title: Alignment of the transcription start site coincides with increased transcriptional activity from the human asparagine synthetase gene following amino acid deprivation of HepG2 cells.
abstract: Transcription initiation sites of the asparagine synthetase gene were investigated in human hepatoma cells after amino acid limitation by incubation in amino acid-complete minimal essential medium or medium lacking histidine. Cells incubated in complete minimal essential medium had mRNA transcripts with starting positions spanning across the 69 nucleotides immediately upstream of a previously designated transcription start site (+1), whereas the majority of mRNA transcripts started at nucleotide (+1) in cells incubated in histidine-free medium. Similar results were obtained regardless of whether the analysis was by 5' rapid amplification of cDNA ends or a ribonuclease protection assay. Low ASNS mRNA expression in amino acid-complete medium was associated with the wide range of initiation sites, whereas preferred alignment of the general transcription machinery at nucleotide (+1), observed in the amino acid deprived condition, was associated with a concurrent increase in transcription activity. To our knowledge, these results are the first example in a mammalian cell of transcription start selection by nutrient availability.
authors.affiliation: Department of Biochemistry and Molecular Biology, Center for Mammalian Genetics, and Center for Nutritional Sciences, University of Florida College of Medicine, Gainesville, FL 32610-0245, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Chen
authors.forename: Michael S
authors.initials: MS
authors.lastname: Kilberg
mesh_terms: D000596:Amino Acids / Q000008:administration & dosage*; D001217:Aspartate-Ammonia Ligase / Q000737:chemistry / Q000235:genetics*; D006528:Carcinoma, Hepatocellular; D045744:Cell Line, Tumor; D003470:Culture Media; D006639:Histidine / Q000008:administration & dosage; D006801:Humans; D008113:Liver Neoplasms; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D024363:Transcription Initiation Site; D014158:Transcription, Genetic
chemical_list: D000596:Amino Acids; D003470:Culture Media; D012333:RNA, Messenger; D006639:Histidine; D001217:Aspartate-Ammonia Ligase