title: Neutropenia-associated ELANE mutations disrupting translation initiation produce novel neutrophil elastase isoforms.
abstract: Hereditary neutropenia is usually caused by heterozygous germline mutations in the ELANE gene encoding neutrophil elastase (NE). How mutations cause disease remains uncertain, but two hypotheses have been proposed. In one, ELANE mutations lead to mislocalization of NE. In the other, ELANE mutations disturb protein folding, inducing an unfolded protein response in the endoplasmic reticulum (ER). In this study, we describe new types of mutations that disrupt the translational start site. At first glance, they should block translation and are incompatible with either the mislocalization or misfolding hypotheses, which require mutant protein for pathogenicity. We find that start-site mutations, instead, force translation from downstream in-frame initiation codons, yielding amino-terminally truncated isoforms lacking ER-localizing (pre) and zymogen-maintaining (pro) sequences, yet retain essential catalytic residues. Patient-derived induced pluripotent stem cells recapitulate hematopoietic and molecular phenotypes. Expression of the amino-terminally deleted isoforms in vitro reduces myeloid cell clonogenic capacity. We define an internal ribosome entry site (IRES) within ELANE and demonstrate that adjacent mutations modulate IRES activity, independently of protein-coding sequence alterations. Some ELANE mutations, therefore, appear to cause neutropenia via the production of amino-terminally deleted NE isoforms rather than by altering the coding sequence of the full-length protein.
authors.affiliation: Department of Pathology, University of Washington School of Medicine, Seattle, WA;
authors.forename: Timothy
authors.initials: T
authors.lastname: Tidwell
authors.forename: Jeremy
authors.initials: J
authors.lastname: Wechsler
authors.forename: Ramesh C
authors.initials: RC
authors.lastname: Nayak
authors.forename: Lisa
authors.initials: L
authors.lastname: Trump
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Salipante
authors.forename: Jerry C
authors.initials: JC
authors.lastname: Cheng
authors.forename: Jean
authors.initials: J
authors.lastname: Donadieu
authors.forename: Taly
authors.initials: T
authors.lastname: Glaubach
authors.forename: Seth J
authors.initials: SJ
authors.lastname: Corey
authors.forename: H Leighton
authors.initials: HL
authors.lastname: Grimes
authors.forename: Carolyn
authors.initials: C
authors.lastname: Lutzko
authors.forename: Jose A
authors.initials: JA
authors.lastname: Cancelas
authors.forename: Marshall S
authors.initials: MS
authors.lastname: Horwitz
mesh_terms: D017209:Apoptosis; D003062:Codon; D004252:DNA Mutational Analysis; D004721:Endoplasmic Reticulum / Q000378:metabolism; D018922:HL-60 Cells; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000166:cytology; D019272:Leukocyte Elastase / Q000235:genetics* / Q000378:metabolism*; D009154:Mutation; D009503:Neutropenia / Q000378:metabolism*; D009504:Neutrophils / Q000166:cytology; D010641:Phenotype; D014176:Protein Biosynthesis; D011489:Protein Denaturation; D017510:Protein Folding; D020033:Protein Isoforms / Q000378:metabolism; D020298:U937 Cells
chemical_list: D003062:Codon; D020033:Protein Isoforms; D019272:Leukocyte Elastase