Band 3 Courcouronne: Homozygous Mutation Ser667Phe Causes Severe Hereditary Spherocytosis and Incomplete Distal Renal Tubular Acidosis.

Abstract We describe the second case of a homozygous mutation in band 3 (anion exchanger 1 (AE1), SLC4A1) causing both hereditary spherocytosis (HS) and distal renal tubular acidosis (dRTA). This new variant differed from the previous homozygous variant (Band 3 Coimbra, Ribeiro et al, Blood2000: 96, 1602) in that a significant amount of band 3 was present in the red cell membrane and the dRTA was incomplete. In the proband, an Algerian male baby, a severe hemolytic anemia rapidly developed following birth. Low hemoglobin (3.5 g Hb/dL) at D12 demanded a first transfusion. Hepato-splenomegaly, marked palor and jaundice were noted. Eight transfusions were administered in the following months. Subtotal splenectomy, performed at the age of 9 months, cancelled the transfusional needs. Veinous blood examined after splenectomy showed band 3 to be reduced to ~35% of normal, as shown by immunoblotting. The other known proteins of the band 3/Rh macrocomplex were also found to be reduced. The parents were first cousins. Both showed mild spherocytosis associated with a mild band 3 deficiency. DNA sequence analysis revealed a novel homozygous mutation: TCC to TTC at codon 667 in exon 16, leading to an amino acid substitution: Ser667Phe, located in proposed transmembrane helix 8. Both parents were heterozygous for the same mutation. Anion transport (sulphate uptake) in the patient’s red cells was ~40% normal, showing that transport specific activity of the mutant band 3 was not affected. The mutant red cell band 3 and kidney band 3 were expressed in Xenopus oocytes, with and without co-expression of glycophorin A (GPA). There was very little chloride transport detected in oocytes expressing either mutant red cell or kidney protein alone, but transport was partially rescued by co-expression of GPA. After birth the child showed a temporary acidosis which spontaneously receded. No nephrocalcinosis has been noted to date. At 2 years of age, an ammonium chloride challenge suggested that the child has incomplete dRTA; over the seven hours of the test the blood bicarbonates decreased down to 15.6 mmoles/L, but urinary pH remained above 5.90. Stable expression of mutant kidney band 3 in non-polarised Madin-Darby canine kidney (MDCK) cells showed that the mutant protein was retained in the endoplasmic reticulum. We are currently investigating the effects of this mutant in polarized MDCK cells. Overall our results suggest that the Ser667Phe does not affect the anion transport function of band 3 but causes a trafficking defect in both red blood cells and kidney cells. The trafficking defect may be less severe in red blood cells where it is probably attenuated by the chaperone-like effect of GPA, which is not expressed in kidney cells. The fact that the hematological manifestations are far more conspicuous than their nephrologic counterpart will be discussed.

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Band 3 Courcouronnes (Ser667Phe): a trafficking mutant differentially rescued by wild-type band 3 and glycophorin A

Blood ◽

10.1182/blood-2007-07-099473 ◽

2008 ◽

Vol 111 (11) ◽

pp. 5380-5389 ◽

Cited By ~ 35

Author(s):

Ashley M. Toye ◽

Rosalind C. Williamson ◽

Moudji Khanfar ◽

Brigitte Bader-Meunier ◽

Thérèse Cynober ◽

...

Keyword(s):

Renal Tubular Acidosis ◽

Band 3 ◽

Distal Renal Tubular Acidosis ◽

Glycophorin A ◽

Homozygous Mutation ◽

Kidney Cells ◽

Wild Type ◽

Anion Exchanger 1 ◽

Type Band ◽

Renal Tubular

Abstract We describe a mutation in human erythrocyte band 3 (anion exchanger 1; SLC4A1) causing both hereditary spherocytosis and distal renal tubular acidosis. The proband developed a transfusion-dependent, hemolytic anemia following birth. Immunoblotting showed band 3 was reduced to approximately 35% of wildtype; other proteins of the band 3/Rh macrocomplex were also reduced. DNA sequence analysis revealed a novel homozygous mutation, c.2000C>T, leading to the amino acid substitution Ser667Phe. The parents were heterozygous for the same mutation. Sulfate influx in the patient's erythrocytes was approximately 40% wild type. The mutant band 3 produced very little chloride influx when expressed in Xenopus oocytes. Influx was partially rescued by coexpression of glycophorin A and also rescued by coexpression of wild-type band 3. At 2 years of age, an ammonium chloride challenge showed the child has incomplete distal renal tubular acidosis (dRTA). Stable expression of mutant kidney band 3 in both nonpolarized and polarized Madin-Darby canine kidney cells showed that most of the mutant protein was retained in the endoplasmic reticulum. Overall our results suggest that the Ser667Phe does not affect the anion transport function of band 3, but causes a trafficking defect in both erythrocytes and kidney cells.

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Cell Physiology and Molecular Mechanism of Anion Transport by Erythrocyte Band 3/AE1

AJP Cell Physiology ◽

10.1152/ajpcell.00275.2021 ◽

2021 ◽

Author(s):

Michael L. Jennings

Keyword(s):

Transmembrane Protein ◽

Experimental System ◽

Membrane Skeleton ◽

Band 3 ◽

Anion Transport ◽

Future Research ◽

Cell Physiology ◽

Red Cell ◽

Tightly Coupled ◽

Renal Tubular

The major transmembrane protein of the red blood cell, known as band 3, AE1, and SLC4A1, has two main functions: 1) catalysis of Cl-/HCO3- exchange, one of the steps in CO2 excretion; 2) anchoring the membrane skeleton. This review summarizes the 150 year history of research on red cell anion transport and band 3 as an experimental system for studying membrane protein structure and ion transport mechanisms. Important early findings were that red cell Cl- transport is a tightly coupled 1:1 exchange and band 3 is labeled by stilbenesulfonate derivatives that inhibit anion transport. Biochemical studies showed that the protein is dimeric or tetrameric (paired dimers) and that there is one stilbenedisulfonate binding site per subunit of the dimer. Transport kinetics and inhibitor characteristics supported the idea that the transporter acts by an alternating access mechanism with intrinsic asymmetry. The sequence of band 3 cDNA provided a framework for detailed study of protein topology and amino acid residues important for transport. The identification of genetic variants produced insights into the roles of band 3 in red cell abnormalities and distal renal tubular acidosis. The publication of the membrane domain crystal structure made it possible to propose concrete molecular models of transport. Future research directions include improving our understanding of the transport mechanism at the molecular level and of the integrative relationships among band 3, hemoglobin, carbonic anhydrase, and gradients (both transmembrane and subcellular) of HCO3-, Cl-, O2, CO2, pH, and NO metabolites during pulmonary and systemic capillary gas exchange.

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Band 3 Edmonton I, a novel mutant of the anion exchanger 1 causing spherocytosis and distal renal tubular acidosis

Biochemical Journal ◽

10.1042/bj20091525 ◽

2010 ◽

Vol 426 (3) ◽

pp. 379-388 ◽

Cited By ~ 28

Author(s):

Carmen Chu ◽

Naomi Woods ◽

Nunghathai Sawasdee ◽

Helene Guizouarn ◽

Bernard Pellissier ◽

...

Keyword(s):

Renal Tubular Acidosis ◽

Anion Exchanger ◽

Failure To Thrive ◽

Renal Stones ◽

Band 3 ◽

Distal Renal Tubular Acidosis ◽

Kidney Cells ◽

Gene Encoding ◽

Anion Exchanger 1 ◽

Renal Tubular

dRTA (distal renal tubular acidosis) and HS (hereditary spherocytosis) are two diseases that can be caused by mutations in the gene encoding the AE1 (anion exchanger 1; Band 3). dRTA is characterized by defective urinary acidification, leading to metabolic acidosis, renal stones and failure to thrive. HS results in anaemia, which may require regular blood transfusions and splenectomy. Mutations in the gene encoding AE1 rarely cause both HS and dRTA. In the present paper, we describe a novel AE1 mutation, Band 3 Edmonton I, which causes dominant HS and recessive dRTA. The patient is a compound heterozygote with the new mutation C479W and the previously described mutation G701D. Red blood cells from the patient presented a reduced amount of AE1. Expression in a kidney cell line showed that kAE1 (kidney AE1) C479W is retained intracellularly. As kAE1 is a dimer, we performed co-expression studies and found that, in kidney cells, kAE1 C479W and G701D proteins traffic independently from each other despite their ability to form heterodimers. Therefore the patient carries one kAE1 mutant that is retained in the Golgi (G701D) and another kAE1 mutant (C479W) located in the endoplasmic reticulum of kidney cells, and is thus probably unable to reabsorb bicarbonate into the blood. We conclude that the C479W mutant is a novel trafficking mutant of AE1, which causes HS due to a decreased cell-surface AE1 protein and results in dRTA due to its intracellular retention in kidney.

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Familial distal renal tubular acidosis is associated with mutations in the red cell anion exchanger (Band 3, AE1) gene.

Journal of Clinical Investigation ◽

10.1172/jci119694 ◽

1997 ◽

Vol 100 (7) ◽

pp. 1693-1707 ◽

Cited By ~ 242

Author(s):

L J Bruce ◽

D L Cope ◽

G K Jones ◽

A E Schofield ◽

M Burley ◽

...

Keyword(s):

Renal Tubular Acidosis ◽

Anion Exchanger ◽

Band 3 ◽

Distal Renal Tubular Acidosis ◽

Red Cell ◽

Renal Tubular

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Band 3 Walton, a C-terminal deletion associated with distal renal tubular acidosis, is expressed in the red cell membrane but retained internally in kidney cells

Blood ◽

10.1182/blood.v99.1.342 ◽

2002 ◽

Vol 99 (1) ◽

pp. 342-347 ◽

Cited By ~ 56

Author(s):

Ashley M. Toye ◽

Lesley J. Bruce ◽

Robert J. Unwin ◽

Oliver Wrong ◽

Michael J. A. Tanner

Keyword(s):

Cell Surface ◽

Renal Tubular Acidosis ◽

Band 3 ◽

Normal Band ◽

Distal Renal Tubular Acidosis ◽

Mutant Protein ◽

Kidney Cells ◽

Kidney Cell Line ◽

Transport Activity ◽

Renal Tubular

Human band 3 Walton is an AE1 mutation that results in the deletion of the 11 COOH-terminal amino acids of the protein and is associated with dominant distal renal tubular acidosis. The properties of band 3 Walton expressed with normal band 3 in the heterozygous mutant erythrocytes and the kidney isoform expressed in Xenopusoocytes and in the Madin-Darby canine kidney cell line were examined. The mutant erythrocytes have normal hematology but have reduced band 3 Walton content. Transport studies showed that erythrocyte band 3 Walton has normal sulfate transport activity, and kidney band 3 Walton has normal chloride transport activity when expressed inXenopus oocytes. The mutant protein is clearly able to reach the cell surface of erythrocytes and oocytes. In contrast, while normal kidney band 3 was expressed at the cell surface in the kidney cell line, the Walton mutant protein was retained intracellularly within the kidney cells. The results demonstrate that band 3 Walton is targeted differently in erythrocytes and kidney cells and indicate that the COOH-terminal tail of band 3 is required to allow movement to the cell surface in kidney cells. It is proposed here that the mutant band 3 gives rise to dominant distal renal tubular acidosis by inhibiting the movement of normal band 3 to the cell surface. It is suggested that this results from the association of the normal and mutant proteins in band 3 hetero-oligomers, which causes the intracellular retention of normal band 3 with the mutant protein.

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Band 3 mutations, renal tubular acidosis and South-East Asian ovalocytosis in Malaysia and Papua New Guinea: loss of up to 95% band 3 transport in red cells

Biochemical Journal ◽

10.1042/bj3500041 ◽

2000 ◽

Vol 350 (1) ◽

pp. 41-51 ◽

Cited By ~ 70

Author(s):

Lesley J. BRUCE ◽

Oliver WRONG ◽

Ashley M. TOYE ◽

Mark T. YOUNG ◽

Graham OGLE ◽

...

Keyword(s):

Papua New Guinea ◽

East Asian ◽

Band 3 ◽

Anion Transport ◽

Red Cells ◽

Red Cell ◽

Transport Activity ◽

Anion Transport Activity ◽

Renal Tubular ◽

Compound Heterozygotes

We describe three mutations of the red-cell anion exchanger band 3 (AE1, SLC4A1) gene associated with distal renal tubular acidosis (dRTA) in families from Malaysia and Papua New Guinea: Gly701 → Asp (G701D), Ala858 → Asp (A858D) and deletion of Val850 (δV850). The mutations A858D and ∆V850 are novel; all three mutations seem to be restricted to South-East Asian populations. South-East Asian ovalocytosis (SAO), resulting from the band 3 deletion of residues 400–408, occurred in many of the families but did not itself result in dRTA. Compound heterozygotes of each of the dRTA mutations with SAO all had dRTA, evidence of haemolytic anaemia and abnormal red-cell properties. The A858D mutation showed dominant inheritance and the recessive ∆V850 and G701D mutations showed a pseudo-dominant phenotype when the transport-inactive SAO allele was also present. Red-cell and Xenopus oocyte expression studies showed that the ∆V850 and A858D mutant proteins have greatly decreased anion transport when present as compound heterozygotes (∆V850/A858D, ∆V850/SAO or A858D/SAO). Red cells with A858D/SAO had only 3% of the SO42- efflux of normal cells, the lowest anion transport activity so far reported for human red cells. The results suggest dRTA might arise by a different mechanism for each mutation. We confirm that the G701D mutant protein has an absolute requirement for glycophorin A for movement to the cell surface. We suggest that the dominant A858D mutant protein is possibly mis-targeted to an inappropriate plasma membrane domain in the renal tubular cell, and that the recessive ∆V850 mutation might give dRTA because of its decreased anion transport activity.

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The association between familial distal renal tubular acidosis and mutations in the red cell anion exchanger (band 3, AE1) gene

Biochemistry and Cell Biology ◽

10.1139/o98-072 ◽

1998 ◽

Vol 76 (5) ◽

pp. 723-728 ◽

Cited By ~ 19

Author(s):

Lesley J Bruce ◽

Robert J Unwin ◽

Oliver Wrong ◽

Michael JA Tanner

Keyword(s):

Renal Tubular Acidosis ◽

Anion Exchanger ◽

Autosomal Dominant ◽

Collecting Duct ◽

Band 3 ◽

Distal Renal Tubular Acidosis ◽

Xenopus Laevis Oocytes ◽

Red Cell ◽

Transport Activity ◽

Renal Tubular

In distal renal tubular acidosis (dRTA) the tubular secretion of hydrogen ion in the distal nephron is impaired, leading to the development of metabolic acidosis, frequently accompanied by hypokalemia, nephrocalcinosis, and metabolic bone disease. The condition can be familial, when it is usually inherited as an autosomal dominant, though there is a rarer autosomal recessive form associated with nerve deafness. It has been shown that the autosomal dominant form of dRTA is associated with a defect in the anion exchanger (AE1) of the renal collecting duct intercalated cell. This transporter is a product of the same gene (AE1) as the erythrocyte anion exchanger, band 3. In this review we will look at the evidence for this association. Studies of genomic DNA from families with this disorder have shown, both by genetic linkage studies and by DNA sequencing, that affected individuals are heterozygous for mutations in the AE1 gene whilst unaffected family members have a normal band 3 sequence. Mutations have been found in the region of proposed helices 6 and 7 of the membrane domain of band 3 and involve amino acids Arg-589 and Ser-613, and in the COOH-terminal domain of band 3. Studies of red cell band 3 from these families have provided information on the effect these mutations have on the structure and function of erythrocyte band 3. Expression studies of the erythroid and kidney isoforms of the mutant AE1 proteins, in Xenopus laevis oocytes, have shown that they retained chloride transport activity, suggesting that the disease in the dRTA families is not related simply to the anion transport activity of the mutated proteins. A possible explanation for the dominant effect of these mutant AE1 proteins in the kidney cell is that these mutations affect the targeting of AE1 from the basolateral to the apical membrane of the alpha-intercalated cell.Key words: erythrocyte, kidney, acidosis.

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