protein, S cerevisiae; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D047908:Intracellular Signaling Peptides and Proteins; C110280:LST8 protein, S cerevisiae; D015800:Protozoan Proteins; C121735:Ras-interacting protein 3, Dictyostelium; D011953:Receptors, Cyclic AMP; D029701:Saccharomyces cerevisiae Proteins; C504817:TSC11 protein, S cerevisiae; C068125:cyclic AMP receptor cAR1; D000242:Cyclic AMP; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt