Fine-tuned protein-lipid interactions in biological membranes: exploration and implications of the ORMDL-ceramide negative feedback loop in the endoplasmic reticulum.

Biological membranes consist of a lipid bilayer in which integral membrane proteins are embedded. Based on the compositional complexity of the lipid species found in membranes, and on their specific and selective interactions with membrane proteins, we recently suggested that membrane bilayers can be best described as "finely-tuned molecular machines." We now discuss one such set of lipid-protein interactions by describing a negative feedback mechanism operating in the de novo sphingolipid biosynthetic pathway, which occurs in the membrane of the endoplasmic reticulum, and describe the atomic interactions between the first enzyme in the pathway, namely serine palmitoyl transferase, and the product of the fourth enzyme in the pathway, ceramide. We explore how hydrogen-bonding and hydrophobic interactions formed between Asn13 and Phe63 in the serine palmitoyl transferase complex and ceramide can influence the ceramide content of the endoplasmic reticulum. This example of finely-tuned biochemical interactions raises intriguing mechanistic questions about how sphingolipids and their biosynthetic enzymes could have evolved, particularly in light of their metabolic co-dependence.

Involvement of lipid-translocating exporter family proteins in determination of myriocin sensitivity in budding yeast.

Myriocin is an inhibitor of serine palmitoyltransferase involved in the initial biosynthetic step for sphingolipids, and causes potent growth inhibition in eukaryotic cells. In budding yeast, Rsb1, Rta1, Pug1, and Ylr046c are known as the Lipid-Translocating Exporter (LTE) family and believed to contribute to export of various cytotoxic lipophilic compounds. It was reported that Rsb1 is a transporter responsible for export of intracellularly accumulated long-chain bases, which alleviate the cytotoxicity. In this study, it was found that LTE family genes are involved in determination of myriocin sensitivity in yeast. Analyses of effects of deletion and overexpression of LTE family genes suggested that all LTEs contribute to suppression of cytotoxicity of myriocin. It was confirmed that RSB1 overexpression suppressed reduction in complex sphingolipid levels caused by myriocin treatment, possibly exporting myriocin to outside of the cell. These results suggested that LTE family genes function as a defense mechanism against myriocin.

Concomitant targeting of FLT3 and SPHK1 exerts synergistic cytotoxicity in FLT3-ITD+ acute myeloid leukemia by inhibiting ß-catenin activity via the PP2A-GSK3ß axis.

BACKGROUND: Approximately 25-30% of patients with acute myeloid leukemia (AML) have FMS-like receptor tyrosine kinase-3 (FLT3) mutations that contribute to disease progression and poor prognosis. Prolonged exposure to FLT3 tyrosine kinase inhibitors (TKIs) often results in limited clinical responses due to diverse compensatory survival signals. Therefore, there is an urgent need to elucidate the mechanisms underlying FLT3 TKI resistance. Dysregulated sphingolipid metabolism frequently contributes to cancer progression and a poor therapeutic response. However, its relationship with TKI sensitivity in FLT3-mutated AML remains unknown. Thus, we aimed to assess mechanisms of FLT3 TKI resistance in AML. METHODS: We performed lipidomics profiling, RNA-seq, qRT-PCR, and enzyme-linked immunosorbent assays to determine potential drivers of sorafenib resistance. FLT3 signaling was inhibited by sorafenib or quizartinib, and SPHK1 was inhibited by using an antagonist or via knockdown. Cell growth and apoptosis were assessed in FLT3-mutated and wild-type AML cell lines via Cell counting kit-8, PI staining, and Annexin-V/7AAD assays. Western blotting and immunofluorescence assays were employed to explore the underlying molecular mechanisms through rescue experiments using SPHK1 overexpression and exogenous S1P, as well as inhibitors of S1P2, ß-catenin, PP2A, and GSK3ß. Xenograft murine model, patient samples, and publicly available data were analyzed to corroborate our in vitro results. RESULTS: We demonstrate that long-term sorafenib treatment upregulates SPHK1/sphingosine-1-phosphate (S1P) signaling, which in turn positively modulates ß-catenin signaling to counteract TKI-mediated suppression of FLT3-mutated AML cells via the S1P2 receptor. Genetic or pharmacological inhibition of SPHK1 potently enhanced the TKI-mediated inhibition of proliferation and apoptosis induction in FLT3-mutated AML cells in vitro. SPHK1 knockdown enhanced sorafenib efficacy and improved survival of AML-xenografted mice. Mechanistically, targeting the SPHK1/S1P/S1P2 signaling synergizes with FLT3 TKIs to inhibit ß-catenin activity by activating the protein phosphatase 2 A (PP2A)-glycogen synthase kinase 3ß (GSK3ß) pathway. CONCLUSIONS: These findings establish the sphingolipid metabolic enzyme SPHK1 as a regulator of TKI sensitivity and suggest that combining SPHK1 inhibition with TKIs could be an effective approach for treating FLT3-mutated AML.

Functional Insights into the Sphingolipids C1P, S1P, and SPC in Human Fibroblast-like Synoviocytes by Proteomic Analysis.

The (patho)physiological function of the sphingolipids ceramide-1-phosphate (C1P), sphingosine-1-phosphate (S1P), and sphingosylphosphorylcholine (SPC) in articular joints during osteoarthritis (OA) is largely unknown. Therefore, we investigated the influence of these lipids on protein expression by fibroblast-like synoviocytes (FLSs) from OA knees. Cultured human FLSs (n = 7) were treated with 1 of 3 lipid species-C1P, S1P, or SPC-IL-1ß, or with vehicle. The expression of individual proteins was determined by tandem mass tag peptide labeling followed by high-resolution electrospray ionization (ESI) mass spectrometry after liquid chromatographic separation (LC-MS/MS/MS). The mRNA levels of selected proteins were analyzed using RT-PCR. The 3sphingolipids were quantified in the SF of 18 OA patients using LC-MS/MS. A total of 4930 proteins were determined using multiplex MS, of which 136, 9, 1, and 0 were regulated both reproducibly and significantly by IL-1ß, C1P, S1P, and SPC, respectively. In the presence of IL-1ß, all 3 sphingolipids exerted ancillary effects. Only low SF levels of C1P and SPC were found. In conclusion, the 3 lipid species regulated proteins that have not been described in OA. Our results indicate that charged multivesicular body protein 1b, metal cation symporter ZIP14, glutamine-fructose-6-P transaminase, metallothionein-1F and -2A, ferritin, and prosaposin are particularly interesting proteins due to their potential to affect inflammatory, anabolic, catabolic, and apoptotic mechanisms.

Leech Poecilobdella manillensis protein extract ameliorated hyperuricemia by restoring gut microbiota dysregulation and affecting serum metabolites.

BACKGROUND: Hyperuricemia (HUA) is a public health concern that needs to be solved urgently. The lyophilized powder of Poecilobdella manillensis has been shown to significantly alleviate HUA; however, its underlying metabolic regulation remains unclear. AIM: To explore the underlying mechanisms of Poecilobdella manillensis in HUA based on modulation of the gut microbiota and host metabolism. METHODS: A mouse model of rapid HUA was established using a high-purine diet and potassium oxonate injections. The mice received oral drugs or saline. Additionally, 16S rRNA sequencing and ultra-high performance liquid chromatography with quadrupole time-of-flight mass spectrometry-based untargeted metabolomics were performed to identify changes in the microbiome and host metabolome, respectively. The levels of uric acid transporters and epithelial tight junction proteins in the renal and intestinal tissues were analyzed using an enzyme-linked immunosorbent assay. RESULTS: The protein extract of Poecilobdella manillensis lyophilized powder (49 mg/kg) showed an enhanced anti-trioxypurine ability than that of allopurinol (5 mg/kg) (P < 0.05). A total of nine bacterial genera were identified to be closely related to the anti-trioxypurine activity of Poecilobdella manillensis powder, which included the genera of Prevotella, Delftia, Dialister, Akkermansia, Lactococcus, Escherichia_Shigella, Enterococcus, and Bacteroides. Furthermore, 22 metabolites in the serum were found to be closely related to the anti-trioxypurine activity of Poecilobdella manillensis powder, which correlated to the Kyoto Encyclopedia of Genes and Genomes pathways of cysteine and methionine metabolism, sphingolipid metabolism, galactose metabolism, and phenylalanine, tyrosine, and tryptophan biosynthesis. Correlation analysis found that changes in the gut microbiota were significantly related to these metabolites. CONCLUSION: The proteins in Poecilobdella manillensis powder were effective for HUA. Mechanistically, they are associated with improvements in gut microbiota dysbiosis and the regulation of sphingolipid and galactose metabolism.

Transcriptomics pave the way into mechanisms of cobalt and nickel toxicity: Nrf2-mediated cellular responses in liver carcinoma cells.

Cobalt (Co) and Nickel (Ni) are used nowadays in various industrial applications like lithium-ion batteries, raising concerns about their environmental release and public health threats. Both metals are potentially carcinogenic and may cause neurological and cardiovascular dysfunctions, though underlying toxicity mechanisms have to be further elucidated. This study employs untargeted transcriptomics to analyze downstream cellular effects of individual and combined Co and Ni toxicity in human liver carcinoma cells (HepG2). The results reveal a synergistic effect of Co and Ni, leading to significantly higher number of differentially expressed genes (DEGs) compared to individual exposure. There was a clear enrichment of Nrf2 regulated genes linked to pathways such as glycolysis, iron and glutathione metabolism, and sphingolipid metabolism, confirmed by targeted analysis. Co and Ni exposure alone and combined caused nuclear Nrf2 translocation, while only combined exposure significantly affects iron and glutathione metabolism, evidenced by upregulation of HMOX-1 and iron storage protein FTL. Both metals impact sphingolipid metabolism, increasing dihydroceramide levels and decreasing ceramides, sphingosine and lactosylceramides, along with diacylglycerol accumulation. By combining transcriptomics and analytical methods, this study provides valuable insights into molecular mechanisms of Co and Ni toxicity, paving the way for further understanding of metal stress.

Thyroid hormone receptor-beta agonist HSK31679 alleviates MASLD by modulating gut microbial sphingolipids.

BACKGROUND & AIMS: As the first approved medication for metabolic dysfunction-associated steatohepatitis (MASH), thyroid hormone receptor-beta (THR-ß) agonist MGL-3196 (Resmetirom) is highly spotlighted as the liver-directed, bioactive oral drug. However, it was also identified with remarkable heterogeneity of individual clinical efficacy and its interference with gut microbiota in host hepatoenteral circulation was still undocumented. METHODS: We compared MASH attenuation by MGL-3196 and its derivative drug HSK31679 between germ-free (GF) and specific-pathogen free (SPF) mice to evaluate the role of gut microbiota. Then cross-omics analyses of microbial metagenome, metabolome and single-cell RNA-sequencing were applied into the randomized, double-blind, placebo-controlled multiple-ascending-dose (MAD) cohort of HSK31679 treatment (n = 40), to comprehensively investigate the altered gut microbiota metabolism and circulating immune signatures. RESULTS: HSK31679 outperformed MGL-3196 in ameliorating MASH diet-induced steatohepatitis of SPF mice but not GF mice. In the MAD cohort of HSK31679, relative abundance of B. thetaiotaomicron was significantly enriched to impair glucosylceramide synthase (GCS)-catalyzed monoglucosylation of microbial Cer(d18:1/16:0) and Cer(d18:1/24:1). In stark contrast to the non-inferiority MASH resolution between MGL-3196 and HSK31679 for GFBTΔGCS mice, HSK31679 manifested superior steatohepatitis alleviation than MGL-3196 for GFBTWT mice, due to its steric hindrance with R123 and Y401 of gut microbial GCS. For participants with high fecal GCS activity, the administration of 160 mg HSK31679 induced a shift in peripheral compartments towards an immunosuppressive niche, characterized by decreased CD8α+ dendritic cells and MINCLE+ macrophages. CONCLUSIONS: This study provided novel insights into the indispensable gut microbiota for HSK31679 treatment, which revealed microbial GCS may serve as its prognostic biomarker of MASH treatment, as well as the new target for further strategies of microbiota-based MASH therapeutics. IMPACT AND IMPLICATIONS: Remarkable heterogeneity of individual clinical efficacy of THR-ß agonists and their interferences with microbiome in host hepatoenteral circulation are poorly understood. In our current germ-free mice models and randomized, double-blind multiple-dose cohort study, we identified microbial GCS as the prognostic biomarker of HSK31679 treatment, as well as the new target for further strategies of microbiota-based MASLD therapeutics.

Functional characterization of two survival factor 1 genes in Mucor lusitanicus.

Survival factor 1 (Svf1) protein has been described in some ascomycetous fungi where it was found to be contributing to several essential physiological processes, such as response to osmotic, oxidative and cold stresses, sphingolipid biosynthesis, morphogenesis, sporulation, antifungal resistance, and pathogenicity. It was also suggested that it can be a novel central regulator affecting the expression of various genes. In the present study, function of this protein and the encoding genes is described for the first time in a fungus (i.e., in Mucor lusitanicus) belonging to the order Mucorales. M. lusitanicus has two putative svf1 genes named svf1a and svf1b. Expression of both genes was proven. Although the expression of svf1a was affected by several environmental stresses and knocking out the gene affected adaptation to low temperatures and the sporulation ability, the main survival factor functions, such as participation in the maintenance of the viability, the response to oxidative and cold stresses, and the sphingolipid biosynthesis, could be associated with Svf1b, suggesting a central regulatory role to this protein. Interestingly, knockout of both genes affected the pathogenicity of the fungus in a Drosophila model. IMPORTANCE: Mucor lusitanicus is a widely used model organism to study various biological processes in the basal fungal group Mucorales. Several members of this group can be agents of mucormycosis, an opportunistic fungal infection, which is associated with high mortality, rapid progression, and wide resistance to the commonly used antifungal agents. Svf1 proteins have so far only been identified in fungi, where they have been involved in pathogenicity and resistance to antifungal agents in many cases. Only a limited number of factors affecting the stress response, antifungal resistance, and virulence of Mucorales fungi have been revealed. Elucidating the function of a fungus-specific protein that may regulate these processes may bring us closer to understanding the pathogenesis of these fungi.

Circulating sphingolipids in relation to cognitive decline and incident dementia: The Cardiovascular Health Study.

INTRODUCTION: Whether circulating levels of sphingolipids are prospectively associated with cognitive decline and dementia risk is uncertain. METHODS: We measured 14 sphingolipid species in plasma samples from 4488 participants (mean age 76.2 years; 40% male; and 25% apolipoprotein E (APOE) ε4 allele carriers). Cognitive decline was assessed annually across 6 years using modified Mini-Mental State Examination (3MSE) and Digital Symbol Substitution Test (DSST). Additionally, a subset of 3050 participants were followed for clinically adjudicated dementia. RESULTS: Higher plasma levels of sphingomyelin-d18:1/16:0 (SM-16) were associated with a faster cognitive decline measured with 3MSE, in contrast, higher levels of sphingomyelin-d18:1/22:0 (SM-22) were associated with slower decline in cognition measured with DSST. In Cox regression, higher levels of SM-16 (hazard ration [HR] = 1.24 [95% confidence interval [CI]: 1.08-1.44]) and ceramide-d18:1/16:0 (Cer-16) (HR = 1.26 [95% CI: 1.10-1.45]) were associated with higher risk of incident dementia. DISCUSSION: Several sphingolipid species appear to be involved in cognitive decline and dementia risk. Highlights: Plasma levels of sphingolipids were associated with cognitive decline and dementia risk.Ceramides and sphingomyelins with palmitic acid were associated with faster annual cognitive decline and increased risk of dementia.The direction of association depended on the covalently bound saturated fatty acid chain length in analysis of cognitive decline.

Identifying distinct markers in two Sorghum varieties for baijiu fermentation using untargeted metabolomics and molecular network approaches.

The quality of strong-flavor Baijiu, a prominent Chinese liquor, is intricately tied to the choice of sorghum variety used in fermentation. However, a significant gap remains in our understanding of how glutinous and non-glutinous sorghum varieties comprehensively impact Baijiu flavor formation through fermentation metabolites. This study employed untargeted metabolomics combined with feature-based molecular networking (FBMN) to explore the unique metabolic characteristics of these two sorghum varieties during fermentation. FBMN analysis revealed 267 metabolites within both types of fermented sorghum (Zaopei) in the cellar. Further multidimensional statistical analyses highlighted sphingolipids, 2,5-diketopiperazines, and methionine derivatives as critical markers for quality control. These findings represent a significant advancement in our understanding and provide valuable insights for regulating the quality of Baijiu flavors.

Alterations to sphingolipid metabolism from antipsychotic administration in healthy volunteers are restored following the use of cannabidiol.

Randomized clinical trials substantiate cannabidiol (CBD) as a next-generation antipsychotic, effective in alleviating positive and negative symptoms associated with psychosis, while minimising the adverse effects seen with established treatments. Although the mechanisms remain debated, CBD is known to induce drug-responsive changes in lipid-based retrograde neurotransmitters. Lipid aberrations are also frequently observed with antipsychotics, which may contribute to their efficacy or increase the risk of undesirables, including metabolic dysfunction, obesity and dyslipidaemia. Our study investigated CBD's impact following lipid responses triggered by interaction with second-generation antipsychotics (SGA) in a randomized phase I safety study. Untargeted mass spectrometry assessed the lipidomic profiles of human sera, collected from 38 healthy volunteers. Serum samples were obtained prior to commencement of any medication (t = 0), 3 days after consecutive administration of one of the five, placebo-controlled, treatment arms designed to achieve steady-state concentrations of each SGA (amisulpride, 150 mg/day; quetiapine, 300 mg/day; olanzapine 10 mg/day; risperidone, 3 mg/day), and after six successive days of SGA treatment combined with CBD (800 mg/day). Receiver operating characteristics (ROC) refined 3712 features to a putative list of 15 lipids significantly altered (AUC > 0.7), classified into sphingolipids (53 %), glycerolipids (27 %) and glycerophospholipids (20 %). Targeted mass spectrometry confirmed reduced sphingomyelin and ceramide levels with antipsychotics, which mapped along their catabolic pathway and were restored by CBD. These sphingolipids inversely correlated with body weight after olanzapine, quetiapine, and risperidone treatment, where CBD appears to have arrested or attenuated these effects. Herein, we propose CBD may alleviate aberrant sphingolipid metabolism and that further investigation into sphingolipids as markers for monitoring side effects of SGAs and efficacy of CBD is warranted.

Alterations of ceramide synthesis induce PD-L1 internalization and signaling to regulate tumor metastasis and immunotherapy response.

Programmed death ligand 1, PD-L1 (CD274), facilitates immune evasion and exerts pro-survival functions in cancer cells. Here, we report a mechanism whereby internalization of PD-L1 in response to alterations of bioactive lipid/ceramide metabolism by ceramide synthase 4 (CerS4) induces sonic hedgehog (Shh) and transforming growth factor ß receptor signaling to enhance tumor metastasis in triple-negative breast cancers (TNBCs), exhibiting immunotherapy resistance. Mechanistically, data showed that internalized PD-L1 interacts with an RNA-binding protein, caprin-1, to stabilize Shh/TGFBR1/Wnt mRNAs to induce ß-catenin signaling and TNBC growth/metastasis, consistent with increased infiltration of FoxP3+ regulatory T cells and resistance to immunotherapy. While mammary tumors developed in MMTV-PyMT/CerS4-/- were highly metastatic, targeting the Shh/PD-L1 axis using sonidegib and anti-PD-L1 antibody vastly decreased tumor growth and metastasis, consistent with the inhibition of PD-L1 internalization and Shh/Wnt signaling, restoring anti-tumor immune response. These data, validated in clinical samples and databases, provide a mechanism-based therapeutic strategy to improve immunotherapy responses in metastatic TNBCs.

Parental exposure to acrylamide disrupts sphingolipid metabolism and impairs transgenerational neurodevelopment in zebrafish (Danio rerio) offspring.

Acrylamide exposure has become an emerging environmental and food safety issue, and its toxicity poses a potential threat to public health worldwide. However, limited studies have paid attention to the detrimental effects of parental exposure to acrylamide on the neurodevelopment in zebrafish offspring. In this study, the embryos were life-cycle exposed to acrylamide (0.125 and 0.25 mM) for 180 days. Subsequently, these zebrafish (F0) were allowed to mate, and their offspring (F1) were collected to culture in clean water from embryos to adults. We employed developmental and morphological observations, behavioral profiles, metabolomics analyses, and transcriptional level examinations to investigate the transgenerational neurotoxicity with parental exposure to acrylamide. Our results showed that parental exposure to acrylamide harms the birth, development, and behavior characterization of the F1 zebrafish larvae, including poor egg quality, increased mortality rates, abnormal heart rates, slowed swimming activity, and heightened anxiety behavior, and continuously disturbs mental health in F1 adult zebrafish. The transcriptional analysis showed that parental chronic exposure to acrylamide deteriorates the neurodevelopment in F1 larvae. In addition, metabolomics analyses revealed that sphingolipid metabolism disruption may be associated with the observed abnormal development and behavioral response in unexposed F1 offspring. Overall, the present study provides pioneer evidence that acrylamide induces transgenerational neurotoxicity via targeting and disrupting sphingolipid metabolism, which reveals intergenerational transmission of acrylamide exposure and unravels its spatiotemporal toxicological effect on neurodevelopment.

Comprehensive metabolic modulations of sphingolipids are promising severity indicators in COVID-19.

The COVID-19 pandemic, caused by SARS-CoV-2, has had a significant worldwide impact, affecting millions of people. COVID-19 is characterized by a heterogenous clinical phenotype, potentially involving hyperinflammation and prolonged tissue damage, although the exact underlying mechanisms are yet to be fully understood. Sphingolipid metabolites, which govern cell survival and proliferation, have emerged as key players in inflammatory signaling and cytokine responses. Given the complex metabolic pathway of sphingolipids, this study aimed to understand their potential role in the pathogenesis of COVID-19. We conducted a comprehensive examination of sphingolipid modulations across groups classified based on disease severity, incorporating a time-course in serum and urine samples. Several sphingolipids, including sphingosine, lactosylceramide, and hexosylceramide, emerged as promising indicators of COVID-19 severity, as validated by correlation analyses conducted on both serum and urine samples. Other sphingolipids, such as sphingosine 1-phosphate, ceramides, and deoxy-dihydroceramides, decreased in both COVID-19 patients and individuals with non-COVID infectious diseases. This suggests that these sphingolipids are not specifically associated with COVID-19 but rather with pathological conditions caused by infectious diseases. Our analysis of urine samples revealed elevated levels of various sphingolipids, with changes dependent on disease severity, potentially highlighting the acute kidney injury associated with COVID-19. This study illuminates the intricate relationship between disturbed sphingolipid metabolism, COVID-19 severity, and clinical factors. These findings provide valuable insights into the broader landscape of inflammatory diseases.

Plasma sphingolipids, dopaminergic degeneration and clinical progression in idiopathic Parkinson's disease.

BACKGROUND: Sphingolipid dysregulation in Parkinson's disease (PD) may affect the release and uptake of striatal dopamine. However, the longitudinal relationship between sphingolipids, striatal dopaminergic degeneration, and clinical correlates in idiopathic PD (iPD) remain unclear. OBJECTIVE: To investigate the relationship between plasma sphingolipids, striatal dopamine transporter specific binding ratio (DAT-SBR) and clinical symptoms in iPD. METHODS: We included 283 iPD patients and 121 healthy controls (HC) from the Parkinson's Progression Markers Initiative (PPMI), utilizing available data on plasma sphingolipids (sphingomyelin [SM] and ceramide [CER]), striatal DAT-SBR and clinical assessments. Linear mixed models and mediation analyses were used to examine the relationship between sphingolipids, DAT-SBR, and clinical progression in iPD. RESULTS: Lower baseline SM levels were significantly associated with a faster decline in DAT-SBR in both the caudate (p = 0.015) and putamen (p = 0.002), with the putamen association remaining significant after Bonferroni correction (p = 0.015). No significant association was found for CER. Patients in the lowest quartile of baseline SM showed faster progression in MDS-UPDRS I (p = 0.013) and II (p = 0.011), while those in the lowest quartile of baseline CER showed faster progression in MDS-UPDRS II (p = 0.013) and III (p = 0.033). The progression rate of caudate DAT-SBR partially mediated the relationships between SM and progression in MDS-UPDRS I and II (p < 0.01). CONCLUSION: Sphingolipids are associated with worse dopaminergic degeneration and potentially linked to faster progression in iPD, holding the promise for identifying individuals with faster progression in iPD.

Oxidative stress and plasma ceramides in broiler chickens.

The selection for rapid growth in chickens has rendered meat-type (broiler) chickens susceptible to develop metabolic syndrome and thus inflammation. The sphingolipid ceramide has been linked as a marker of oxidative stress in mammals, however, the relationship between sphingolipid ceramide supply and oxidative stress in broiler chickens has not been investigated. Therefore, we employed a lipidomic approach to investigate the changes in circulating sphingolipid ceramides in context of allopurinol-induced oxidative stress in birds. Day zero hatched chicks (n = 60) were equally divided into six groups; an unsupplemented control, an allopurinol group (25 mg/kg body weight), a conjugated linoleic acid (CLA) group where half of the oil used in the control diet was substituted for a CLA oil mixture, a CLA and an allopurinol group utilizing the same dose of CLA and allopurinol, a berberine (BRB) group consisting of berberine supplementation (200 mg/kg feed), and a BRB and allopurinol group, utilizing the same dose of BRB and allopurinol. Conjugated linoleic acid and berberine were utilized to potentially enhance antioxidant activity and suppress the oxidative stress induced by allopurinol treatment. Body weight, plasma uric acid, nonesterified fatty acids (NEFA) and sphingolipid ceramides were quantified. Allopurinol induced an inflammatory state as measured by a significant reduction in plasma uric acid - an antioxidant in birds as well as a metabolic waste product. Results showed that both total and saturated sphingolipid ceramides declined (p < 0.05) with age in unsupplemented chicks, although plasma ceramides C16:0 and 18:0 increased in concentration over the study period. Simple total and saturated sphingolipid ceremide's were further decreased (p < 0.05) with allopurinol supplementation, however, this may be an indirect consequence of inducing an inflammatory state. Neither CLA or BRB were able to significantly attenuate the decline. The administration of allopurinol specifically targets the liver which in birds, is the primary organ for fatty acids synthesis. For this reason, sphingolipid ceramide production might have been unwittingly affected by the addition of allopurinol.

Sphingolipid metabolism and regulated cell death in malignant melanoma.

Malignant melanoma (MM) is a highly invasive and therapeutically resistant skin malignancy, posing a significant clinical challenge in its treatment. Programmed cell death plays a crucial role in the occurrence and progression of MM. Sphingolipids (SP), as a class of bioactive lipids, may be associated with many kinds of diseases. SPs regulate various forms of programmed cell death in tumors, including apoptosis, necroptosis, ferroptosis, and more. This review will delve into the mechanisms by which different types of SPs modulate various forms of programmed cell death in MM, such as their regulation of cell membrane permeability and signaling pathways, and how they influence the survival and death fate of MM cells. An in-depth exploration of the role of SPs in programmed cell death in MM aids in unraveling the molecular mechanisms of melanoma development and holds significant importance in developing novel therapeutic strategies.

Duzhong Fang ameliorates cognitive impairment of Parkinsonian mice by suppressing neuronal apoptotic pathway.

Parkinson's disease (PD) is a complex multisystem neurodegenerative disease, and cognitive impairment is a common symptom in the trajectory of PD. Duzhong Fang (DZF) consists of Eucommia ulmoides, Dendrobium, Rehmanniae Radix, and Dried Ginger. Our previous study showed that DZF improves motor deficits in mice. However, whether DZF can ameliorate cognitive impairment in PD has not been reported. In this study, we established mice models of PD induced by rotenone and examined the effect of DZF on cognitive impairment in Parkinson's disease (PD-CI). The results confirmed that DZF treatment not only significantly improved the motor deficits in PD mice and decreased the loss of dopaminergic neurons, but also had significant effects in improving cognitive impairment. We further integrate serum metabolome and network pharmacology to explore the mechanisms by which DZF improves PD-CI. The results revealed that DZF can treat PD-CI by regulating sphingolipid metabolism to inhibit neuronal apoptotic pathway. In conclusion, preliminary studies confirmed that DZF contributes to the improvement of cognitive ability in PD, and our results provide a potential drug for the clinical treatment of PD and a theoretical foundation for DZF in clinical application.

How has the evolution of our understanding of the compartmentalization of sphingolipid biosynthesis over the past 30 years altered our view of the evolution of the pathway?

Sphingolipids are unique among cellular lipids inasmuch as their biosynthesis is compartmentalized between the endoplasmic reticulum (ER) and the Golgi apparatus. This compartmentalization was first recognized about thirty years ago, and the current review not only updates studies on the compartmentalization of sphingolipid biosynthesis, but also discusses the ramifications of this feature for our understanding of how the pathway could have evolved. Thus, we augment some of our recent studies by inclusion of two further molecular pathways that need to be considered when analyzing the evolutionary requirements for generation of sphingolipids, namely contact sites between the ER and the Golgi apparatus, and the mechanism(s) of vesicular transport between these two organelles. Along with evolution of the individual enzymes of the pathway, their subcellular localization, and the supply of essential metabolites via the anteome, it becomes apparent that current models to describe evolution of the sphingolipid biosynthetic pathway may need substantial refinement.

Sphingolipidomic profiling of human Dental Pulp Stem Cells undergoing osteogenic differentiation.

It is now recognized that sphingolipids are involved in the regulation and pathophysiology of several cellular processes such as proliferation, migration, and survival. Growing evidence also implicates them in regulating the behaviour of stem cells, the use of which is increasingly finding application in regenerative medicine. A shotgun lipidomic study was undertaken to determine whether sphingolipid biomarkers exist that can regulate the proliferation and osteogenic differentiation of human Dental Pulp Stem Cells (hDPSCs). Sphingolipids were extracted and identified by direct infusion into an electrospray mass spectrometer. By using cells cultured in osteogenic medium and in medium free of osteogenic stimuli, as a control, we analyzed and compared the SPLs profiles. Both cellular systems were treated at different times (72 hours, 7 days, and 14 days) to highlight any changes in the sphingolipidomic profiles in the subsequent phases of the differentiation process. Signals from sphingolipid species demonstrating clear differences were selected, their relative abundance was determined, and statistical differences were analyzed. Thus, our work suggests a connection between sphingolipid metabolism and hDPSC osteogenic differentiation and provides new biomarkers for improving hDPSC-based orthopaedic regenerative medicine.