Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0002895 (sickle cell disease)
 11,747 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The role of the human erythrocyte membrane in degrading hemoglobin and hemoglobin subunits was investigated by determined the total radioactivity (cpm) of the nascent alpha and beta globin chains attached to the membrane after labeling of intact cells with 14C-leucine. In conditions characterized by balanced globin synthesis (normal and sickle cell anemia), the total radioactivity of membrane-attached alpha globin is always less than membrane-attached beta globin (alpha/beta = 0.60 +/- 0.10) despite the equal synthesis of alpha and beta chains in the hemolysate. In conditions characterized by unbalanced globin synthesis (alpha-thal and beta-thal traits) the cpm of membrane-attached alpha are also less than those of membrane-attached beta. Attachment of globin chains to the membrane is not related to the net ionic charge of individual chains, but the amount of attachment is related to the relative size of the free intracellular alpha chain pool. The alpha/beta ratio of less than 1 is not due to selective attachment of nascent beta chains or selective destruction of nascent alpha chains. The data indicate that part of the discrepancy between membrane and hemolysate alpha/beta radioactivities seen in the conditions studied is due to different rates of entry into the membrane and catabolism of newly labeled globin polypeptide chains by it.
 ...
PMID:Catabolism of hemoglobin by human erythrocyte membranes. 68 24

L-Azetidine-2-carboxylic acid, the naturally occurring lower homologue of L-proline, is incorporated into hemoglobin S (sickle hemoglobin) in vitro. Sickle erythrocytes from patients with sickle cell anemia incubated with L-[3H] azetidine-2-carboxylate synthesized radiolabeled hemoglobin which when isolated from cell lysates, co-chromatographed with hemoglobin S on DEAE-cellulose columns. The alpha/beta ratio of azetidine carboxylate incorporation into the globin chains of sickle hemoglobin was 0.94, which is consistent with the presence of four proline residues in each polypeptide chain. Incorporation of azetidine carboxylate into hot trichloroacetic acid-insoluble material in sickle erythrocytes indicated that the homologue was present in the polypeptide backbone of the globin chains of sickle hemoglobin. Amino acid analysis of the hot trichloroacetic acid-insoluble material from sickle erythrocytes which had been incubated with radiolabeled azetidine carboxylate indicated that 75% of the radioactivity could be accounted for as intact homologue while 20% of the radioactivity co-chromatographed with alanine. These results suggest that azetidine carboxylate is incorporated unaltered into hemoglobin S in addition to being metabolized to alanine in sickle erythrocytes prior to incorporation into protein. The kinetics of thermal precipitation of hemoglobin S (oxygen ligand) into which radioactive azetidine carboxylate or radioactive proline had been incorporated in vitro is identical. This observation, together with the behavior of hemoglobin S and the globin chains from hemoglobin S containing azetidine carboxylate during ion-exchange chromatography, indicates that homologue replacement of prolyl residues does not significantly alter the overall charge or stability of the hemoglobin S tetramer. Azetidine carboxylate did not inhibit uptake of radiolabeled proline by sickle erythrocytes suggesting that the homologue does not adversely affect amino acid transport in these cells.
 ...
PMID:Incorporation of L-azetidine-2-carboxylic acid into hemoglobin S in sickle erythrocytes in vitro. 97 36

Restriction site polymorphisms are normal inherited variations in DNA that can be readily detected by restriction endonuclease analysis. Currently, 17 such polymorphisms are recognized within a 60 kb (kilobase) stretch of DNA which includes the beta-globin gene complex. Because of their proximity to the beta-globin gene, often these restriction site polymorphisms can be used to predict inheritance of beta-globin variants that produce disease. For example, restriction site polymorphisms can be used for prenatal diagnosis for the large majority of couples at risk of having a child with beta-thalassemia. When each member of such a couple is heterozygous at one or more of these 17 sites, family studies are usually successful in determining which forms of the polymorphism are co-inherited with the beta-thalassemia genes in that particular family. Subsequently, study of fetal DNA isolated from amniocytes obtained by midtrimester amniocentesis or from chorionic villi obtained by first trimester chorion biopsy will reveal which DNA polymorphisms that fetus has inherited. By deductive reasoning one can then predict which beta-globin genes it has co-inherited. Because of the general nature of these polymorphisms, which are related to the beta-globin gene and its variants only because of their proximity on chromosome 11, they are potentially useful in the prenatal diagnosis of any beta-chain hemoglobinopathy. Some hemoglobinopathies (including alpha-thalassemia, sickle cell anemia, and some cases of beta-thalassemia) can be detected directly by DNA analysis. In these cases in utero diagnosis does not need to rely on restriction site polymorphisms, which require preliminary family studies and are not applicable in all at risk pregnancies. Recently, genetic probes, which are necessary for detecting restriction site polymorphisms, have been isolated for sequences of several genes whose protein products are important in blood coagulation. These include probes for all three genes whose polypeptide products combine to form the fibrinogen molecule as well as probes for the prothrombin, Factor IX, Factor VIII, and antithrombin III genes. Defects in these genes are expected to be the causes of afibrinogenemia, prothrombin deficiency, hemophilia B, hemophilia A, and antithrombin III deficiency, respectively. From experience with other genes, it is expected that restriction site polymorphisms within and/or flanking these genes will be found.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:Prenatal diagnosis of hemoglobinopathies by DNA analysis. 299 37

Genetic and biochemical evidence indicates that in beta-thalassemia there is impaired synthesis of the beta-globin chains of hemoglobin A. In patients heterozygous for the hemoglobinopathies, hemoglobin S and hemoglobin C, the mutant beta-chain is produced in smaller amounts than normal beta(A). Defective m-RNA translation has been suggested as a possible cause of decreased beta-globin polypeptide synthesis in thalassemia and the hemoglobinopathies. In the present study, the ribosomal assembly of beta-globin chains was examined in the peripheral, nucleated red blood cells and reticulocytes of patients with Cooley's anemia, thalassemia intermedia, sickle thalassemia, sickle cell anemia, hemoglobin C disease, and in hemolytic anemias not associated with a hemoglobinopathy. The translation times of beta(A), beta(S), and beta(C) did not differ significantly (average times; beta(A) = 75 sec, range 43-114, beta(S) = 69 sec, beta(C) = 92 sec). In thalassemia, no evidence was found for a delay in translation as the cause of the marked impairment of beta-globin synthesis. In several specimens of peripheral blood from thalassemic patients, the translation time of the beta-chain was even shorter than in nonthalassemic specimens (average time = 45 sec, range 35-59). The results suggest that the defect in beta-globin synthesis in beta-thalassemia is due to impaired initiation of beta-globin chain assembly or a quantitative deficiency in m-RNA.
 ...
PMID:Translation of -globin m-RNA in -thalassemia and the S and C hemoglobinopathies. 500 20

Thalassemia syndromes and hemoglobinopathies are of clinical genetic significance because of the severity of the sequelae associated with particular genetic constitutions in these conditions, their occurrence at high frequencies in certain populations of Mediterranean, African, and Asian origin, and the high frequency of recurrence in pregnancies of at risk families. Application of recently developed techniques of molecular genetics to the antenatal diagnosis of the most deleterious of these conditions (homozygous beta-thalassemia [Cooley's anemia], homozygous alpha-thalassemia [Barts hydrops fetalis], sickle cell anemia, and related severe homoglobinopathies) now affords parents the option to interrupt a pregnancy in which the fetus has the genetic constitution causing one of these abnormalities. The two different analytical strategies utilize fetal cells obtained by aminocentesis. In one, fetal blood is obtained either by sonographically guided placental aspiration or by aspiration from a placental vein directed by fetoscopy. Globin chain synthesis is monitored by the incorporation of radiolabelled amino acids in the isolated erythrocytes and the determination of the ratio of radioactive label incorporated into the various globin chains separated by column chromatography or electrophoresis. This technique is applicable to the antenatal diagnosis of alpha-and beta-thalassemia and to selected hemoglobinopathies. However, in the most experienced centers, fetal blood sampling is associated with a greatly increased risk of fetal loss. The other analytical approach utilizes desoxyribonucleic acid (DNA) isolated from fibroblasts to evaluate the presence of quantitatively and/or qualitatively normal DNA sequences, which constitute the structural gene(s) encoding specific globin polypeptide chains. This approach is most generally applicable to the detection of structural gene deletions as in a alpha-thalassemia; maternal and fetal risk is the same as that for conventional amniocentesis.
 ...
PMID:Prenatal diagnosis of thalassemias and hemoglobinopathies. 625 19

The genes responsible for the transmission of sickle cell syndromes from one generation to the next were introduced into the new world during the 17th century. However, this disease was not recorded in the medical literature in the United States until 1910 by Herrick of Chicago. During the next 40 years, many additional cases were reported and a fairly large bibliography developed which dealt essentially with descriptive, clinical and pathological aspects of the disease. New interest in the syndrome occurred in 1949 when Pauling and his associates, employing chemical and electrophoretic techniques, showed that an abnormal hemoglobin was responsible for the sickling phenomenon. In the same year, Neel and Beet, working independently of each other, clarified the inheritance of the disease on the basis of the heterozygous-homozygous hypothesis. In 1958, Ingraham combined the techniques of electrophoresis, chromatography, and trypsin digestion ("fingerprinting") to show that the difference between hemoglobins A, C, and S was in the amino acid sequence of the polypeptide chains which make up the hemoglobin molecule. However, despite these notable advances, interest in the disease remained at a relatively low scientific and health care priority until February 1971, when President Nixon in his message to Congress indicated that greater attention and support for sickle cell disease should be made available at the national level. This paper will review some of the important legislative, political, and organizational initiatives which have had a significant impact on the development and implementation of the current national sickle cell disease program in the United States.
 ...
PMID:Historical review of legislative and national initiatives for sickle cell disease. 636 20

Although K-Cl cotransporter (KCC1) mRNA is expressed in many tissues, K-Cl cotransport activity has been measured in few cell types, and detection of endogenous KCC1 polypeptide has not yet been reported. We have cloned the mouse erythroid KCC1 (mKCC1) cDNA and its flanking genomic regions and mapped the mKCC1 gene to chromosome 8. Three anti-peptide antibodies raised against recombinant mKCC1 function as immunoblot and immunoprecipitation reagents. The tissue distributions of mKCC1 mRNA and protein are widespread, and mKCC1 RNA is constitutively expressed during erythroid differentiation of ES cells. KCC1 polypeptide or related antigen is present in erythrocytes of multiple species in which K-Cl cotransport activity has been documented. Erythroid KCC1 polypeptide abundance is elevated in proportion to reticulocyte counts in density-fractionated cells, in bleeding-induced reticulocytosis, in mouse models of sickle cell disease and thalassemia, and in the corresponding human disorders. mKCC1-mediated uptake of (86)Rb into Xenopus oocytes requires extracellular Cl(-), is blocked by the diuretic R(+)-[2-n-butyl-6,7-dichloro-2-cyclopentyl-2, 3-dihydro-1-oxo-1H-indenyl-5-yl-)oxy]acetic acid, and exhibits an erythroid pattern of acute regulation, with activation by hypotonic swelling, N-ethylmaleimide, and staurosporine and inhibition by calyculin and okadaic acid. These reagents and findings will expedite studies of KCC1 structure-function relationships and of the pathobiology of KCC1-mediated K-Cl cotransport.
 ...
PMID:Mouse K-Cl cotransporter KCC1: cloning, mapping, pathological expression, and functional regulation. 1056 83

K-Cl cotransport regulates cell volume and chloride equilibrium potential. Inhibition of erythroid K-Cl cotransport has emerged as an important adjunct strategy for the treatment of sickle cell anemia. However, structure-function relationships among the polypeptide products of the four K-Cl cotransporter (KCC) genes are little understood. We have investigated the importance of the N- and C-terminal cytoplasmic domains of mouse KCC1 to its K-Cl cotransport function expressed in Xenopus oocytes. Truncation of as few as eight C-terminal amino acids (aa) abolished function despite continued polypeptide accumulation and surface expression. These C-terminal loss-of-function mutants lacked a dominant negative phenotype. Truncation of the N-terminal 46 aa diminished function. Removal of 89 or 117 aa (Delta(N)117) abolished function despite continued polypeptide accumulation and surface expression and exhibited dominant negative phenotypes that required the presence of the C-terminal cytoplasmic domain. The dominant negative loss-of-function mutant Delta(N)117 was co-immunoprecipitated with wild type KCC1 polypeptide, and its co-expression did not reduce wild type KCC1 at the oocyte surface. Delta(N)117 also exhibited dominant negative inhibition of human KCC1 and KCC3 and, with lower potency, mouse KCC4 and rat KCC2.
 ...
PMID:A dominant negative mutant of the KCC1 K-Cl cotransporter: both N- and C-terminal cytoplasmic domains are required for K-Cl cotransport activity. 1155 54

A new recombinant, human anti-sickling beta-globin polypeptide designated beta(AS3) (betaGly(16) --> Asp/betaGlu(22) --> Ala/betaThr(87) --> Gln) was designed to increase affinity for alpha-globin. The amino acid substitutions at beta22 and beta87 are located at axial and lateral contacts of the sickle hemoglobin (HbS) polymers and strongly inhibit deoxy-HbS polymerization. The beta16 substitution confers the recombinant beta-globin subunit (beta(AS3)) with a competitive advantage over beta(S) for interaction with the alpha-globin polypeptide. Transgenic mouse lines that synthesize high levels of HbAS3 (alpha(2)beta(AS3)(2)) were established, and recombinant HbAS3 was purified from hemolysates and then characterized. HbAS3 binds oxygen cooperatively and has an oxygen affinity that is comparable with fetal hemoglobin. Delay time experiments demonstrate that HbAS3 is a potent inhibitor of HbS polymerization. Subunit competition studies confirm that beta(AS3) has a distinct advantage over beta(S) for dimerization with alpha-globin. When equal amounts of beta(S)- and beta(AS3)-globin monomers compete for limiting alpha-globin chains up to 82% of the tetramers formed is HbAS3. Knock-out transgenic mice that express exclusively human HbAS3 were produced. When these mice were bred with knock-out transgenic sickle mice the beta(AS3) polypeptides corrected all hematological parameters and organ pathology associated with the disease. Expression of beta(AS3)-globin should effectively lower the concentration of HbS in erythrocytes of patients with sickle cell disease, especially in the 30% percent of these individuals who coinherit alpha-thalassemia. Therefore, constructs expressing the beta(AS3)-globin gene may be suitable for future clinical trials for sickle cell disease.
 ...
PMID:A recombinant human hemoglobin with anti-sickling properties greater than fetal hemoglobin. 1508 88

The cytoplasmic domain of band 3 serves as a center of erythrocyte membrane organization and constitutes the major substrate of erythrocyte tyrosine kinases. Tyrosine phosphorylation of band 3 is induced by several physiologic stimuli, including malaria parasite invasion, cell shrinkage, normal cell aging, and oxidant stress (thalassemias, sickle cell disease, glucose-6-phosphate dehydrogenase deficiency, etc). In an effort to characterize the biologic sequelae of band 3 tyrosine phosphorylation, we looked for changes in the polypeptide's function that accompany its phosphorylation. We report that tyrosine phosphorylation promotes dissociation of band 3 from the spectrin-actin skeleton as evidenced by: (1) a decrease in ankyrin affinity in direct binding studies, (2) an increase in detergent extractability of band 3 from ghosts, (3) a rise in band 3 cross-linkability by bis-sulfosuccinimidyl-suberate, (4) significant changes in erythrocyte morphology, and (5) elevation of the rate of band 3 diffusion in intact cells. Because release of band 3 from its ankyrin and adducin linkages to the cytoskeleton can facilitate changes in multiple membrane properties, tyrosine phosphorylation of band 3 is argued to enable adaptive changes in erythrocyte biology that permit the cell to respond to the above stresses.
 ...
PMID:Regulation of membrane-cytoskeletal interactions by tyrosine phosphorylation of erythrocyte band 3. 2147 68


1 2 Next >>