| Autor: |
IJspeert H; Department of Immunology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands.; Laboratory for Immunology, Department of Pediatrics, Leiden University Medical Center, Leiden, Netherlands., van Schouwenburg PA; Department of Immunology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands., Pico-Knijnenburg I; Laboratory for Immunology, Department of Pediatrics, Leiden University Medical Center, Leiden, Netherlands., Loeffen J; Department of Pediatric Oncology and Hematology, Erasmus Medical Centre, Sophia Children's Hospital, Rotterdam, Netherlands., Brugieres L; Department of Pediatric and Adolescent Oncology, Gustave Roussy Cancer Campus, Villejuif, France., Driessen GJ; Department of Paediatrics, Juliana Children's Hospital, Haga Teaching Hospital, The Hague, Netherlands., Blattmann C; Department of Pediatric Hematology and Oncology, Palliative Care, Olgahospital Klinikum Stuttgart, Stuttgart, Germany., Suerink M; Department of Clinical Genetics, Leiden University Medical Center, Leiden, Netherlands., Januszkiewicz-Lewandowska D; Department of Pediatric Oncology, Hematology and Transplantology, Poznan University of Medical Sciences, Poznań, Poland., Azizi AA; Department of Pediatrics and Adolescent Medicine, Medical University Vienna, Vienna, Austria., Seidel MG; Research Unit Pediatric Hematology and Immunology, Division of Pediatric Hematology-Oncology, Department of Pediatrics and Adolescent Medicine, Medical University Graz, Graz, Austria., Jacobs H; Division of Tumor Biology and Immunology, The Netherlands Cancer Institute, Amsterdam, Netherlands., van der Burg M; Laboratory for Immunology, Department of Pediatrics, Leiden University Medical Center, Leiden, Netherlands. |
| Abstrakt: |
The generation of high-affinity antibodies depends on somatic hypermutation (SHM). SHM is initiated by the activation-induced cytidine deaminase (AID), which generates uracil (U) lesions in the B-cell receptor (BCR) encoding genes. Error-prone processing of U lesions creates a typical spectrum of point mutations during SHM. The aim of this study was to determine the molecular mechanism of SHM in humans; currently available knowledge is limited by the number of mutations analyzed per patient. We collected a unique cohort of 10 well-defined patients with bi-allelic mutations in genes involved in base excision repair (BER) ( UNG ) or mismatch repair (MMR) ( MSH2, MSH6 , or PMS2 ) and are the first to present next-generation sequencing (NGS) data of the BCR, allowing us to study SHM extensively in humans. Analysis using ARGalaxy revealed selective skewing of SHM mutation patterns specific for each genetic defect, which are in line with the five-pathway model of SHM that was recently proposed based on mice data. However, trans-species comparison revealed differences in the role of PMS2 and MSH2 in strand targeting between mice and man. In conclusion, our results indicate a role for UNG, MSH2, MSH6, and PMS2 in the generation of SHM in humans comparable to their function in mice. However, we observed differences in strand targeting between humans and mice, emphasizing the importance of studying molecular mechanisms in a human setting. The here developed method combining NGS and ARGalaxy analysis of BCR mutation data forms the basis for efficient SHM analyses of other immune deficiencies. |
