Erythrocyte membrane changes of chorea-acanthocytosis are the result of altered Lyn kinase activity

Department of Medicine, University of Verona, Piazzale Lo Scuro 10, Verona, Italy.
Blood (Impact Factor: 10.45). 09/2011; 118(20):5652-63. DOI: 10.1182/blood-2011-05-355339
Source: PubMed


Acanthocytic RBCs are a peculiar diagnostic feature of chorea-acanthocytosis (ChAc), a rare autosomal recessive neurodegenerative disorder. Although recent years have witnessed some progress in the molecular characterization of ChAc, the mechanism(s) responsible for generation of acanthocytes in ChAc is largely unknown. As the membrane protein composition of ChAc RBCs is similar to that of normal RBCs, we evaluated the tyrosine (Tyr)-phosphorylation profile of RBCs using comparative proteomics. Increased Tyr phosphorylation state of several membrane proteins, including band 3, β-spectrin, and adducin, was noted in ChAc RBCs. In particular, band 3 was highly phosphorylated on the Tyr-904 residue, a functional target of Lyn, but not on Tyr-8, a functional target of Syk. In ChAc RBCs, band 3 Tyr phosphorylation by Lyn was independent of the canonical Syk-mediated pathway. The ChAc-associated alterations in RBC membrane protein organization appear to be the result of increased Tyr phosphorylation leading to altered linkage of band 3 to the junctional complexes involved in anchoring the membrane to the cytoskeleton as supported by coimmunoprecipitation of β-adducin with band 3 only in ChAc RBC-membrane treated with the Lyn-inhibitor PP2. We propose this altered association between membrane skeleton and membrane proteins as novel mechanism in the generation of acanthocytes in ChAc.

Download full-text


Available from: Giel J C G M Bosman
  • Source
    • "Foller et al. [30] found altered signaling of PI3K, Rac1 and PAK1 and a higher fraction of depolymerized actin in ChAc erythrocytes indicating an impaired assembly of the junctional complex. DeFranceschi et al. [31] describe increased tyrosine phosphorylation of the cytoskeletal components β-spectrin and adducin and the integral membrane protein band 3 and implicate alterations in the composition of the junctional complex from co-immunoprecipitation studies. Increased phosphorylation and activity of the band 3 anion exchanger in ChAc erythrocytes has already been reported previously [32]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Neuroacanthocytosis (NA) refers to a group of heterogenous, rare genetic disorders, namely chorea acanthocytosis (ChAc), McLeod syndrome (MLS), Huntington's disease-like 2 (HDL2) and pantothenate kinase associated neurodegeneration (PKAN), that mainly affect the basal ganglia and are associated with similar neurological symptoms. PKAN is also assigned to a group of rare neurodegenerative diseases, known as NBIA (neurodegeneration with brain iron accumulation), associated with iron accumulation in the basal ganglia and progressive movement disorder. Acanthocytosis, the occurrence of misshaped erythrocytes with thorny protrusions, is frequently observed in ChAc and MLS patients but less prevalent in PKAN (about 10%) and HDL2 patients. The pathological factors that lead to the formation of the acanthocytic red blood cell shape are currently unknown. The aim of this study was to determine whether NA/NBIA acanthocytes differ in their functionality from normal erythrocytes. Several flow-cytometry-based assays were applied to test the physiological responses of the plasma membrane, namely drug-induced endocytosis, phosphatidylserine exposure and calcium uptake upon treatment with lysophosphatidic acid. ChAc red cell samples clearly showed a reduced response in drug-induced endovesiculation, lysophosphatidic acid-induced phosphatidylserine exposure, and calcium uptake. Impaired responses were also observed in acanthocyte-positive NBIA (PKAN) red cells but not in patient cells without shape abnormalities. These data suggest an "acanthocytic state" of the red cell where alterations in functional and interdependent membrane properties arise together with an acanthocytic cell shape. Further elucidation of the aberrant molecular mechanisms that cause this acanthocytic state may possibly help to evaluate the pathological pathways leading to neurodegeneration.
    Full-text · Article · Oct 2013 · PLoS ONE
  • Source
    • "Studies in í µí»½-thal erythrocytes have shown that proteins from both cytoskeleton network and membrane are targeted by the oxidative stress. In red cells spectrins are key proteins of the cytoskeleton network, [14] [15]. Studies in í µí»½-thal erythrocytes show that spectrins are involved by the oxidative damage, resulting in perturbation of their interactions with other cytoskeleton proteins such as actin or with proteins from multiprotein complexes bridging the membrane to the cytoskeleton as protein 4.1 [15]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: β -thalassemia is a worldwide distributed monogenic red cell disorder, characterized by the absence or reduced β -globin chain synthesis. Despite the extensive knowledge of the molecular defects causing β -thalassemia, less is known about the mechanisms responsible for the associated ineffective erythropoiesis and reduced red cell survival, which sustain anemia of β -thalassemia. The unbalance of alpha-gamma chain and the presence of pathological free iron promote a severe red cell membrane oxidative stress, which results in abnormal β -thalassemic red cell features. These cells are precociously removed by the macrophage system through two mechanisms: the removal of phosphatidylserine positive cells and through the natural occurring antibody produced against the abnormally clustered membrane protein band 3. In the present review we will discuss the changes in β -thalassemic red cell homeostasis related to the oxidative stress and its connection with production of microparticles and with malaria infection. The reactive oxygen species (ROS) are also involved in ineffective erythropoiesis of β -thalassemia through still partially known pathways. Novel cytoprotective systems such as ASHP, eIF2 α , and peroxiredoxin-2 have been suggested to be important against ROS in β -thalassemic erythropoiesis. Finally, we will discuss the results of the major in vitro and in vivo studies with antioxidants in β -thalassemia.
    Full-text · Article · Sep 2013 · Oxidative Medicine and Cellular Longevity
  • Source
    • "1SA and 1SB). The combined treatment with Na-vanadate and diamide produced the highest levels of phosphorylation of Tyr 8 on band 3, in agreement with previous reports [28] [20]. As these studies involved exposing intact red cells to oxidative agents it is difficult to discriminate if the observed effects on membrane association of PRDX2 are the result of membrane modifications or modification of PRDX2 or both. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Band-3 (B3), the anion transporter is an integral membrane protein that plays a key structural role by anchoring the plasma membrane to the spectrin-based membrane skeleton in the red cell. In addition, it also plays a critical role in the assembly of glycolytic enzymes to regulate red cell metabolism. However, its ability to recruit proteins that can prevent membrane oxidation has not been previously explored. In the present study, using a variety of experimental approaches including cross-linking studies, fluorescence and dichroic measurements, surface-plasmon-resonance analysis, and proteolytic digestion assays, we document that the anti-oxidant protein, Peroxiredoxin-2 (PRDX2), the third most abundant cytoplasmic protein in RBCs, interacts with the cytoplasmic domain of B3. The surface electrostatic potential analysis and stoichiometry measurements revealed that the N-terminal peptide of B3 is involved in interaction. PRDX2 underwent a conformational change upon its binding to B3 without losing its peroxidase activity. Hemichrome formation induced by phenylhydrazine (PHZ) of RBCs prevented membrane association of PRDX2 implying over lapping binding sites. Documentation of the absence of binding of PRDX2 to B3 Neapolis red cell membranes in which the initial N-terminal 11 amino acids are deleted, enabled us to conclude that PRDX2 binds to the N-terminal cytoplasmic domain of B3 and that the first 11 amino acid of this domain are crucial for PRDX2 membrane-association in intact RBCs. These findings imply yet another important role for B3 in regulating red cell membrane function.
    Full-text · Article · Oct 2012 · Free Radical Biology and Medicine
Show more