Study of inherited thrombocytopenia resulting from mutations in ETV6 or RUNX1 using a human pluripotent stem cell model

• Published in: Stem cell reports 2021-06, Vol.16 (6), p.1458-1467
• Main Authors: Borst, Sara, Nations, Catriana C., Klein, Joshua G., Pavani, Giulia, Maguire, Jean Ann, Camire, Rodney M., Drazer, Michael W., Godley, Lucy A., French, Deborah L., Poncz, Mortimer, Gadue, Paul
• Format: Article
• Language: English
• Subjects: Cells, Cultured; Core Binding Factor Alpha 2 Subunit - genetics; Core Binding Factor Alpha 2 Subunit - metabolism; embryonic stem cells; ETS Translocation Variant 6 Protein; ETV6; Genetic Predisposition to Disease; Hematopoiesis; Humans; Induced Pluripotent Stem Cells - metabolism; iPSCs; megakaryocyte; Megakaryocytes - metabolism; Models, Biological; Mutation; Phenotype; Proto-Oncogene Proteins c-ets - genetics; Proto-Oncogene Proteins c-ets - metabolism; Repressor Proteins - genetics; Repressor Proteins - metabolism; Runx1; Thrombocytopenia - genetics; Thrombocytopenia - metabolism
• ISSN: 2213-6711; 2213-6711
• DOI: 10.1016/j.stemcr.2021.04.013

Inherited thrombocytopenia results in low platelet counts and increased bleeding. Subsets of these patients have monoallelic germline mutations in ETV6 or RUNX1 and a heightened risk of developing hematologic malignancies. Utilizing CRISPR-Cas9, we compared the in vitro phenotype of hematopoietic progenitor cells and megakaryocytes derived from induced pluripotent stem cell (iPSC) lines harboring mutations in either ETV6 or RUNX1. Both mutant lines display phenotypes consistent with a platelet-bleeding disorder. Surprisingly, these cellular phenotypes were largely distinct. The ETV6-mutant iPSCs yield more hematopoietic progenitor cells and megakaryocytes, but the megakaryocytes are immature and less responsive to agonist stimulation. On the contrary, RUNX1-mutant iPSCs yield fewer hematopoietic progenitor cells and megakaryocytes, but the megakaryocytes are more responsive to agonist stimulation. However, both mutant iPSC lines display defects in proplatelet formation. Our work highlights that, while patients harboring germline ETV6 or RUNX1 mutations have similar clinical phenotypes, the molecular mechanisms may be distinct. [Display omitted] •ETV6-mutant iPSCs yield more HPCs and MKs•RUNX1-mutant iPSCs yield fewer HPCs and MKs•Both ETV6-mutant and RUNX1-mutant MKs display proplatelet formation defects Borst et al. report the first ETV6-mutant iPSC line to model inherited thrombocytopenia with predisposition for hematologic malignancy. Using CRISPR-Cas9 technology, they generate sets of isogenic iPSC lines with patient-specific mutations in ETV6 or RUNX1, both of which lead to thrombocytopenia and high cancer risk. Disparate phenotypes between the two genotypes are identified, suggesting the mechanism of disease is different.