title: Multi-functional regulation of 4E-BP gene expression by the Ccr4-Not complex.
abstract: The mechanistic target of rapamycin (mTOR) signaling pathway is highly conserved from yeast to humans. It senses various environmental cues to regulate cellular growth and homeostasis. Deregulation of the pathway has been implicated in many pathological conditions including cancer. Phosphorylation cascades through the pathway have been extensively studied but not much is known about the regulation of gene expression of the pathway components. Here, we report that the mRNA level of eukaryotic translation initiation factor (eIF) subunit 4E-binding protein (4E-BP) gene, one of the key mTOR signaling components, is regulated by the highly conserved Ccr4-Not complex. RNAi knockdown of Not1, a putative scaffold protein of this protein complex, increases the mRNA level of 4E-BP in Drosophila Kc cells. Examination of the gene expression mechanism using reporter swap constructs reveals that Not1 depletion increases reporter mRNAs with the 3'UTR of 4E-BP gene, but decreases the ones with the 4E-BP promoter region, suggesting that Ccr4-Not complex regulates both degradation and transcription of 4E-BP mRNA. These results indicate that the Ccr4-Not complex controls expression of a single gene at multiple levels and adjusts the magnitude of the total effect. Thus, our study reveals a novel regulatory mechanism of a key component of the mTOR signaling pathway at the level of gene expression.
authors: Institute of Molecular Systems Biology, Swiss Federal Institute of Technology (ETH) Zurich, Wolfgang Pauli Str. 16, 8093, Zürich, Switzerland.
authors: Hirokazu
authors: H
authors: Okada
authors: Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton Campus, Wellington Road, Clayton, Victoria, 3800, Australia.
authors: Ralf B
authors: RB
authors: Schittenhelm
authors: Institute of Molecular Systems Biology, Swiss Federal Institute of Technology (ETH) Zurich, Wolfgang Pauli Str. 16, 8093, Zürich, Switzerland.
authors: Anna
authors: A
authors: Straessle
authors: Institute of Molecular Systems Biology, Swiss Federal Institute of Technology (ETH) Zurich, Wolfgang Pauli Str. 16, 8093, Zürich, Switzerland.
authors: Ernst
authors: E
authors: Hafen
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D048429:Cell Size / Q000187:drug effects; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology / Q000235:genetics*; D005786:Gene Expression Regulation; D007328:Insulin / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism; D010448:Peptide Initiation Factors / Q000235:genetics* / Q000378:metabolism; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000235:genetics; D014176:Protein Biosynthesis; D020871:RNA Stability / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins; D012260:Ribonucleases / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D020413:3' Untranslated Regions; D002352:Carrier Proteins; D029721:Drosophila Proteins; D007328:Insulin; D047908:Intracellular Signaling Peptides and Proteins; C568695:NOT1 protein, Drosophila; D010448:Peptide Initiation Factors; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C410006:Thor protein, Drosophila; C501437:CCR4 protein, Drosophila; D012260:Ribonucleases