Sterol Metabolism Research Articles

Microbial dysbiosis and fecal metabolomic perturbations in Yorkshire Terriers with chronic enteropathy

Dysbiosis and perturbations of fecal metabolic profiles have been reported in dogs with inflammatory bowel disease. Currently the incidence of dysbiosis and the fecal metabolomic profile in Yorkshire Terriers with chronic enteropathy (YTE) and the effects of treatment are unknown. This prospective observational study analyzed the dysbiosis index (DI) and fecal bile acid, sterol and fatty acid profiles in 14 Yorkshire Terriers with active YTE, 11 dogs in clinical remission, and 26 healthy Yorkshire Terriers. YTE was associated with dysbiosis and a significant increase in fatty acids (docosanoate, p = 0.002; gondoate, p = 0.026; erucate, p < 0.001; nervonate, p < 0.001; linolenate, p < 0.001), and plant sterols (campesterol, p < 0.001; brassicasterol, p = 0.024). The abundances of Fusobacterium (p < 0.001) and Cl. hiranonis (p = 0.018) and the concentrations of the secondary bile acid ursodeoxycholic acid (p = 0.033) and the plant sterol sitostanol (p = 0.003) were significantly decreased compared to healthy dogs. Dysbiosis, abundances of Fusobacterium, Cl. hiranonis and fecal concentrations of bile acids and sterols did not recover after treatment, while fecal fatty acid concentrations decreased in treated dogs. YTE is associated with dysbiosis and changes in bile acid, fatty acid, and sterol metabolism. These changes only recovered partially despite clinical remission. They might be breed-specific and involved in the pathogenesis of YTE.

Effect of the Addition of Buckwheat Sprouts Modified with the Addition of Saccharomyces cerevisiae var. boulardii to an Atherogenic Diet on the Metabolism of Sterols, Stanols and Fatty Acids in Rats.

The aim of the study was to evaluate the effect of the addition of Fagopyrum esculentum Moench buckwheat sprouts modified with the addition of Saccharomyces cerevisiae var. boulardii to an atherogenic diet on the metabolism of sterols and fatty acids in rats. It was noticed in the study that the group fed with modified sprouts (HFDPRS) had a greater amount of sterols by 75.2%, compared to the group fed on an atherogenic diet (HFD). The content of cholesterol in the liver and feces was lower in the HFDPRS group than the HFD group. In the serum of the HFDPRS group, a more significant amount of the following acids was observed: C18:2 (increase by 13.5%), C20:4 (increase by 15.1%), and C22:6 (increase by 13.1%), compared to the HFDCS group. Regarding the biochemical parameters, it was noted that the group fed the diet with the addition of probiotic-rich sprouts diet had lower non-HDL, LDL-C and CRP ratios compared to the group fed the high-fat diet. The obtained results indicate that adding modified buckwheat sprouts to the diet by adding the probiotic strain of the yeast may have a significant impact on the metabolism of the indicated components in the organism.

Modular remodeling of sterol metabolism for overproduction of 7-dehydrocholesterol in engineered yeast

Vitamin D3 is a fat-soluble vitamin essential for the human body, and the biosynthesis of its precursor, 7-dehydrocholesterol (7-DHC), gains extensive attention. In this work, six genes (tHMG1, IDI1, ERG1, ERG11, ADH2, ERG7) and a transcription factor mutant UPC2G888A were overexpressed, increasing the 7-DHC titer from 1.2 to 115.3 mg/L. The CRISPR-mediated activation and repression systems were constructed and applied to the synthesis of 7-DHC, increasing the 7-DHC titer to 312.4 mg/L. Next, enzymes were compartmentalized into the endoplasmic reticulum (ER) and the ER lumen was enlarged by overexpressing INO2. The 7-DHC titer of the finally engineered yeast reached 455.6 mg/L in a shake flask and 2870 mg/L in a 5 L bioreactor, the highest 7-DHC titer reported so far. Overall, this study achieved a highly efficient 7-DHC synthesis by remodeling the complicated sterol synthesis modules, paving the way for large-scale 7-DHC bioproduction in the future.

Copper Acts Synergistically With Fluconazole in Candida glabrata by Compromising Drug Efflux, Sterol Metabolism, and Zinc Homeostasis.

The synergistic combinations of drugs are promising strategies to boost the effectiveness of current antifungals and thus prevent the emergence of resistance. In this work, we show that copper and the antifungal fluconazole act synergistically against Candida glabrata, an opportunistic pathogenic yeast intrinsically tolerant to fluconazole. Analyses of the transcriptomic profile of C. glabrata after the combination of copper and fluconazole showed that the expression of the multidrug transporter gene CDR1 was decreased, suggesting that fluconazole efflux could be affected. In agreement, we observed that copper inhibits the transactivation of Pdr1, the transcription regulator of multidrug transporters and leads to the intracellular accumulation of fluconazole. Copper also decreases the transcriptional induction of ergosterol biosynthesis (ERG) genes by fluconazole, which culminates in the accumulation of toxic sterols. Co-treatment of cells with copper and fluconazole should affect the function of proteins located in the plasma membrane, as several ultrastructural alterations, including irregular cell wall and plasma membrane and loss of cell wall integrity, were observed. Finally, we show that the combination of copper and fluconazole downregulates the expression of the gene encoding the zinc-responsive transcription regulator Zap1, which possibly, together with the membrane transporters malfunction, generates zinc depletion. Supplementation with zinc reverts the toxic effect of combining copper with fluconazole, underscoring the importance of this metal in the observed synergistic effect. Overall, this work, while unveiling the molecular basis that supports the use of copper to enhance the effectiveness of fluconazole, paves the way for the development of new metal-based antifungal strategies.

Metabolomics and Transcriptomics Analysis of Pollen Germination Response to Low-Temperature in Pitaya (Hylocereus polyrhizus).

Cross-pollination can improve the percentage of fruit set and fruit weight for most red flesh varieties in pitaya. The technology of pollen storage was very important for successful cross-pollination. However, till present, the technology of pollen storage is unsatisfactory in pitaya production. In this study, pitaya pollen stored at low temperature was taken as the research object, and its physicochemical indexes, metabolomics, and transcriptomics were studied. The results showed that in vitro pollen germination rate decreased significantly with the increase in storage time. Soluble sugar and soluble protein content of pollen peaked on the first day of storage, whereas its relative conductivity, and manlondialdehyde (MDA) and proline contents increased gradually during storage. At the same time, the antioxidant enzyme system of pollen was also affected. Superoxide dismutase (SOD) activity decreased, while the activities of catalase (CAT) and peroxidase (POD) increased and superoxide anion generation rate increased gradually during storage. According to the metabolomics results, amino acid, peptide, nucleotide, plant hormone, terpene, alcohol, phenol, flavonoid, sterol, vitamin, ester, sphingolipid, and ketone contents increased significantly during storage, whereas flavonoid and pigment contents declined gradually. During pollen storage, the gene expressions related to carbohydrate metabolism, protein metabolism, acid and lipid metabolism, sterol metabolism, plant hormone metabolism, and signal transductions were significantly downregulated. With KEGG pathway analysis, isoquinoline alkaloid biosynthesis, tyrosine metabolism, alanine, aspartate, and glutamate metabolism of pollen were affected significantly during low-temperature storage. Correlation analysis showed that the gene expression patterns of HuRP2, HuUPL1, and HuAAT2 had significant effects on pollen germination. D-arabinose 5-phosphate and myricetin were positively correlated with pollen germination rate, which was valuable for studying preservation agents. In this study, the changes in pollen during low-temperature storage were described from the level of metabolites and genes, which could provide theoretical support for the research and development of pollen long-term storage technology in pitaya.

Sex-specific lipid dysregulation in the Abca7 knockout mouse brain.

Alzheimer’s disease is a devastating neurodegenerative disease that affects more women than men. The pathomechanism underlying the sex disparity, especially in the brain, is unclear. ABCA7 is one of the strongest susceptibility genes for Alzheimer’s disease. It mediates the transport of lipids across membranes and is associated with pathways related to amyloid-β neuropathology. However, the role of ABCA7 in the regulation of brain lipids is largely unknown. Sex-specific differences in the pathological link between brain lipid dysregulation and amyloid-β are also unknown. Here, we undertook quantitative discovery lipidomics of male and female Abca7 knockout (n = 52) and wild type (n = 35) mouse brain using sophisticated liquid chromatography/mass spectrometry. We identified 61 lipid subclasses in the mouse brain and found sex-specific differences in lipids that were altered with Abca7 deletion. The altered lipids belong to cellular pathways that control cell signalling, sterol metabolism, mitochondrial function and neuroprotection. We also investigated the relationship between lipids and amyloid-β levels in the Abca7 knockout mice and found elevated free cholesterol only in female mice that was significantly correlated with amyloid-β42 levels. In male Abca7 knockout mice, the neuroprotective ganglioside GD1a levels were elevated and inversely correlated with amyloid-β42 levels. Collectively, these results demonstrate that Abca7 deletion leads to sex-specific lipid dysregulation in the brain, providing insight into the underlying sex disparity in the aetiology of Alzheimer’s disease.

Sterol metabolism regulates clathrin‐mediated endocytosis and intracellular trafficking within isogenic stem cell models

Clathrin‐mediated endocytosis (CME) is a critical cellular pathway for regulation of intracellular signaling, vesicular recycling, and receptor sensitization. While CME is a molecularly complex process which was previously shown to be inhibited by cholesterol depletion, the precise impact of sterol metabolism on CME, the cellular mechanisms involved, and the relevance to disease pathology remain unclear. To determine the impact of sterol homeostasis on CME and possible roles for CME within diseases impacted by cholesterol metabolism, CRISPR/Cas9 gene editing was utilized to fluorescently label clathrin light chain A and dynamin 2 in both immortalized and induced pluripotent stem cell (iPSC) models. To model how cholesterol levels and disease‐relevant sterol changes observed in cholesterol biosynthetic disorders (characterized by the substitution of cellular cholesterol for sterol intermediates) impact endocytosis, CME was analyzed under varying biochemical states. Live cell imaging demonstrated clathrin immobilization at the cell membrane and functional CME impairment occurred following either cholesterol depletion or upon accumulation of sterol species incapable of supporting ordered lipid domains. Polarized total internal reflection fluorescence microscopy demonstrated prolonged clathrin lifetimes associated with endocytic pits with variable curvature in correlation with sterol abundance and support of phase separation. To address the impact of sterol‐mediated CME on neurodevelopment, human iPSCs were analyzed at various stages of differentiation for trafficking deficits following sterol depletion or cholesterol metabolism disruption. CME deficits in iPSCs preceded loss of pluripotency, morphological changes, or aberrant differentiation events observed following cholesterol depletion or sterol intermediate accumulation. CME deficits were also cell‐stage specific, CME activity corresponded to the rate of intracellular sterol metabolism, and organellar deficits with disease relevance resulted from CME deficiencies. Ongoing studies are investigating the consequences of sterol depletion and sterol substitution on developmental signaling pathways and cellular function to provide insight into the mechanistic requirements for sterol homeostasis in CME‐mediated cellular trafficking.

Antiamyloid β toxicity effect of genistein via activation of DAF-16 and HSP-16.2 signal pathways in Caenorhabditis elegans.

β-Amyloid toxicity (Aβ) is an important pathological factor of Alzheimer's disease (AD). Studies have shown that genistein can reduce the toxicity of Aβ to a certain extent; however, the specific mechanism is still uncertain. In the study, we applied Caenorhabditis elegans strains expressing Aβ peptides to evaluate the role of genistein inhibiting Aβ toxicity and the undying mechanism. Genistein influencing the sterol metabolism pathway, the HSP-16.2 pathway, and lipofuscin in different strains of C. elegans were studied using reverse transcription-polymerase chain reaction, fluorescence labeling, RNA interference (RNAi), and so forth. Our results showed that genistein alleviated the paralysis of transgenic C. elegans strains. Furthermore, in AD C. elegans, genistein reduced the fluorescence of lipofuscin, downregulated the messenger RNA (mRNA) level of vit-3 and vit-6 which were related to the sterol metabolism pathway, significantly increased the mRNA level and protein level of HSP-16.2, increased the nuclear translocation of the DAF-16 transcription factor and increased the survival rate after heat stress, which was closely associated with HSP-16.2 levels. However, the paralysis-alleviating effect of genistein was greatly reduced because of RNAi-mediated inhibition of hsp-16.2, indicating that the anti-Aβ toxicity effect of genistein was greatly dependent on HSP-16.2. The above results suggest that genistein inhibiting the toxicity of Aβ in C. elegans, is involved in the modulation of the sterol metabolism pathway by promoting transcription factor DAF-16 translocation into the nucleus, increasing the expression level of HSP-16.2, and reducing the levels of lipofuscin through its antioxidant activity.

Lipid metabolism, immune and apoptosis transcriptomic responses of the hepatopancreas of Chinese mitten crab to the exposure to microcystin-LR

Global warming is favouring the incidence, intensity and duration of harmful cyanobacterial blooms. Microcystin-LR (MC-LR), a hepatotoxic agent, is produced during cyanobacterial blooms. To understand the molecular mechanisms of acute hepatotoxic effect of low doses of MC-LR in crab, we examined differentially expressed genes in samples of the hepatopancreas of Chinese mitten crab (Eriocheir sinensis) collected in 48 h after injections of MC-LR at doses of 0, 25, 50, and 75 µg/kg. The results revealed that MC-LR induced changes in corresponding gene led to the accumulation of triglycerides. MC-LR exposure affected sterol metabolism. Apoptosis-related genes such as Fas-L, Bcl-XL, Cytc, AiF, p53, PERK, calpain, CASP2, CASP7, α-tubulin, PARP, GF, G12, and PKC were upregulated. Conversely, expression levels of CASP10 and ASK1 were downregulated. Genes related to the regulation of actin cytoskeleton (Rho, ROCK, MLCP, MLC, PAK, and PFN) were upregulated. Further, expression levels of genes encoding fatty acid elongation-related enzymes were upregulated, but the expression of genes related to fatty acid synthesis was slightly down regulated. Taken together, these results demonstrated the hepatic toxicity and molecular mechanisms of changes in lipid metabolism, immune and apoptosis in Chinese mitten crab under the MC-LR-induced stress, which is the first report on crabs and performs a comprehensive analysis and a new insight of the molecular toxicological responses in crabs.

Disorders in sterol metabolism: A case series

Disorders in sterol metabolism: A case series

Sexual dimorphism: increased sterol excretion leads to hypocholesterolaemia in female hyperbilirubinaemic Gunn rats.

Circulating bilirubin is associated with reduced serum cholesterol concentrations in humans and in hyperbilirubinaemic Gunn rats. However, mechanisms contributing to hypocholesterolaemia remain unknown. Therefore, this study aimed to investigate cholesterol synthesis, transport and excretion in mutant Gunn rats. Adult Gunn and control rats were assessed for daily faecal sterol excretion using metabolic cages, and water was supplemented with [1‐13C]‐acetate to determine cholesterol synthesis. Bile was collected to measure biliary lipid secretion. Serum and liver were collected for biochemical analysis and for gene/protein expression using RT‐qPCR and western blot, respectively. Additionally, serum was collected and analysed from juvenile rats. A significant interaction of sex, age and phenotype on circulating lipids was found with adult female Gunn rats reporting significantly lower cholesterol and phospholipids. Female Gunn rats also demonstrated elevated cholesterol synthesis, greater biliary lipid secretion and increased total faecal cholesterol and bile acid excretion. Furthermore, they possessed increased hepatic low‐density lipoprotein (LDL) receptor and SREBP2 expression. In contrast, there were no changes to sterol metabolism in adult male Gunn rats. This is the first study to demonstrate elevated faecal sterol excretion in female hyperbilirubinaemic Gunn rats. Increased sterol excretion creates a negative intestinal sterol balance that is compensated for by increased cholesterol synthesis and LDL receptor expression. Therefore, reduced circulating cholesterol is potentially caused by increased hepatic uptake via the LDL receptor. Future studies are required to further evaluate the sexual dimorphism of this response and whether similar findings occur in females with benign unconjugated hyperbilirubinaemia (Gilbert's syndrome).Key points Female adult hyperbilirubinaemic (Gunn) rats demonstrated lower circulating cholesterol, corroborating human studies that report a negative association between bilirubin and cholesterol concentrations.Furthermore, female Gunn rats had elevated sterol excretion creating a negative intestinal sterol balance that was compensated for by elevated cholesterol synthesis and increased hepatic low‐density lipoprotein (LDL) receptor expression.Therefore, elevated LDL receptor expression potentially leads to reduced circulating cholesterol levels in female Gunn rats providing an explanation for the hypocholesterolaemia observed in humans with elevated bilirubin levels.This study also reports a novel interaction of sex with the hyperbilirubinaemic phenotype on sterol metabolism because changes were only reported in females and not in male Gunn rats.Future studies are required to further evaluate the sexual dimorphism of this response and whether similar findings occur in females with benign unconjugated hyperbilirubinaemia (Gilbert's syndrome).

The Effect of Orlistat on Sterol Metabolism in Obese Patients.

BackgroundOrlistat, a reversible inhibitor of pancreatic and gastric lipase, is known to have anti-obesity and antioxidant properties. Cholesterol intermediates and metabolites have diverse and important functions in cardiovascular disease. Therefore, we aimed to evaluate the effect of orlistat on sterol metabolism in overweight and obese adults after weight loss during the intervention or weight loss at 12 weeks.MethodsA total of 51 (27 in the control group and 24 in the experimental group), patients with a BMI of 27 or greater were randomly assigned in a 1:1 ratio to receive either orlistat (120 mg) three times a day plus phentermine hydrochloride (37.5 mg) once daily or a placebo three times a day plus phentermine hydrochloride (37.5 mg) once daily. The primary study outcome was sterol metabolism.ResultsThe experimental group exhibited significantly decreased metabolic signatures of serum sterols, free cholesterol, sitosterol, 7α-hydroxycholesterol (7α-OHC), and 7β-OHC at 12 weeks. The experimental group also exhibited significantly decreased metabolic ratios of sitosterol and 7α-OHC to cholesterol at 12 weeks. Regarding changes in sterol signatures from baseline to 6-month follow-up, free cholesterol, plant sterols, and cholesterol precursors tended to decrease with weight loss during the intervention and increase again as the weight was regained in both groups.ConclusionOrlistat treatment improves oxysterol metabolism in overweight and obese adults. Our findings support that orlistat plays a crucial role in the process of endothelial dysfunction and atherosclerosis via oxysterol modulation.

Sterol Metabolism Differentially Contributes to Maintenance and Exit of Quiescence.

Nutrient starvation initiates cell cycle exit and entry into quiescence, a reversible, non-proliferative state characterized by stress tolerance, longevity and large-scale remodeling of subcellular structures. Depending on the nature of the depleted nutrient, yeast cells are assumed to enter heterogeneous quiescent states with unique but mostly unexplored characteristics. Here, we show that storage and consumption of neutral lipids in lipid droplets (LDs) differentially impacts the regulation of quiescence driven by glucose or phosphate starvation. Upon prolonged glucose exhaustion, LDs were degraded in the vacuole via Atg1-dependent lipophagy. In contrast, yeast cells entering quiescence due to phosphate exhaustion massively over-accumulated LDs that clustered at the vacuolar surface but were not engulfed via lipophagy. Excessive LD biogenesis required contact formation between the endoplasmic reticulum and the vacuole at nucleus-vacuole junctions and was accompanied by a shift of the cellular lipid profile from membrane towards storage lipids, driven by a transcriptional upregulation of enzymes generating neutral lipids, in particular sterol esters. Importantly, sterol ester biogenesis was critical for long-term survival of phosphate-exhausted cells and supported rapid quiescence exit upon nutrient replenishment, but was dispensable for survival and regrowth of glucose-exhausted cells. Instead, these cells relied on de novo synthesis of sterols and fatty acids for quiescence exit and regrowth. Phosphate-exhausted cells efficiently mobilized storage lipids to support several rounds of cell division even in presence of inhibitors of fatty acid and sterol biosynthesis. In sum, our results show that neutral lipid biosynthesis and mobilization to support quiescence maintenance and exit is tailored to the respective nutrient scarcity.

Simvastatin Resistance of Leishmania amazonensis Induces Sterol Remodeling and Cross-Resistance to Sterol Pathway and Serine Protease Inhibitors.

The sterol biosynthesis pathway of Leishmania spp. is used as a pharmacological target; however, available information about the mechanisms of the regulation and remodeling of sterol-related genes is scarce. The present study investigated compensatory mechanisms of the sterol biosynthesis pathway using an inhibitor of HMG-CoA reductase (simvastatin) and by developing drug-resistant parasites to evaluate the impact on sterol remodeling, cross-resistance, and gene expression. Simvastatin-resistant L. amazonensis parasites (LaSimR) underwent reprogramming of sterol metabolism manifested as an increase in cholestane- and stigmastane-based sterols and a decrease in ergostane-based sterols. The levels of the transcripts of sterol 24-C-methyltransferase (SMT), sterol C14-α-demethylase (C14DM), and protease subtilisin (SUB) were increased in LaSimR. LaSimR was cross-resistance to ketoconazole (a C14DM inhibitor) and remained sensitive to terbinafine (an inhibitor of squalene monooxygenase). Sensitivity of the LaSimR mutant to other antileishmanial drugs unrelated to the sterol biosynthesis pathway, such as trivalent antimony and pentamidine, was similar to that of the wild-type strain; however, LaSimR was cross-resistant to miltefosine, general serine protease inhibitor N-p-tosyl-l-phenylalanine chloromethyl ketone (TPCK), subtilisin-specific inhibitor 4-[(diethylamino)methyl]-N-[2-(2-methoxyphenyl)ethyl]-N-(3R)-3-pyrrolidinyl-benzamide dihydrochloride (PF-429242), and tunicamycin. The findings on the regulation of the sterol pathway can support the development of drugs and protease inhibitors targeting this route in parasites.

Gene Expression in Embryos From Norwegian Red Bulls With High or Low Non Return Rate: An RNA-Seq Study of in vivo-Produced Single Embryos.

During the last decade, paternal effects on embryo development have been found to have greater importance than previously believed. In domestic cattle, embryo mortality is an issue of concern, causing huge economical losses for the dairy cattle industry. In attempts to reveal the paternal influence on embryo death, recent approaches have used transcriptome profiling of the embryo to find genes and pathways affected by different phenotypes in the bull. For practical and economic reasons, most such studies have used in vitro produced embryos. The aim of the present study was to investigate the differences in the global transcriptome of in vivo produced embryos, derived from sires with either high or low field fertility measured as the non-return rate (NRR) on day 56 after first AI of the inseminated cows. Superovulated heifers (n = 14) in the age span of 12–15 months were artificially inseminated with semen from either high fertility (n = 6) or low fertility (n = 6) bulls. On day seven after insemination, embryos were retrieved through uterine flushing. Embryos with first grade quality and IETS stage 5 (early blastocyst), 6 (blastocyst) or 7 (expanded blastocyst) were selected for further processing. In total, RNA extracted from 24 embryos was sequenced using Illumina sequencing, followed by differential expression analysis and gene set enrichment analysis. We found 62 genes differentially expressed between the two groups (adj.p-value<0.05), of which several genes and their linked pathways could explain the different developmental capacity. Transcripts highly expressed in the embryos from low fertility bulls were related to sterol metabolism and terpenoid backbone synthesis, while transcripts highly expressed in the high fertility embryos were linked to anti-apoptosis and the regulation of cytokine signaling. The leukocyte transendothelial migration and insulin signaling pathways were associated with enrichments in both groups. We also found some highly expressed transcripts in both groups which can be considered as new candidates in the regulation of embryo development. The present study is an important step in defining the paternal influence in embryonic development. Our results suggest that the sire’s genetic contribution affects several important processes linked to pre-and peri implantation regulation in the developing embryo.

Single PFAS and PFAS mixtures affect nuclear receptor- and oxidative stress-related pathways in precision-cut liver slices of Atlantic cod (Gadus morhua)

The aim of the present study was to investigate effects of per- and polyfluoroalkyl substances (PFAS), both single compounds and a mixture of these, using precision-cut liver slices (PCLS) from Atlantic cod (Gadus morhua). PCLS were exposed for 48 h to perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA) and perfluorononanoate (PFNA) (10, 50 and 100 μM), and three mixtures of these at equimolar concentrations (10, 50 and 100 μM). Transcriptomic responses were assessed using RNA sequencing. Among exposures to single PFAS, PFOS produced the highest number of differentially expressed genes (DEGs) compared to PFOA and PFNA (86, 25 and 31 DEGs, respectively). Exposure to the PFAS mixtures resulted in a markedly higher number of DEGs (841). Clustering analysis revealed that the expression pattern of the PFAS mixtures were more similar to PFOS compared to PFOA and PFNA, suggesting that effects induced by the PFAS mixtures may largely be attributed to PFOS. Pathway analysis showed significant enrichment of pathways related to oxidative stress, cholesterol metabolism and nuclear receptors in PFOS-exposed PCLS. Fewer pathways were significantly enriched following PFOA and PFNA exposure alone. Significantly enriched pathways following mixture exposure included lipid biosynthesis, cancer-related pathways, nuclear receptor pathways and oxidative stress-related pathways such as ferroptosis. The expression of most of the genes within these pathways was increased following PFAS exposure. Analysis of non-additive effects in the 100 μM PFAS mixture highlighted genes involved in the antioxidant response and membrane transport, among others, and the majority of these genes had synergistic expression patterns in the mixture. Nevertheless, 90% of the DEGs following mixture exposure showed additive expression patterns, suggesting additivity to be the major mixture effect. In summary, PFAS exposure promoted effects on cellular processes involved in oxidative stress, nuclear receptor pathways and sterol metabolism in cod PCLS, with the strongest effects observed following PFAS mixture exposure.

Human gray and white matter metabolomics to differentiate APOE-dependent metabolic changes in early and late Alzheimer's disease.

Many have suggested that irregularities in metabolism play an underlying role in the progression of Alzheimer's Disease (AD). A detailed knowledge of the biochemical composition of AD brain tissue vs normal brain tissue will be key in understanding the metabolic processes underlying AD, especially as they relate to APOE genotype. Here we perform a metabolomics analysis on the brain tissue of a large cohort of community-based participants in the UK-ADC brain bank to characterize the biochemical profiles of brains with and without Alzheimer's disease and other mixed pathologies based on APOE genotype and disease stage. The global biochemical profiles of post-mortem human brain tissue from the gray matter of Brodmann area 9 was determined using mass spectroscopy. Brain tissue from 158 community-based older adult volunteers was analyzed. Metabolites were quantified using global untargeted metabolomics (HD4) and compared between cohorts using Welch's two-sample t-test to approximate fold change of metabolites between disease stage and APOE genotype. Random forest was used to rank metabolites in order of importance for predicting AD presence in tissue. Late stage disease in the APOE E4 genotype has decreases in lysophospholipids, long chain polyunsaturated fatty acids, endocannabinoids, and branched fatty acids as well as N-acetylserine in the gray matter. Late stage disease in the APOE E4 genotype has increases in phospholipid metabolism and decreases in amino acid metabolism and Vitamin B6. The APOE E4 genotype is associated with increases in gamma-glutamyl amino acids, lysophospholipid, and amino acid metabolism and decreases in urea cycle, sterol, stachydrine, and benzoate metabolism during early stages of disease, but that there are few metabolic differences between genotypes in later disease. Alzheimer's disease has increases in phospholipid metabolism and decreases in amino acid metabolism compared to normal. Early stage disease showed many metabolic differences between genotypes and late stage tissues looked remarkably similar across genotype. This suggests there may be metabolically distinct pathways that each genotype takes to produce a tissue with common endpoint of disease characterized by an AD biochemical profile. Further studies are needed to examine whether these metabolites are consistently altered in Alzheimer's disease.

Ethanol resistance in Drosophila melanogaster has increased in parallel cold-adapted populations and shows a variable genetic architecture within and between populations.

Understanding the genetic properties of adaptive trait evolution is a fundamental crux of biological inquiry that links molecular processes to biological diversity. Important uncertainties persist regarding the genetic predictability of adaptive trait change, the role of standing variation, and whether adaptation tends to result in the fixation of favored variants. Here, we use the recurrent evolution of enhanced ethanol resistance in Drosophila melanogaster during this species’ worldwide expansion as a promising system to add to our understanding of the genetics of adaptation. We find that elevated ethanol resistance has evolved at least three times in different cooler regions of the species’ modern range—not only at high latitude but also in two African high‐altitude regions. Applying a bulk segregant mapping framework, we find that the genetic architecture of ethanol resistance evolution differs substantially not only between our three resistant populations, but also between two crosses involving the same European population. We then apply population genetic scans for local adaptation within our quantitative trait locus regions, and we find potential contributions of genes with annotated roles in spindle localization, membrane composition, sterol and alcohol metabolism, and other processes. We also apply simulation‐based analyses that confirm the variable genetic basis of ethanol resistance and hint at a moderately polygenic architecture. However, these simulations indicate that larger‐scale studies will be needed to more clearly quantify the genetic architecture of adaptive evolution and to firmly connect trait evolution to specific causative loci.

Human induced pluripotent stem cell derived hepatocytes provide insights on parenteral nutrition associated cholestasis in the immature liver

Parenteral nutrition-associated cholestasis (PNAC) significantly limits the safety of intravenous parenteral nutrition (PN). Critically ill infants are highly vulnerable to PNAC-related morbidity and mortality, however the impact of hepatic immaturity on PNAC is poorly understood. We examined developmental differences between fetal/infant and adult livers, and used human induced pluripotent stem cell-derived hepatocyte-like cells (iHLC) to gain insights into the contribution of development to altered sterol metabolism and PNAC. We used RNA-sequencing and computational techniques to compare gene expression patterns in human fetal/infant livers, adult liver, and iHLC. We identified distinct gene expression profiles between the human feta/infant livers compared to adult liver, and close resemblance of iHLC to human developing livers. Compared to adult, both developing livers and iHLC had significant downregulation of xenobiotic, bile acid, and fatty acid metabolism; and lower expression of the sterol metabolizing gene ABCG8. When challenged with stigmasterol, a plant sterol found in intravenous soy lipids, lipid accumulation was significantly higher in iHLC compared to adult-derived HepG2 cells. Our findings provide insights into altered bile acid and lipid metabolizing processes in the immature human liver, and support the use of iHLC as a relevant model system of developing liver to study lipid metabolism and PNAC.

CK syndrome: a rare cause of developmental delay in a young boy.

CK syndrome is a rare disorder caused by mutation in the NSDHL (NAD(P) dependent steroid dehydrogenase-like) gene at the Xq28 locus. It has expanded the spectrum of disorders associated with X-linked mental retardation and defects in sterol metabolism. There are only a few reports defining the phenotypic spectrum of this rare disorder. We describe a new patient from the Indian subcontinent who presented with dysmorphism, global developmental delay and epilepsy. We also add left ventricular concentric hypertrophy and sensory neuropathy, which have not been reported previously. Our report suggests that CK syndrome may be unrecognized due to limited clinical knowledge and restricted availability of genetic testing. The expansion of the phenotype may also lead to a better understanding of biochemical anomalies and management approaches.