title: Systematic analysis of the PTEN 5' leader identifies a major AUU initiated proteoform.
abstract: Abundant evidence for translation within the 5' leaders of many human genes is rapidly emerging, especially, because of the advent of ribosome profiling. In most cases, it is believed that the act of translation rather than the encoded peptide is important. However, the wealth of available sequencing data in recent years allows phylogenetic detection of sequences within 5' leaders that have emerged under coding constraint and therefore allow for the prediction of functional 5' leader translation. Using this approach, we previously predicted a CUG-initiated, 173 amino acid N-terminal extension to the human tumour suppressor PTEN. Here, a systematic experimental analysis of translation events in the PTEN 5' leader identifies at least two additional non-AUG-initiated PTEN proteoforms that are expressed in most human cell lines tested. The most abundant extended PTEN proteoform initiates at a conserved AUU codon and extends the canonical AUG-initiated PTEN by 146 amino acids. All N-terminally extended PTEN proteoforms tested retain the ability to downregulate the PI3K pathway. We also provide evidence for the translation of two conserved AUG-initiated upstream open reading frames within the PTEN 5' leader that control the ratio of PTEN proteoforms.
authors.affiliation: School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland.
authors.forename: Ioanna
authors.initials: I
authors.lastname: Tzani
authors.affiliation: Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Ivaylo P
authors.initials: IP
authors.lastname: Ivanov
authors.affiliation: School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia.
authors.forename: Dmitri E
authors.initials: DE
authors.lastname: Andreev
authors.affiliation: School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland.
authors.forename: Ruslan I
authors.initials: RI
authors.lastname: Dmitriev
authors.affiliation: School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland.
authors.forename: Kellie A
authors.initials: KA
authors.lastname: Dean
authors.affiliation: School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland.
authors.forename: Pavel V
authors.initials: PV
authors.lastname: Baranov
authors.affiliation: School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland Department of Human Genetics, University of Utah, Salt Lake City, UT 84112-5330, USA.
authors.forename: John F
authors.initials: JF
authors.lastname: Atkins
authors.affiliation: School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland g.loughran@ucc.ie.
authors.forename: Gary
authors.initials: G
authors.lastname: Loughran
mesh_terms: D020121:5' Untranslated Regions; D001483:Base Sequence; D045744:Cell Line, Tumor; D003062:Codon; D017124:Conserved Sequence; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D061986:MCF-7 Cells; D016366:Open Reading Frames; D051059:PTEN Phosphohydrolase / Q000235:genetics* / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010802:Phylogeny; D014176:Protein Biosynthesis; D020033:Protein Isoforms / Q000378:metabolism
chemical_list: D020121:5' Untranslated Regions; D003062:Codon; D020033:Protein Isoforms; D019869:Phosphatidylinositol 3-Kinases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human
keywords: AUU; PTEN-L; non-AUG; uORF