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LNK/SH2B3 regulates IL-7 receptor signaling in normal and malignant B-progenitors.

ABSTRACT: Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a high-risk ALL commonly associated with alterations that affect the tyrosine kinase pathway, tumor suppressors, and lymphoid transcription factors. Loss-of-function mutations in the gene-encoding adaptor protein LNK (also known as SH2B3) are found in Ph-like ALLs; however, it is not clear how LNK regulates normal B cell development or promotes leukemogenesis. Here, we have shown that combined loss of Lnk and tumor suppressors Tp53 or Ink4a/Arf in mice triggers a highly aggressive and transplantable precursor B-ALL. Tp53-/-Lnk-/- B-ALLs displayed similar gene expression profiles to human Ph-like B-ALLs, supporting use of this model for preclinical and molecular studies. Preleukemic Tp53-/-Lnk-/- pro-B progenitors were hypersensitive to IL-7, exhibited marked self-renewal in vitro and in vivo, and were able to initiate B-ALL in transplant recipients. Mechanistically, we demonstrated that LNK regulates pro-B progenitor homeostasis by attenuating IL-7-stimuated JAK/STAT5 signaling via a direct interaction with phosphorylated JAK3. Moreover, JAK inhibitors were effective in prolonging survival of mice transplanted with Lnk-/-Tp53-/- leukemia. Additionally, synergistic administration of PI3K/mTOR and JAK inhibitors further abrogated leukemia development. Hence, our results suggest that LNK suppresses IL-7R/JAK/STAT signaling to restrict pro-/pre-B progenitor expansion and leukemia development, providing a pathogenic mechanism and a potential therapeutic approach for B-ALLs with LNK mutations.

SUBMITTER: Cheng Y

PROVIDER: S-EPMC4811117 | biostudies-literature | 2016 Apr

REPOSITORIES: biostudies-literature

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LNK/SH2B3 regulates IL-7 receptor signaling in normal and malignant B-progenitors.

Cheng Ying Y Chikwava Kudakwashe K Wu Chao C Zhang Haibing H Bhagat Anchit A Pei Dehua D Choi John K JK Tong Wei W

The Journal of clinical investigation 20160314 4

Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a high-risk ALL commonly associated with alterations that affect the tyrosine kinase pathway, tumor suppressors, and lymphoid transcription factors. Loss-of-function mutations in the gene-encoding adaptor protein LNK (also known as SH2B3) are found in Ph-like ALLs; however, it is not clear how LNK regulates normal B cell development or promotes leukemogenesis. Here, we have shown that combined loss of Lnk and tumor suppre ...[more]

PMID: 26974155

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Project description:Human genome-wide association studies have revealed novel genetic loci that are associated with coronary heart disease. One such locus resides in LNK/SH2B3, which in mice is expressed in hematopoietic cells and suppresses thrombopoietin signaling via its receptor myeloproliferative leukemia virus oncogene. However, the mechanisms underlying the association of LNK single-nucleotide polymorphisms with coronary heart disease are poorly understood.To understand the functional effects of LNK single-nucleotide polymorphisms and explore the mechanisms whereby LNK loss of function impacts atherosclerosis and thrombosis.Using human cord blood, we show that the common TT risk genotype (R262W) of LNK is associated with expansion of hematopoietic stem cells and enhanced megakaryopoiesis, demonstrating reduced LNK function and increased myeloproliferative leukemia virus oncogene signaling. In mice, hematopoietic Lnk deficiency leads to accelerated arterial thrombosis and atherosclerosis, but only in the setting of hypercholesterolemia. Hypercholesterolemia acts synergistically with LNK deficiency to increase interleukin 3/granulocyte-macrophage colony-stimulating factor receptor signaling in bone marrow myeloid progenitors, whereas in platelets cholesterol loading combines with Lnk deficiency to increase activation. Platelet LNK deficiency increases myeloproliferative leukemia virus oncogene signaling and AKT activation, whereas cholesterol loading decreases SHIP-1 phosphorylation, acting convergently to increase AKT and platelet activation. Together with increased myelopoiesis, platelet activation promotes prothrombotic and proatherogenic platelet/leukocyte aggregate formation.LNK (R262W) is a loss-of-function variant that promotes thrombopoietin/myeloproliferative leukemia virus oncogene signaling and platelet and leukocyte production. In mice, LNK deficiency is associated with both increased platelet production and activation. Hypercholesterolemia acts in platelets and hematopoietic progenitors to exacerbate thrombosis and atherosclerosis associated with LNK deficiency.

Project description:BackgroundLNK/SH2B3 inhibits Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling by hematopoietic cytokine receptors. Genome-wide association studies have shown association of a common single nucleotide polymorphism in LNK (R262W, T allele) with neutrophilia, thrombocytosis, and coronary artery disease. We have shown that LNK(TT) reduces LNK function and that LNK-deficient mice display prominent platelet-neutrophil aggregates, accelerated atherosclerosis, and thrombosis. Platelet-neutrophil interactions can promote neutrophil extracellular trap (NET) formation. The goals of this study were to assess the role of NETs in atherosclerosis and thrombosis in mice with hematopoietic Lnk deficiency.MethodsWe bred mice with combined deficiency of Lnk and the NETosis-essential enzyme PAD4 (peptidyl arginine deiminase 4) and transplanted their bone marrow into Ldlr-/- mice. We evaluated the role of LNK in atherothrombosis in humans and mice bearing a gain of function variant in JAK2 (JAK2V617F).ResultsLnk-deficient mice displayed accelerated carotid artery thrombosis with prominent NETosis that was completely reversed by PAD4 deficiency. Thrombin-activated Lnk-/- platelets promoted increased NETosis when incubated with Lnk-/- neutrophils compared with wild-type platelets or wild-type neutrophils. This involved increased surface exposure and release of oxidized phospholipids (OxPL) from Lnk-/- platelets, as well as increased priming and response of Lnk-/- neutrophils to OxPL. To counteract the effects of OxPL, we introduced a transgene expressing the single-chain variable fragment of E06 (E06-scFv). E06-scFv reversed accelerated NETosis, atherosclerosis, and thrombosis in Lnk-/- mice. We also showed increased NETosis when human induced pluripotent stem cell-derived LNK(TT) neutrophils were incubated with LNK(TT) platelet/megakaryocytes, but not in isogenic LNK(CC) controls, confirming human relevance. Using data from the UK Biobank, we found that individuals with the JAK2VF mutation only showed increased risk of coronary artery disease when also carrying the LNK R262W allele. Mice with hematopoietic Lnk+/- and Jak2VF clonal hematopoiesis showed accelerated arterial thrombosis but not atherosclerosis compared with Jak2VFLnk+/+ controls.ConclusionsHematopoietic Lnk deficiency promotes NETosis and arterial thrombosis in an OxPL-dependent fashion. LNK(R262W) reduces LNK function in human platelets and neutrophils, promoting NETosis, and increases coronary artery disease risk in humans carrying Jak2VF mutations. Therapies targeting OxPL may be beneficial for coronary artery disease in genetically defined human populations.

Dataset Information

LNK/SH2B3 regulates IL-7 receptor signaling in normal and malignant B-progenitors.

Publications

LNK/SH2B3 regulates IL-7 receptor signaling in normal and malignant B-progenitors.

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