title: Modeling the ferrochelatase c.315-48C modifier mutation for erythropoietic protoporphyria (EPP) in mice.
abstract: Erythropoietic protoporphyria (EPP) is caused by deficiency of ferrochelatase (FECH), which incorporates iron into protoporphyrin IX (PPIX) to form heme. Excitation of accumulated PPIX by light generates oxygen radicals that evoke excessive pain and, after longer light exposure, cause ulcerations in exposed skin areas of individuals with EPP. Moreover, ∼5% of the patients develop a liver dysfunction as a result of PPIX accumulation. Most patients (∼97%) have a severeFECHmutation (Mut)in transto an intronic polymorphism (c.315-48C), which reduces ferrochelatase synthesis by stimulating the use of an aberrant 3' splice site 63 nt upstream of the normal site for exon 4. In contrast, with the predominant c.315-48T allele, the correct splice site is mostly used, and individuals with a T/Mut genotype do not develop EPP symptoms. Thus, the C allele is a potential target for therapeutic approaches that modify this splicing decision. To provide a model for pre-clinical studies of such approaches, we engineered a mouse containing a partly humanizedFechgene with the c.315-48C polymorphism. F1 hybrids obtained by crossing these mice with another inbred line carrying a severeFechmutation (named m1Pas) show a very strong EPP phenotype that includes elevated PPIX in the blood, enlargement of liver and spleen, anemia, as well as strong pain reactions and skin lesions after a short period of light exposure. In addition to the expected use of the aberrant splice site, the mice also show a strong skipping of the partly humanized exon 3. This will limit the use of this model for certain applications and illustrates that engineering of a hybrid gene may have unforeseeable consequences on its splicing.
authors.affiliation: Institute of Laboratory Medicine, Municipal Hospital Triemli, Zürich 8063, Switzerland.
authors.forename: Jasmin
authors.identifier: 0000-0001-7272-8824
authors.initials: J
authors.lastname: Barman-Aksözen
authors.affiliation: Institute of Cell Biology, University of Bern, Bern 3012, Switzerland.
authors.forename: Paulina
authors.identifier: 0000-0002-0964-6364
authors.initials: P
authors.lastname: C Wiek
authors.affiliation: Institute of Cell Biology, University of Bern, Bern 3012, Switzerland.
authors.forename: Vijay B
authors.initials: VB
authors.lastname: Bansode
authors.affiliation: Ozgene Pty Ltd, Bentley DC, WA 6983, Australia.
authors.forename: Frank
authors.initials: F
authors.lastname: Koentgen
authors.affiliation: Institute of Cell Biology, University of Bern, Bern 3012, Switzerland.
authors.forename: Judith
authors.initials: J
authors.lastname: Trüb
authors.affiliation: Center for Transgenic Models, University of Basel, Basel 4002, Switzerland.
authors.forename: Pawel
authors.initials: P
authors.lastname: Pelczar
authors.affiliation: Division of Trauma Surgery, University Hospital Zürich, Zürich 8091, Switzerland.
authors.forename: Paolo
authors.identifier: 0000-0002-0163-9055
authors.initials: P
authors.lastname: Cinelli
authors.affiliation: Institute of Laboratory Medicine, Municipal Hospital Triemli, Zürich 8063, Switzerland.
authors.forename: Xiaoye
authors.initials: X
authors.lastname: Schneider-Yin
authors.affiliation: Institute of Cell Biology, University of Bern, Bern 3012, Switzerland Elisabeth.Minder@triemli.zuerich.ch daniel.schuemperli@izb.unibe.ch.
authors.forename: Daniel
authors.identifier: 0000-0002-9644-134X
authors.initials: D
authors.lastname: Schümperli
authors.affiliation: Institute of Laboratory Medicine, Municipal Hospital Triemli, Zürich 8063, Switzerland Elisabeth.Minder@triemli.zuerich.ch daniel.schuemperli@izb.unibe.ch.|Porphyria Outpatient Clinics, Municipal Hospital Triemli, Zürich 8063, Switzerland.
authors.forename: Elisabeth I
authors.initials: EI
authors.lastname: Minder
mesh_terms: D000483:Alleles; D017398:Alternative Splicing / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D001773:Blood Cells / Q000473:pathology; D001947:Breeding; D004195:Disease Models, Animal; D005091:Exons / Q000235:genetics; D005294:Ferrochelatase / Q000235:genetics*; D005838:Genotype; D059765:Homologous Recombination / Q000235:genetics; D006801:Humans; D008027:Light; D008099:Liver / Q000473:pathology; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009154:Mutation / Q000235:genetics*; D009929:Organ Size; D046351:Protoporphyria, Erythropoietic / Q000097:blood / Q000201:enzymology* / Q000235:genetics* / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012867:Skin / Q000473:pathology / Q000528:radiation effects
chemical_list: D012333:RNA, Messenger; D005294:Ferrochelatase
keywords: Liver dysfunction; Mouse model; Photosensitivity; Protoporphyrin IX (PPIX); Rare disease; Splicing defect