title: Sro7 and Sro77, the yeast homologues of the Drosophila lethal giant larvae (Lgl), regulate cell proliferation via the Rho1-Tor1 pathway.
abstract: Saccharomyces cerevisiae Sro7 and Sro77 are homologues of the Drosophila tumour suppressor lethal giant larvae (Lgl), which regulates cell polarity in Drosophila epithelial cells. Here, we showed that double mutation of SRO7/SRO77 was defective in colony growth. The colony of the SRO7/SRO77 double deletion was much smaller than the WT and appeared to be round with a smooth surface, compared with the WT. Analysis using transmission electron microscopy revealed multiple defects of the colony cells, including multiple budding, multiple nuclei, cell lysis and dead cells, suggesting that the double deletion caused defects in cell polarity and cell wall integrity (CWI). Overexpression of RHO1, one of the central regulators of cell polarity and CWI, fully recovered the sro7Δ/sro77Δ phenotype. We further demonstrated that sro7Δ/sro77Δ caused a decrease of the GTP-bound, active Rho1, which in turn caused an upregulation of TOR1. Deletion of TOR1 in sro7Δ/sro77Δ (sro7Δ/sro77Δ/tor1Δ) recovered the cell growth and colony morphology, similar to WT. Our results suggested that the tumour suppressor homologue SRO7/SRO77 regulated cell proliferation and yeast colony development via the Rho1-Tor1 pathway.
authors: Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA.
authors: Liang-Chun
authors: LC
authors: Liou
authors: Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA.
authors: Qun
authors: Q
authors: Ren
authors: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, PR China.
authors: Qiuqiang
authors: Q
authors: Gao
authors: Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA.
authors: Zhaojie
authors: Z
authors: Zhang
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D016764:Cell Polarity; D002473:Cell Wall / Q000502:physiology / Q000648:ultrastructure; D015966:Gene Expression Regulation, Fungal; D046529:Microscopy, Electron, Transmission; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development* / Q000502:physiology / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D019869:Phosphatidylinositol 3-Kinases; D010744:Phosphoric Monoester Hydrolases; D029701:Saccharomyces cerevisiae Proteins; D020741:rho GTP-Binding Proteins; C116430:SRO7 protein, S cerevisiae; C083324:TOR1 protein, S cerevisiae; C110553:INP53 protein, S cerevisiae; C051302:RHO1 protein, S cerevisiae