Tuning MPL signaling to influence hematopoietic stem cell differentiation and inhibit essential thrombocythemia progenitors.

Abstract

Thrombopoietin (TPO) and the TPO-receptor (TPO-R, or c-MPL) are essential for hematopoietic stem cell (HSC) maintenance and megakaryocyte differentiation. Agents that can modulate TPO-R signaling are highly desirable for both basic research and clinical utility. We developed a series of surrogate protein ligands for TPO-R, in the form of diabodies (DBs), that homodimerize TPO-R on the cell surface in geometries that are dictated by the DB receptor binding epitope, in effect "tuning" downstream signaling responses. These surrogate ligands exhibit diverse pharmacological properties, inducing graded signaling outputs, from full to partial TPO agonism, thus decoupling the dual functions of TPO/TPO-R. Using single-cell RNA sequencing and HSC self-renewal assays we find that partial agonistic diabodies preserved the stem-like properties of cultured HSCs, but also blocked oncogenic colony formation in essential thrombocythemia (ET) through inverse agonism. Our data suggest that dampening downstream TPO signaling is a powerful approach not only for HSC preservation in culture, but also for inhibiting oncogenic signaling through the TPO-R.

• Authors: Lu Cui, Ignacio Moraga, Tristan Lerbs, Camille Van Neste, Stephan Wilmes, Naotaka Tsutsumi, Aaron Claudius Trotman-Grant, Milica Gakovic, Sarah Andrews, Jason Gotlib, Spyros Darmanis, Martin Enge, Stephen Quake, Ian S Hitchcock, Jacob Piehler, K Christopher Garcia, Gerlinde Wernig
• Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 118 Issue 2 (01 12 2021) ISSN: 1091-6490 [Electronic] United States
• PMID: 33384332 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2021 the Author(s). Published by PNAS.

Chemical References

• Epitopes
• Ligands
• Neoplasm Proteins
• Proto-Oncogene Proteins
• Receptors, Cytokine
• Receptors, Thrombopoietin
• MPL protein, human
• Thrombopoietin

Topics

• Cell Differentiation (physiology)
• Cell Membrane (metabolism)
• Epitopes (immunology)
• Hematopoiesis (drug effects)
• Hematopoietic Stem Cells (metabolism)
• Humans
• Ligands
• Megakaryocytes (metabolism)
• Neoplasm Proteins (metabolism)
• Proto-Oncogene Proteins (metabolism)
• Receptors, Cytokine (metabolism)
• Receptors, Thrombopoietin (immunology, metabolism, physiology)
• Signal Transduction (physiology)
• Thrombocythemia, Essential (metabolism)
• Thrombopoietin (metabolism, physiology)