Increased Ripk1-mediated bone marrow necroptosis leads to myelodysplasia and bone marrow failure in mice.

Abstract

Hematopoiesis is a dynamic system that requires balanced cell division, differentiation, and death. The 2 major modes of programmed cell death, apoptosis and necroptosis, share molecular machinery but diverge in outcome with important implications for the microenvironment; apoptotic cells are removed in an immune silent process, whereas necroptotic cells leak cellular contents that incite inflammation. Given the importance of cytokine-directed cues for hematopoietic cell survival and differentiation, the impact on hematopoietic homeostasis of biasing cell death fate to necroptosis is substantial and poorly understood. Here, we present a mouse model with increased bone marrow necroptosis. Deletion of the proapoptotic Bcl-2 family members Bax and Bak inhibits bone marrow apoptosis. Further deletion of the BH3-only member Bid (to generate Vav CreBaxBakBid triple-knockout [TKO] mice) leads to unrestrained bone marrow necroptosis driven by increased Rip1 kinase (Ripk1). TKO mice display loss of progenitor cells, leading to increased cytokine production and increased stem cell proliferation and exhaustion and culminating in bone marrow failure. Genetically restoring Ripk1 to wild-type levels restores peripheral red cell counts as well as normal cytokine production. TKO bone marrow is hypercellular with abnormal differentiation, resembling the human disorder myelodysplastic syndrome (MDS), and we demonstrate increased necroptosis in MDS bone marrow. Finally, we show that Bid impacts necroptotic signaling through modulation of caspase-8-mediated Ripk1 degradation. Thus, we demonstrate that dysregulated necroptosis in hematopoiesis promotes bone marrow progenitor cell death that incites inflammation, impairs hematopoietic stem cells, and recapitulates the salient features of the bone marrow failure disorder MDS.

• Authors: Patrice N Wagner, Qiong Shi, Christi T Salisbury-Ruf, Jing Zou, Michael R Savona, Yuri Fedoriw, Sandra S Zinkel
• Journal: Blood (Blood) Vol. 133 Issue 2 Pg. 107-120 (01 10 2019) ISSN: 1528-0020 [Electronic] United States
• PMID: 30413413 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)
• Copyright: © 2019 by The American Society of Hematology.

Chemical References

• BH3 Interacting Domain Death Agonist Protein
• Bak1 protein, mouse
• Bid protein, mouse
• Cytokines
• bcl-2 Homologous Antagonist-Killer Protein
• Receptor-Interacting Protein Serine-Threonine Kinases
• Ripk1 protein, mouse

Topics

• Animals
• BH3 Interacting Domain Death Agonist Protein (physiology)
• Bone Marrow (metabolism, pathology)
• Bone Marrow Diseases (etiology, metabolism, pathology)
• Cells, Cultured
• Cytokines (metabolism)
• Hematopoietic Stem Cells (metabolism, pathology)
• Inflammation (etiology, metabolism, pathology)
• Mice
• Mice, Inbred C57BL
• Mice, Knockout
• Myelodysplastic Syndromes (etiology, metabolism, pathology)
• Necrosis
• Receptor-Interacting Protein Serine-Threonine Kinases (physiology)
• bcl-2 Homologous Antagonist-Killer Protein (physiology)