title: Spatial focalization of pheromone/MAPK signaling triggers commitment to cell-cell fusion.
abstract: Cell fusion is universal in eukaryotes for fertilization and development, but what signals this process is unknown. Here, we show in Schizosaccharomyces pombe that fusion does not require a dedicated signal but is triggered by spatial focalization of the same pheromone-GPCR (G-protein-coupled receptor)-MAPK signaling cascade that drives earlier mating events. Autocrine cells expressing the receptor for their own pheromone trigger fusion attempts independently of cell-cell contact by concentrating pheromone release at the fusion focus, a dynamic actin aster underlying the secretion of cell wall hydrolases. Pheromone receptor and MAPK cascade are similarly enriched at the fusion focus, concomitant with fusion commitment in wild-type mating pairs. This focalization promotes cell fusion by immobilizing the fusion focus, thus driving local cell wall dissolution. We propose that fusion commitment is imposed by a local increase in MAPK concentration at the fusion focus, driven by a positive feedback between fusion focus formation and focalization of pheromone release and perception.
authors: Department of Fundamental Microbiology, University of Lausanne, CH-1015 Lausanne, Switzerland.
authors: Omaya
authors: http://orcid.org/0000-0002-6673-3149
authors: O
authors: Dudin
authors: Department of Fundamental Microbiology, University of Lausanne, CH-1015 Lausanne, Switzerland.
authors: Laura
authors: L
authors: Merlini
authors: Department of Fundamental Microbiology, University of Lausanne, CH-1015 Lausanne, Switzerland.
authors: Sophie G
authors: http://orcid.org/0000-0002-5317-2557
authors: SG
authors: Martin
mesh_terms: D019898:Autocrine Communication / Q000502:physiology; D020935:MAP Kinase Signaling System / Q000502:physiology*; D010675:Pheromones / Q000378:metabolism*; D043563:Receptors, Pheromone / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000166:cytology* / Q000502:physiology*; D029702:Schizosaccharomyces pombe Proteins / Q000378:metabolism*
chemical_list: D010675:Pheromones; D043563:Receptors, Pheromone; D029702:Schizosaccharomyces pombe Proteins
keywords: G-protein-coupled receptor signaling; MAP kinase cascade; cell–cell fusion; fertilization; fission yeast Schizosaccharomyces pombe; formin; pheromone