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4107 Human DOCK11 Deficiency Causes Defective Erythropoiesis and Systemic Inflammation

Program: Oral and Poster Abstracts
Session: 509. Bone Marrow Failure and Cancer Predisposition Syndromes: Congenital: Poster III
Hematology Disease Topics & Pathways:
Research, Fundamental Science, autoimmune disorders, Translational Research, Bone Marrow Failure Syndromes, Inherited Marrow Failure Syndromes, Diseases, Immune Disorders, immunodeficiency
Monday, December 11, 2023, 6:00 PM-8:00 PM

Jana Block1,2,3*, Christina Rashkova1,2,3,4*, Irinka Castanon2*, Jessica Platon5*, Samaneh Zoghi2,3*, Mitsuhiro Fujiwara6*, Beatriz Chaves7,8,9*, Rouven Schoppmeyer10,11,12*, Caspar Van Der Made13,14*, Rocio Cabrera-Perez15*, Frederike Leonie Harms16*, Rico Chandra Ardy1,2,3*, Samin Alavi17*, Laia Alsina18,19,20*, Rainiero Avila Polo15*, Paula Sanchez Moreno21*, Raul Jimenez Heredia1,2,3,4*, Thomas Hannich3*, Johannes Huppa22*, Martin Distel1*, Winfried Pickl23,24*, Jeffrey Yoder25*, David Traver26*, Karin Engelhardt27*, Tobias Linden28*, Leo Kager1,4,29*, Sophie Hambleton27*, Alexander Hoischen13,14*, Sabine Illsinger28,30*, Zahra Chavoshzadeh31*, Kerstin Kutsche16*, Lydie Da Costa5,32,33,34*, Jaap Van Buul10,11,12*, Joan Calzada-Hernandez19,35*, Jordi Anton19,20,35*, Olaf Neth21*, Julien Viaud36*, Akihiko Nishikimi6*, Loic Dupre2,7,37* and Kaan Boztug1,2,3,4,29*

1St. Anna Children's Cancer Research Institute, Vienna, Austria
2Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases, Vienna, Austria
3CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
4Medical University of Vienna, Department of Pediatrics and Adolescent Medicine, Vienna, Austria
5HEMATIM UR4666, Université de Picardie Jules Verne, Amiens, France
6Biosafety Division, Research Institute, National Center for Geriatrics and Gerontology, Obu, Japan
7Toulouse Institute for Infectious and Inflammatory Diseases, INSERM, CNRS, Paul Sabatier Universtiy, Toulouse, France
8National Institute of Science and Technology on Neuroimmunomodulation, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
9Computational Modeling Group, Oswaldo Cruz Foundation (Fiocruz), Eusebio, Brazil
10Molecular Cell Biology Lab, Department of Molecular Hematology, Sanquin Research, Amsterdam, Netherlands
11Vascular Cell Biology Lab, Department of Medical Biochemistry, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands
12Leeuwenhoek Center for Advanced Microscopy, Section of Molecular Cytology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands
13Radboud University Medical Center for Infectious Diseases (RCI), Department of Internal Medicine, Radboud University Medical Center, Nijmegen, Netherlands
14Department of Human Genetics, Department of Internal Medicine, Radboud University Medical Center, Nijmegen, Netherlands
15Department of Pathology, Hospital Universitario Virgen del Rocío, Sevilla, Spain
16Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
17Pediatric Congenital Hematologic Disorders Research Center, Mofid Children's Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran (Islamic Republic of)
18Clinical Immunology and Primary Immunodeficiencies Unit, Allergy and Clinical Immunology Department, Hospital Sant Joan de Déu, Barcelona, Spain
19Study Group for Immune Dysfunction Diseases in Children (GEMDIP), Institut de Recerca Sant Joan de Déu, Barcelona, Spain
20Department of Surgery and Surgical Specializations, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
21Pediatric Infectious Diseases, Rheumatology and Immunology Unit, Hospital Universitario Virgen del Rocío, Institute of Biomedicine of Seville (IBIS)/ Universidad de Sevilla/CSIC, Red de Investigación Traslacional en Infectología Pediátrica RITIP, Sevilla, Spain
22Medical University of Vienna, Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Vienna, Austria
23Karl Landsteiner University of Health Sciences, Krems, Austria
24Medical University of Vienna, Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Vienna, Austria
25Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, NC
26Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA
27Primary Immunodeficiency Group, Newcastle University Translational and Clinical Research Institute, Newcastle Upon Tyne, United Kingdom
28Klinik für Neuropädiatrie und Stoffwechselerkrankungen, Zentrum für Kinder- und Jugendmedizin, Oldenburg, Germany
29St. Anna Children's Hospital, Vienna, Austria
30Centre for Pediatric and Adolescent Medicine, Department of Pediatric Kidney, Liver and Metabolic Diseases and Neuropediatrics, Hannover Medical School, Hannover, Germany
31Allergy and Clinical immunology Department, Mofid Children’s Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran (Islamic Republic of)
32University of Paris, Paris, France
33Service d'Hématologie Biologique (Hematology Diagnostic Lab), AP-HP, Hôpital R. Debré, Paris, France
34Laboratory of Excellence for Red Cells, LABEX GR-Ex, Paris, France
35Pediatric Rheumatology Division, Hospital Sant Joan de Déu Barcelona, Esplugues de Llobregat, Barcelona, Spain
36Institute of Cardiovascular and Metabolic Diseases (I2MC), INSERM UMR1297, Paul Sabatier University, Toulouse, France
37Medical University of Vienna, Department of Dermatology, Vienna, Austria

Erythropoiesis involves significant changes in the cells, which are mediated by the plasma membrane and the actin cytoskeleton. The composition of the actin cytoskeleton and the interaction between its components are dynamically modified during erythropoiesis, however the precise role that different actin regulators play during erythroid differentiation is poorly understood.

The dedicator of cytokinesis (DOCK) family member DOCK11 regulates actin cytoskeleton dynamics via its guanine nucleotide exchange factor (GEF) activity, resulting in activation of the small Rho GTPase CDC42. CDC42 has been implicated in regulating the early stages of erythroid development, as well as the terminal maturation steps involving enucleation. However, the role of human DOCK11 in hematopoietic cell function and human disease had not been defined.

We analyzed a cohort of four patients from four unrelated families presenting with recurrent infections, early-onset severe immune dysregulation, systemic inflammation, as well as normocytic anemia and anisocytosis of unknown origin. Using whole-exome sequencing, we identified rare, hemizygous germline mutations in DOCK11 in these patients. Two mutations - an early stop-gain mutation and a

To study the role of DOCK11 during erythropoiesis, we generated a dock11-knockout zebrafish model. We found that the dock11-knockout zebrafish embryos recapitulated the anemia and aberrant erythrocyte morphology observed in human DOCK11 deficiency. The anemia was amenable to rescue with constitutively active CDC42, suggesting that DOCK11 regulates erythrocyte numbers in a CDC42-dependent manner. As a next step we modeled human erythroid differentiation in vitro using an erythroid liquid culture system starting from purified CD34+ cells. ShRNA-mediated knockdown of DOCK11 in CD34+ cells revealed impairment of cell growth and differentiation during erythroid development. In line with moderate erythroid hypoplasia observed in the bone marrow of one of the patients, these data suggest an erythroid-intrinsic role of DOCK11 during erythropoiesis.

As the patients with germline DOCK11 defects also presented with recurrent infections and systemic inflammation, we further assessed the role of DOCK11 in immune cells. In line with its role in actin dynamics, we found that human DOCK11 regulates T‑cell morphology and migration, suggesting that defects in DOCK11 might impact the T cells’ capability to fight infections. We further uncovered that the immune dysregulation observed in the patients involved aberrant T-cell activation and cytokine production. Mechanistically, using cells from DOCK11-deficient patients and Dock11-knockout mice, we were able to show that Dock11 regulates cytokine production at the transcriptional level by modulating the nuclear translocation of the T-cell transcription factor NFATc1, known to regulate the production of several cytokines.

Collectively, we identified germline loss-of-function mutations affecting the actin regulator DOCK11 in a previously unknown disorder associating anemia and systematic inflammation. This work earmarks the DOCK11‑CDC42 axis as an attractive future target for the treatment of a broader range of immune and hematological diseases

Disclosures: No relevant conflicts of interest to declare.

*signifies non-member of ASH