Elucidating Genetic and Biochemical Aspects of the P1 and Sda Carbohydrate Histo- Blood Group Antigens Stenfelt, Linn 2020 Document Version: Publisher's PDF, also known as Version of record Link to publication Citation for published version (APA): a Stenfelt, L. (2020). Elucidating Genetic and Biochemical Aspects of the P1 and Sd Carbohydrate Histo-Blood Group Antigens. Lund University, Faculty of Medicine. 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LUND UNIVERSITY PO Box 117 221 00 Lund +46 46-222 00 00 Elucidating Genetic and Biochemical Aspects of the P1 and Sda Carbohydrate Histo-Blood Group Antigens LINN STENFELT FACULTY OF MEDICINE | LUND UNIVERSITY At the beginning of the 20th century Karl Landsteiner discovered the ABO histo-blood group system. This discovery became the cornerstone for prediction of safe human-to- human blood transfusions in modern medicine. Today, close to 40 blood group systems have been acknowledged by the International Society of Blood Transfusion (ISBT). Donor- patient matching can be achieved by traditional serological hemagglutination methods as well as newly developed blood group genotyping techniques. Genotyping requires an understanding of the underlying locus and genetic variations that determine blood group status. The aim of this thesis was to establish the molecular mechanisms and genetic bases of the carbohydrate histo-blood group antigens P1 and Sda. In addition, the biochemical carriers of the antigenic structures were investigated. The findings presented here open up for genotypic prediction of these blood groups and also allowed ISBT to establish the SID histo-blood group system. Lund University, Faculty of Medicine 199527 Doctoral Dissertation Series 2020:90 ISBN 978-91-7619-952-7 789176 ISSN 1652-8220 9 Elucidating Genetic and Biochemical Aspects of the P1 and Sda Carbohydrate Histo-Blood Group Antigens Elucidating Genetic and Biochemical Aspects of the P1 and Sda Carbohydrate Histo-Blood Group Antigens Linn Stenfelt DOCTORAL DISSERTATION by due permission of the Faculty of Medicine, Lund University, Sweden. To be defended September 18 at 13.15 in Belfragesalen, BMC, Lund Faculty opponent Professor Steven L. Spitalnik, M.D. Department of Pathology & Cell Biology, Columbia University, New York City, NY, USA Organization Document name LUND UNIVERSITY DOCTORAL DISSERTATION Department of Laboratory Medicine Date of issue Division of Hematology and Transfusion Medicine September 18th 2020 Author Linn Stenfelt Sponsoring organization Title and subtitle Elucidating Genetic and Biochemical Aspects of the P1 and Sda Carbohydrate Histo-Blood Group Antigens Abstract Human histo-blood groups are inherited polymorphic variants that occur in the molecular structures on the human red blood cell (RBC) surface. Introducing foreign RBCs into a recipient lacking an antigen may activate the humoral defence leading to a hemolytic transfusion reaction. Antigenic differences can also cause hemolytic disease of the fetus and newborn (HDFN). Blood group antigens are implicated as receptors in pathogen invasion and their expression are often altered in cancerous tissues. Blood group antigens are carried by protein or carbohydrate structures. Carbohydrate antigens are synthesized stepwise by glycosyltransferases and are carried on glycosphingolipids or glycoproteins anchored into the RBC membrane. The aim of this work was to elucidate the molecular genetic mechanisms behind the P1 and Sda antigens, as well as to study their glycan structures. The P1 antigen belongs to the P1PK blood group system. Silencing of A4GALT causes the null phenotype (Pk–, P1–) of this k k system. However, the consequence of the genetic differences between the P1 (P+, P1+) and P2 (P+, P1–) phenotypes, i.e. the molecular mechanism underlying how P1 antigen is expressed, has remained unknown. Additionally, there have been divided views regarding the molecular carriers of the P1 antigen, Galα1-4Galβ1- 4GlcNAc-R. The Sda antigen GalNAcβ1-4(NeuAcα2-3)Gal-R was associated with the B4GALNT2 gene already in 2003. However, the genetic basis of the Sd(a–) phenotype was never revealed. Through EMSA experiments the Runt-related transcription factor 1 (RUNX1) was identified to bind P1 alleles specifically, dependent on rs5751348 in A4GALT. Knock-down of RUNX1 decreased the A4GALT mRNA levels, establishing its effect as a P1/P2-discriminating factor. Based on these findings a genotyping assay was implemented at the Nordic Reference Laboratory for Genomic Blood Group Typing in Lund, Sweden. P1 was also established to be carried on glycoproteins in N-glycan conjugates, in addition to glycosphingolipids. Sequencing of B4GALNT2 in nine Sd(a–) individuals identified the missense mutation rs7224888 as highly associated with the phenotype. Additionally, the splice-site polymorphism rs72835417, and the rare missense variants rs148441237 and rs61743617 were encountered in the Sd(a–) cohort. In silico studies identified a close correlation between expression of B4GALNT2 and the cancer-associated lncRNA RP11-708H21.4 locus, located directly downstream of the gene. Finally, the Sd(a–) associated SNP rs7224888 was shown to abolish Sda synthase activity in over-expression experiments. The epitope was evaluated with DBA lectin binding, fluorescence microscopy, enzyme immunoblots and mass spectrometry. The latter confirmed that the glycotransferase utilizes substrates on both on N- and O-glycan elongation. Understanding the molecular mechanism underlying the P1 antigen as well as defining the genetic background of the Sd(a–) phenotype has enabled genotyping approaches for clinical practice. Additionally, the confirmation of B4GALNT2 expressing the Sda synthase, has allowed the International Society of Blood Transfusion (ISBT) to move the Sda antigen from the series of high-frequency antigens to its own, new blood group system designated SID, no. 038. Key words Blood group, P1 antigen, Sda antigen, A4GALT, B3GALNT2, glycosyltransferase, red blood cell, transfusion medicine Classification system and/or index terms (if any) Supplementary bibliographical information Language English ISSN 1652-8220 ISBN 978-91-7619-952-7 Recipient’s notes Number of pages 76 Price Security classification I, the undersigned, being the copyright owner of the abstract of the above-mentioned dissertation, hereby grant to all reference sources permission to publish and disseminate the abstract of the above-mentioned dissertation. Signature Date 2020-08-27 Elucidating Genetic and Biochemical Aspects of the P1 and Sda Carbohydrate Histo-Blood Group Antigens Linn Stenfelt Cover by Linn Stenfelt Copyright Linn Stenfelt Paper 1 © by The American Society of Hematology Paper 2 © by John Wiley & Sons Paper 3 © by Elsevier Paper 4 © by the Authors (Manuscript unpublished) Faculty of Medicine Department of Laboratory Medicine ISBN 978-91-7619-952-7 ISSN 1652-8220 Lund University, Faculty of Medicine Doctoral Dissertation Series 2020:90 Printed in Sweden by Media-Tryck, Lund University Lund 2020 Table of Contents Table of Contents .................................................................................................... 7 Abbreviations .......................................................................................................... 9 List of publications ............................................................................................... 11 Abstract ................................................................................................................. 13 Introduction .......................................................................................................... 15 Transfusion medicine ................................................................................... 15 The need of blood in modern medicine ............................................... 16 Histo-blood groups and the immune response .................................... 17 Transfusion-related complications ...................................................... 20 Other medical implications where histo-blood groups play a role ...... 21 Blood groups and infectious disease ................................................... 23 Blood group characterization .............................................................. 24 Erythropoiesis .............................................................................................. 25 Genetic regulation of RBC formation ................................................. 27 Glycosylation ............................................................................................... 29 Carbohydrate blood group