title: Pathogenesis of ELANE-mutant severe neutropenia revealed by induced pluripotent stem cells.
abstract: Severe congenital neutropenia (SCN) is often associated with inherited heterozygous point mutations in ELANE, which encodes neutrophil elastase (NE). However, a lack of appropriate models to recapitulate SCN has substantially hampered the understanding of the genetic etiology and pathobiology of this disease. To this end, we generated both normal and SCN patient-derived induced pluripotent stem cells (iPSCs), and performed genome editing and differentiation protocols that recapitulate the major features of granulopoiesis. Pathogenesis of ELANE point mutations was the result of promyelocyte death and differentiation arrest, and was associated with NE mislocalization and activation of the unfolded protein response/ER stress (UPR/ER stress). Similarly, high-dose G-CSF (or downstream signaling through AKT/BCL2) rescues the dysgranulopoietic defect in SCN patient-derived iPSCs through C/EBPβ-dependent emergency granulopoiesis. In contrast, sivelestat, an NE-specific small-molecule inhibitor, corrected dysgranulopoiesis by restoring normal intracellular NE localization in primary granules; ameliorating UPR/ER stress; increasing expression of CEBPA, but not CEBPB; and promoting promyelocyte survival and differentiation. Together, these data suggest that SCN disease pathogenesis includes NE mislocalization, which in turn triggers dysfunctional survival signaling and UPR/ER stress. This paradigm has the potential to be clinically exploited to achieve therapeutic responses using lower doses of G-CSF combined with targeting to correct NE mislocalization.
authors.forename: Ramesh C
authors.initials: RC
authors.lastname: Nayak
authors.forename: Lisa R
authors.initials: LR
authors.lastname: Trump
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Aronow
authors.forename: Kasiani
authors.initials: K
authors.lastname: Myers
authors.forename: Parinda
authors.initials: P
authors.lastname: Mehta
authors.forename: Theodosia
authors.initials: T
authors.lastname: Kalfa
authors.forename: Ashley M
authors.initials: AM
authors.lastname: Wellendorf
authors.forename: C Alexander
authors.initials: CA
authors.lastname: Valencia
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Paddison
authors.forename: Marshall S
authors.initials: MS
authors.lastname: Horwitz
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
mesh_terms: D022782:CCAAT-Enhancer-Binding Protein-beta / Q000235:genetics / Q000378:metabolism; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D059865:Endoplasmic Reticulum Stress / Q000235:genetics; D005260:Female; D030342:Genetic Diseases, Inborn / Q000201:enzymology / Q000235:genetics; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology; D042381:Granulocyte Precursor Cells / Q000201:enzymology; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000201:enzymology*; D019272:Leukocyte Elastase / Q000235:genetics / Q000378:metabolism; D008297:Male; D038042:Myelopoiesis / Q000235:genetics*; D009503:Neutropenia; D009504:Neutrophils / Q000201:enzymology*; D017354:Point Mutation; D056811:Unfolded Protein Response / Q000235:genetics
chemical_list: D022782:CCAAT-Enhancer-Binding Protein-beta; D022762:CCAAT-Enhancer-Binding Proteins; C515848:CEBPA protein, human; C545012:CEBPB protein, human; D016179:Granulocyte Colony-Stimulating Factor; D019272:Leukocyte Elastase