title: Amino acid limitation induces expression of CHOP, a CCAAT/enhancer binding protein-related gene, at both transcriptional and post-transcriptional levels.
abstract: In mammals, plasma concentrations of amino acids are affected by nutritional or pathological conditions. Here we examined the role of amino acid limitation in regulating the expression of CHOP, a CCAAT/enhancer binding protein (C/EBP)-related gene. CHOP protein is capable of interacting with other C/EBPs to modify their DNA binding activities and may function as a negative regulator of these transcription factors. Our data show that leucine limitation in human cell lines leads to induction of CHOP mRNA and protein in a dose-dependent manner. CHOP mRNA induction is rapidly reversed by leucine replenishment. Elevated mRNA levels result from both an increase in the rate of CHOP transcription and an increase in the CHOP mRNA stability. Using a transient expression assay, we show that a promoter fragment, when linked to a reporter gene, is sufficient to mediate the regulation of CHOP expression by leucine starvation in HeLa cells. In addition, we found that decreasing amino acid concentration by itself can induce CHOP expression independently of a cellular stress due to protein synthesis inhibition. Moreover, CHOP expression is induced at leucine concentrations in the range of those observed in blood of protein-restricted animals suggesting that amino acids can participate, in concert with hormones, in the regulation of gene expression.
authors.affiliation: Unité de Nutrition Cellulaire et Moléculaire, INRA de Theix, 63122 Saint Genès Champanelle, France.
authors.forename: A
authors.initials: A
authors.lastname: Bruhat
authors.forename: C
authors.initials: C
authors.lastname: Jousse
authors.forename: X Z
authors.initials: XZ
authors.lastname: Wang
authors.forename: D
authors.initials: D
authors.lastname: Ron
authors.forename: M
authors.initials: M
authors.lastname: Ferrara
authors.forename: P
authors.initials: P
authors.lastname: Fafournoux
mesh_terms: D022762:CCAAT-Enhancer-Binding Proteins; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics*; D003609:Dactinomycin / Q000494:pharmacology; D015870:Gene Expression; D005947:Glucose / Q000172:deficiency; D006367:HeLa Cells; D006801:Humans; D007930:Leucine / Q000172:deficiency*; D009687:Nuclear Proteins / Q000235:genetics*; D011401:Promoter Regions, Genetic; D011499:Protein Processing, Post-Translational; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D051742:Transcription Factor CHOP; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; C497249:DDIT3 protein, human; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D014157:Transcription Factors; D051742:Transcription Factor CHOP; D003609:Dactinomycin; D007930:Leucine; D005947:Glucose