A novel signalling screen demonstrates that CALR mutations activate essential MAPK signalling and facilitate megakaryocyte differentiation

K Kollmann, W Warsch, C Gonzalez-Arias, F L Nice, E Avezov, J Milburn, J Li, D Dimitropoulou, S Biddie, M Wang, E Poynton, M Colzani, M R Tijssen, S Anand, U McDermott, B Huntly, T Green

Research output: Contribution to journalArticlepeer-review


Most myeloproliferative neoplasm (MPN) patients lacking JAK2 mutations harbour somatic CALR mutations that are thought to activate cytokine signalling although the mechanism is unclear. To identify kinases important for survival of CALR-mutant cells, we developed a novel strategy (KISMET) that utilizes the full range of kinase selectivity data available from each inhibitor and thus takes advantage of off-target noise that limits conventional small-interfering RNA or inhibitor screens. KISMET successfully identified known essential kinases in haematopoietic and non-haematopoietic cell lines and identified the mitogen activated protein kinase (MAPK) pathway as required for growth of the CALR-mutated MARIMO cells. Expression of mutant CALR in murine or human haematopoietic cell lines was accompanied by myeloproliferative leukemia protein (MPL)-dependent activation of MAPK signalling, and MPN patients with CALR mutations showed increased MAPK activity in CD34 cells, platelets and megakaryocytes. Although CALR mutations resulted in protein instability and proteosomal degradation, mutant CALR was able to enhance megakaryopoiesis and pro-platelet production from human CD34+ progenitors. These data link aberrant MAPK activation to the MPN phenotype and identify it as a potential therapeutic target in CALR-mutant positive MPNs.
Original languageEnglish
Pages (from-to)934-944
Number of pages11
Issue number4
Early online date14 Oct 2016
Publication statusPublished - Apr 2017


  • Antigens, CD34/metabolism
  • Calreticulin/antagonists & inhibitors
  • Cell Differentiation
  • Cell Line
  • Drug Discovery
  • Ectopic Gene Expression/drug effects
  • Fetal Blood/cytology
  • Humans
  • Janus Kinase 2/antagonists & inhibitors
  • Megakaryocytes/cytology
  • Mitogen-Activated Protein Kinases/metabolism
  • Mutation
  • Proteasome Endopeptidase Complex/metabolism
  • Protein Kinase Inhibitors/pharmacology
  • Protein Stability
  • Proto-Oncogene Proteins B-raf/genetics
  • Signal Transduction/drug effects
  • Thrombopoiesis/genetics
  • ras Proteins/genetics

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