Supplementary MaterialsDocument S1
Supplementary MaterialsDocument S1. shift metabolic state dynamically. Right here, we demonstrate specific wiring from the sphingolipidome over the individual hematopoietic hierarchy and discover that hereditary or pharmacologic modulation from the sphingolipid enzyme DEGS1 regulates lineage differentiation. Inhibition of DEGS1 in hematopoietic stem and progenitor cells through the changeover from quiescence to mobile activation with SpL synthesis, which changes dihydroceramide (dhCer) to Cer; both hereditary ablation and inhibition using the artificial retinoid fenretinide/circumstances considered to promote cord blood (CB) HSC activation and expansion, they actually lose HSC function due to impaired proteostatic programs. By contrast, inhibition of DEGS1 in human HSCs with 4HPR treatment before quiescence exit in culture induced a coordinated response of proteostatic cellular stress programs, including autophagy to maintain HSC self-renewal. Despite culture, HSCs following SpL modulation functionally show higher self-renewal relative to cultured cells without treatment pointing to P7C3 a linkage between SpLs, proteostatic quality control P7C3 programs, and HSC self-renewal in the Ly6a transition from quiescence to cellular activation. Results DEGS1 Influences SpL Composition in the Human Hematopoietic Hierarchy and Is Functionally Required for HSC Repopulation We undertook transcriptome analysis of highly resolved subpopulations of the human hematopoietic hierarchy and found that lipid signaling and metabolism genes involved in SpLs are differentially expressed (false discovery rate [FDR]? 0.05; fold change [FC] 1.5) in LT-HSCs and ST-HSCs (as defined in Laurenti et?al., 2015, Notta et?al., 2011, Notta et?al., 2016) compared to committed progenitors (Figures 1A and S1A). Previous lipid measurements of mammalian cells indicated that SpLs contribute only 10% of the cellular lipidome, mostly represented by structural sphingomyelins (SMs) and glycosphingolipids (van Meer and de Kroon, 2011). Overlaying the differentially expressed SpL genes (Figure?1A) onto the metabolic pathway (Hannun and Obeid, 2018) showed many of the SpL genes highly expressed in HSCs centered around those involved in the synthesis of the low abundant bioactive dhCer and Cer species (Figure?S1A). To assess whether there is distinct SpL biosynthesis across the cell types comprising the?human hematopoietic hierarchy, especially at the level of these less abundant SpLs, we isolated CD34+CD38? stem-enriched (stem) and CD34+CD38+ progenitor-enriched (progenitor) cells and 5 mature blood lineages (B and T lymphocytes, monocytes, neutrophils, and erythrocytes) from CB by flow cytometry. These populations were subjected to Cer, dhCer, sphingosine, S1P, dhSph, dhS1P, hexosylceramides (HexCer) (Cer containing glucose or galactose), and SM measurement using liquid chromatography mass spectrometry (LC-MS) (Figures 1B and S1BCS1H). SMs were P7C3 the most abundant SpLs in our analysis (Figures 1B and S1H; 72%C94%), consistent with previous lipidome profiling in mammalian cells (van Meer and de Kroon, 2011). Importantly, our profiling identified the accumulation of S1P specifically in erythrocytes (Figure?S1E), confirming this lineage-specific association and the robustness of our sphingolipidome profiling (Dahm et?al., 2006). We found no significant differences in SpL content between stem and progenitor cells except in the amount of dhCer carrying the C16:0 fatty acid, providing evidence for differential wiring of SpL synthesis at the lipid level in HSPCs (Figure?1C). By contrast, the mature lineages showed significant differences from stem and/or progenitor cells (Figures S1CCS1H). Importantly, we saw that B cells, neutrophils, and erythrocytes were significantly different in their ratio of Cer/dhCer from stem cells (Figure?1D). In contrast, T?cells and monocytes did not differ in the Cer/dhCer ratio, raising the question of whether Cer homeostasis regulates HPSC fate and lineage commitment decisions. DEGS1 expression levels are significantly increased in LT-HSCs, ST-HSCs, and granulocyte-monocyte progenitors (GMPs) following 6?h of cytokine stimulation, suggesting increasing SpL-generated Cer pools may be an early event in the transition from quiescence to cellular activation (Figure?1E). To determine whether alterations in the Cer/dhCer ratio were.