ABSTRACT
Hemoglobin E (HbE)/ß-thalassemia has a wide spectrum of clinical manifestations that cannot be explained purely by its genetic background. Circulating extracellular vesicles (EVs) are one factor that likely contributes to disease severity. This study has explored the differences in protein composition and quantity between EVs from HbE/ß-thalassemic patients and healthy individuals. We used tandem mass tag labeling mass spectrometry to analyze the EV proteins isolated from the plasma of 15 patients compared with the controls. To reduce biological variation between individuals, the EV proteins isolated from randomly assigned groups of 5 HbE/ß-thalassemic patients were pooled and compared with 5 pooled age- and sex-matched controls in 3 separate experiments. Alpha hemoglobin-stabilizing protein had the highest fold increase. Catalase, superoxide dismutase, T-complex proteins, heat shock proteins, transferrin receptor, ferritin, and cathepsin S were also upregulated in thalassemic circulating EVs. Importantly, haptoglobin and hemopexin were consistently reduced in patients' EVs across all data sets, in keeping with the existing hemolysis that occurs in thalassemia. The proteomic data analysis of EV samples isolated from 6 individual HbE/ß-thalassemic patients and western blotting results corroborated these findings. In conclusion, we have successfully identified consistent alterations of protein quantity between EVs from HbE/ß-thalassemic and healthy individuals. This work highlights haptoglobin, hemopexin, and cathepsin S as potential clinically relevant biomarkers for levels of hemolysis and inflammation. Monitoring of these plasma proteins could help in the clinical management of thalassemia.
Subject(s)
Extracellular Vesicles/chemistry , Hemoglobin E , Proteomics/methods , beta-Thalassemia/pathology , Biomarkers/blood , Case-Control Studies , Cathepsins/blood , Female , Haptoglobins/analysis , Hemolysis , Hemopexin/analysis , Humans , Inflammation/diagnosis , Male , Mass SpectrometryABSTRACT
Tn polyagglutination results from inactivating mutations in C1GALT1C1, an X-borne gene encoding a core 1 beta3-galactosyltransferase-specific molecular chaperone (cosmc) required for the functioning of T-synthase (beta 1,3-galactosyltransferase), a glycosyltransferase essential for the correct biosynthesis of O-glycans. This study found novel inactivating mutations (Glu152Lys, Ser193Pro and Met1Ile) in the coding sequence of C1GALT1C1 in three Tn positive individuals and a complete lack of C1GALT1C1 cDNA expression was observed in an additional Tn positive individual. In addition, expression of ST6GALNAC1, which encodes (alpha-N-acetyl-neuraminyl-2,3-beta-galactosyl-1, 3)-N-acetylgalactosaminide alpha-2,6-sialyltransferase 1 and gives rise to sialyl-Tn antigen, was present at comparable levels in normal and Tn-positive human erythroblasts. Expression studies of wild-type and Tn positive C1GALT1C1 cDNA in the Jurkat cell line confirmed that the amino acid substitutions observed in Tn are inactivating. Analysis of the transcriptome of cultured normal and Tn positive erythroblasts revealed numerous differences in gene expression. Reduced transcript levels for fatty acid binding protein 5 (FABP5) and plexin D1 (PLXND1), and increased levels for aquaporin 3 (AQP3) were confirmed by quantitative real-time polymerase chain reaction. These data show that alteration of O-glycan structures resulting from T-synthase deficiency is accompanied by altered expression of a wide variety of genes in erythroid cells.
Subject(s)
Antigens, Tumor-Associated, Carbohydrate/genetics , Galactosyltransferases/genetics , Hemagglutination/genetics , Molecular Chaperones/genetics , Mutation/genetics , Blood Cells/metabolism , Erythroblasts/metabolism , Galactosyltransferases/metabolism , Humans , Phenotype , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
BACKGROUND: The KEL2/KEL1 (k/K) blood group polymorphism represents 578C>T in the KEL gene and Thr193Met in the Kell glycoprotein. Anti-KEL1 can cause severe hemolytic disease of the fetus and newborn. Molecular genotyping for KEL*1 is routinely used for assessing whether a fetus is at risk. Red blood cells (RBCs) from a KEL:1 blood donor (D1) were found to have abnormal KEL1 expression during evaluation of anti-KEL1 reagents. STUDY DESIGN AND METHODS: Kell genotyping methods, including KEL exon 6 direct sequencing, were applied. KEL cDNA from D1 was sequenced. Flow cytometry was used to assess KEL1 and KEL2 RBC expression. RESULTS: RBCs from the donor, her mother, and an unrelated donor gave weak or negative reactions with some anti-KEL1 reagents. Other Kell-system antigens appeared normal. The three individuals were homozygous for KEL C578 (KEL*2) but heterozygous for a 577A>T transversion, encoding Ser193. They appeared to be KEL*2 homozygotes by routine genotyping methods. Flow cytometry revealed weak KEL1 expression and normal KEL2, similar to that of KEL*2 homozygotes. CONCLUSION: Ser193 in the Kell glycoprotein appears to result in expression of abnormal KEL1, in addition to KEL2. The mutation is not detected by routine Kell genotyping methods and, because of unpredicted KEL1 expression, could lead to a misdiagnosis.
Subject(s)
Base Sequence/genetics , Gene Expression , Glycoproteins/genetics , Kell Blood-Group System/genetics , Mutation, Missense , Polymorphism, Single Nucleotide , Adult , Blood Donors , DNA Mutational Analysis/methods , DNA, Complementary/genetics , Erythroblastosis, Fetal/genetics , Exons/genetics , Female , Fetal Diseases/genetics , Heterozygote , Homozygote , Humans , Infant, Newborn , MaleABSTRACT
BACKGROUND: Lutheran is a complex blood group system consisting of 18 identified antigens. There are four pairs of allelic antigens, whereas others are independently expressed antigens of a high frequency. Lutheran antigens are carried by the Lutheran glycoproteins, which are a product of a single gene LU. STUDY DESIGN AND METHODS: Genomic DNA from 21 individuals of 12 Lutheran phenotypes was used for PCR amplification of selected LU exons that were directly sequenced and compared to control DNA of a common Lutheran phenotype. RESULTS: Lutheran phenotypes were mostly caused by single-nucleotide polymorphisms within LU, resulting in single amino acid changes. The following mutations were observed: in LU:-4, G524A, Arg175Gln; in LU:-5, G326A, Arg109His; in LU:-6,9, C824T, Ser275Phe; in LU:-8,14, T611A, Met204Lys; in LU:-13, three point mutations (C1340T, Ser447Leu, C1671T silent mutation for Ser557 and A1742T, Gln581Leu); in LU:-16, C679T, Arg227Cys; in LU:-17, G340A, Glu114Lys; and in LU:-20, C905T, Thr302Met. Two LU:-12 samples had differing results: one individual had a deletion 99GCGCTT, Arg34 and Leu35, whereas the second LU:-12 sample had a point mutation G419A, Arg140Gln. CONCLUSION: The results revealed the genetic background of 11 Lutheran antigens and suggested their placement on the Lutheran glycoprotein.
