title: Allorecognition, via TgrB1 and TgrC1, mediates the transition from unicellularity to multicellularity in the social amoeba Dictyostelium discoideum.
abstract: The social amoeba Dictyostelium discoideum integrates into a multicellular organism when individual starving cells aggregate and form a mound. The cells then integrate into defined tissues and develop into a fruiting body that consists of a stalk and spores. Aggregation is initially orchestrated by waves of extracellular cyclic adenosine monophosphate (cAMP), and previous theory suggested that cAMP and other field-wide diffusible signals mediate tissue integration and terminal differentiation as well. Cooperation between cells depends on an allorecognition system comprising the polymorphic adhesion proteins TgrB1 and TgrC1. Binding between compatible TgrB1 and TgrC1 variants ensures that non-matching cells segregate into distinct aggregates prior to terminal development. Here, we have embedded a small number of cells with incompatible allotypes within fields of developing cells with compatible allotypes. We found that compatibility of the allotype encoded by the tgrB1 and tgrC1 genes is required for tissue integration, as manifested in cell polarization, coordinated movement and differentiation into prestalk and prespore cells. Our results show that the molecules that mediate allorecognition in D. discoideum also control the integration of individual cells into a unified developing organism, and this acts as a gating step for multicellularity.
authors.affiliation: Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Shigenori
authors.initials: S
authors.lastname: Hirose
authors.affiliation: Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA Structural and Computational Biology and Molecular Biophysics Program, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Balaji
authors.initials: B
authors.lastname: Santhanam
authors.affiliation: Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Mariko
authors.initials: M
authors.lastname: Katoh-Kurosawa
authors.affiliation: Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA Structural and Computational Biology and Molecular Biophysics Program, Baylor College of Medicine, Houston, TX 77030, USA akuspa@bcm.edu gadi@bcm.edu.
authors.forename: Gad
authors.initials: G
authors.lastname: Shaulsky
authors.affiliation: Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA akuspa@bcm.edu gadi@bcm.edu.
authors.forename: Adam
authors.initials: A
authors.lastname: Kuspa
mesh_terms: D000483:Alleles; D000818:Animals; D002448:Cell Adhesion; D002450:Cell Communication; D002454:Cell Differentiation; D002465:Cell Movement; D002633:Chemotaxis / Q000502:physiology; D000242:Cyclic AMP / Q000378:metabolism; D004023:Dictyostelium / Q000166:cytology* / Q000235:genetics; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D049452:Green Fluorescent Proteins / Q000378:metabolism; D009024:Morphogenesis; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000378:metabolism*; D011485:Protein Binding; D015800:Protozoan Proteins / Q000378:metabolism*; D011995:Recombination, Genetic; D014158:Transcription, Genetic
chemical_list: D019038:Platelet Glycoprotein GPIb-IX Complex; D015800:Protozoan Proteins; C094990:adhesion receptor; D049452:Green Fluorescent Proteins; D000242:Cyclic AMP
keywords: Development; Self-/non-self-recognition; Social amoebae