title: Finding new components of the target of rapamycin (TOR) signaling network through chemical genetics and proteome chips.
abstract: The TOR (target of rapamycin) proteins play important roles in nutrient signaling in eukaryotic cells. Rapamycin treatment induces a state reminiscent of the nutrient starvation response, often resulting in growth inhibition. Using a chemical genetic modifier screen, we identified two classes of small molecules, small-molecule inhibitors of rapamycin (SMIRs) and small-molecule enhancers of rapamycin (SMERs), that suppress and augment, respectively, rapamycin's effect in the yeast Saccharomyces cerevisiae. Probing proteome chips with biotinylated SMIRs revealed putative intracellular target proteins, including Tep1p, a homolog of the mammalian PTEN (phosphatase and tensin homologue deleted on chromosome 10) tumor suppressor, and Ybr077cp (Nir1p), a protein of previously unknown function that we show to be a component of the TOR signaling network. Both SMIR target proteins are associated with PI(3,4)P2, suggesting a mechanism of regulation of the TOR pathway involving phosphatidylinositides. Our results illustrate the combined use of chemical genetics and proteomics in biological discovery and map a path for creating useful therapeutics for treating human diseases involving the TOR pathway, such as diabetes and cancer.
authors.affiliation: Howard Hughes Medical Institute, Harvard Institute of Chemistry and Cell Biology, and Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA. jinghuang@mednet.ucla.edu
authors.forename: Jing
authors.initials: J
authors.lastname: Huang
authors.forename: Heng
authors.initials: H
authors.lastname: Zhu
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Haggarty
authors.forename: David R
authors.initials: DR
authors.lastname: Spring
authors.forename: Heejun
authors.initials: H
authors.lastname: Hwang
authors.forename: Fulai
authors.initials: F
authors.lastname: Jin
authors.forename: Michael
authors.initials: M
authors.lastname: Snyder
authors.forename: Stuart L
authors.initials: SL
authors.lastname: Schreiber
mesh_terms: D006801:Humans; D019169:Jurkat Cells; D008954:Models, Biological; D040081:Protein Array Analysis; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism*; D040901:Proteomics; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus