Homozygous deletion of EPB41 genuine AUG-containing exons results in mRNA splicing defects, NMD activation and protein 4.1R complete deficiency in hereditary elliptocytosis

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 elli...

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Bibliographic Details
Published in:	Blood cells, molecules, & diseases Vol. 47; no. 3; pp. 158 - 165
Main Authors:	Baklouti, Faouzi, Morinière, Madeleine, Haj-Khélil, Amel, Fénéant-Thibault, Madeleine, Gruffat, Henri, Couté, Yohann, Ninot, Alain, Guitton, Corinne, Delaunay, Jean
Format:	Journal Article
Language:	English
Published:	United States Elsevier Inc 15-10-2011
Subjects:	Child Consanguinity Cytoskeletal Proteins - deficiency Cytoskeletal Proteins - genetics Elliptocytosis, Hereditary - genetics Elliptocytosis, Hereditary - metabolism Erythrocyte Erythrocytes, Abnormal - metabolism Exons - genetics Humans Membrane protein Membrane Proteins - deficiency Membrane Proteins - genetics Molecular Sequence Data mRNA splicing mRNA stability NMD Nonsense Mediated mRNA Decay - genetics Peptide Chain Initiation, Translational Protein 4.1R RNA Splicing - genetics RNA, Messenger - genetics RNA, Messenger - metabolism Sequence Deletion - genetics Splenectomy - methods Erythrocyte RBC Membrane protein Protein 4.1R NMD mRNA splicing EBV mRNA stability
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Summary:	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.
Bibliography:	ObjectType-Case Study-2 SourceType-Scholarly Journals-1 ObjectType-Feature-4 content type line 23 ObjectType-Report-1 ObjectType-Article-3
ISSN:	1079-9796 1096-0961
DOI:	10.1016/j.bcmd.2011.07.001