Loss of pleckstrin-2 reverts lethality and vascular occlusions in JAK2V617F-positive myeloproliferative neoplasms
Baobing Zhao, … , Charles S. Abrams, Peng Ji
Baobing Zhao, … , Charles S. Abrams, Peng Ji
Published November 20, 2017
Citation Information: J Clin Invest. 2018;128(1):125-140. https://doi.org/10.1172/JCI94518.
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Loss of pleckstrin-2 reverts lethality and vascular occlusions in JAK2V617F-positive myeloproliferative neoplasms

Abstract

V617F driver mutation of JAK2 is the leading cause of the Philadelphia-chromosome-negative myeloproliferative neoplasms (MPNs). Although thrombosis is a leading cause of mortality and morbidity in MPNs, the mechanisms underlying their pathogenesis are unclear. Here, we identified pleckstrin-2 (Plek2) as a downstream target of the JAK2/STAT5 pathway in erythroid and myeloid cells, and showed that it is upregulated in a JAK2V617F-positive MPN mouse model and in patients with MPNs. Loss of Plek2 ameliorated JAK2V617F-induced myeloproliferative phenotypes including erythrocytosis, neutrophilia, thrombocytosis, and splenomegaly, thereby reverting the widespread vascular occlusions and lethality in JAK2V617F-knockin mice. Additionally, we demonstrated that a reduction in red blood cell mass was the main contributing factor in the reversion of vascular occlusions. Thus, our study identifies Plek2 as an effector of the JAK2/STAT5 pathway and a key factor in the pathogenesis of JAK2V617F-induced MPNs, pointing to Plek2 as a viable target for the treatment of MPNs.

Authors

Baobing Zhao, Yang Mei, Lan Cao, Jingxin Zhang, Ronen Sumagin, Jing Yang, Juehua Gao, Matthew J. Schipma, Yanfeng Wang, Chelsea Thorsheim, Liang Zhao, Timothy Stalker, Brady Stein, Qiang Jeremy Wen, John D. Crispino, Charles S. Abrams, Peng Ji

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Figure 1

Plek2 is transcriptionally regulated by erythropoietin.

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Plek2 is transcriptionally regulated by erythropoietin. (A) The level of...
(A) The level of Plek2 was detected by Western blot analysis. Ter119+ indicates Ter119-positive mouse fetal liver erythroblasts. D1 to D3 indicate different days of mouse fetal liver culture. Hsc70 was used as a loading control. (B) Ter119-negative mouse fetal liver erythroblasts were cultured in SCF-containing medium followed by culture with or without Epo (2 U/ml). The levels of Plek2 were detected by Western blot analysis. (C) Time course of Plek2 expression in response to Epo. The levels of Plek2 were detected by Western blot analysis. (D) Flow cytometric assay for the gating of erythroid populations in different developmental stages. Populations I to VI represent the least differentiated to enucleated RBC. (E) Plek2 expression in different populations of erythroblasts as in D analyzed by an intracellular flow cytometric assay. The data are representative of 3 independent experiments. (F) Epo drives the transcriptional upregulation of Plek2. Ter119-negative fetal liver erythroblasts were cultured with or without Epo for the indicated period. The mRNA levels of Plek2 were analyzed by a real-time PCR assay. (G) Quantitative PCR analysis of the mRNA expression of Plek2 in indicated cells. D0 indicates freshly purified Ter119-negative mouse fetal liver erythroblasts. SCF-12h, -24h and Epo-12h, -24h indicate Ter119-negative mouse fetal liver erythroblasts cultured in SCF- and Epo-containing medium for the indicated amount of time, respectively. (H) Effects of Epo on the mRNA expression of Plek1. Ter119-negative fetal liver erythroblasts were cultured with or without Epo for the indicated amount of time. The mRNA levels of Plek1 were analyzed by a real-time PCR assay. (I) Quantitative PCR analysis of the mRNA expression of Plek1 in indicated cells as in G.