title: Out-of-frame start codons prevent translation of truncated nucleo-cytosolic cathepsin L in vivo.
abstract: The lysosomal protease cathepsin L has been reported to cleave various functionally important cytosolic or nuclear proteins. To explain nucleo-cytosolic localization of cathepsin L, it has been hypothesized that skipping of the first start codon during translation initiation results in an N-terminally truncated protein lacking the endoplasmic reticulum-import signal. Here we demonstrate that out-of-frame AUGs prevent translation of truncated cathepsin L in cell culture as well as in a new knock-in mouse model. We further evaluate potential roles of nuclear cathepsin L during early embryonic development. Our analysis reveals normal epiblast development of cathepsin L-deficient embryos, but uncovers a pronounced lysosomal storage phenotype in the extra-embryonic tissue of the visceral endoderm. In conclusion, the phenotypes of cathepsin L deficiency can be fully assigned to lack of canonically targeted cathepsin L, while the biogenesis and functionality of nucleo-cytosolic cathepsin L remain elusive.
authors.affiliation: 1] Institute of Molecular Medicine and Cell Research, Albert-Ludwigs-University Freiburg, D-79104 Freiburg, Germany [2] Faculty of Biology, Albert-Ludwigs-University Freiburg, D-79104 Freiburg, Germany.
authors.forename: Martina
authors.initials: M
authors.lastname: Tholen
authors.affiliation: 1] Institute of Molecular Medicine and Cell Research, Albert-Ludwigs-University Freiburg, D-79104 Freiburg, Germany [2] Faculty of Biology, Albert-Ludwigs-University Freiburg, D-79104 Freiburg, Germany [3] BIOSS Centre of Biological Signalling Studies, Albert-Ludwigs-University, D-79104 Freiburg, Germany.
authors.forename: Larissa E
authors.initials: LE
authors.lastname: Hillebrand
authors.affiliation: Institute of Molecular Medicine and Cell Research, Albert-Ludwigs-University Freiburg, D-79104 Freiburg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Tholen
authors.affiliation: 1] Faculty of Biology, Albert-Ludwigs-University Freiburg, D-79104 Freiburg, Germany [2] Centre for Clinical Research, Renal Department, University Medical Centre, D-79106 Freiburg, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Sedelmeier
authors.affiliation: 1] BIOSS Centre of Biological Signalling Studies, Albert-Ludwigs-University, D-79104 Freiburg, Germany [2] Centre for Clinical Research, Renal Department, University Medical Centre, D-79106 Freiburg, Germany.
authors.forename: Sebastian J
authors.initials: SJ
authors.lastname: Arnold
authors.affiliation: 1] Institute of Molecular Medicine and Cell Research, Albert-Ludwigs-University Freiburg, D-79104 Freiburg, Germany [2] BIOSS Centre of Biological Signalling Studies, Albert-Ludwigs-University, D-79104 Freiburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Reinheckel
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D056668:Cathepsin L / Q000172:deficiency / Q000235:genetics*; D002467:Cell Nucleus / Q000378:metabolism*; D018387:Codon, Initiator / Q000737:chemistry / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism*; D004622:Embryo, Mammalian; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D016368:Frameshift Mutation; D018507:Gene Expression Regulation, Developmental; D055879:Gene Knock-In Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010641:Phenotype; D061251:Primary Cell Culture; D014176:Protein Biosynthesis; D012867:Skin / Q000166:cytology / Q000196:embryology / Q000378:metabolism
chemical_list: D018387:Codon, Initiator; D056668:Cathepsin L; C534278:Ctsl protein, mouse