Adapting the energy metabolism state to changing bioenergetic demands is essential for mammalian development accompanying massive cell proliferation and cell differentiation. However, it remains ...unclear how developing embryos meet the changing bioenergetic demands during the chorioallantoic branching (CB) stage, when the maternal-fetal exchange of gases and nutrients is promoted. In this study, using metabolome analysis with mass-labeled glucose, we found that developing embryos redirected glucose carbon flow into the pentose phosphate pathway via suppression of the key glycolytic enzymes PFK-1 and aldolase during CB. Concomitantly, embryos exhibited an increase in lactate pool size and in the fractional contribution of glycolysis to lactate biosynthesis. Imaging mass spectrometry visualized lactate-rich tissues, such as the dorsal or posterior neural tube, somites and head mesenchyme. Furthermore, we found that the heterochronic gene Lin28a could act as a regulator of the metabolic changes observed during CB. Perturbation of glucose metabolism rewiring by suppressing Lin28a downregulation resulted in perinatal lethality. Thus, our work demonstrates that developing embryos rewire glucose metabolism following CB for normal development.
Although oxidized phosphatidylcholines (oxPCs) play critical roles in numerous pathological events, the type and production sites of endogenous oxPCs remain unknown because of the lack of structural ...information and dedicated analytical methods. Herein, a library of 465 oxPCs is constructed using high-resolution mass spectrometry-based non-targeted analytical methods and employed to detect 70 oxPCs in mice with acetaminophen-induced acute liver failure. We show that doubly oxygenated polyunsaturated fatty acid (PUFA)-PCs (PC PUFA;O2), containing epoxy and hydroxide groups, are generated in the early phase of liver injury. Hybridization with in-vivo
O labeling and matrix-assisted laser desorption/ionization-tandem MS imaging reveals that PC PUFA;O2 are accumulated in cytochrome P450 2E1-expressing and glutathione-depleted hepatocytes, which are the major sites of liver injury. The developed library and visualization methodology should facilitate the characterization of specific lipid peroxidation events and enhance our understanding of their physiological and pathological significance in lipid peroxidation-related diseases.
In the geological disposal system of high-level radioactive and transuranic wastes, an increase in Ca concentration (arising from the alteration of cementitious materials) could affect the retention ...of other radionuclides due to competitive sorption. Batch sorption experiments were performed to investigate the sorption behavior of Ca and its competition with other divalent cations (Sr and Ni) on the edge sites of Kunipia F montmorillonite under alkaline conditions. Ca sorption increased with pH (when pH > 8) and it was more pronounced under high ionic strength conditions, indicating that Ca formed a surface complexation with the edge sites. The sorption behavior of Sr was similar to that of Ca. Meanwhile, the Ni sorption increased with pH, when this was >6 (for lower pH values than in the case of Ca and Sr), Ni tends to form surface complexes more readily than Ca and Sr. The results of a fitting analysis conducted based on the 2-site protolysis non-electrostatic surface complexation and cation exchange (2SPNE SC/CE) model indicate that Ca and Sr sorb onto the ≡SW2OH sites and Ni sorbs onto the ≡SSOH sites. Additionally, the sorption of the CaOH+ and SrOH+ ionic pair species by cation exchange was implied at pH ~ 12. Competitive sorption experiments were also carried out to evaluate the effect of Ca on the sorption of Sr and Ni. Sr sorption decreased with Ca concentration in the alkaline pH region, whereas Ni sorption was not affected by Ca concentration. Overall, these results indicate that Ca and Sr sorb onto the same sites, while Ca and Ni sorb onto different sites; additionally, the competitive sorption seemed to depend on chemical similarities (e.g., hydrolysis behavior). The sorption model parameters obtained from the single-element batch sorption experiments successfully reproduced the results of the competitive sorption experiments.
•Ca sorption and its effects on Sr and Ni sorption on montmorillonite under alkaline conditions were investigated.•Ca and Sr form surface complexation with the edge sites of montmorillonite.•Ca and Sr compete with each other under alkaline conditions, whereas Ca and Ni do not.•The 2SPNE SC/CE model reproduced the results of the competitive sorption experiments.
Octacalcium phosphate (OCP) has been considered as the layer component of calcium phosphate, but whether it achieves the ionic-exchange ability of conventional layer components is unclear. As OCP is ...highly biocompatible, understanding its ionic-exchange properties would potentially expand its pharmaceutical and medical applications. Herein, we demonstrate that the substituted cations in ammonium (NH
4
)-substituted octacalcium phosphate (OCP-NH
4
) and sodium (Na)-containing ammonium phosphate solutions undergo ion exchanges with OCP interlayers. Replacing NH
4
+
with Na
+
did not alter the crystal structure of OCP, confirming that a substituted cation exchange process similar to that in other layered compounds occurs in OCP.
Octacalcium phosphate (OCP) has been considered as the layer component of calcium phosphate, but whether it achieves the ionic-exchange ability of conventional layer components is unclear. In this study, we demonstrated the evidence of ionic exchange process at the interlayer of OCP.
Murine coronavirus (CoV) is a beta-CoV that infects mice by binding to carcinoembryonic antigen-related cell adhesion molecule 1. Intraperitoneal infection with the murine CoV strain JHM (JHMV) ...induces acute mild hepatitis in mice. While both innate and acquired immune responses play a significant role in the protection against murine CoV infection in mice, CD8+ cytotoxic T lymphocytes (CTLs) and interferon-γ are essential for viral clearance in JHMV-induced hepatitis. In addition, CoVs are characterized by high diversity, caused by mutations, recombination, and gene gain/loss. 25V16G is an immune-escape JHMV variant, which lacks a dominant CTL epitope. By evading immune responses, 25V16G establishes persistent infections, leading to granulomatous serositis in interferon-γ-deficient mice. These examples of CoV-associated pathogenesis in mice might provide useful information on other CoV infections, including coronavirus disease 2019 (COVID-19).
Spermidine (SPD) delays age-related pathologies in various organisms. SPD supplementation overcame the impaired immunotherapy against tumors in aged mice by increasing mitochondrial function and ...activating CD8
+
T cells. Treatment of naïve CD8
+
T cells with SPD acutely enhanced fatty acid oxidation. SPD conjugated to beads bound to the mitochondrial trifunctional protein (MTP). In the MTP complex, synthesized and purified from
Escherichia coli
, SPD bound to the α and β subunits of MTP with strong affinity and allosterically enhanced their enzymatic activities. T cell–specific deletion of the MTP α subunit abolished enhancement of programmed cell death protein 1 (PD-1) blockade immunotherapy by SPD, indicating that MTP is required for SPD-dependent T cell activation.
Spermidine fights cancer in aging mice
Abundance of the polyamine spermidine decreases in aging mice, and supplementation can have restorative effects and extend life span. Al-Habsi
et al
. explored whether loss of spermidine might contribute to loss of antitumor immunity in aged mice. Restoration of spermidine concentrations enhanced antitumor responses stimulated by programmed death ligand-1 (PD-L1) monoclonal antibody therapy. Spermidine appeared to directly affect T cell function by increasing fatty acid oxidation. Tagged spermidine bound to components of the mitochondrial trifunctional protein complex, thus increasing fatty acid oxidation and the production of ATP. The authors propose that these effects may contribute to the effects of spermidine in promoting longevity. —LBR
Spermidine helps to restore antitumor immunity in older mice.
INTRODUCTION
In mammals, the power of the immune system decreases with age. This is because of multiple factors, including a decrease in the output and diversity of the antigenic repertoire of T cells caused by thymus involution; changes in the cellular metabolism caused by inflammation; and defective proliferative, differentiation, or survival capacities of the immune cells. Aged individuals frequently suffer from severe infections and cancers, and often the therapies applied, including programmed cell death protein 1 (PD-1) blockade in cancer immunotherapy, are ineffective when compared with results in young patients. A biogenic polyamine, spermidine (SPD), decreases with age, and SPD supplementation was shown to improve or delay several age-related pathologies, including those of the immune system. Among the proposed mechanisms responsible for rejuvenation of the immune system by SPD were enhanced autophagy, translational activity, and mitochondrial metabolism. SPD supplementation has previously been shown to enhance the antitumor immunity in animal models. However, it remains largely unknown how SPD deficiency relates to the T cell immune suppression induced by aging.
RATIONALE
Because CD8
+
T cells are key players in tumor immunity, we investigated how aging would affect the metabolic and functional characteristics of CD8
+
T cells. We asked whether SPD insufficiency could be a factor contributing to nonresponsiveness to PD-1 antibody therapy in aged mice. We sought to characterize the CD8
+
T cell population changes induced by SPD supplementation in aged mice and to identify the molecular mechanisms for the SPD action.
RESULTS
We found that the total and free intracellular concentrations of SPD in CD8
+
T cells from aged mice were about half as much as the concentrations found in young mice. Bioenergetically, aged CD8
+
T cells showed impaired mitochondrial activity with lower oxygen consumption rate, adenosine 5′-triphosphate (ATP) production, and fatty acid oxidation (FAO) activity compared with young CD8
+
T cells.
We show that SPD supplementation enhanced the antitumor activity of PD-1 blockade immunotherapy in aged mice. SPD supplementation proved to also be effective in young mice with tumors unresponsive to single anti–programmed death-ligand 1 (PD-L1) antibody therapy. SPD and anti–PD-L1 antibody combination treatment enhanced the proliferation, cytokine production, and mitochondrial ATP production of CD8
+
T cells in vivo. In vitro, SPD effectively enhanced mitochondrial functions and metabolized palmitate into tricarboxylic acid cycle components within 1 hour, which suggests the possibility of direct SPD binding to mitochondria-related proteins. Biochemical analysis identified SPD binding to mitochondrial trifunctional protein (MTP), which is the central enzyme of fatty acid β-oxidation. MTP is composed of α and β subunits, both of which bind SPD. Several assays using the MTP synthesized and purified from
Escherichia coli
revealed that SPD bound with strong affinity binding affinity (dissociation constant,
K
d
) = 0.1 μM and allosterically enhanced their enzymatic FAO activities. Furthermore, we found that spermine, another polyamine derived from SPD with important cellular protective functions, also directly binds to MTP and competitively inhibits FAO activity of SPD, which suggests the importance of SPD and spermine balance for FAO evaluation in aged cells. T cell–specific deletion of the MTP α subunit abolished enhancement of PD-1 blockade immunotherapy by SPD, indicating that MTP is required for SPD-dependent T cell activation.
CONCLUSION
SPD enhances FAO by directly binding and activating the MTP. SPD supplementation enhances the FAO activity and boosts the mitochondrial activities and cytotoxic functions of CD8
+
T cells. We provide new insights into the properties of SPD that may facilitate the development of strategies to prevent and improve outcomes of age-related immune pathologies and combat unresponsiveness to PD-1 blockade therapy in cancers, regardless of age.
SPD binds to MTP and activates FAO in T cells.
SPD directly activates MTP, which plays a central role in FAO. SPD concentration is decreased in aged T cells, leading to low FAO activity and ATP production compared with those in young T cells. SPD supplementation activates FAO in aged and young T cells, which enhances the efficacy of PD-1 blockade cancer immunotherapy. CoA, coenzyme A; TCA, tricarboxylic acid; ETC, electron transport chain. Figure created by Biorender
We report the detection of a group of endogenous low molecular weight metabolites (LMWM) in mouse brain (80–500 Da) using TiO2 nanoparticles (NPs) in nanoparticle-assisted laser ...desorption/ionization-imaging mass spectrometry (Nano-PALDI-IMS) without any washing and separation step prior to MS analysis. The identification of metabolites using TiO2 NPs was compared with a conventional organic matrix 2,5-dihydroxybenzoic acid (DHB) where signals of 179 molecules were specific to TiO2 NPs, 4 were specific to DHB, and 21 were common to both TiO2 NPs and DHB. The use of TiO2 NPs enabled the detection of a higher number of LMWM as compared to DHB and gold NPs as a matrix. This approach is a simple, inexpensive, washing, and separation free for imaging and identification of LMWM in mouse brain. We believe that the biochemical information from distinct regions of the brain using a Nano-PALDI-IMS will be helpful in elucidating the imbalances linked with diseases in biomedical samples.
Silica is not only a biocompatible trace element but also an essential element for bone formation and metabolism. Therefore, it is often doped into bioceramics such as calcium phosphate and calcium ...carbonate for enhancing biomaterial ability. Heretofore, organic silica materials are employed as silica sources, but the residual organic matter is a significant drawback in biomaterial applications. Therefore, in this study, we introduce a one-pot inorganic synthesis method for the formation of silica-doped octacalcium phosphate (OCP) using Na
2
SiO
3
as the silica source. Silica was intercalated into the OCP unit lattice, replacing its hydrous layer structure, and then a layer-by-layer structure of apatite and silica was formed. Furthermore, by immersing the fabricated silica-doped OCP into suitable solutions, both silica-doped hydroxyapatite and carbonate apatite were fabricated through a one-step inorganic processes.
We introduced a one-pot synthesis method for silica doping of calcium phosphate. Silica easily incorporated into OCP interlayer optimizing Na
2
SiO
3
concentrations.
The hypothalamus plays a central role in monitoring and regulating systemic glucose metabolism. The brain is enriched with phospholipids containing poly-unsaturated fatty acids, which are ...biologically active in physiological regulation. Here, we show that intraperitoneal glucose injection induces changes in hypothalamic distribution and amounts of phospholipids, especially arachidonic-acid-containing phospholipids, that are then metabolized to produce prostaglandins. Knockdown of cytosolic phospholipase A2 (cPLA2), a key enzyme for generating arachidonic acid from phospholipids, in the hypothalamic ventromedial nucleus (VMH), lowers insulin sensitivity in muscles during regular chow diet (RCD) feeding. Conversely, the down-regulation of glucose metabolism by high fat diet (HFD) feeding is improved by knockdown of cPLA2 in the VMH through changing hepatic insulin sensitivity and hypothalamic inflammation. Our data suggest that cPLA2-mediated hypothalamic phospholipid metabolism is critical for controlling systemic glucose metabolism during RCD, while continuous activation of the same pathway to produce prostaglandins during HFD deteriorates glucose metabolism.
Progesterone-receptor membrane component 1 (PGRMC1/Sigma-2 receptor) is a haem-containing protein that interacts with epidermal growth factor receptor (EGFR) and cytochromes P450 to regulate cancer ...proliferation and chemoresistance; its structural basis remains unknown. Here crystallographic analyses of the PGRMC1 cytosolic domain at 1.95 Å resolution reveal that it forms a stable dimer through stacking interactions of two protruding haem molecules. The haem iron is five-coordinated by Tyr113, and the open surface of the haem mediates dimerization. Carbon monoxide (CO) interferes with PGRMC1 dimerization by binding to the sixth coordination site of the haem. Haem-mediated PGRMC1 dimerization is required for interactions with EGFR and cytochromes P450, cancer proliferation and chemoresistance against anti-cancer drugs; these events are attenuated by either CO or haem deprivation in cancer cells. This study demonstrates protein dimerization via haem-haem stacking, which has not been seen in eukaryotes, and provides insights into its functional significance in cancer.
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