Dataset Information

The Role of LNK (SH2B3) in the Regulation of JAK-STAT Signalling in Haematopoiesis.

ABSTRACT: LNK is a member of the SH2B family of adaptor proteins and is a non-redundant regulator of cytokine signalling. Cytokines are secreted intercellular messengers that bind to specific receptors on the surface of target cells to activate the Janus Kinase-Signal Transducer and Activator of Transcription (JAK-STAT) signalling pathway. Activation of the JAK-STAT pathway leads to proliferative and often inflammatory effects, and so the amplitude and duration of signalling are tightly controlled. LNK binds phosphotyrosine residues to signalling proteins downstream of cytokines and constrains JAK-STAT signalling. Mutations in LNK have been identified in a range of haematological and inflammatory diseases due to increased signalling following the loss of LNK function. Here, we review the regulation of JAK-STAT signalling via the adaptor protein LNK and discuss the role of LNK in haematological diseases.

SUBMITTER: Morris R

PROVIDER: S-EPMC8781068 | biostudies-literature | 2021 Dec

REPOSITORIES: biostudies-literature

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The Role of LNK (SH2B3) in the Regulation of JAK-STAT Signalling in Haematopoiesis.

Morris Rhiannon R Butler Liesl L Perkins Andrew A Kershaw Nadia J NJ Babon Jeffrey J JJ

Pharmaceuticals (Basel, Switzerland) 20211224 1

LNK is a member of the SH2B family of adaptor proteins and is a non-redundant regulator of cytokine signalling. Cytokines are secreted intercellular messengers that bind to specific receptors on the surface of target cells to activate the Janus Kinase-Signal Transducer and Activator of Transcription (JAK-STAT) signalling pathway. Activation of the JAK-STAT pathway leads to proliferative and often inflammatory effects, and so the amplitude and duration of signalling are tightly controlled. LNK bi ...[more]

PMID: 35056081

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Project description:IntroductionBone marrow transplantation (BMT) is a complex process regulated by different cytokines and growth factors. The pleiotropic cytokine IL-6 (Interleukin-6) and related cytokines of the same family acting on the common signal transducer gp130 are known to play a key role in bone marrow (BM) engraftment. In contrast, the exact signalling events that control IL-6/gp130-driven haematopoietic stem cell development during BMT remain unresolved.MethodsConditional gp130 knockout and knockin mice were used to delete gp130 expression (gp130(?Mx)), or to selectively disrupt gp130-dependent Ras (gp130(?MxRas)) or STAT signalling (gp130(?MxSTAT)) in BM cells. BM derived from the respective strains was transplanted into irradiated wildtype hosts and repopulation of various haematopoietic lineages was monitored by flow cytometry.ResultsBM derived from gp130 deficient donor mice (gp130(?Mx)) displayed a delayed engraftment, as evidenced by reduced total white blood cells (WBC), marked thrombocytopenia and anaemia in the early phase after BMT. Lineage analysis unravelled a restricted development of CD4(+) and CD8(+) T-cells, CD19(+) B-cells and CD11b(+) myeloid cells after transplantation of gp130-deficient BM grafts. To further delineate the two major gp130-induced signalling cascades, Ras-MAPK and STAT1/3-signalling respectively, we used gp130(?MxRas) and gp130(?MxSTAT) donor BM. BMT of gp130(?MxSTAT) cells significantly impaired engraftment of CD4(+), CD8(+), CD19(+) and CD11b(+) cells, whereas gp130(?MxRas) BM displayed a selective impairment in early thrombopoiesis. Importantly, gp130-STAT1/3 signalling deficiency in BM grafts severely impaired survival of transplanted mice, thus demonstrating a pivotal role for this pathway in BM graft survival and function.ConclusionOur data unravel a vital function of IL-6/gp130-STAT1/3 signals for BM engraftment and haematopoiesis, as well as for host survival after transplantation. STAT1/3 and ras-dependent pathways thereby exert distinct functions on individual bone-marrow-lineages.

Project description:RationaleHuman 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.ObjectiveTo understand the functional effects of LNK single-nucleotide polymorphisms and explore the mechanisms whereby LNK loss of function impacts atherosclerosis and thrombosis.Methods and resultsUsing 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.ConclusionsLNK (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.

Dataset Information

The Role of LNK (SH2B3) in the Regulation of JAK-STAT Signalling in Haematopoiesis.

Publications

The Role of LNK (SH2B3) in the Regulation of JAK-STAT Signalling in Haematopoiesis.

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