title: Expression of yeast high mobility group protein HMO1 is regulated by TOR signaling.
abstract: Expression of ribosomal proteins is controlled by the Target of Rapamycin (TOR) kinase. The Saccharomyces cerevisiae Forkhead-like transcription factor Fhl1 is important for this regulation, and its localization to ribosomal protein gene promoters requires the high mobility group protein HMO1. We show here that HMO1 expression is similarly controlled by TOR signaling. Reporter constructs in which lacZ is under control of the HMO1 promoter show that HMO1 promoter activity is repressed on inactivation of TOR and that HMO1 is required for this repression. Chromatin immunoprecipitation shows that Fhl1 localizes to the HMO1 promoter in an HMO1-dependent fashion and that it centers on a predicted Fhl1 site, and removal of the Fhl1 site in the HMO1 promoter attenuates the response to rapamycin. Taken together, our data show that the HMO1 promoter is regulated by TOR signaling, and that TOR can signal through an HMO1- and Fhl1-dependent mechanism, as proposed for TOR-mediated regulation of ribosomal protein expression. The shared mechanism of regulation further reinforces the central role of HMO1 in TOR-mediated regulation of ribosomal protein gene expression.
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
authors.forename: Lijuan
authors.initials: L
authors.lastname: Xiao
authors.forename: Edwin
authors.initials: E
authors.lastname: Kamau
authors.forename: David
authors.initials: D
authors.lastname: Donze
authors.forename: Anne
authors.initials: A
authors.lastname: Grove
mesh_terms: D051858:Forkhead Transcription Factors / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D006609:High Mobility Group Proteins / Q000096:biosynthesis* / Q000235:genetics; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000378:metabolism; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology
chemical_list: C495776:FHL1 protein, S cerevisiae; D051858:Forkhead Transcription Factors; C103154:HMO1 protein, S cerevisiae; D006609:High Mobility Group Proteins; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; D017346:Protein Serine-Threonine Kinases; C500749:target of rapamycin protein, S cerevisiae; D020123:Sirolimus