PPIL2 is a target of the JAK2/STAT5 pathway and promotes myeloproliferation via degradation of p53
Pan Wang, Xu Han, Kehan Ren, Ermin Li, Honghao Bi, Inci Aydemir, Madina Sukhanova, Yijie Liu, Jing Yang, Peng Ji
Pan Wang, Xu Han, Kehan Ren, Ermin Li, Honghao Bi, Inci Aydemir, Madina Sukhanova, Yijie Liu, Jing Yang, Peng Ji
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Research Article Cell biology Hematology

PPIL2 is a target of the JAK2/STAT5 pathway and promotes myeloproliferation via degradation of p53

Abstract

The activated JAK2/STAT pathway is characteristic of myeloproliferative neoplasms (MPNs). The pleckstrin 2 (PLEK2) signalosome is downstream of the JAK2/STAT5 pathway and plays an important role in MPN development. The detailed molecular composition of this signalosome is unclear. Here, we reveal peptidylprolyl isomerase-like 2 (PPIL2) as a critical component of the complex in regulating human and murine erythropoiesis. PPIL2 was a direct target of STAT5 and was upregulated in patients with MPN and in a Jak2V617F MPN mouse model. Mechanistically, PPIL2 interacted with and catalyzed p53 polyubiquitination and proteasome-mediated degradation to promote cell growth. Ppil2 deficiency, or inhibition by cyclosporin A, led to a marked upregulation of p53 in vivo and ameliorated myeloproliferative phenotypes in Jak2V617F mice. Cyclosporin A also markedly reduced JAK2-mutated erythroid and myeloid proliferation in an induced pluripotent stem cell–derived human bone marrow organoid model. Our findings reveal PPIL2 as a critical component of the PLEK2 signalosome in driving MPN pathogenesis through negative regulation of p53, thus providing a target and opportunity for drug repurposing using cyclosporin A to treat MPNs.

Authors

Pan Wang, Xu Han, Kehan Ren, Ermin Li, Honghao Bi, Inci Aydemir, Madina Sukhanova, Yijie Liu, Jing Yang, Peng Ji

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Figure 5

Inhibition of Ppil2 blocks erythropoiesis in vitro and ameliorates MPN symptoms in Jak2V617F-knockin mice.

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Inhibition of Ppil2 blocks erythropoiesis in vitro and ameliorates MPN s...
(A) Mouse bone marrow lineage-negative cells were cultured in EPO medium for 2 days in the presence of the indicated amount of cyclosporin A (CsA). The cell number was quantified on day 2. (B) Quantification of indicated cell populations detected by flow cytometry in cells from A. (C) Western blotting of Ppil2 in cells from A. Hsc70 was used as a loading control. (D) Western blotting of the indicated proteins in HEK293T cells treated with 20 μM CsA for the indicated amount of time. (E) Western blotting of indicated proteins in the nuclear and cytoplasmic fractions of HEK293T cells treated with the indicated amount of CsA for 12 hours. (F) Western blotting of indicated proteins following anti-V5 IP of HEK293T cells transfected with the indicated constructs and treated with or without 20 μM CsA for 12 hours before being harvested. (G) Schematic illustration of experimental design where total bone marrow cells from 2-month-old Jak2V617F-knockin mice (CD45.2+) were transplanted into lethally irradiated recipient mice (CD45.1+). One month after transplant, the recipient mice were treated with 60 mg/kg CsA or vehicle control once every day for 1 week. (H) Complete blood count of the indicated mice from G. Control: n = 9, CsA: n = 10, Jak2V617F: n = 9, Jak2V617F+CsA: n = 6. (I) Spleen weight of the indicated mice from G. (J) Representative H&E staining of the indicated organs from the indicated mice in G. Scale bars: 100 μm. Arrows point to enlarged megakaryocytes in Jak2V617F mice. The comparison among multiple groups was evaluated with 1-way ANOVA (A, B, I, and H). *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001.