This article reports metabolic consequences of JAK2-mutant myeloproliferative neoplasms (MPNs) with a therapeutic translational impact: expression of mutant JAK2 induces abnormal metabolic activity of MPN cells, resulting in hypoglycemia, adipose tissue atrophy, and early mortality.

We studied a subset of hematopoietic stem cells (HSCs) that are defined by elevated expression of CD41 (CD41hi) and show bias for differentiation towards megakaryocytes (Mk). Mouse models of myeloproliferative neoplasms (MPN) expressing JAK2-V617F (VF) or a JAK2 exon 12 mutation (E12) displayed increased frequencies and percentages of the CD41hi versusCD41lo HSCs compared to wildtype controls. An increase in CD41hi HSCs that correlated with JAK2-V617F mutant allele burden was also found in bone marrow from MPN patients. CD41hi HSCs produced higher numbers of Mk-colonies HSC in single cell cultures in vitro, but showed reduced long-term reconstitution potential compared to CD41lo HSCs in competitive transplantations in vivo. RNA expression profiling showed upregulated cell cycle, Myc, and oxidative phosphorylation gene signatures in CD41hi HSCs, while CD41lo HSCs showed higher gene expression of interferon, JAK/STAT and TNFα/NFkB signaling pathways. Higher cell cycle activity and elevated levels of reactive oxygen species were confirmed in CD41hi HSCs by flow cytometry. Expression of Epcr, a marker for quiescent HSCs inversely correlated with expression of CD41 in mice, but did not show such reciprocal expression pattern in MPN patients. Treatment with interferon-α further increased the frequency and percentage of CD41hi HSCs and reduced the numbers of JAK2-V617F positive HSCs in mice and patients with MPN. The shift towards the CD41hi subset of HSCs by interferon-α provides a possible mechanism of how interferon-α preferentially targets the JAK2 mutant clone.