Novel drivers and modifiers of MPL-dependent oncogenic transformation identified by deep mutational scanning

Jessica L. Bridgford, Su Min Lee, Christine M.M. Lee, Paola Guglielmelli, Elisa Rumi, Daniela Pietra, Stephen Wilcox, Yash Chhabra, Alan F. Rubin, Mario Cazzola, Alessandro M. Vannucchi, Andrew J. Brooks, Matthew E. Call, Melissa J. Call

Research output: Contribution to journalArticlepeer-review

Abstract

The single transmembrane domain (TMD) of the human thrombopoietin receptor (TpoR/myeloproliferative leukemia [MPL] protein), encoded by exon 10 of the MPL gene, is a hotspot for somatic mutations associated with myeloproliferative neoplasms (MPNs). Approximately 6% and 14% of JAK2 V617F- essential thrombocythemia and primary myelofibrosis patients, respectively, have "canonical" MPL exon 10 driver mutations W515L/K/R/A or S505N, which generate constitutively active receptors and consequent loss of Tpo dependence. Other "noncanonical" MPL exon 10 mutations have also been identified in patients, both alone and in combination with canonical mutations, but, in almost all cases, their functional consequences and relevance to disease are unknown. Here, we used a deep mutational scanning approach to evaluate all possible single amino acid substitutions in the human TpoR TMD for their ability to confer cytokine-independent growth in Ba/F3 cells. We identified all currently recognized driver mutations and 7 novel mutations that cause constitutive TpoR activation, and a much larger number of second-site mutations that enhance S505N-driven activation. We found examples of both of these categories in published and previously unpublished MPL exon 10 sequencing data from MPN patients, demonstrating that some, if not all, of the new mutations reported here represent likely drivers or modifiers of myeloproliferative disease.

Original languageEnglish
Pages (from-to)287-292
Number of pages6
JournalBlood
Volume135
Issue number4
DOIs
Publication statusPublished - Jan 23 2020

ASJC Scopus subject areas

  • Biochemistry
  • Immunology
  • Hematology
  • Cell Biology

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