Analysis of novel sph (spherocytosis) alleles in mice reveals allele-specific loss of band 3 and adducin in alpha-spectrin-deficient red cells.
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.
Robledo
Raymond F
RF
The Jackson Laboratory, Bar Harbor, ME, USA.
Lambert
Amy J
AJ
Birkenmeier
Connie S
CS
Cirlan
Marius V
MV
Cirlan
Andreea Flavia M
AF
Campagna
Dean R
DR
Lux
Samuel E
SE
Peters
Luanne L
LL
D000483:Alleles; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001457:Anion Exchange Protein 1, Erythrocyte / Q000172:deficiency* / Q000235:genetics*; D001483:Base Sequence; D002148:Calmodulin-Binding Proteins / Q000097:blood / Q000172:deficiency* / Q000235:genetics*; D018389:Codon, Nonsense; D017931:DNA Primers / Q000235:genetics; D004910:Erythrocyte Membrane / Q000378:metabolism; D004913:Erythrocytes, Abnormal / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D016688:Mice, Inbred NOD; D008817:Mice, Mutant Strains; D008969:Molecular Sequence Data; D009154:Mutation; D020125:Mutation, Missense; D020871:RNA Stability / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013049:Spectrin / Q000172:deficiency* / Q000235:genetics*; D013103:Spherocytosis, Hereditary / Q000097:blood* / Q000235:genetics* / Q000473:pathology; D000099291:Adducins
D001457:Anion Exchange Protein 1, Erythrocyte; D002148:Calmodulin-Binding Proteins; D018389:Codon, Nonsense; D017931:DNA Primers; D013049:Spectrin; D000099291:Adducins