Acyl carrier protein OsMTACP2 confers rice cold tolerance at the booting stage.

Low temperatures occurring at the booting stage in rice (Oryza sativa L.) often result in yield loss by impeding male reproductive development. However, the underlying mechanisms by which rice responds to cold at this stage remain largely unknown. Here, we identified MITOCHONDRIAL ACYL CARRIER PROTEIN 2 (OsMTACP2), the encoded protein of which mediates lipid metabolism involved in the cold response at the booting stage. Loss of OsMTACP2 function compromised cold tolerance, hindering anther cuticle and pollen wall development, resulting in abnormal anther morphology, lower pollen fertility and seed setting. OsMTACP2 was highly expressed in tapetal cells and microspores during anther development, with the encoded protein localizing to both mitochondria and the cytoplasm. Comparative transcriptomic analysis revealed differential expression of genes related to lipid metabolism between the wild type and the Osmtacp2-1 mutant in response to cold. Through a lipidomic analysis, we demonstrated that wax esters, which are the primary lipid components of the anther cuticle and pollen walls, function as cold-responsive lipids. Their levels increased dramatically in the wild type but not in Osmtacp2-1 when exposed to cold. Additionally, mutants of two cold induced genes of wax ester biosynthesis, ECERIFERUM1 and WAX CRYSTAL-SPARSE LEAF2, showed decreased cold tolerance. These results suggest that OsMTACP2-mediated wax ester biosynthesis is essential for cold tolerance in rice at the booting stage.

Dysregulation of acyl carnitines, pentose phosphate pathway and arginine and ornithine metabolism are associated with decline in intrinsic capacity in Chinese older adults.

BACKGROUND: Intrinsic capacity is the combination of individual physical and mental abilities, reflecting the aging degree of the older adults. However, the mechanisms and metabolic characteristics of the decline in intrinsic capacity are still unclear. AIMS: To identify metabolic signatures and associated pathways of decline in intrinsic capacity based on the metabolite features. METHODS: We recruited 70 participants aged 77.19 ± 8.31 years. The five domains of intrinsic capacity were assessed by Short Physical Performance Battery (for mobility), Montreal cognition assessment (for cognition), 30-Item Geriatric Depression Scale (for psychology), self-reported hearing/visual impairment (for sensory) and Nutritional risk screening (for vitality), respectively. The serum samples of participants were analyzed by liquid chromatography-mass spectrometry-based metabolomics, followed by metabolite set enrichment analysis and metabolic pathway analysis. RESULTS: There were 50 participants with a decline in intrinsic capacity in at least one of the domains. A total of 349 metabolites were identified from their serum samples. Overall, 24 differential metabolites, 5 metabolite sets and 13 pathways were associated with the decline in intrinsic capacity. DISCUSSION: Our results indicated that decline in intrinsic capacity had unique metabolomic profiles. CONCLUSION: The specific change of acyl carnitines was observed to be a feature of decline in intrinsic capacity. Dysregulation of the pentose phosphate pathway and of arginine and ornithine metabolism was strongly associated with the decline in intrinsic capacity.

Low-input lipidomics reveals lipid metabolism remodelling during early mammalian embryo development.

Lipids are indispensable for energy storage, membrane structure and cell signalling. However, dynamic changes in various categories of endogenous lipids in mammalian early embryonic development have not been systematically characterized. Here we comprehensively investigated the dynamic lipid landscape during mouse and human early embryo development. Lipid signatures of different developmental stages are distinct, particularly for the phospholipid classes. We highlight that the high degree of phospholipid unsaturation is a conserved feature as embryos develop to the blastocyst stage. Moreover, we show that lipid desaturases such as SCD1 are required for in vitro blastocyst development and blastocyst implantation. One of the mechanisms is through the regulation of unsaturated fatty-acid-mediated fluidity of the plasma membrane and apical proteins and the establishment of apical-basal polarity during development of the eight-cell embryo to the blastocyst. Overall, our study provides an invaluable resource about the remodelling of the endogenous lipidome in mammalian preimplantation embryo development and mechanistic insights into the regulation of embryogenesis and implantation by lipid unsaturation.

Brain glucose induces tolerance of Cryptococcus neoformans to amphotericin B during meningitis.

Antibiotic tolerance is the ability of a susceptible population to survive high doses of cidal drugs and has been shown to compromise therapeutic outcomes in bacterial infections. In comparison, whether fungicide tolerance can be induced by host-derived factors during fungal diseases remains largely unknown. Here, through a systematic evaluation of metabolite-drug-fungal interactions in the leading fungal meningitis pathogen, Cryptococcus neoformans, we found that brain glucose induces fungal tolerance to amphotericin B (AmB) in mouse brain tissue and patient cerebrospinal fluid via the fungal glucose repression activator Mig1. Mig1-mediated tolerance limits treatment efficacy for cryptococcal meningitis in mice via inhibiting the synthesis of ergosterol, the target of AmB, and promoting the production of inositolphosphorylceramide, which competes with AmB for ergosterol. Furthermore, AmB combined with an inhibitor of fungal-specific inositolphosphorylceramide synthase, aureobasidin A, shows better efficacy against cryptococcal meningitis in mice than do clinically recommended therapies.

PAFAH2 suppresses synchronized ferroptosis to ameliorate acute kidney injury.

Synchronized ferroptosis contributes to nephron loss in acute kidney injury (AKI). However, the propagation signals and the underlying mechanisms of the synchronized ferroptosis for renal tubular injury remain unresolved. Here we report that platelet-activating factor (PAF) and PAF-like phospholipids (PAF-LPLs) mediated synchronized ferroptosis and contributed to AKI. The emergence of PAF and PAF-LPLs in ferroptosis caused the instability of biomembranes and signaled the cell death of neighboring cells. This cascade could be suppressed by PAF-acetylhydrolase (II) (PAFAH2) or by addition of antibodies against PAF. Genetic knockout or pharmacological inhibition of PAFAH2 increased PAF production, augmented synchronized ferroptosis and exacerbated ischemia/reperfusion (I/R)-induced AKI. Notably, intravenous administration of wild-type PAFAH2 protein, but not its enzymatically inactive mutants, prevented synchronized tubular cell death, nephron loss and AKI. Our findings offer an insight into the mechanisms of synchronized ferroptosis and suggest a possibility for the preventive intervention of AKI.

Skeletal muscle-secreted DLPC orchestrates systemic energy homeostasis by enhancing adipose browning.

MyoD is a skeletal muscle-specifically expressed transcription factor and plays a critical role in regulating myogenesis during muscle development and regeneration. However, whether myofibers-expressed MyoD exerts its metabolic function in regulating whole body energy homeostasis in vivo remains largely unknown. Here, we report that genetic deletion of Myod in male mice enhances the oxidative metabolism of muscle and, intriguingly, renders the male mice resistant to high fat diet-induced obesity. By performing lipidomic analysis in muscle-conditioned medium and serum, we identify 1,2-dilinoleoyl-sn-glycero-3-phosphocholine (DLPC) as a muscle-released lipid that is responsible for MyoD-orchestrated body energy homeostasis in male Myod KO mice. Functionally, the administration of DLPC significantly ameliorates HFD-induced obesity in male mice. Mechanistically, DLPC is found to induce white adipose browning via lipid peroxidation-mediated p38 signaling in male mice. Collectively, our findings not only uncover a novel function of MyoD in controlling systemic energy homeostasis through the muscle-derived lipokine DLPC but also suggest that the DLPC might have clinical potential for treating obesity in humans.

Ceramide d18:1/24:1 as a potential biomarker to differentiate obesity subtypes with unfavorable health outcomes.

BACKGROUND: The criteria for metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO) remain controversial. This research aimed to identify a potential biomarker to differentiate the subtypes of obesity. METHODS: The study conducted a lipidomic evaluation of ceramide in the serum of 77 Chinese adults who had undergone hyperinsulinemic-euglycemic clamps. These adults were divided into three groups according to the clinical data: normal weight control group (N = 21), MHO (N = 20), and MUO (N = 36). RESULTS: The serum Cer d18:1/24:1 level in the MHO group was lower than that in the MUO group. As the Cer d18:1/24:1 level increased, insulin sensitivity decreased, and the unfavorable parameters increased in parallel. Multivariate logistic regression analysis revealed that serum Cer d18:1/24:1 levels were independently correlated with MUO in obesity. Individuals with higher levels of Cer d18:1/24:1 also had an elevated risk of cardiovascular disease. Most ceramide subtype levels increased in obesity compared to normal-weight individuals, but the levels of serum Cer d18:0/18:0 and Cer d18:1/16:0 decreased in obesity. CONCLUSIONS: The relationships between ceramide subtypes and metabolic profiles might be heterogeneous in populations with different body weights. Cer d18:1/24:1 could be a biomarker that can be used to differentiate MUO from MHO, and to better predict who will develop unfavorable health outcomes among obese individuals. TRIAL REGISTRATION: The First Affiliated Hospital of Nanjing Medical University's Institutional Review Board authorized this study protocol, and all participants provided written informed consent (2014-SR-003) prior to study entry.

Maternal High Fat Diet in Lactation Impacts Hypothalamic Neurogenesis and Neurotrophic Development, Leading to Later Life Susceptibility to Obesity in Male but Not Female Mice.

Early life nutrition can reprogram development and exert long-term consequences on body weight regulation. In mice, maternal high-fat diet (HFD) during lactation predisposed male but not female offspring to diet-induced obesity when adult. Molecular and cellular changes in the hypothalamus at important time points are examined in the early postnatal life in relation to maternal diet and demonstrated sex-differential hypothalamic reprogramming. Maternal HFD in lactation decreased the neurotropic development of neurons formed at the embryo stage (e12.5) and impaired early postnatal neurogenesis in the hypothalamic regions of both males and females. Males show a larger increased ratio of Neuropeptide Y (NPY) to Pro-opiomelanocortin (POMC) neurons in early postnatal neurogenesis, in response to maternal HFD, setting an obese tone for male offspring. These data provide insights into the mechanisms by which hypothalamic reprograming by early life overnutrition contributes to the sex-dependent susceptibility to obesity in adult life in mice.

Multi-omics profiling reveals rhythmic liver function shaped by meal timing.

Post-translational modifications (PTMs) couple feed-fast cycles to diurnal rhythms. However, it remains largely uncharacterized whether and how meal timing organizes diurnal rhythms beyond the transcriptome. Here, we systematically profile the daily rhythms of the proteome, four PTMs (phosphorylation, ubiquitylation, succinylation and N-glycosylation) and the lipidome in the liver from young female mice subjected to either day/sleep time-restricted feeding (DRF) or night/wake time-restricted feeding (NRF). We detect robust daily rhythms among different layers of omics with phosphorylation the most nutrient-responsive and succinylation the least. Integrative analyses reveal that clock regulation of fatty acid metabolism represents a key diurnal feature that is reset by meal timing, as indicated by the rhythmic phosphorylation of the circadian repressor PERIOD2 at Ser971 (PER2-pSer971). We confirm that PER2-pSer971 is activated by nutrient availability in vivo. Together, this dataset represents a comprehensive resource detailing the proteomic and lipidomic responses by the liver to alterations in meal timing.

Centrins control chicken cone cell lipid droplet dynamics through lipid-droplet-localized SPDL1.

As evolutionarily conserved organelles, lipid droplets (LDs) carry out numerous functions and have various subcellular localizations in different cell types and species. In avian cone cells, there is a single apically localized LD. We demonstrated that CIDEA (cell death inducing DFFA like effector a) and microtubules promote the formation of the single LD in chicken cone cells. Centrins, which are well-known centriole proteins, target to the cone cell LD via their C-terminal calcium-binding domains. Centrins localize on cone cell LDs with the help of SPDL1-L (spindle apparatus coiled-coil protein 1-L), a previously uncharacterized isoform of the kinetochore-associated dynein adaptor SPDL1. The loss of CETN3 or overexpression of a truncated CETN1 abrogates the apical localization of the cone cell LD. Simulation analysis showed that multiple LDs or a single mispositioned LD reduces the light sensitivity. Collectively, our findings identify a role of centrins in the regulation of cone cell LD localization, which is important for the light sensitivity of cone cells.

Multiomics Approaches Identify Biomarkers for BAT Thermogenesis.

Brown adipose tissue (BAT) thermogenesis confers beneficial effects on metabolic diseases such as obesity and type-2 diabetes. Nevertheless, the mechanism and lipid driving the process that evokes this response have not been investigated yet. Here, a multiomics approach of integrative transcriptomics and lipidomics is used to explore the mechanism of regulating thermogenesis in BAT and providing promising lipid biomarkers and biomarker genes for thermogenic activators as antiobesity drugs. Lipidomics analysis demonstrated that a high abundance of glycerophospholipids and sphingolipids was more significant in BAT than in WAT. Enrichment analysis of upregulated DEGs between WAT and BAT screened suggested that the differences were mainly involved in lipid metabolism. Besides, ß3-adrenergic agonist stimulation reduced the levels of TAG and DAG and increased the content of PC, PE, CL, and LPC and expression of genes involved in thermogenesis, fatty acid elongation, and glycerophospholipid metabolism in BAT. In this study, based on interpreting the inherent characterization of BAT as thermogenic tissue through comparison with WAT as fat storage tissue, adrenergic stimulation-induced BAT thermogenesis further identified specific lipid biomarkers (7 TAG species, 10 PC species, 1 LPC species, and 1 CL species) and Elovl3 and Crat gene biomarkers, which may provide targets for combating obesity by boosting BAT thermogenesis.

Differential effects of social isolation on oligodendrocyte development in different brain regions: insights from a canine model.

Social isolation (SI) exerts diverse adverse effects on brain structure and function in humans. To gain an insight into the mechanisms underlying these effects, we conducted a systematic analysis of multiple brain regions from socially isolated and group-housed dogs, whose brain and behavior are similar to humans. Our transcriptomic analysis revealed reduced expression of myelin-related genes specifically in the white matter of prefrontal cortex (PFC) after SI during the juvenile stage. Despite these gene expression changes, myelin fiber organization in PFC remained unchanged. Surprisingly, we observed more mature oligodendrocytes and thicker myelin bundles in the somatosensory parietal cortex in socially isolated dogs, which may be linked to an increased expression of ADORA2A, a gene known to promote oligodendrocyte maturation. Additionally, we found a reduced expression of blood-brain barrier (BBB) structural components Aquaporin-4, Occludin, and Claudin1 in both PFC and parietal cortices, indicating BBB disruption after SI. In agreement with BBB disruption, myelin-related sphingolipids were increased in cerebrospinal fluid in the socially isolated group. These unexpected findings show that SI induces distinct alterations in oligodendrocyte development and shared disruption in BBB integrity in different cortices, demonstrating the value of dogs as a complementary animal model to uncover molecular mechanisms underlying SI-induced brain dysfunction.

Distinctive metabolic remodeling in TYMP deficiency beyond mitochondrial dysfunction.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is caused by mutations in the TYMP gene, which encodes thymidine phosphorylase (TP). As a cytosolic metabolic enzyme, TP defects affect biological processes that are thought to not be limited to the abnormal replication of mitochondrial DNA. This study aimed to elucidate the characteristic metabolic alterations and associated homeostatic regulation caused by TYMP deficiency. The pathogenicity of novel TYMP variants was evaluated in terms of clinical features, genetic analysis, and structural instability. We analyzed plasma samples from three patients with MNGIE; three patients with m.3243A > G mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS); and four healthy controls (HC) using both targeted and untargeted metabolomics techniques. Transcriptomics analysis and bioenergetic studies were performed on skin fibroblasts from participants in these three groups. A TYMP overexpression experiment was conducted to rescue the observed changes. Compared with controls, specific alterations in nucleosides, bile acids, and steroid metabolites were identified in the plasma of MNGIE patients. Comparable mitochondrial dysfunction was present in fibroblasts from patients with TYMP deficiency and in those from patients with the m.3243A > G mutation. Distinctively decreased sterol regulatory element binding protein (SREBP) regulated cholesterol metabolism and fatty acid (FA) biosynthesis as well as reduced FA degradation were revealed in fibroblasts with TYMP deficiency. The restoration of thymidine phosphorylase activity rescued the observed changes in MNGIE fibroblasts. Our findings indicated that more widespread metabolic disturbance may be caused by TYMP deficiency in addition to mitochondrial dysfunction, which expands our knowledge of the biochemical outcome of TYMP deficiency. KEY MESSAGES: Distinct metabolic profiles in patients with TYMP deficiency compared to those with m.3243A > G mutation. TYMP deficiency leads to a global disruption of nucleoside metabolism. Cholesterol and fatty acid metabolism are inhibited in individuals with MNGIE. TYMP is functionally related to SREBP-regulated pathways. Potential metabolite biomarkers that could be valuable clinical tools to improve the diagnosis of MNGIE.

Adipocyte Rnf20 ablation increases the fast-twitch fibers of skeletal muscle via lysophosphatidylcholine 16:0.

Both adipose tissue and skeletal muscle are highly dynamic tissues and interact at the metabolic and hormonal levels in response to internal and external stress, and they coordinate in maintaining whole-body metabolic homeostasis. In our previous study, we revealed that adipocyte-specific Rnf20 knockout mice (ASKO mice) exhibited lower fat mass but higher lean mass, providing a good model for investigating the adipose-muscle crosstalk and exploring the effect of the adipocyte Rnf20 gene on the physiology and metabolism of skeletal muscle. Here, we confirmed that ASKO mice exhibited the significantly increased body weight and gastrocnemius muscle weight. Fiber-type switching in the soleus muscle of ASKO mice was observed, as evidenced by the increased number of fast-twitch fibers and decreased number of slow-twitch fibers. Serum metabolites with significant alteration in abundance were identified by metabolomic analysis and the elevated lysophosphatidylcholine 16:0 [LysoPC (16:0)] was observed in ASKO mice. In addition, lipidome analysis of gonadal white adipose tissue revealed a significant increase in LysoPCs and LysoPC (16:0) in ASKO mice. Furthermore, knockdown of Rnf20 gene in 3T3-L1 cells significantly increased the secretion of LysoPC, suggesting that LysoPC might be a critical metabolite in the adipose-muscle crosstalk of ASKO mice. Furthermore, in vitro study demonstrated that LysoPC (16:0) could induce the expression of fast-twitch muscle fibers related genes in differentiated C2C12 cells, indicating its potential role in adipose-muscle crosstalk. Taken together, these findings not only expand our understanding of the biological functions of Rnf20 gene in systemic lipid metabolism, but also provide insight into adipose tissue dysfunction-induced physiological alterations in skeletal muscle.

Emerging roles and therapeutic potentials of sphingolipids in pathophysiology: Emphasis on fatty acyl heterogeneity.

Sphingolipids not only exert structural roles in cellular membranes, but also act as signaling molecules in various physiological and pathological processes. A myriad of studies have shown that abnormal levels of sphingolipids and their metabolic enzymes are associated with a variety of human diseases. Moreover, blood sphingolipids can also be used as biomarkers for disease diagnosis. This review summarizes the biosynthesis, metabolism, and pathological roles of sphingolipids, with emphasis on the biosynthesis of ceramide, the precursor for the biosynthesis of complex sphingolipids with different fatty acyl chains. The possibility of using sphingolipids for disease prediction, diagnosis, and treatment is also discussed. Targeting endogenous ceramides and complex sphingolipids along with their specific fatty acyl chain to promote future drug development will also be discussed.

Daytime-restricted feeding enhances running endurance without prior exercise in mice.

Physical endurance and energy conservation are essential for survival in the wild. However, it remains unknown whether and how meal timing regulates physical endurance and muscle diurnal rhythms. Here, we show that day/sleep time-restricted feeding (DRF) enhances running endurance by 100% throughout the circadian cycle in both male and female mice, compared to either ad libitum feeding or night/wake time-restricted feeding. Ablation of the circadian clock in the whole body or the muscle abolished the exercise regulatory effect of DRF. Multi-omics analysis revealed that DRF robustly entrains diurnal rhythms of a mitochondrial oxidative metabolism-centric network, compared to night/wake time-restricted feeding. Remarkably, muscle-specific knockdown of the myocyte lipid droplet protein perilipin-5 completely mimics DRF in enhancing endurance, enhancing oxidative bioenergetics and outputting rhythmicity to circulating energy substrates, including acylcarnitine. Together, our work identifies a potent dietary regimen to enhance running endurance without prior exercise, as well as providing a multi-omics atlas of muscle circadian biology regulated by meal timing.

Homeostasis of flavonoids and triterpenoids most likely modulates starch metabolism for pollen tube penetration in rice.

In angiosperms, the timely delivery of sperm cell nuclei by pollen tube (PT) to the ovule is vital for double fertilization. Penetration of PT into maternal stigma tissue is a critical step for sperm cell nuclei delivery, yet little is known about the process. Here, a male-specific and sporophytic mutant xt6, where PTs are able to germinate but unable to penetrate the stigma tissue, is reported in Oryza sativa. Through genetic study, the causative gene was identified as Chalcone synthase (OsCHS1), encoding the first enzyme in flavonoid biosynthesis. Indeed, flavonols were undetected in mutant pollen grains and PTs, indicating that the mutation abolished flavonoid biosynthesis. Nevertheless, the phenotype cannot be rescued by exogenous application of quercetin and kaempferol as reported in maize and petunia, suggesting a different mechanism exists in rice. Further analysis showed that loss of OsCHS1 function disrupted the homeostasis of flavonoid and triterpenoid metabolism and led to the accumulation of triterpenoid, which inhibits significantly α-amylase activity, amyloplast hydrolysis and monosaccharide content in xt6, these ultimately impaired tricarboxylic acid (TCA) cycle, reduced ATP content and lowered the turgor pressure as well. Our findings reveal a new mechanism that OsCHS1 modulates starch hydrolysis and glycometabolism through modulating the metabolic homeostasis of flavonoids and triterpenoids which affects α-amylase activity to maintain PT penetration in rice, which contributes to a better understanding of the function of CHS1 in crop fertility and breeding.

OsTST1, a key tonoplast sugar transporter from source to sink, plays essential roles in affecting yields and height of rice (Oryza sativa L.).

MAIN CONCLUSION: OsTST1 affects yield and development and mediates sugar transportation of plants from source to sink in rice, which influences the accumulation of intermediate metabolites from tricarboxylic acid cycle indirectly. Tonoplast sugar transporters (TSTs) are essential for vacuolar sugar accumulation in plants. Carbohydrate transport across tonoplasts maintains the metabolic balance in plant cells, and carbohydrate distribution is crucial to plant growth and productivity. Large plant vacuoles store high concentrations of sugars to meet plant requirements for energy and other biological processes. The abundance of sugar transporter affects crop biomass and reproductive growth. However, it remains unclear whether the rice (Oryza sativa L.) sugar transport protein OsTST1 affects yield and development. In this study, we found that OsTST1 knockout mutants generated via CRISPR/Cas9 exhibited slower development, smaller seeds, and lower yield than wild type (WT) rice plants. Notably, plants overexpressing OsTST1 showed the opposite effects. Changes in rice leaves at 14 days after germination (DAG) and at 10 days after flowering (DAF) suggested that OsTST1 affected the accumulation of intermediate metabolites from the glycolytic pathway and the tricarboxylic acid (TCA) cycle. The modification of the sugar transport between cytosol and vacuole mediated by OsTST1 induces deregulation of several genes including transcription factors (TFs). In summary, no matter the location of sucrose and sink is, these preliminary results revealed that OsTST1 was important for sugar transport from source to sink tissues, thus affecting plant growth and development.

Global determination of reaction rates and lipid turnover kinetics in Mus musculus.

Metabolism is fundamental to life, but measuring metabolic reaction rates remains challenging. Here, we applied C13 fluxomics to monitor the metabolism of dietary glucose carbon in 12 tissues, 9 brain compartments, and over 1,000 metabolite isotopologues over a 4-day period. The rates of 85 reactions surrounding central carbon metabolism are determined with elementary metabolite unit (EMU) modeling. Lactate oxidation, not glycolysis, occurs at a comparable pace with the tricarboxylic acid cycle (TCA), supporting lactate as the primary fuel. We expand the EMU framework to track and quantify metabolite flows across tissues. Specifically, multi-organ EMU simulation of uridine metabolism shows that tissue-blood exchange, not synthesis, controls nucleotide homeostasis. In contrast, isotopologue fingerprinting and kinetic analyses reveal the brown adipose tissue (BAT) having the highest palmitate synthesis activity but no apparent contribution to circulation, suggesting a tissue-autonomous synthesis-to-burn mechanism. Together, this study demonstrates the utility of dietary fluxomics for kinetic mapping in vivo and provides a rich resource for elucidating inter-organ metabolic cross talk.