title: Homozygous deletion of EPB41 genuine AUG-containing exons results in mRNA splicing defects, NMD activation and protein 4.1R complete deficiency in hereditary elliptocytosis.
abstract: Complete loss of protein 4.1R in red blood cell membrane is a very rare condition in humans. We here explore the third case. The morphological and biochemical observations suggested that the proband suffers from homozygous hereditary elliptocytosis. Both parents, who are consanguineous, have an elliptocytosis with no cell fragmentation, typical of a heterozygous 4.1R deficiency with a silent allele. A genomic deletion was found; it encompasses about 50 kb of genomic DNA, and suppresses the two key exons 2 and 4, which contain the two functional AUG translation initiation sites in erythroid and nonerythroid cells. The alternative first exons are intact, hence preserving the transcription potential of the altered gene. Extensive analysis of 4.1R transcripts revealed multiple splicing defects upstream of the deleted sequences. Importantly, we found that most of the transcripts generated from the altered gene are intercepted by the nonsense-mediated mRNA decay mechanism, suggesting that the massive degradation of the mRNA species jeopardizes the production of shortened but functional protein 4.1R from an alternative translation initiation site downstream of the deletion.
authors.affiliation: mRNA Metabolism in Normal and Pathological Cells, CNRS, Université Lyon 1, Villeurbanne, France. faouzi.baklouti@univ-lyon1.fr
authors.forename: Faouzi
authors.initials: F
authors.lastname: Baklouti
authors.forename: Madeleine
authors.initials: M
authors.lastname: Morinière
authors.forename: Amel
authors.initials: A
authors.lastname: Haj-Khélil
authors.forename: Madeleine
authors.initials: M
authors.lastname: Fénéant-Thibault
authors.forename: Henri
authors.initials: H
authors.lastname: Gruffat
authors.forename: Yohann
authors.initials: Y
authors.lastname: Couté
authors.forename: Alain
authors.initials: A
authors.lastname: Ninot
authors.forename: Corinne
authors.initials: C
authors.lastname: Guitton
authors.forename: Jean
authors.initials: J
authors.lastname: Delaunay
mesh_terms: D002648:Child; D003241:Consanguinity; D003598:Cytoskeletal Proteins / Q000172:deficiency / Q000235:genetics; D004612:Elliptocytosis, Hereditary / Q000235:genetics / Q000378:metabolism; D004913:Erythrocytes, Abnormal / Q000378:metabolism; D005091:Exons / Q000235:genetics; D006801:Humans; D008565:Membrane Proteins / Q000172:deficiency / Q000235:genetics; D008969:Molecular Sequence Data; D059365:Nonsense Mediated mRNA Decay / Q000235:genetics*; D010442:Peptide Chain Initiation, Translational; D012326:RNA Splicing / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion / Q000235:genetics*; D013156:Splenectomy / Q000379:methods
chemical_list: D003598:Cytoskeletal Proteins; D008565:Membrane Proteins; D012333:RNA, Messenger; C028841:erythrocyte membrane band 4.1 protein