PPIL2 is a target of the JAK2/STAT5 pathway and promotes myeloproliferation via degradation of p53
Pan Wang, … , Jing Yang, Peng Ji
Pan Wang, … , Jing Yang, Peng Ji
Published May 8, 2025
Citation Information: J Clin Invest. 2025;135(13):e181394. https://doi.org/10.1172/JCI181394.
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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 3

PPIL2 is a downstream target of the JAK2/STAT5 pathway and is upregulated in patients with MPNs.

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PPIL2 is a downstream target of the JAK2/STAT5 pathway and is upregulate...
(A) Western blotting of Ppil2 in bone marrow lineage-negative cells cultured in SCF medium for 12 hours, then with or without EPO (2 U/mL) for the indicated times. (B) qPCR of Ppil2 mRNA expression in bone marrow lineage-negative cells treated with SCF or EPO over time. (C and D) Western blot (C) and qPCR (D) of Ppil2 in cultured erythroblasts treated with varying does of ruxolitinib for 20 hours. Hsc70 was used as a loading control. (E and F) Western blot (E) and qPCR (F) of Ppil2 in erythroblasts transduced with WT Jak2 or Jak2V617F mutant. (G and H) Western blotting (G) and PCR (H) of Ppil2 in erythroblasts treated with the Stat5 inhibitors for 20 hours. (I and J) Western blotting (I) and qPCR (J) of Ppil2 in erythroblasts transduced with WT Stat5 or constitutively active (CA) mutant. (K) Relative luciferase activity in HEK293T cells transfected with control or STAT5 (OV) constructs. (L) Schematic of STAT5 binding sites on PPIL2 promoter and mutant sequence. (M) DNA pulldown assay by Western blotting using biotin-labeled PPIL2 promoter or mutant with 24-hour EPO-treated mouse linage-negative cell lysate. (N) ChIP-qPCR of Ppil2 promoter fragment pulled down by anti-Stat5 with IgG as the control. (O and P) PPIL2 mRNA levels in patients with MPN by subtype (O) and mutation status (P) from the GSE54644 dataset. (Q) PPIL2 mRNA in PBMCs from an independent cohort of patients with MPN. (R) Western blot of PPIL2 in PBMCs from normal and patients with MPN from Q. The comparison between 2 groups was evaluated with 2-tailed t test (K, N, Q, and O), and the comparison among multiple groups was evaluated with 1-way ANOVA (B, D, F, H, J, O, and P). ns, nonsignificant; *P < 0.05, **P < 0.01, ***P < 0.001, and **** P < 0.0001.