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Haematologica. 2019 Jan 17. pii: haematol.2018.194555. doi: 10.3324/haematol.2018.194555. [Epub ahead of print]

Molecular mechanisms of bleeding disorder-associated GFI1BQ287* mutation and its affected pathways in megakaryocytes and platelets.

Author information

1
Dept. Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherland.
2
Dept. of Hematopoiesis, Sanquin Research-Academic Medical Center, Amsterdam, The Netherlands.
3
Department of Plasma Proteins, Sanquin Research, Amsterdam, The Netherlands.
4
Department of Research Facilities, Sanquin Research, Amsterdam, The Netherlands.
5
Department of Molecular Biology, Radboud University Nijmegen, the Netherlands.
6
Department of Hematology, Radboud University Medical Center, Nijmegen, The Netherlands.
7
Department of Biochemistry, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
8
Sanquin Research.
9
Dept. Laboratory Medicine, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherland; bert.vanderreijden@radboudumc.nl.

Abstract

Dominant-negative mutations in transcription factor Growth Factor Independence-1B (GFI1B) like GFI1B-Q287*, cause a bleeding disorder characterized by a plethora of megakaryocyte and platelet abnormalities. The deregulated molecular mechanisms and pathways are unknown. Here we show that both normal and Q287* mutant GFI1B interacted most strongly with the LSD1-RCOR-HDAC co-repressor complex in megakaryoblasts. Sequestration of this complex by GFI1B-Q287* and chemical separation of GFI1B from LSD1, induced abnormalities in normal megakaryocytes comparable to those seen in patients. Megakaryocytes derived from GFI1B-Q287* induced pluripotent stem cells also phenocopied abnormalities seen in patients. Proteome studies on normal and mutant induced pluripotent stem cell derived megakaryocytes identified a multitude of deregulated pathways downstream of GFI1B-Q287* including cell division and interferon signaling. Proteome studies on platelets from GFI1B-Q287* patients showed reduced expression of proteins implicated in platelet function, and elevated expression of proteins normally downregulated during megakaryocyte differentiation. Thus, GFI1B and LSD1 regulate a broad developmental program during megakaryopoiesis, and GFI1B-Q287* deregulates this program through LSD1-RCOR-HDAC sequestering.

KEYWORDS:

Megakaryopoiesis; Platelets; Proteomics; Transcriptional regulation; iPSC

PMID:
30655368
DOI:
10.3324/haematol.2018.194555
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