Heme degradation enzyme biliverdin IXβ reductase is required for stem cell glutamine metabolism

Abstract

Bioenergetic requirements of hematopoietic stem cells and pluripotent stem cells (PSCs) vary with lineage fate, and cellular adaptations rely largely on substrate (glucose/glutamine) availability and mitochondrial function to balance tricarboxylic acid (TCA)-derived anabolic and redox-regulated antioxidant functions. Heme synthesis and degradation converge in a linear pathway that utilizes TCA cycle-derived carbon in cataplerotic reactions of tetrapyrrole biosynthesis, terminated by NAD(P)H-dependent biliverdin reductases (IXα, BLVRA and IXβ, BLVRB) that lead to bilirubin generation and cellular antioxidant functions. We now demonstrate that PSCs with targeted deletion of display physiologically defective antioxidant activity and cellular viability, associated with a glutamine-restricted defect in TCA entry that was computationally predicted using gene/metabolite topological network analysis and subsequently validated by bioenergetic and isotopomeric studies. Defective BLVRB-regulated glutamine utilization was accompanied by exaggerated glycolytic accumulation of the rate-limiting hexokinase reaction product glucose-6-phosphate.-deficient embryoid body formation (a critical size parameter of early lineage fate potential) demonstrated enhanced sensitivity to the pentose phosphate pathway (PPP) inhibitor 6-aminonicotinamide with no differences in the glycolytic pathway inhibitor 2-deoxyglucose. These collective data place heme catabolism in a crucial pathway of glutamine-regulated bioenergetic metabolism and suggest that early stages of lineage fate potential require glutamine anaplerotic functions and an intact PPP, which are, in part, regulated by BLVRB activity. In principle, BLVRB inhibition represents an alternative strategy for modulating cellular glutamine utilization with consequences for cancer and hematopoietic metabolism.

Age‐restricted functional and developmental differences of neonatal platelets

“…Whereas aggregate data demonstrated that equivalent numbers of transcripts were up‐ ( N = 1008) or down‐regulated ( N = 1196), DEFA3 and HBG1/2 displayed < 2‐fold change over time. There were no differences in D0/D5 platelet phenotypic markers JC1 (viability marker of mitochondrial potential), 56 CD41 + , or CD41 + /Annexin V + events, excluding that transcriptomic differences were caused by cell death and RNA degradation (Figure 5G). These data establish that (1) for a subset of genes displaying concordantly abundant RiboSeq and RNA expression patterns, ribosomal occupancy selectively shapes and regulates transcript decay in CB platelets, and (2) DEFA3 and HBG1/2 retain abundance characteristics as stable biomarkers for neonatal platelet detection in vivo .…”

“…Cells were expanded in SFEM II medium for 24–48 h prior to terminal MK differentiation using serum‐free SFEM containing MK expansion supplement CC220 (STEMCELL Technologies). Differentiation was monitored by flow cytometry, gating on live 7‐actinomycin D (7‐AAD)‐negative cells for immunophenotypic quantification of CD41a (integrin α IIb , MK), Annexin V as a marker of PS exposure and apoptosis, 34,36 or JC1 (Thermo Fisher) as a sensitive marker of mitochondrial membrane potential (ΔΨm) 37,38 …”

“…Differentiation was monitored by flow cytometry, gating on live 7-actinomycin D (7-AAD)-negative cells for immunophenotypic quantification of CD41a (integrin α IIb , MK), Annexin V as a marker of PS exposure and apoptosis, 34,36 or JC1 (Thermo Fisher) as a sensitive marker of mitochondrial membrane potential (ΔΨm). 37,38…”

SETD1A regulates transcriptional pause release of heme biosynthesis genes in leukemia

“…Gln and Glu are known ingredients for the heme biosynthesis pathway, and defective Gln metabolism was also observed in heme degradation enzyme BLVRB -knockout cells. 24 We therefore hypothesized that SETD1A-deficient cells may have lower consumption of these metabolites ( Figure 3G ). To examine the role of the heme biosynthesis pathway in Gln accumulation, we evaluated Gln levels in COX15 - or HMBS -knockout cells.…”

First Attempt to Couple Proteomics with the AhR Reporter Gene Bioassay in Soil Pollution Monitoring and Assessment

“…Being reported to be significantly up-regulated in different cancers [54], it is also induced by rosiglitazone [55], an anti-diabetic drug, a derivative of troglitazone, that we found. Enrichment analysis also suggests a response to hypoxia and oxidative stress by HYOU1, MVP, GSTM2, quinone oxidoreductase-like protein 1, TST, BLVRB, and PRDX1 up-regulation in cells exposed to soil extracts (DxCS), as well as BLVRB related to heme degradation [56][57][58]. Interestingly, atrazine could be the cause of the observed oxidative stress [49].…”