Early-life vitamin B12 orchestrates lipid peroxidation to ensure reproductive success via SBP-1/SREBP1 in Caenorhabditis elegans

Maternal B12 deficiency during pregnancy dysregulates fatty acid metabolism and induces inflammation in human adipose tissue

BACKGROUND

Adipose tissue (AT) responds to excess calorie intake; however, the deficit in micronutrients accompanied by the modern lifestyle is often overlooked. Micronutrient deficiency in pregnancy, particularly vitamin B12 (B12), is commonly associated with higher adiposity, dyslipidemia, and type 2 diabetes (T2D). Studies have demonstrated that dyslipidemia can trigger pro-inflammatory status. However, the release of the pro-inflammatory factors in a tissue-specific micronutrient deficient environment is unexplored. Therefore, we investigated the role of B12 deficiency on lipid metabolism and inflammatory mediators in both in vitro and ex vivo models including human pre-adipocytes, primary adipocytes, mature human white AT (WAT), and its association with metabolic risk.

METHODS

Paired abdominal subcutaneous and omental WAT (ScWAT and OmWAT) were chosen based on serum B12 (< 150 pM) from 115 Caucasian pregnant women. Human primary Sc adipocytes from women with different BMI (lean, overweight, obese, morbidly obese) and pre-adipocyte cell line (Chub-S7) were differentiated in various concentrations of B12. Serum B12, folate, lipids, cytokines, biochemical parameters, gene expression, intracellular triglyceride (TG), and mitochondrial function were assessed.

RESULTS

In pregnant women with low B12 levels, BMI and serum TG were significantly higher, and high-density lipoprotein (HDL) was lower (p < 0.05). B12 deficiency in both depots of AT correlated with higher expression of genes in fatty acid (FA) synthesis, elongation, desaturation, TG synthesis, and reduced fatty acid oxidation (FAO) (p < 0.05). In vitro adipocytes with low B12 demonstrated that TG synthesis utilizing radiolabeled FA was higher and mitochondrial function was impaired. We also found that the expression of pro-inflammatory cytokines in AT was increased, and circulatory cytokines inversely associated with serum B12 (p < 0.05).

CONCLUSIONS

Our novel data highlights that B12 deficiency dysregulates lipids and induces inflammation in AT and circulation, which could contribute to adipocyte dysfunction exacerbating cardiometabolic risk during pregnancy.

The direct targets of metformin in diabetes and beyond

Metformin, an oral antihyperglycemic drug that has been in use for over 60 years, remains a first-line therapy for type 2 diabetes (T2D). Numerous studies have suggested that metformin promotes health benefits beyond T2D management, including weight loss, cancer prevention and treatment, and anti-aging, through several proposed mechanistic targets. Here we discuss the established effects of metformin and the progress made in identifying its direct targets. Additionally, we emphasize the importance of elucidating the structural bases of the drug and its direct targets. Ultimately, this review aims to highlight the current state of knowledge regarding metformin and its related emerging discoveries, while also outlining critical future research directions.

Gut microbial metabolism in ferroptosis and colorectal cancer

Ferroptosis is programmed cell death induced by iron-driven lipid peroxidation. Numerous studies have shown that ferroptosis is implicated in the progression of colorectal cancer (CRC) and has emerged as a promising strategy to combat therapy-resistant CRC. While the intrinsic antiferroptotic and proferroptotic pathways in CRC cells have been well characterized, extrinsic metabolism pathways regulating ferroptosis in CRC pathogenesis remain less understood. Emerging evidence shows that gut microbial metabolism is tightly correlated with the progression of CRC. This review provides an overview of gut microbial metabolism and discusses how these metabolites derived from intestinal microflora contribute to cancer plasticity through ferroptosis. Targeting gut microbe-mediated ferroptosis is a potential approach for CRC treatment.

Network properties constrain natural selection on gene expression in Caenorhabditis elegans

Gene regulatory networks (GRNs) integrate genetic and environmental signals to coordinate complex phenotypes and evolve through a balance of selection and drift. Using publicly available datasets from Caenorhabditis elegans, we investigated the extent of natural selection on transcript abundance by linking population-scale variation in gene expression to fecundity, a key fitness component. While the expression of most genes covaried only weakly with fitness, which is typical for polygenic traits, we identified seven transcripts under significant directional selection. These included nhr-114 and feh-1, implicating variation in nutrient-sensing and metabolic pathways as impacting fitness. Stronger directional selection on tissue-specific and older genes highlighted the germline and nervous system as focal points of adaptive change. Network position further constrained selection on gene expression; high-connectivity genes faced stronger stabilizing and directional selection, highlighting GRN architecture as a key factor in microevolutionary dynamics. The activity of transcription factors such as zip-3, which regulates mitochondrial stress responses, emerged as targets of selection, revealing potential links between energy homeostasis and fitness. Our findings demonstrate how GRNs mediate the interplay between selection and drift, shaping microevolutionary trajectories of gene expression and phenotypic diversity.

Dietary and nutritional interventions for human diseases: their modulatory effects on ferroptosis

A balanced diet is essential for maintaining human health. Increasing evidence suggests that dietary and nutritional interventions contribute to disease management and are associated with reduced healthcare costs and economic burden. Ferroptosis, a novel type of regulated cell death (RCD) driven by lipid peroxidation, has been shown to be involved in various pathological conditions, including diabetes, ischemia/reperfusion (I/R) injury, inflammation-related diseases, and cancer. Therefore, specifically targeting the uncontrolled ferroptosis process may offer new therapeutic opportunities. Of note, certain interventions, such as small-molecule compounds, natural products, herbal medicines, and non-pharmacological approaches, have been reported to prevent and treat multiple human diseases by reversing the dysregulation of ferroptosis. In this review, we present the key molecular mechanisms that regulate ferroptosis. Importantly, interventions targeting ferroptosis are summarized from the perspective of dietary patterns, food and nutrients. By understanding these advances, innovative ideas can be provided for individualized dietary interventions and treatment strategies.

Mechanisms of Vitamins Inhibiting Ferroptosis

Ferroptosis is an iron-dependent form of cell death, which is characterized by the uncontrolled and overwhelming peroxidation of cell membrane lipids. Ferroptosis has been implicated in the progression of various pathologies, including steatotic liver, heart failure, neurodegenerative diseases, and diabetes. Targeted inhibition of ferroptosis provides a promising strategy to treat ferroptosis-related diseases. Multivitamins, including vitamins A, B, C, D, E, and K, have shown a good ability to inhibit ferroptosis. For example, vitamin A significantly upregulated the expression of several key ferroptotic gatekeepers genes through nuclear retinoic acid receptors and retinoic X receptors (RAR/RXR). Vitamin B6 could compensate for the impaired glutathione (GSH) levels and restore Glutathione peroxidase 4 (GPX4) expression in cells, ultimately inhibiting ferroptosis. Vitamin D could up-regulate the expression of several anti-ferroptosis proteins by activating vitamin D receptors. Vitamin E and hydroquinone vitamin K (VKH2) can directly inhibit the propagation of lipid peroxidation, thereby inhibiting ferroptosis. In this review, we summarize the currently understood mechanisms by which vitamins inhibit ferroptosis to provide reference information for future research on the development of ferroptosis inhibitors.

The pathogenesis and targeted therapies of intervertebral disc degeneration induced by cartilage endplate inflammation

Intervertebral disc degeneration (IVDD) is the leading cause of low back pain, where degeneration and death of nucleus pulposus cells within the intervertebral disc (IVD) can be obviously revealed. This degeneration can result in an imbalance in the extracellular matrix due to the loss of proteoglycans and water content, which can further lead to catabolic and anabolic dysfunction of the IVD. Recently, the dysfunction of cartilage endplate (CEP) during aging has drawn large attention due to its essential functions in contributing nutrient exchange and maintaining IVD homeostasis. Furthermore, the inflammation and disturbed homeostasis of CEP not only accelerate the degradation of nucleus pulposus extracellular matrix, but also exacerbate IVDD by causing nucleus pulposus cell death through other pathological factors. Here in this review, we summarized the possible pathological factors and the underlying mechanisms of the CEP inflammation-induced IVDD, including exosomes degeneration, CEP calcification, ferroptosis, mechanical changes, and cell senescence. Besides, changes of miRNAs, pain-related neural reflex arc and pathways associated with CEP inflammation-induced IVDD are also reviewed. In addition, new strategies specifically designed for CEP inflammation-induced IVDD are also discussed in the last section. We hope this paper can not only offer some new insights for advancing novel strategies for treating IVDD, but also serve as a valuable reference for researchers in this field.

Dietary methionine functions in proliferative zone maintenance and egg production via sams-1 in Caenorhabditis elegans

The maintenance of germ cells is critical for the prosperity of offspring. The amount of food consumption is known to be closely related to reproduction, i.e. the number of eggs decreases under calorie-restricted conditions in various organisms. Previous studies in Caenorhabditis elegans have reported that calorie restriction reduces the number of eggs and the reduction can be rescued by methionine. However, the effect of methionine on the reproductive process has not been fully understood. In this study, to assess the gonadal function of methionine metabolism, we firstly demonstrated that a depletion in dietary methionine resulted in reduced levels of S-adenosyl-l-methionine (SAM) and S-adenosyl homocysteine in wild-type N2, but not in glp-1 mutants, which possess only a few germ cells. Second, we found no recovery in egg numbers upon methionine administration in SAM synthase (sams)-1 mutants. Furthermore, a reduced number of proliferative zone nuclei exhibited in the sams-1 mutants was not rescued via methionine. Thus, our results have shown that dietary methionine is required for the normal establishment of both the germline progenitor pool and fecundity, mediated by sams-1.

Nutritional vitamin B12 regulates RAS/MAPK-mediated cell fate decisions through one-carbon metabolism

Vitamin B12 is an essential nutritional co-factor for the folate and methionine cycles, which together constitute one-carbon metabolism. Here, we show that dietary uptake of vitamin B12 modulates cell fate decisions controlled by the conserved RAS/MAPK signaling pathway in C. elegans. A bacterial diet rich in vitamin B12 increases vulval induction, germ cell apoptosis and oocyte differentiation. These effects are mediated by different one-carbon metabolites in a tissue-specific manner. Vitamin B12 enhances via the choline/phosphatidylcholine metabolism vulval induction by down-regulating fat biosynthesis genes and increasing H3K4 tri-methylation, which results in increased expression of RAS/MAPK target genes. Furthermore, the nucleoside metabolism and H3K4 tri-methylation positively regulate germ cell apoptosis and oocyte production. Using mammalian cells carrying different activated KRAS and BRAF alleles, we show that the effects of methionine on RAS/MAPK-regulated phenotype are conserved in mammals. Our findings suggest that the vitamin B12-dependent one-carbon metabolism is a limiting factor for diverse RAS/MAPK-induced cellular responses.

Transcriptome analysis of porcine oocytes during postovulatory aging

Decreased oocyte quality is a significant contributor to the decline in female fertility that accompanies aging in mammals. Oocytes rely on mRNA stores to support their survival and integrity during the protracted period of transcriptional dormancy as they await ovulation. However, the changes in mRNA levels and interactions that occur during porcine oocyte maturation and aging remain unclear. In this study, the mRNA expression profiles of porcine oocytes during the GV, MII, and aging (24 h after the MII stage) stages were explored by transcriptome sequencing to identify the key genes and pathways that affect oocyte maturation and postovulatory aging. The results showed that 10,929 genes were coexpressed in porcine oocytes during the GV stage, MII stage, and aging stage. In addition, 3037 genes were expressed only in the GV stage, 535 genes were expressed only in the MII stage, and 120 genes were expressed only in the aging stage. The correlation index between the GV and MII stages (0.535) was markedly lower than that between the MII and aging stages (0.942). A total of 3237 genes, which included 1408 upregulated and 1829 downregulated genes, were differentially expressed during porcine oocyte postovulatory aging (aging stage vs. MII stage). Key functional genes, including ATP2A1, ATP2A3, ATP2B2, NDUFS1, NDUFA2, NDUFAF3, SREBF1, CYP11A1, CYP3A29, GPx4, CCP110, STMN1, SPC25, Sirt2, SYCP3, Fascin1/2, PFN1, Cofilin, Tmod3, FLNA, LRKK2, CHEK1/2, DDB1/2, DDIT4L, and TONSL, and key molecular pathways, such as the calcium signaling pathway, MAPK signaling pathway, TGF-β signaling pathway, PI3K/Akt signaling pathway, FoxO signaling pathway, gap junctions, and thermogenesis, were found in abundance during porcine postovulatory aging. These genes are mainly involved in the regulation of many biological processes, such as oxidative stress, calcium homeostasis, mitochondrial function, and lipid peroxidation, during porcine oocyte postovulatory aging. These results contribute to a more in-depth understanding of the biological changes, key regulatory genes and related biological pathways that are involved in oocyte aging and provide a theoretical basis for improving the efficiency of porcine embryo production in vitro and in vivo.

Nutrient vitamins enabled metabolic regulation of ferroptosis via reactive oxygen species biology

Vitamins are dietary components necessary for cellular metabolic balance, especially redox homeostasis; deficient or excessive supply may give rise to symptoms of psychiatric disorders. Exploring the nutritional and metabolic pathways of vitamins could contribute to uncovering the underlying pathogenesis of ferroptosis-associated diseases. This mini-review aims to provide insights into vitamins closely linked to the regulation of ferroptosis from the perspective of cellular reactive oxygen species biology. The mainstream reprogramming mechanisms of ferroptosis are overviewed, focusing on unique biological processes of iron metabolism, lipid metabolism, and amino acid metabolism. Moreover, recent breakthroughs in therapeutic interventions targeting ferroptosis via fully utilizing vitamin-based pharmacological tools were overviewed, covering vitamins (B, C, E, and K). Finally, mechanism insight related to vitamin-associated nutrient signaling was provided, highlighting the pharmacological benefits of metabolically reprogramming ferroptosis-associated diseases.

Microbiota succession influences nematode physiology in a beetle microcosm ecosystem

Unravelling the multifaceted and bidirectional interactions between microbiota and host physiology represents a major scientific challenge. Here, we utilise the nematode model, Pristionchus pacificus, coupled to a laboratory-simulated decay process of its insect host, to mimic natural microbiota succession and investigate associated tripartite interactions. Metagenomics reveal that during initial decay stages, the population of vitamin B-producing bacteria diminishes, potentially due to a preferential selection by nematodes. As decay progresses to nutrient-depleted stages, bacteria with smaller genomes producing less nutrients become more prevalent. Lipid utilisation and dauer formation, representing key nematode survival strategies, are influenced by microbiota changes. Additionally, horizontally acquired cellulases extend the nematodes' reproductive phase due to more efficient foraging. Lastly, the expressions of Pristionchus species-specific genes are more responsive to natural microbiota compared to conserved genes, suggesting their importance in the organisms' adaptation to its ecological niche. In summary, we show the importance of microbial successions and their reciprocal interaction with nematodes for insect decay in semi-artificial ecosystems.

Exposure to 6-PPD quinone causes ferroptosis activation associated with induction of reproductive toxicity in Caenorhabditis elegans

Exposure to N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6-PPDQ) caused toxicity on Caenorhabditis elegans, including reproductive toxicity. However, the underlying mechanisms for this induced reproductive toxicity by 6-PPDQ remain largely unclear. We examined possible association of ferroptosis activation with reproductive toxicity of 6-PPDQ. In 1-100 μg/L 6-PPDQ exposed nematodes, Fe2+ content was increased, which was accompanied with enhanced lipid peroxidation, increased malonydialdehyde (MDA) content, and decreased L-glutathione (GSH) content. Exposure to 1-100 μg/L 6-PPDQ decreased expressions of ftn-1 encoding ferritin, ads-1 encoding AGPS, and gpx-6 encoding GPX4 and increased expression of bli-3 encoding dual oxidase. After 6-PPDQ exposure, RNAi of ftn-1 decreased ads-1 and gpx-6 expressions and increased bli-3 expression. RNAi of ftn-1, ads-1, and gpx-6 strengthened alterations in ferroptosis related indicators, and RNAi of bli-3 suppressed changes of ferroptosis related indicators in 6-PPDQ exposed nematodes. Meanwhile, RNAi of ftn-1, ads-1, and gpx-6 induced susceptibility, and RNAi of bli-3 caused resistance to 6-PPDQ reproductive toxicity. Moreover, expressions of DNA damage checkpoint genes (clk-2, mrt-2, and hus-1) could be increased by RNAi of ftn-1, ads-1, and gpx-6 in 6-PPDQ exposed nematodes. Therefore, our results demonstrated activation of ferroptosis in nematodes exposed to 6-PPDQ at environmentally relevant concentrations, and this ferroptosis activation was related to reproductive toxicity of 6-PPDQ.

Ferroptosis inhibition by oleic acid mitigates iron-overload-induced injury

Iron overload, characterized by accumulation of iron in tissues, induces a multiorgan toxicity whose mechanisms are not fully understood. Using cultured cell lines, Caenorhabditis elegans, and mice, we found that ferroptosis occurs in the context of iron-overload-mediated damage. Exogenous oleic acid protected against iron-overload-toxicity in cell culture and Caenorhabditis elegans by suppressing ferroptosis. In mice, oleic acid protected against FAC-induced liver lipid peroxidation and damage. Oleic acid changed the cellular lipid composition, characterized by decreased levels of polyunsaturated fatty acyl phospholipids and decreased levels of ether-linked phospholipids. The protective effect of oleic acid in cells was attenuated by GW6471 (PPAR-α antagonist), as well as in Caenorhabditis elegans lacking the nuclear hormone receptor NHR-49 (a PPAR-α functional homologue). These results highlight ferroptosis as a driver of iron-overload-mediated damage, which is inhibited by oleic acid. This monounsaturated fatty acid represents a potential therapeutic approach to mitigating organ damage in iron overload individuals.

Navigating the B vitamins: Dietary diversity, microbial synthesis, and human health

B vitamins are intricately involved in various physiological processes vital for health. Their significance is complicated by the heterogeneous landscape of B vitamin distribution in diets and the contributions of the gut microbiota. Here, we delve into the impact of these factors on B vitamins and introduce strategies, with a focus on microbiota-based therapeutic options, to enhance their availability for improved well-being. Additionally, we provide an ecological and evolutionary perspective on the importance of B vitamins to human-microbiota interactions. In the dynamic realms of nutrition and microbiome science, these essential micronutrients continue to play a fundamental role in our understanding of disease development.

Mitochondrial GTP metabolism controls reproductive aging in C. elegans

Healthy mitochondria are critical for reproduction. During aging, both reproductive fitness and mitochondrial homeostasis decline. Mitochondrial metabolism and dynamics are key factors in supporting mitochondrial homeostasis. However, how they are coupled to control reproductive health remains unclear. We report that mitochondrial GTP (mtGTP) metabolism acts through mitochondrial dynamics factors to regulate reproductive aging. We discovered that germline-only inactivation of GTP- but not ATP-specific succinyl-CoA synthetase (SCS) promotes reproductive longevity in Caenorhabditis elegans. We further identified an age-associated increase in mitochondrial clustering surrounding oocyte nuclei, which is attenuated by GTP-specific SCS inactivation. Germline-only induction of mitochondrial fission factors sufficiently promotes mitochondrial dispersion and reproductive longevity. Moreover, we discovered that bacterial inputs affect mtGTP levels and dynamics factors to modulate reproductive aging. These results demonstrate the significance of mtGTP metabolism in regulating oocyte mitochondrial homeostasis and reproductive longevity and identify mitochondrial fission induction as an effective strategy to improve reproductive health.

PM2.5 induced neurotoxicity through unbalancing vitamin B12 metabolism by gut microbiota disturbance

Fine particulate matter (PM2.5) in the atmosphere is easily accompanied by toxic and harmful substances, causing serious harm to human health, including cognitive impairment. Vitamin B12 (VitB12) is an essential micronutrient that is synthesized by bacteria and contributes to neurotransmitter synthesis as a nutrition and signaling molecule. However, the relationship between VitB12 attenuation of cognitive impairment and intestinal microbiota regulation in PM2.5 exposure has not been elucidated. In this study, we demonstrated that PM2.5 caused behavioral defects and neuronal damage in Caenorhabditis elegans (C. elegans), along with significant gene expression changes in neurotransmitter receptors and a decrease in VitB12 content, causing behavioral defects and neuronal damage in C. elegans. Methylcobalamin (MeCbl), a VitB12 analog, alleviated PM2.5-induced neurotoxicity in C. elegans. Moreover, using in vivo and in vitro models, we discovered that long-term exposure to PM2.5 led to changes in the structure of the gut microbiota, resulting in an imbalance of the VitB12-associated metabolic pathway followed by cognitive impairment. MeCbl supplementation could increase the diversity of the bacteria, reduce harmful substance contents, and restore the concentration of short-chain fatty acids (SCFAs) and neurotransmitters to the level of the control group to some degree. Here, a new target to mitigate the harm caused by PM2.5 was discovered, supplying MeCbl for relieving intestinal and intracellular neurotransmitter disorders. Our results also provide a reference for the use of VitB12 to target the adjustment of the human intestinal microbiota to improve metabolic disorders in people exposed to PM2.5.

Exosomes drive ferroptosis by stimulating iron accumulation to inhibit bacterial infection in crustaceans

Ferroptosis, characterized by iron-dependent cell death, has recently emerged as a critical defense mechanism against microbial infections. The present study aims to investigate the involvement of exosomes in the induction of ferroptosis and the inhibition of bacterial infection in crustaceans. Our findings provide compelling evidence for the pivotal role of exosomes in the immune response of crustaceans, wherein they facilitate intracellular iron accumulation and activate the ferroptotic pathways. Using RNA-seq and bioinformatic analysis, we demonstrate that cytochrome P450 (CYP) can effectively trigger ferroptosis. Moreover, by conducting an analysis of exosome cargo proteins, we have identified the participation of six-transmembrane epithelial antigen of prostate 4 in the regulation of hemocyte ferroptotic sensitivity. Subsequent functional investigations unveil that six-transmembrane epithelial antigen of prostate 4 enhances cellular Fe2+ levels, thereby triggering Fenton reactions and accelerating CYP-mediated lipid peroxidation, ultimately culminating in ferroptotic cell death. Additionally, the Fe2+-dependent CYP catalyzes the conversion of arachidonic acid into 20-hydroxyeicosatetraenoic acid, which activates the peroxisome proliferator-activated receptor. Consequently, the downstream target of peroxisome proliferator-activated receptor, cluster of differentiation 36, promotes intracellular fatty acid accumulation, lipid peroxidation, and ferroptosis. These significant findings shed light on the immune defense mechanisms employed by crustaceans and provide potential strategies for combating bacterial infections in this species.

Maternal aging increases offspring adult body size via transmission of donut-shaped mitochondria

Maternal age at childbearing has continued to increase in recent decades. However, whether and how it influences offspring adult traits are largely unknown. Here, using adult body size as the primary readout, we reveal that maternal rather than paternal age has an evolutionarily conserved effect on offspring adult traits in humans, Drosophila, and Caenorhabditis elegans. Elucidating the mechanisms of such effects in humans and other long-lived animals remains challenging due to their long life course and difficulties in conducting in vivo studies. We thus employ the short-lived and genetically tractable nematode C. elegans to explore the mechanisms underlying the regulation of offspring adult trait by maternal aging. By microscopic analysis, we find that old worms transmit aged mitochondria with a donut-like shape to offspring. These mitochondria are rejuvenated in the offspring's early life, with their morphology fully restored before adulthood in an AMPK-dependent manner. Mechanistically, we demonstrate that early-life mitochondrial dysfunction activates AMPK, which in turn not only alleviates mitochondrial abnormalities but also activates TGFβ signaling to increase offspring adult size. Together, our findings provide mechanistic insight into the ancient role of maternal aging in shaping the traits of adult offspring.

Nuclear hormone receptor NHR-49 is an essential regulator of stress resilience and healthy aging in Caenorhabditis elegans

The genome of Caenorhabditis elegans encodes 284 nuclear hormone receptor, which perform diverse functions in development and physiology. One of the best characterized of these is NHR-49, related in sequence and function to mammalian hepatocyte nuclear factor 4α and peroxisome proliferator-activated receptor α. Initially identified as regulator of lipid metabolism, including fatty acid catabolism and desaturation, additional important roles for NHR-49 have since emerged. It is an essential contributor to longevity in several genetic and environmental contexts, and also plays vital roles in the resistance to several stresses and innate immune response to infection with various bacterial pathogens. Here, we review how NHR-49 is integrated into pertinent signaling circuits and how it achieves its diverse functions. We also highlight areas for future investigation including identification of regulatory inputs that drive NHR-49 activity and identification of tissue-specific gene regulatory outputs. We anticipate that future work on this protein will provide information that could be useful for developing strategies to age-associated declines in health and age-related human diseases.

An integrated view of lipid metabolism in ferroptosis revisited via lipidomic analysis

Ferroptosis is a form of regulated cell death characterized by iron-dependent lipid peroxidation. This process contributes to cellular and tissue damage in various human diseases, such as cardiovascular diseases, neurodegeneration, liver disease, and cancer. Although polyunsaturated fatty acids (PUFAs) in membrane phospholipids are preferentially oxidized, saturated/monounsaturated fatty acids (SFAs/MUFAs) also influence lipid peroxidation and ferroptosis. In this review, we first explain how cells differentially synthesize SFA/MUFAs and PUFAs and how they control fatty acid pools via fatty acid uptake and β-oxidation, impacting ferroptosis. Furthermore, we discuss how fatty acids are stored in different lipids, such as diacyl or ether phospholipids with different head groups; triglycerides; and cholesterols. Moreover, we explain how these fatty acids are released from these molecules. In summary, we provide an integrated view of the diverse and dynamic metabolic processes in the context of ferroptosis by revisiting lipidomic studies. Thus, this review contributes to the development of therapeutic strategies for ferroptosis-related diseases.

Live or death in cells: from micronutrition metabolism to cell fate

Micronutrients and cell death have a strong relationship and both are essential for human to maintain good body health. Dysregulation of any micronutrients causes metabolic or chronic diseases, including obesity, cardiometabolic condition, neurodegeneration, and cancer. The nematode Caenorhabditis elegans is an ideal genetic organism for researching the mechanisms of micronutrients in metabolism, healthspan, and lifespan. For example, C. elegans is a haem auxotroph, and the research of this special haem trafficking pathway contributes important reference to mammal study. Also, C. elegans characteristics including anatomy simply, clear cell lineage, well-defined genetics, and easily differentiated cell forms make it a powerful tool for studying the mechanisms of cell death including apoptosis, necrosis, autophagy, and ferroptosis. Here, we describe the understanding of micronutrient metabolism currently and also sort out the fundamental mechanisms of different kinds of cell death. A thorough understanding of these physiological processes not only builds a foundation for developing better treatments for various micronutrient disorders but also provides key insights into human health and aging.

Mitochondrial GTP Metabolism Regulates Reproductive Aging

Healthy mitochondria are critical for reproduction. During aging, both reproductive fitness and mitochondrial homeostasis decline. Mitochondrial metabolism and dynamics are key factors in supporting mitochondrial homeostasis. However, how they are coupled to control reproductive health remains unclear. We report that mitochondrial GTP metabolism acts through mitochondrial dynamics factors to regulate reproductive aging. We discovered that germline-only inactivation of GTP- but not ATP-specific succinyl-CoA synthetase (SCS), promotes reproductive longevity in Caenorhabditis elegans. We further revealed an age-associated increase in mitochondrial clustering surrounding oocyte nuclei, which is attenuated by the GTP-specific SCS inactivation. Germline-only induction of mitochondrial fission factors sufficiently promotes mitochondrial dispersion and reproductive longevity. Moreover, we discovered that bacterial inputs affect mitochondrial GTP and dynamics factors to modulate reproductive aging. These results demonstrate the significance of mitochondrial GTP metabolism in regulating oocyte mitochondrial homeostasis and reproductive longevity and reveal mitochondrial fission induction as an effective strategy to improve reproductive health.

Phosphatidylcholine deficiency increases ferroptosis susceptibility in the C. elegans germline

Ferroptosis, a regulated and iron-dependent form of cell death characterized by peroxidation of membrane phospholipids, has tremendous potential for the therapy of human diseases. The causal link between phospholipid homeostasis and ferroptosis is incompletely understood. Here, we reveal that spin-4, a previously identified regulator of the "B12-one-carbon cycle-phosphatidylcholine (PC)" pathway, sustains germline development and fertility by ensuring PC sufficiency in the nematode Caenorhabditis elegans. Mechanistically, SPIN-4 regulates lysosomal activity which is required for B12-associated PC synthesis. PC deficiency-induced sterility can be rescued by reducing the levels of polyunsaturated fatty acids (PUFAs), reactive oxygen species (ROS) , and redox-active iron, which indicates that the sterility is mediated by germline ferroptosis. These results highlight the critical role of PC homeostasis in ferroptosis susceptibility and offer a new target for pharmacological approaches.

Over-Expressed GATA-1S, the Short Isoform of the Hematopoietic Transcriptional Factor GATA-1, Inhibits Ferroptosis in K562 Myeloid Leukemia Cells by Preventing Lipid Peroxidation

Ferroptosis is a recently recognized form of regulated cell death involving lipid peroxidation. Glutathione peroxidase 4 (GPX4) plays a central role in the regulation of ferroptosis through the suppression of lipid peroxidation generation. Connections have been reported between ferroptosis, lipid metabolism, cancer onset, and drug resistance. Recently, interest has grown in ferroptosis induction as a potential strategy to overcome drug resistance in hematological malignancies. GATA-1 is a key transcriptional factor controlling hematopoiesis-related gene expression. Two GATA-1 isoforms, the full-length protein (GATA-1FL) and a shorter isoform (GATA-1S), are described. A balanced GATA-1FL/GATA-1S ratio helps to control hematopoiesis, with GATA-1S overexpression being associated with hematological malignancies by promoting proliferation and survival pathways in hematopoietic precursors. Recently, optical techniques allowed us to highlight different lipid profiles associated with the expression of GATA-1 isoforms, thus raising the hypothesis that ferroptosis-regulated processes could be involved. Lipidomic and functional analysis were conducted to elucidate these mechanisms. Studies on lipid peroxidation production, cell viability, cell death, and gene expression were used to evaluate the impact of GPX4 inhibition. Here, we provide the first evidence that over-expressed GATA-1S prevents K562 myeloid leukemia cells from lipid peroxidation-induced ferroptosis. Targeting ferroptosis is a promising strategy to overcome chemoresistance. Therefore, our results could provide novel potential therapeutic approaches and targets to overcome drug resistance in hematological malignancies.

The antidiabetic drug metformin aids bacteria in hijacking vitamin B12 from the environment through RcdA

Years of use of the antidiabetic drug metformin has long been associated with the risk of vitamin B12 (B12) deficiency in type 2 diabetes (T2D) patients, although the underlying mechanisms are unclear. Accumulating evidence has shown that metformin may exert beneficial effects by altering the metabolism of the gut microbiota, but whether it induces human B12 deficiency via modulation of bacterial activity remains poorly understood. Here, we show that both metformin and the other biguanide drug phenformin markedly elevate the accumulation of B12 in E. coli. By functional and genomic analysis, we demonstrate that both biguanides can significantly increase the expression of B12 transporter genes, and depletions of vital ones, such as tonB, nearly completely abolish the drugs' effect on bacterial B12 accumulation. Via high-throughput screens in E. coli and C. elegans, we reveal that the TetR-type transcription factor RcdA is required for biguanide-mediated promotion of B12 accumulation and the expressions of B12 transporter genes in bacteria. Together, our study unveils that the antidiabetic drug metformin helps bacteria gather B12 from the environment by increasing the expressions of B12 transporter genes in an RcdA-dependent manner, which may theoretically reduce the B12 supply to T2D patients taking the drug over time.