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Behrens K, Kauppi M, Viney EM, Kueh AJ, Hyland CD, Willson TA, Salleh L, de Graaf CA, Babon JJ, Herold MJ, Nicola NA, Alexander WS. Differential in vivo roles of Mpl cytoplasmic tyrosine residues in murine hematopoiesis and myeloproliferative disease. Leukemia 2024; 38:1342-1352. [PMID: 38491305 PMCID: PMC11147766 DOI: 10.1038/s41375-024-02219-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 03/02/2024] [Accepted: 03/05/2024] [Indexed: 03/18/2024]
Abstract
Thrombopoietin (Tpo), which binds to its specific receptor, the Mpl protein, is the major cytokine regulator of megakaryopoiesis and circulating platelet number. Tpo binding to Mpl triggers activation of Janus kinase 2 (Jak2) and phosphorylation of the receptor, as well as activation of several intracellular signalling cascades that mediate cellular responses. Three tyrosine (Y) residues in the C-terminal region of the Mpl intracellular domain have been implicated as sites of phosphorylation required for regulation of major Tpo-stimulated signalling pathways: Mpl-Y565, Mpl-Y599 and Mpl-Y604. Here, we have introduced mutations in the mouse germline and report a consistent physiological requirement for Mpl-Y599, mutation of which resulted in thrombocytopenia, deficient megakaryopoiesis, low hematopoietic stem cell (HSC) number and function, and attenuated responses to myelosuppression. We further show that in models of myeloproliferative neoplasms (MPN), where Mpl is required for pathogenesis, thrombocytosis was dependent on intact Mpl-Y599. In contrast, Mpl-Y565 was required for negative regulation of Tpo responses; mutation of this residue resulted in excess megakaryopoiesis at steady-state and in response to myelosuppression, and exacerbated thrombocytosis associated with MPN.
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Affiliation(s)
- Kira Behrens
- Blood Cells and Blood Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia.
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia.
| | - Maria Kauppi
- Blood Cells and Blood Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Elizabeth M Viney
- Blood Cells and Blood Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia
| | - Andrew J Kueh
- Blood Cells and Blood Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia
- Olivia Newton-John Cancer Research Institute, Heidelberg, VIC, Australia
- School of Cancer Medicine, La Trobe University, Heidelberg, VIC, 3084, Australia
| | - Craig D Hyland
- Blood Cells and Blood Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia
| | - Tracy A Willson
- Blood Cells and Blood Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Liam Salleh
- Blood Cells and Blood Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia
| | - Carolyn A de Graaf
- Blood Cells and Blood Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Jeffrey J Babon
- Blood Cells and Blood Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Marco J Herold
- Blood Cells and Blood Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia
- Olivia Newton-John Cancer Research Institute, Heidelberg, VIC, Australia
- School of Cancer Medicine, La Trobe University, Heidelberg, VIC, 3084, Australia
| | - Nicos A Nicola
- Blood Cells and Blood Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Warren S Alexander
- Blood Cells and Blood Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3010, Australia
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Roy A, Shrivastva S, Naseer S. In and out: Traffic and dynamics of thrombopoietin receptor. J Cell Mol Med 2021; 25:9073-9083. [PMID: 34448528 PMCID: PMC8500957 DOI: 10.1111/jcmm.16878] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/27/2021] [Accepted: 08/04/2021] [Indexed: 12/17/2022] Open
Abstract
Thrombopoiesis had long been a challenging area of study due to the rarity of megakaryocyte precursors in the bone marrow and the incomplete understanding of its regulatory cytokines. A breakthrough was achieved in the early 1990s with the discovery of the thrombopoietin receptor (TpoR) and its ligand thrombopoietin (TPO). This accelerated research in thrombopoiesis, including the uncovering of the molecular basis of myeloproliferative neoplasms (MPN) and the advent of drugs to treat thrombocytopenic purpura. TpoR mutations affecting its membrane dynamics or transport were increasingly associated with pathologies such as MPN and thrombocytosis. It also became apparent that TpoR affected hematopoietic stem cell (HSC) quiescence while priming hematopoietic stem cells (HSCs) towards the megakaryocyte lineage. Thorough knowledge of TpoR surface localization, dimerization, dynamics and stability is therefore crucial to understanding thrombopoiesis and related pathologies. In this review, we will discuss the mechanisms of TpoR traffic. We will focus on the recent progress in TpoR membrane dynamics and highlight the areas that remain unexplored.
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Affiliation(s)
- Anita Roy
- Kusuma School of Biological Sciences, Indian Institute of Technology, New Delhi, India
| | - Saurabh Shrivastva
- Kusuma School of Biological Sciences, Indian Institute of Technology, New Delhi, India
| | - Saadia Naseer
- Kusuma School of Biological Sciences, Indian Institute of Technology, New Delhi, India
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Eltrombopag inhibits Type I interferon-mediated antiviral signaling by decreasing cellular iron. Biochem Pharmacol 2021; 186:114436. [PMID: 33539815 DOI: 10.1016/j.bcp.2021.114436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 01/04/2021] [Accepted: 01/20/2021] [Indexed: 11/21/2022]
Abstract
Thrombocytopenia is common among patients with viral hepatitis, limiting the use of antiviral therapy. Eltrombopag (EP) is a thrombopoietin receptor (TPO-R) agonist that has been approved for treatment of immune thrombocytopenia patients with hepatitis virus infection. Interferon-α (IFN-α) plays a crucial role in the antiviral response, and is recommended as the first-line agent for chronic hepatitis B patients. Here, we investigated whether EP inhibits the production of IFN-stimulated genes (ISGs) induced by IFN-α through the TPO-R-independent pathway by mediating reactive oxygen species production by iron chelation. Our results assessed the inhibitory effect of EP on IFN-α signaling, which contributes to the downregulation of ISGs produced by monocytes and sheds light on the underlying mechanisms using iron chelation to treat patients with hepatitis-related immunological thrombocytopenia.
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