Analysis of novel sph (spherocytosis) alleles in mice reveals allele-specific loss of band 3 and adducin in alpha-spectrin-deficient red cells.

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Alternative-Splicing, Amino-Acid-Sequence, Animals, Anion-Exchange-Protein-1-Erythrocyte, Base-Sequence, Calmodulin-Binding-Proteins, Codon-Nonsense, DNA-Primers, Erythrocyte-Membrane, Erythrocytes-Abnormal, Mice-Inbred-C57BL, Mice-Inbred-NOD, Mice-Mutant-Strains, Molecular-Sequence-Data, Mutation, Mutation-Missense, RNA-Stability, Sequence-Homology-Amino-Acid, Spectrin, Spherocytosis-Hereditary

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Blood 2010 Mar; 115(9):1804-14.


Five spontaneous, allelic mutations in the alpha-spectrin gene, Spna1, have been identified in mice (spherocytosis [sph], sph(1J), sph(2J), sph(2BC), sph(Dem)). All cause severe hemolytic anemia. Here, analysis of 3 new alleles reveals previously unknown consequences of red blood cell (RBC) spectrin deficiency. In sph(3J), a missense mutation (H2012Y) in repeat 19 introduces a cryptic splice site resulting in premature termination of translation. In sph(Ihj), a premature stop codon occurs (Q1853Stop) in repeat 18. Both mutations result in markedly reduced RBC membrane spectrin content, decreased band 3, and absent beta-adducin. Reevaluation of available, previously described sph alleles reveals band 3 and adducin deficiency as well. In sph(4J), a missense mutation occurs in the C-terminal EF hand domain (C2384Y). Notably, an equally severe hemolytic anemia occurs despite minimally decreased membrane spectrin with normal band 3 levels and present, although reduced, beta-adducin. The severity of anemia in sph(4J) indicates that the highly conserved cysteine residue at the C-terminus of alpha-spectrin participates in interactions critical to membrane stability. The data reinforce the notion that a membrane bridge in addition to the classic protein 4.1-p55-glycophorin C linkage exists at the RBC junctional complex that involves interactions between spectrin, adducin, and band 3.