T cell activation is associated with a profound and rapid metabolic response to meet increased energy demands for cell division, differentiation and development of effector function. Glucose uptake and engagement of the glycolytic pathway are major checkpoints for this event. Here we show that the low-affinity, concentration-dependent glucose transporter 2 (Glut2) regulates the development of CD8+ T cell effector responses in mice by promoting glucose uptake, glycolysis and glucose storage. Expression of Glut2 is modulated by environmental factors including glucose and oxygen availability and extracellular acidification. Glut2 is highly expressed by circulating, recently primed T cells, allowing efficient glucose uptake and storage. In glucose-deprived inflammatory environments, Glut2 becomes downregulated, thus preventing passive loss of intracellular glucose. Mechanistically, Glut2 expression is regulated by a combination of molecular interactions involving hypoxia-inducible factor-1 alpha, galectin-9 and stomatin. Finally, we show that human T cells also rely on this glucose transporter, thus providing a potential target for therapeutic immunomodulation.
© 2023. The Author(s).

Hematopoiesis requires the coordinated differentiation of hematopoietic stem cells and progenitor cells (HSPCs) in multiple tissues. Although differentiation of HSPCs in bone marrow (BM) has been well-studied, our knowledge about the migration and differentiation of HSPCs cross tissues is limited. Here, we collected and integrated single-cell RNA-seq data of human CD34+ cells, which represent HSPCs, from BM, peripheral blood (PB), thymus and mobilized PB (mPB), to investigate the hematopoiesis cross tissues. We constructed a cell atlas of HSPCs cross tissues and found most HSPC subsets in BM had counterparts in PB, indicating migration of HSPCs from BM to PB has a much broad spectrum. We found B progenitors highly expressed CXCR4 for anchoring in BM, while cells with low expression of CXCR4 facilitate their migration out of BM. Among the HSPC subsets from thymus, we only found the counterparts of the earliest thymic progenitors (ETPs) in BM and PB, potentially indicating that ETPs were the subsets that migrated from BM to PB and thymus. We found interaction signaling including CD99 - CD99 , CXCL12 - CXCR4 and CCL19 - CCR7 played important roles in ETP homing to thymus. Briefly, these data provided a single unified developmental spectrum of hematopoiesis cross different tissues, connected by cell migration.

Preclinical studies of primary cancer cells are typically done after tumors are removed from patients or animals at ambient atmospheric oxygen (O2, ~21%). However, O2 concentrations in organs are in the ~3 to 10% range, with most tumors in a hypoxic or 1 to 2% O2 environment in vivo. Although effects of O2 tension on tumor cell characteristics in vitro have been studied, these studies are done only after tumors are first collected and processed in ambient air. Similarly, sensitivity of primary cancer cells to anticancer agents is routinely examined at ambient O2. Here, we demonstrate that tumors collected, processed, and propagated at physiologic O2 compared to ambient air display distinct differences in key signaling networks including LGR5/WNT, YAP, and NRF2/KEAP1, nuclear reactive oxygen species, alternative splicing, and sensitivity to targeted therapies. Therefore, evaluating cancer cells under physioxia could more closely recapitulate their physiopathologic status in the in vivo microenvironment.

Glycogen storage disease type 1a (GSD Ia) is a rare inherited metabolic disorder caused by mutations in the glucose-6-phosphatase (G6PC1) gene. When untreated, GSD Ia leads to severe fasting-induced hypoglycemia. Although current intensive dietary management aims to prevent hypoglycemia, patients still experience hypoglycemic events. Poor glycemic control in GSD Ia is associated with hypertriglyceridemia, hepatocellular adenoma and carcinoma, and also with an increased bleeding tendency of unknown origin.
To evaluate the effect of glycemic control on leukocyte levels and coagulation in GSD Ia, we employed hepatocyte-specific G6pc1 deficient (L-G6pc-/-) mice under fed or fasted conditions, to match good or poor glycemic control in GSD Ia, respectively.
We found that fasting-induced hypoglycemia in L-G6pc-/- mice decreased blood leukocytes, specifically proinflammatory Ly6Chi monocytes, compared to controls. Refeeding reversed this decrease. The decrease in Ly6Chi monocytes was accompanied by an increase in plasma corticosterone levels and was prevented by the glucocorticoid receptor antagonist mifepristone. Further, fasting-induced hypoglycemia in L-G6pc-/- mice prolonged bleeding time in the tail vein bleeding assay, with reversal by refeeding. This could not be explained by changes in coagulation factors V, VII, or VIII, or von Willebrand factor. While the prothrombin and activated partial thromboplastin time as well as total platelet counts were not affected by fasting-induced hypoglycemia in L-G6pc-/- mice, ADP-induced platelet aggregation was disturbed.
These studies reveal a relationship between fasting-induced hypoglycemia, decreased blood monocytes, and disturbed platelet aggregation in L-G6pc-/- mice. While disturbed platelet aggregation likely accounts for the bleeding phenotype in GSD Ia, elevated plasma corticosterone decreases the levels of proinflammatory monocytes. These studies highlight the necessity of maintaining good glycemic control in GSD Ia.
Copyright © 2021 The Author(s). Published by Elsevier GmbH.. All rights reserved.

Crlz-1 was expressed along with Wnt3a in the rapidly proliferating centroblasts within the dark zone of germinal center (GC) during humoral immune responses. Significantly, Crlz-1 relayed a Wnt/β-catenin signal to the expression of Bcl-6, the master regulator of centroblasts, by mobilizing the cytoplasmic CBFβ into the nucleus to allow Runx/CBFβ heterodimerization and its subsequent binding to the Bcl-6 promoter. The knockdown of Crlz-1 or β-catenin, as well as inhibition of Wnt signaling in the centroblasts, led to the decreased expression of Bcl-6 and, thereby, the altered expression of its various target genes, resulting in their diminished proliferation. Consistently, the administration of Wnt inhibitors into the immunized mice impaired or abolished GC reaction, with concomitant decreases of Crlz-1 and Bcl-6 expression and, thus, centroblastic proliferation. Our observation that Wnt/β-catenin signaling via Crlz-1 regulates GC reaction would suggest developmental strategies for vaccine adjuvants and cancer therapeutics because both immune efficacy and accidental lymphoma depend on GC reaction. Our studies of Crlz-1 were performed using human cell lines, mice, and their primary cells.
Copyright © 2019 by The American Association of Immunologists, Inc.