| 1. |
- Sen, Taha, et al.
(författare)
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Enhancing mitochondrial function in vivo rescues MDS-like anemia induced by pRb deficiency
- 2020
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Ingår i: Experimental Hematology. - : Elsevier BV. - 0301-472X. ; 88, s. 28-41
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Tidskriftsartikel (refereegranskat)abstract
- Erythropoiesis is intimately coupled to cell division, and deletion of the cell cycle regulator retinoblastoma protein (pRb) causes anemia in mice. Erythroid-specific deletion of pRb has been found to result in inefficient erythropoiesis because of deregulated coordination of cell cycle exit and mitochondrial biogenesis. However, the pathophysiology remains to be fully described, and further characterization of the link between cell cycle regulation and mitochondrial function is needed. To this end we further assessed conditional erythroid-specific deletion of pRb. This resulted in macrocytic anemia, despite elevated levels of erythropoietin (Epo), and an accumulation of erythroid progenitors in the bone marrow, a phenotype strongly resembling refractory anemia associated with myelodysplastic syndromes (MDS). Using high-fractionation fluorescence-activated cell sorting analysis for improved phenotypic characterization, we illustrate that erythroid differentiation was disrupted at the orthochromatic stage. Transcriptional profiling of sequential purified populations revealed failure to upregulate genes critical for mitochondrial function such as Pgc1β, Alas2, and Abcb7 specifically at the block, together with disturbed heme production and iron transport. Notably, deregulated ABCB7 causes ring sideroblastic anemia in MDS patients, and the mitochondrial co-activator PGC1β is heterozygously lost in del5q MDS. Importantly, the anemia could be rescued through enhanced PPAR signaling in vivo via either overexpression of Pgc1β or bezafibrate administration. In conclusion, lack of pRb results in MDS-like anemia with disrupted differentiation and impaired mitochondrial function at the orthochromatic erythroblast stage. Our findings reveal for the first time a role for pRb in heme and iron regulation, and indicate that pRb-induced anemia can be rescued in vivo through therapeutic enhancement of PPAR signaling.
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| 2. |
- Singbrant, Sofie, et al.
(författare)
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Prospective isolation of radiation induced erythroid stress progenitors reveals unique transcriptomic and epigenetic signatures enabling increased erythroid output
- 2020
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Ingår i: Haematologica. - : Ferrata Storti Foundation (Haematologica). - 0390-6078 .- 1592-8721. ; 105:11, s. 2561-2571
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Tidskriftsartikel (refereegranskat)abstract
- Massive expansion of erythroid progenitor cells is essential for surviving anemic stress. Research towards understanding this critical process, referred to as stress-erythropoiesis, has been hampered due to the lack of specific marker-combinations enabling analysis of the distinct stress-progenitor cells capable of providing radioprotection and enhanced red blood cell production. Here we present a method for the precise identification and in vivo validation of progenitor cells contributing to both steady-state and stress-erythropoiesis, enabling for the first time in-depth molecular characterization of these cells. Differential expression of surface markers CD150, CD9 and Sca1 defines a hierarchy of splenic stress-progenitors during irradiation-induced stress recovery in mice, and provides high-purity isolation of the functional stress erythroid burst-forming-units (stress-BFU-E) with a 100-fold improved enrichment compared to the state-of-the-art. By transplanting purified stress-progenitors expressing the fluorescent protein Kusabira Orange, we determined their kinetics in vivo and demonstrated that CD150+CD9+Sca1 -stress-BFU-E provide a massive but transient radioprotective erythroid wave, followed by multi-lineage reconstitution from CD150+CD9+Sca1+ multi-potent stem/progenitor cells. Whole genome transcriptional analysis revealed that stress-BFU-E express gene signatures more associated with erythropoiesis and proliferation compared to steady-state BFU-E, and are bone morphogenetic protein 4-responsive. Evaluation of chromatin accessibility through ATAC sequencing reveals enhanced and differential accessibility to binding sites of the chromatin-looping transcription factor CTCF in stress-BFU-E compared to steady-state BFU-E. Our findings offer a molecular insight into the unique capacity of stress-BFU-E to rapidly form erythroid cells in response to anemia and constitute an important step towards identifying novel erythropoiesis stimulating agents.
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