Original Research ARTICLE
CEBPE-mutant specific granule deficiency correlates with aberrant granule organization and substantial proteome alterations in neutrophils
- 1Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases, Austria
- 2CeMM Research Center for Molecular Medicine (OAW), Austria
- 3Clinical Institute of Pathology, Medizinische Universität Wien, Austria
- 4Department of Pediatric Hematology and Oncology, University Hospital Motol, Czechia
- 5Department of Clinical Immunology and Allergology, Masaryk University, Czechia
- 6Department of Pediatric Hematology, University Hospital Brno, Czechia
- 7Center for Chronic Immunodeficiency (CCI), Germany
- 8Center of Pediatrics and Adolescent Medicine, University Medical Center and University of Freiburg, Germany
- 9Department of Pediatrics and Adolescent Medicine, Medizinische Universität Wien, Austria
- 10Department of Pediatrics, St. Anna Kinderspital and Children’s Cancer Research Institute, Austria
Specific granule deficiency (SGD) is a rare disorder characterized by abnormal neutrophils evidenced by reduced granules, absence of granule proteins, and atypical bilobed nuclei. Mutations in CCAAT/enhancer binding protein-ε (CEBPE) are one molecular etiology of the disease. Although C/EBPε has been studied extensively, the impact of CEBPE mutations on neutrophil biology remains elusive.
Here, we identified two SGD patients bearing a previously described heterozygous mutation (p.Val218Ala) in CEBPE. We took this rare opportunity to characterize SGD neutrophils in terms of granule distribution and protein content. Granules of patient neutrophils were clustered and polarized, suggesting that not only absence of specific granules but also defects affecting other granules contribute to the phenotype. Our analysis showed that remaining granules displayed mixed protein content and lacked several glycoepitopes. To further elucidate the impact of mutant CEBPE, we performed detailed proteomic analysis of SGD-neutrophils. Beside an absence of several granule proteins in patient cells, we observed increased expression of members of the linker of nucleoskeleton and cytoskeleton complex (nesprin-2, vimentin, lamin-B2), which control nuclear shape. This suggests that absence of these proteins in healthy individuals might be responsible for segmented shapes of neutrophilic nuclei.
In conclusion, we show that the heterozygous mutation p.Val218Ala in CEBPE causes SGD through prevention of nuclear localization of the protein product. Furthermore, we uncover that absence of nuclear C/EBPε impacts on spatiotemporal expression and subsequent distribution of several granule proteins and further on expression of proteins controlling nuclear shape.
Keywords: Primary immunodeficiency, Neutrophil granulocytes, Granule organization, specific granule deficiency, C/EBPε
Received: 31 Aug 2017;
Accepted: 08 Mar 2018.
Edited by:Frédéric Rieux-Laucat, INSERM UMR1163 Institut Imagine, France
Reviewed by:Lee-Ann H. Allen, University of Iowa, United States
Arturo Zychlinsky, Max Planck Institute for Infection Biology (MPG), Germany
Copyright: © 2018 Serwas, Dieckmann, Huemer, Mejstrikova, Garncarz, Litzman, Zapletal, Janda, Bennett, Kain, Kerjaschki and Boztug. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Prof. Kaan Boztug, Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases, Vienna, Austria, KBoztug@cemm.oeaw.ac.at