A variant of spectrin low‐expression allele α<sup>LELY</sup> carrying a hereditary elliptocytosis mutation in codon 28

Randon, Jacques; Boulanger, Laurent; Maréchal, J; Garbarz, M; Vallier, Agnès; Ribeiro, Luís; Tamagnini, Gabriele; Dhermy, Didier; Delaunay, Jean

doi:10.1111/j.1365-2141.1994.tb05070.x

Cited by 37 publications

(33 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…HE allele results in mild clinical symptoms, 11 whereas inheritance in trans causes a relative increase in the mRNA produced from the HE αSp allele, which exacerbates the SpD self-association defect and may lead to the HPP phenotype. 10 Thus the increased proportion of defective αβSpD causes a more severe morphological and clinical phenotype.…”

Section: R28hmentioning

confidence: 99%

Novel exon 2 spectrin mutation and intragenic crossover: three morphological phenotypes associated with four distinct spectrin defects

et al. 2013

View full text Add to dashboard Cite

© F e r r a t a S t o r t i F o u n d a t i o n 2 0 1 3Furthermore, the HPP phenotype is normocytic and not microcytic, and there are also numerous elliptocytes present on the peripheral smear; hence, we designate it as atypical HPP. In this manuscript, we clarify the molecular basis of these three phenotypes associated with the novel SPTA R34P mutation and provide new insight into the complexity of erythrocyte membrane disorders. Methods Clinical and routine laboratory studiesAll patients provided written, informed consent before participation in the study. The studies were approved by the University of Utah Institutional Review Board (IRB_00027669). Family AA 79-year old man (propositus of family A, A-I-3) ( Figure 1A) presented with a life-long history of anemia and intermittent jaundice. He and his extended family trace their ancestry to Scottish and Scandinavian forebears who were among the first Mormon settlers of Utah Territory. He had a splenectomy two years prior to presentation that resulted in a partial amelioration of his anemia. He was aware that multiple family members had a history of abnormal red blood cell morphology and some were anemic. His erythrocyte morphology revealed anisopoikilocytosis, fragmented cells, microspherocytes, elliptocytosis and polychromasia ( Figure 2A). Eleven first-degree relatives of his extended family over three generations were evaluated ( Figure 1A). Family BAn apparently unrelated 39-year old female (propositus of family B, B-I-1) ( Figure 3A) was referred to one of the Authors (JTP) for evaluation of very high platelet count and suspected essential thrombocythemia. Since red cell fragmentation can be mistakenly reported as elevated platelet count by laboratory instruments, the accuracy of elevated platelet count has been verified by semiquantitative estimation of platelet count by microscopic evaluation of blood smear by one of the Authors experienced with RBC fragmentation in several HPP patients identified over the last three decades (JTP). She had neonatal hyperbilirubinemia, and since birth has had episodes of jaundice with severe anemia (hemoglobin 70g/L). She had undergone splenectomy three years earlier, with improved anemia and no further episodes of jaundice. HerNovel α spectrin mutation and intragenic crossover haematologica | 2013; 98(12) 1973 ancestors were also among the first Mormon settlers of Utah Territory and were of north European ancestry. After splenectomy, she has had persistently elevated platelet counts (up to 1 million/mL), and was assumed to have essential thrombocythemia and treated intermittently with hydroxyurea. Her physical examination was unremarkable. Peripheral smear revealed significant anisopoikilocytosis, microspherocytes, elliptocytosis, and polychromasia ( Figure 2B). Further studies revealed polyclonal hematopoiesis determined by the X-chromosome transcriptional assay 12 and the absence of JAK2 and cMPL somatic mutations. The clinical diagnosis of atypical HPP and secondary thrombocytosis due to hemolytic anemia ...

show abstract

Section: R28hmentioning

confidence: 99%

Novel exon 2 spectrin mutation and intragenic crossover: three morphological phenotypes associated with four distinct spectrin defects

et al. 2013

View full text Add to dashboard Cite

show abstract

“…, that affects dimer assembly (Alloisio et al, 1991;Wilmotte et al, 1993;Randon et al, 1994). When this mutation is present along with an elliptocytosis mutation on the same chain, symptoms of the elliptocytosis mutation are often silent or mitigated since the ␣ LELY mutation will decrease incorporation of the mutated chain onto the membrane.…”

Section: Lelymentioning

confidence: 99%

Mapping the Human Erythrocyte β-Spectrin Dimer Initiation Site Using Recombinant Peptides and Correlation of Its Phasing with the α-Actinin Dimer Site

Ursitti¹,

Kotula²,

DeSilva

et al. 1996

Journal of Biological Chemistry

View full text Add to dashboard Cite

Human erythroid spectrin dimer assembly is initiated by the association of a specific region near the N-terminal of ␤-spectrin with a complementary region near the C-terminal of ␣-spectrin (Speicher, D. W., Weglarz, L., and DeSilva, T. M. (1992) J. Biol. Chem. 267, 14775-14782). Both spectrin subunits consist primarily of tandem, 106-residue long, homologous, triple-helical motifs. In this study, the minimal region of ␤-spectrin required for association with ␣-spectrin was determined using recombinant peptides. The start site (phasing) for construction of dimerization competent ␤-spectrin peptides was particularly critical. The beginning of the first homologous motif for both ␤-spectrin and the related dimerization site of ␣-actinin is approximately 8 residues earlier than most spectrin motifs. A four-motif ␤-spectrin peptide (␤1-4 ؉ ) with this earlier starting point bound to full-length ␣-spectrin with a K d of about 10 nM, while deletion of these first 8 residues reduced binding nearly 10-fold. N-and C-terminal truncations of one or more motifs from ␤1-4 ؉ showed that the first motif was essential for dimerization since its deletion abolished binding, but ␤1؉ alone could not associate with ␣-monomers. The first two motifs (␤1-2 ؉ ) represented the minimum lateral dimer assembly site with a K d of about 230 nM for interaction with full-length ␣-spectrin or an ␣-spectrin nucleation site recombinant peptide, ␣18 -21. Each additional motif increased the dimerization affinity by approximately 5-fold. In addition to this strong inter-subunit dimer association, interactions between the helices of a single triple-helical motif are frequently strong enough to maintain a noncovalent complex after internal protease cleavage similar to the interactions thought to be involved in tetramer formation. Analysis of hydrodynamic radii of recombinant peptides containing differing numbers of motifs showed that a single motif had a Stokes radius of 2.35 nm, while each additional motif added only 0.85 nm to the Stokes radius. This is the first direct demonstration that spectrin's flexibility arises from regions between each triple helical motif rather than from within the segment itself and suggests that current models of inter-motif connections may need to be revised.The membrane skeleton of the human erythrocyte consists of a network of proteins that associates with the inner surface of the cell membrane and imparts remarkable structural integrity and flexibility to circulating erythrocytes. Spectrin is the major structural component of this specialized submembranous protein network. The basic functional unit of spectrin is a heterodimer formed by side-to-side, antiparallel association of a 280-kDa ␣ subunit with a 246-kDa ␤ subunit. Spectrin dimers associate head-to-head to form tetramers, the predominant form of spectrin in the membrane skeleton. These tetramers cross-link short actin oligomers, an association modulated by band 4

show abstract

“…[25][26][27] This was followed by identification of numerous missense mutations located within the putative hybrid ␣-␤ repeat tetramer binding site that impaired tetramer formation and destabilized red cell membranes. 14,[28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] Attempts to correlate spectrin mutations with clinical severity have been confounded by marked clinical, biochemical, and genetic variability. For instance, the same tetramer site missense mutation has been linked to asymptomatic HE, chronic hemolytic HE, and severe HPP phenotypes in cases where patients spanning multiple generations in larger families were studied.…”

Section: Introductionmentioning

confidence: 99%

Structural and functional effects of hereditary hemolytic anemia-associated point mutations in the alpha spectrin tetramer site

Gaetani

Mootien

Harper

et al. 2008

Blood

View full text Add to dashboard Cite

The most common hereditary elliptocytosis (HE) and hereditary pyropoikilocytosis (HPP) mutations are ␣-spectrin missense mutations in the dimer-tetramer self-association site. In this study, we systematically compared structural and functional properties of the 14 known HE/HPP mutations located in the ␣-spectrin tetramer binding site. All mutant ␣-spectrin recombinant peptides were well folded, stable structures, with only the R34W mutant exhibiting a slight structural destabilization. In contrast, binding affinities measured by isothermal titration calorimetry were greatly variable, ranging from no detectable binding observed for I24S, R28C, R28H, R28S, and R45S to approximately wild-type binding for R34W and K48R. Binding affinities for the other 7 mutants were reduced by approximately 10-to 100-fold relative to wild-type binding. Some sites, such as R28, were hot spots that were very sensitive to even relatively conservative substitutions, whereas other sites were only moderately perturbed by nonconservative substitutions. The R34W and K48R mutations were particularly intriguing mutations that apparently either destabilize tetramers through mechanisms not probed by the univalent tetramer binding assay or represent polymorphisms rather than the pathogenic mutations responsible for observed clinical symptoms. All ␣0 HE/HPP mutations studied here appear to exert their destabilizing effects through molecular recognition rather than structural mechanisms. IntroductionThe hereditary elliptocytosis (HE) syndromes are a common group of disorders characterized by elliptical erythrocytes on peripheral blood smear. [1][2][3][4] These disorders are characterized by marked clinical, biochemical, and genetic heterogeneity. Most patients with typical HE are asymptomatic, but others have chronic hemolysis or the related disorder hereditary pyropoikilocytosis (HPP). Biochemical and genetic heterogeneity is related to qualitative and/or quantitative defects in one of several erythrocyte membrane skeleton proteins, particularly ␣-spectrin, ␤-spectrin, protein 4.1R, or glycophorin C, which leads to mechanical weakness or fragility of the erythrocyte membrane skeleton.The majority of HE-associated defects occur in spectrin, the principal structural component of the red cell membrane skeleton. Spectrin is a flexible, rope-like molecule formed by antiparallel lateral association of 2 subunits, ␣-and ␤-spectrin, which are primarily composed of many tandem, homologous 106 amino acid motifs, or "spectrin type repeats." [5][6][7] Spectrin repeats are highly stable, independently folding 3 helix bundle units that are responsible for imparting much of the strength and flexibility to the erythrocyte membrane skeleton. For example, when conformational changes of membrane skeleton components are probed in intact red cells using cysteine-specific reagents, spectrin is the only membrane skeleton component showing stress-related increases in labeling indicative of tensile stress-related unfolding of specific domains. 8 Assembly of spectrin he...

show abstract

A variant of spectrin low‐expression allele α^LELY carrying a hereditary elliptocytosis mutation in codon 28

Cited by 37 publications

References 13 publications

Novel exon 2 spectrin mutation and intragenic crossover: three morphological phenotypes associated with four distinct spectrin defects

Novel exon 2 spectrin mutation and intragenic crossover: three morphological phenotypes associated with four distinct spectrin defects

Mapping the Human Erythrocyte β-Spectrin Dimer Initiation Site Using Recombinant Peptides and Correlation of Its Phasing with the α-Actinin Dimer Site

Structural and functional effects of hereditary hemolytic anemia-associated point mutations in the alpha spectrin tetramer site

Contact Info

Product

Resources

About

A variant of spectrin low‐expression allele αLELY carrying a hereditary elliptocytosis mutation in codon 28

Cited by 37 publications

References 13 publications

Novel exon 2 spectrin mutation and intragenic crossover: three morphological phenotypes associated with four distinct spectrin defects

Novel exon 2 spectrin mutation and intragenic crossover: three morphological phenotypes associated with four distinct spectrin defects

Mapping the Human Erythrocyte β-Spectrin Dimer Initiation Site Using Recombinant Peptides and Correlation of Its Phasing with the α-Actinin Dimer Site

Structural and functional effects of hereditary hemolytic anemia-associated point mutations in the alpha spectrin tetramer site

Contact Info

Product

Resources

About

A variant of spectrin low‐expression allele α^LELY carrying a hereditary elliptocytosis mutation in codon 28