Three-way translocation (X;20;16)(p11;q13;q23) in essential thrombocythemia implicates NFATC2 in dysregulation of CSF2 expression and megakaryocyte proliferation.
Essential thrombocythemia (ET) is a myeloproliferative neoplasm essentially characterized by excessive production of platelets. Molecular pathogenesis of ET is linked in approximately half of the patients to intracellular cytokine signaling dysregulation as a result of thrombopoietin receptor or Janus kinase 2 (JAK2) mutations. However, genetic defects underlying cytokine transcription have not been associated with ET. Using molecular cytogenetics and whole-genome array analyses, we uncovered a submicroscopic deletion at 20q13.2 in a JAK2V617F-positive ET patient with an acquired complex chromosome translocation. The deletion encompassed the nuclear factor of activated T-cells, cytoplasmic, calcineurin-dependent 2 (NFATC2) gene that encodes a transcription factor involved in the regulation of hematopoietic cytokines. RNA interference-mediated suppression of NFATC2 mRNA or pharmacological inhibition of NFATC2 protein with 11R-VIVIT in cultured JAK2V617F-positive SET-2 megakaryocytes increased colony stimulating factor 2 (granulocyte-macrophage) (CSF2) mRNA and promoted cell proliferation. Moreover, impairment of NFATC2-calcineurin interaction with 11R-VIVIT further reduced the transcription of the NFATC2 gene. Antibody-mediated neutralization of CSF2 cytokine in inhibitor-treated cells prevented 11R-VIVIT-induced cell proliferation, indicating that impairment of NFATC2-calcineurin interaction promotes megakaryocyte proliferation through up-regulation of CSF2 transcription. Our results suggest a model in which haplo-insufficiency of NFATC2 cooperates with activation of the JAK-STAT signaling pathway in the pathogenesis of JAK2V617F-positive ET with del(20q). These results further indicate that pathogenesis of ET may be linked to genetic defects of other transcription factor genes involved in the regulation of cytokine expression.
Departamento de Genética Humana, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisboa, Portugal. luis.vieira@insa.min-saude.pt
Luís
L
Vieira
Andreia
A
Vaz
Paulo
P
Matos
Ana Paula
AP
Ambrósio
Manuel
M
Nogueira
Bárbara
B
Marques
Ana Marques
AM
Pereira
Peter
P
Jordan
Maria Gomes
MG
da Silva
D049109:Cell Proliferation; D002885:Chromosomes, Human, Pair 16 / Q000235:genetics*; D002890:Chromosomes, Human, Pair 20 / Q000235:genetics*; D005260:Female; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D053614:Janus Kinase 2 / Q000235:genetics; D008533:Megakaryocytes / Q000378:metabolism / Q000473:pathology*; D008875:Middle Aged; D050778:NFATC Transcription Factors / Q000235:genetics*; D013920:Thrombocythemia, Essential / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D014178:Translocation, Genetic; D015854:Up-Regulation
D050778:NFATC Transcription Factors; C494006:NFATC2 protein, human; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D053614:Janus Kinase 2