title: Translational repression of the McKusick-Kaufman syndrome transcript by unique upstream open reading frames encoding mitochondrial proteins with alternative polyadenylation sites.
abstract: BACKGROUND
  Upstream open reading frames (uORFs) are commonly found in the 5'-untranslated region (UTR) of many genes and function in translational control. However, little is known about the existence of the proteins encoded by uORFs, and the role of the proteins except translational control. There was no report about uORFs of the McKusick-Kaufman syndrome (MKKS) gene that causes a genetic disorder.
  
  
  METHODS
  Northern blotting, 3'-RACE, and bioinformatics were used for determining the length of transcripts and their 3' ends. Luciferase assay and in vitro translation were used for evaluation of translational regulatory activity of uORFs. Immunoblotting and immunocytochemical analyses were used for detection of uORF-derived protein products and their subcellular localization.
  
  
  RESULTS
  The MKKS gene generates two types of transcripts: a canonical long transcript that encodes both uORFs and MKKS, and a short transcript that encodes only uORFs by using alternative polyadenylation sites at the 5'-UTR. The simultaneous disruption of the uORF initiation codons increased the translation of the downstream ORF. Furthermore, both protein products from the two longest uORFs were detected in the mitochondrial membrane fraction of HeLa cells. Database searches indicated that such uORFs with active alternative polyadenylation sites at the 5'-UTR are atypical but surely exist in human transcripts.
  
  
  CONCLUSIONS
  Multiple uORFs at the 5'-UTR of the MKKS long transcript function as translational repressor for MKKS. Two uORFs are translated in vivo and imported onto the mitochondrial membrane.
  
  
  CONCLUSIONS
  Our findings provide unique insights into production of uORF-derived peptides and functions of uORFs.
authors.affiliation: Division of Neurology, Department of Internal Medicine, Jichi Medical University School of Medicine, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi 329-0498, Japan.
authors.forename: Chizuru
authors.initials: C
authors.lastname: Akimoto
authors.forename: Eiji
authors.initials: E
authors.lastname: Sakashita
authors.forename: Katsumi
authors.initials: K
authors.lastname: Kasashima
authors.forename: Kenji
authors.initials: K
authors.lastname: Kuroiwa
authors.forename: Kaoru
authors.initials: K
authors.lastname: Tominaga
authors.forename: Toshiro
authors.initials: T
authors.lastname: Hamamoto
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Endo
mesh_terms: D020121:5' Untranslated Regions; D000015:Abnormalities, Multiple / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D045744:Cell Line, Tumor; D015723:Gene Library; D017930:Genes, Reporter; D000882:Haplorhini; D006330:Heart Defects, Congenital / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D052202:Hydrocolpos / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008156:Luciferases; D051379:Mice; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D026723:Polyadenylation; D017689:Polydactyly / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D016415:Sequence Alignment; D014591:Uterine Diseases / Q000235:genetics* / Q000378:metabolism / Q000473:pathology
chemical_list: D020121:5' Untranslated Regions; D024101:Mitochondrial Proteins; D012333:RNA, Messenger; D008156:Luciferases