title: A zebrafish model of Poikiloderma with Neutropenia recapitulates the human syndrome hallmarks and traces back neutropenia to the myeloid progenitor.
abstract: Poikiloderma with Neutropenia (PN) is an autosomal recessive genodermatosis characterized by early-onset poikiloderma, pachyonychia, hyperkeratosis, bone anomalies and neutropenia, predisposing to myelodysplasia. The causative C16orf57/USB1 gene encodes a conserved phosphodiesterase that regulates the stability of spliceosomal U6-RNA. The involvement of USB1 in splicing has not yet allowed to unveil the pathogenesis of PN and how the gene defects impact on skin and bone tissues besides than on the haematological compartment. We established a zebrafish model of PN using a morpholino-knockdown approach with two different splicing morpholinos. Both usb1-depleted embryos displayed developmental abnormalities recapitulating the signs of the human syndrome. Besides the pigmentation and osteochondral defects, usb1-knockdown caused defects in circulation, manifested by a reduced number of circulating cells. The overall morphant phenotype was also obtained by co-injecting sub-phenotypic dosages of the two morpholinos and could be rescued by human USB1 RNA. Integrated in situ and real-time expression analyses of stage-specific markers highlighted defects of primitive haematopoiesis and traced back the dramatic reduction in neutrophil myeloperoxidase to the myeloid progenitors showing down-regulated pu.1 expression. Our vertebrate model of PN demonstrates the intrinsic requirement of usb1 in haematopoiesis and highlights PN as a disorder of myeloid progenitors associated with bone marrow dysfunction.
authors.affiliation: Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milan, Italy.
authors.forename: Elisa A
authors.initials: EA
authors.lastname: Colombo
authors.affiliation: Dipartimento di Bioscienze, Università degli Studi di Milano, Milan, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Carra
authors.affiliation: Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milan, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Fontana
authors.affiliation: Dipartimento di Bioscienze, Università degli Studi di Milano, Milan, Italy.|Oncogenesis and Development Section, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Erica
authors.initials: E
authors.lastname: Bresciani
authors.affiliation: Dipartimento di Bioscienze, Università degli Studi di Milano, Milan, Italy.
authors.forename: Franco
authors.initials: F
authors.lastname: Cotelli
authors.affiliation: Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milan, Italy.|Laboratorio di Citogenetica Medica e Genetica Molecolare, IRCCS Istituto Auxologico Italiano, Milan, Italy.
authors.forename: Lidia
authors.initials: L
authors.lastname: Larizza
mesh_terms: D000818:Animals; D015536:Down-Regulation / Q000235:genetics; D006801:Humans; D060172:Morpholinos / Q000235:genetics; D022423:Myeloid Cells / Q000378:metabolism*; D009503:Neutropenia / Q000235:genetics*; D010641:Phenotype; D012326:RNA Splicing / Q000235:genetics; D012342:RNA, Small Nuclear / Q000235:genetics; D012868:Skin Abnormalities / Q000235:genetics*; D012871:Skin Diseases / Q000235:genetics / Q000378:metabolism; D013234:Stem Cells / Q000378:metabolism*; D015027:Zebrafish / Q000235:genetics*
chemical_list: D060172:Morpholinos; D012342:RNA, Small Nuclear; C405486:U6 small nuclear RNA