title: Control of cellular physiology by TM9 proteins in yeast and Dictyostelium.
abstract: TM9 proteins constitute a well defined family, characterized by the presence of a large variable extracellular domain and nine putative transmembrane domains. This family is highly conserved throughout evolution and comprises three members in Dictyostelium discoideum and Saccharomyces cerevisiae and four in humans and mice. In Dictyostelium, previous analysis demonstrated that TM9 proteins are implicated in cellular adhesion. In this study, we generated TM9 mutants in S. cerevisiae and analyzed their phenotype with particular attention to cellular adhesion. S. cerevisiae strains lacking any one of the three TM9 proteins were severely suppressed for adhesive growth and filamentous growth under conditions of nitrogen starvation. In these mutants, expression of the FLO11-lacZ reporter gene was strongly reduced, whereas expression of FRE(Ty1)-lacZ was not, suggesting that TM9 proteins are implicated at a late stage of nutrient-controlled signaling pathways. We also reexamined the phenotype of Dictyostelium TM9 mutant cells, focusing on nutrient-controlled cellular functions. Although the initiation of multicellular development and autophagy was unaltered in Dictyostelium TM9 mutants, nutrient-controlled secretion of lysosomal enzymes was dysregulated in these cells. These results suggest that in both yeast and amoebae, TM9 proteins participate in the control of specific cellular functions in response to changing nutrient conditions.
authors.affiliation: Département de Physiologie et Métabolisme Cellulaire, Centre Médical Universitaire, Université de Genève, rue Michel Servet 1, CH-1211 Genève 4, Switzerland.
authors.forename: Romain
authors.initials: R
authors.lastname: Froquet
authors.forename: Nathalie
authors.initials: N
authors.lastname: Cherix
authors.forename: Raphael
authors.initials: R
authors.lastname: Birke
authors.forename: Mohammed
authors.initials: M
authors.lastname: Benghezal
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Cameroni
authors.forename: François
authors.initials: F
authors.lastname: Letourneur
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Mösch
authors.forename: Claudio
authors.initials: C
authors.lastname: De Virgilio
authors.forename: Pierre
authors.initials: P
authors.lastname: Cosson
mesh_terms: D000818:Animals; D001343:Autophagy; D002448:Cell Adhesion; D004023:Dictyostelium / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D005786:Gene Expression Regulation; D015966:Gene Expression Regulation, Fungal; D008247:Lysosomes / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D008954:Models, Biological; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D015398:Signal Transduction; D013045:Species Specificity
chemical_list: D005656:Fungal Proteins; D008565:Membrane Proteins; C416668:Phg1 protein, Dictyostelium discoideum