Key Genes Of Lipid Metabolism Research Articles

A preclinical model of severe NASH-like liver injury by chronic administration of a high-fat and high-sucrose diet in mice

Non-alcoholic fatty liver disease (NAFLD) is a progressive liver disease, affecting 38% of adults globally. If left untreated, NAFLD may progress to more advanced forms of the disease, including non-alcoholic steatohepatitis (NASH), liver cirrhosis, and fibrosis. Early NAFLD detection is critical to prevent disease progression. Using an obesogenic high-fat and high-sucrose (HF/HS) diet, we characterized the progression of NAFLD in male and female Collaborative Cross CC042 mice after 20-, 40-, and 60-week intervals of chronic HF/HS diet feeding. The incidence and severity of liver steatosis, inflammation, and fibrosis increased in both sexes over time, with male mice progressing to a NASH-like disease state faster than female mice, as indicated by earlier and more pronounced changes in liver steatosis. Histopathological indication of macrovesicular steatosis and gene expression changes of key lipid metabolism genes were found to be elevated in both sexes after 20 weeks of HF/HS diet. Measurement of circulating markers of inflammation (CXCL10 and TNF-α), histopathological analysis of immune cell infiltrates, and gene expression changes in inflammation-related genes indicated significant liver inflammation after 40 and 60 weeks of HF/HS diet exposure in both sexes. Liver fibrosis, as assessed by Picosirius red and Masson's trichrome staining and changes in expression of key fibrosis related genes indicated significant changes after 40 and 60 weeks of HF/HS diet exposure. In conclusion, we present a preclinical animal model of dietary NAFLD progression, which recapitulates human pathophysiological and pathomorphological changes, that could be used to better understand the progression of NAFLD and support development of new therapeutics.

Hypolipidemic effect and gut microbiota regulation of Gypenoside aglycones in rats fed a high-fat diet

Ethnopharmacological relevanceGynostemma pentaphyllum (Thunb.) Makino has traditional applications in Chinese medicine to treat lipid abnormalities. Gypenosides (GPs), the main bioactive components of Gynostemma pentaphyllum, have been reported to exert hypolipidemic effects through multiple mechanisms. The lipid-lowering effects of GPs may be attributed to the aglycone portion resulting from hydrolysis of GPs by the gut microbiota. However, to date, there have been no reports on whether gypenoside aglycones (Agl), the primary bioactive constituents, can ameliorate hyperlipidemia by modulating the gut microbiota. Aim of the studyThis study explored the potential therapeutic effects of gypenoside aglycone (Agl) in a rat model of high-fat diet (HFD)-induced hyperlipidemia. MethodsA hyperlipidemic rat model was established by feeding rats with a high-fat diet. Agl was administered orally, and serum lipid levels were analyzed. Molecular techniques, including RT-polymerase chain reaction (PCR) and fecal microbiota sequencing, were used to investigate the effects of Agl on lipid metabolism and gut microbiota composition. ResultsAgl administration significantly reduced serum levels of total cholesterol (TC), triglycerides (TG), and low-density lipoprotein cholesterol (LDL-C) and mitigated hepatic damage induced by HFD. Molecular investigations have revealed the modulation of key lipid metabolism genes and proteins by Agl. Notably, Agl treatment enriched the gut microbiota with beneficial genera, including Lactobacillus, Akkermansia, and Blautia and promoted specific shifts in Lactobacillus murinus, Firmicutes bacterium CAG:424, and Allobaculum stercoricanis. ConclusionThis comprehensive study established Agl as a promising candidate for the treatment of hyperlipidemia. It also exhibits remarkable hypolipidemic and hepatoprotective properties. The modulation of lipid metabolism-related genes, along with the restoration of gut microbiota balance, provides mechanistic insights. Thus, Agl has great potential for clinical applications in hyperlipidemia management.

Linking genomic prediction of fillet fat content in Atlantic salmon to underlying changes in lipid metabolism regulation

Fillet fat content is an important production trait in Atlantic salmon (Salmo salar) because it influences the flavor, texture, and nutritional properties of the product. Selection can be applied to alter muscle fat content, however how such selection changes the underlying molecular physiology of these animals is unknown. Here, we examine the link between genomic predicted breeding value for fillet fat of 184 fish and gene expression in the liver with an emphasis on lipid metabolism genes. We found that salmon with higher genomic breeding values for fillet fat had higher expression of genes in lipid metabolism pathways. This included key lipid metabolism genes hmgcrab, fasn-b, fads2d5, and fads2d6, and lipid transporters fatp2f, fabp7b, and apobc. We also found several regulators of lipid metabolism with negative correlation to genomic breeding values, including pparg-b, fxr-a, and fxr-b. A quantitative trait loci analysis for variation in gene expression levels (eQTLs) for 167 fillet fat associated genes found that 71 genes had at least one eQTL, and that most were trans eQTLs. Closer examination revealed distinct eQTL clustering on chromosomes 3 and 6, indicating the presence of putative common regulator in these regions. Taken together, these results suggest that salmon with high genomic breeding value for fillet fat have elevated lipid synthesis, elevated lipid transport, and reduced glycerolipid breakdown; and that this is at least partly due to genetic variants that impact the function of top-level transcription factors involved in liver metabolism. Our study sheds light on how genomic selection for reduced or increased fillet fat content in Atlantic salmon alters gene regulation in the liver of the fish. These results could be used to prioritize SNPs with an association to phenotype related gene expression to improve the efficiency and reduce the cost of genomic selection in the future.

ANGPTL3 deficiency impairs lipoprotein production and produces adaptive changes in hepatic lipid metabolism

Angiopoietin-like protein 3 (ANGPTL3) is a hepatically secreted protein and therapeutic target for reducing plasma triglyceride-rich lipoproteins and low-density lipoprotein (LDL) cholesterol. Although ANGPTL3 modulates the metabolism of circulating lipoproteins, its role in triglyceride-rich lipoprotein assembly and secretion remains unknown. CRISPR-associated protein 9 (CRISPR/Cas9) was used to target ANGPTL3 in HepG2 cells (ANGPTL3−/−) whereupon we observed ∼50% reduction of apolipoprotein B100 (ApoB100) secretion, accompanied by an increase in ApoB100 early presecretory degradation via a predominantly lysosomal mechanism. Despite defective particle secretion in ANGPTL3−/− cells, targeted lipidomic analysis did not reveal neutral lipid accumulation in ANGPTL3−/− cells; rather ANGPTL3−/− cells demonstrated decreased secretion of newly synthesized triglycerides and increased fatty acid oxidation. Furthermore, RNA sequencing demonstrated significantly altered expression of key lipid metabolism genes, including targets of peroxisome proliferator-activated receptor α, consistent with decreased lipid anabolism and increased lipid catabolism. In contrast, CRISPR/Cas9 LDL receptor (LDLR) deletion in ANGPTL3−/− cells did not result in a secretion defect at baseline, but proteasomal inhibition strongly induced compensatory late presecretory degradation of ApoB100 and impaired its secretion. Additionally, these ANGPTL3−/−;LDLR−/− cells rescued the deficient LDL clearance of LDLR−/− cells. In summary, ANGPTL3 deficiency in the presence of functional LDLR leads to the production of fewer lipoprotein particles due to early presecretory defects in particle assembly that are associated with adaptive changes in intrahepatic lipid metabolism. In contrast, when LDLR is absent, ANGPTL3 deficiency is associated with late presecretory regulation of ApoB100 degradation without impaired secretion. Our findings therefore suggest an unanticipated intrahepatic role for ANGPTL3, whose function varies with LDLR status.

Abstract C110: miR195 - A potential therapeutic molecule for breast cancer: Present and future

Abstract Breast cancer is the leading cause of death in women worldwide (Globocan 2020). Surgery, chemotherapy as well as radiation therapy are the commonly used modes of treatment and the treatment depends on the tumor type. Patients develop resistance and demonstrate poor prognosis after prolonged treatment. Hence there’s is always a need for new diagnostics and therapeutics. miRNAs are 18-22 nucleotides small RNAs known to play a role in development and disease. Deregulation of miRNAs in diseased conditions can be harnessed as potential therapeutics by miRNA mimics or miRNA inhibition by antimiRs. Till date, several miRNA-targeted therapeutics have reached clinical development. Our laboratory has shown that miR-195 not only down regulates anti-apoptotic protein bcl-2 but also key genes of lipid metabolism (FASN, HMGCR) which are upregulated in breast cancer. The altered calcium signaling is deleterious to cells and is also known to be associated with different hallmarks of cancer. We recently observed that miR-195 perturbs calcium homeostasis in breast cancer cells by down-regulating a major calcium efflux pump present on the plasma membrane. Experimental validation has been performed in breast cancer cells and spheroids using western blotting, qRT-PCR, dual luciferase assay, calcium measurements using flow cytometry and immunofluorescence. MiR-195 alters calcium homeostasis leading to ER stress and autophagy in breast cancer. The current work describes recent advances in our understanding of miRNA-195 in breast cancer. Citation Format: Paresh Purohit, Neeru Saini. miR195 - A potential therapeutic molecule for breast cancer: Present and future [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C110.

Impaired T-Cell Proliferation in Chronic Lymphocytic Leukemia Patients Is Linked to Disturbed Lipid Metabolism and Homeostasis

Background Successful T-cell based anti-cancer therapies require proliferation and longevity of effector T cells, features that highly depend on metabolic processes. T cells from chronic lymphocytic leukemia (CLL) patients are characterized by acquired T-cell dysfunction, resulting in impaired activation, proliferation and cytotoxicity upon in-vitro activation (van Bruggen et al, Blood 2019). Whilst the role of glucose metabolism in activated T-cells is extensively studied, the contribution of other energy sources is less clear. Lipid metabolism has only recently come into focus as an important source of energy for immune cells. Aims Molecular and functional analysis of the lipid metabolic pathway in T cells from CLL patients. Methods Peripheral blood mononuclear cells (PBMCs) of untreated CLL patients and, as controls, age-matched healthy donors (HD) were studied. T cells at baseline and after TCR stimulation were analyzed molecularly using transcriptomics and lipidomics, and extensively characterized at protein level by flow cytometry and confocal imaging. Lipid metabolism was manipulated through culturing cells in lipoprotein deficient serum (LPDS), or in the presence of agonists and inhibitors of specific regulatory pathways. Results We found the uptake of lipids, specifically cholesterol, during T-cell activation essential for proliferation, which was evidenced by a nearly absent proliferative capacity of HD T cells in the lack of exogenous lipids which was fully rescued by re-addition of cholesterol-rich low-density lipoproteins (LDL). As CLL T cells portray an altered proliferation pattern even when cultured in normal medium, transcriptomic analysis was performed to investigate the expression of key lipid metabolism genes. CLL T-cells had reduced expression of the master transcription factors SREBP1/2, governing lipid and cholesterol metabolism, when stimulated in the presence of their autologous CLL cells (Figure 1A). Accordingly, downstream protein involved in the synthesis and desaturation of lipids and LDL uptake (specifically FASN, LDL-R and SCD) were significantly reduced in CLL compared to HD T cells. Remarkably, despite reduced capacity for LDL uptake, an accumulation of neutral lipids was found in CLL T cells especially upon stimulation (Figure 1B), a feature earlier described in dysfunctional macrophages. The lipid accumulation observed in CLL T cells was supported by the lack of expression of ATGL, a crucial enzyme for the utilization of neutral lipids for energy production and building of new membranes. In line with this, mitochondrial lipid oxidation was decreased in stimulated CLL T cells compared to HD. To investigate the composition of the accumulated lipids, lipidomics analysis was performed, revealing differential abundance of specific lipid classes in stimulated CLL versus HD T cells. Triglycerides were increased while cholesterol esters and phospholipids were reduced in CLL T cells. Triglycerides likely constitute the neutral lipids accumulation found in these cells. As cholesterol esters and phospholipids are essential for proper membrane formation, reduced levels of these species can contribute to the reduced proliferative capacity of CLL T cells. Summary/conclusion Altogether, the results presented here demonstrate a disturbed lipid composition and utilization in CLL T-cells, which contributes to T-cell dysfunction on at least two levels: decreased bioenergetics and decreased proliferation. Likewise, lipid deprivation due to both decreased uptake and a misbalanced lipidome leads to altered T-cell function. Therefore, strategies to increase lipid uptake, synthesis and utilization in order to rebalance homeostasis could ameliorate CLL T-cell dysfunction and specifically proliferation-defects in CLL.

Genome-wide comprehensive characterization and transcriptomic analysis of AP2/ERF gene family revealed its role in seed oil and ALA formation in perilla (Perilla frutescens)

Perilla (Perilla frutescens) is a potential specific oilseed crop with an extremely high α-linolenic acid (ALA) content in its seeds. AP2/ERF transcription factors (TFs) play important roles in multiple biological processes. However, limited information is known about the regulatory mechanism of the AP2/ERF family in perilla’s oil accumulation. In this research, we identified 212 AP2/ERF family members in the genome of perilla, and their domain characteristics, collinearity, and sub-genome differentiation were comprehensively analyzed. Transcriptome sequencing revealed that genes encoding key enzymes involved in oil biosynthesis (e.g., ACCs, KASII, GPAT, PDAT and LPAAT) were up-regulated in the high-oil variety. Moreover, the endoplasmic reticulum-localized FAD2 and FAD3 were significantly up-regulated in the high-ALA variety. To investigate the roles of AP2/ERFs in lipid biosynthesis, we conducted a correlation analysis between non-redundant AP2/ERFs and key lipid metabolism genes using WGCNA. A significant correlation was found between 36 AP2/ERFs and 90 lipid metabolism genes. Among them, 12 AP2/ERFs were identified as hub genes and showed significant correlation with lipid synthase genes (e.g., FADs, GPAT and ACSL) and key regulatory TFs (e.g., LEC2, IAA, MYB, UPL3). Furthermore, gene expression analysis identified three AP2/ERFs (WRI, ABI4, and RAVI) potentially playing an important role in the regulation of oil accumulation in perilla. Our study suggests that PfAP2/ERFs are important regulatory TFs in the lipid biosynthesis pathway, providing a foundation for the molecular understanding of oil accumulation in perilla and other oilseed crops.

A novel role of RNase L in the development of nonalcoholic steatohepatitis.

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease and affects about 25% of the population globally. NAFLD has the potential to cause significant liver damage in many patients because it can progress to nonalcoholic steatohepatitis (NASH) and cirrhosis, which substantially increases disease morbidity and mortality. Despite the key role of innate immunity in the disease progression, the underlying molecular and pathogenic mechanisms remain to be elucidated. RNase L is a key enzyme in interferon action against viral infection and displays pleiotropic biological functions such as control of cell proliferation, apoptosis, and autophagy. Recent studies have demonstrated that RNase L is involved in innate immunity. In this study, we revealed that RNase L contributed to the development of NAFLD, which further progressed to NASH in a time-dependent fashion after RNase L wild-type (WT) and knockout mice were fed with a high-fat and high-cholesterol diet. RNase L WT mice showed significantly more severe NASH, evidenced by widespread macro-vesicular steatosis, hepatocyte ballooning degeneration, inflammation, and fibrosis, although physiological and biochemical data indicated that both types of mice developed obesity, hyperglycemia, hypercholesterolemia, dysfunction of the liver, and systemic inflammation at different extents. Further investigation demonstrated that RNase L was responsible for the expression of some key genes in lipid metabolism, inflammation, and fibrosis signaling. Taken together, our results suggest that a novel therapeutic intervention for NAFLD may be developed based on regulating the expression and activity of RNase L.

Akkermansia muciniphila Cell-Free Supernatant Improves Glucose and Lipid Metabolisms in Caenorhabditis elegans.

To explore the mechanism by which Akkermansia muciniphila cell-free supernatant improves glucose and lipid metabolisms in Caenorhabditis elegans, the present study used different dilution concentrations of Akkermansia muciniphila cell-free supernatant as an intervention for with Caenorhabditis elegans under a high-glucose diet. The changes in lifespan, exercise ability, level of free radicals, and characteristic indexes of glucose and lipid metabolisms were studied. Furthermore, the expression of key genes of glucose and lipid metabolisms was detected by qRT-PCR. The results showed that A. muciniphila cell-free supernatant significantly improved the movement ability, prolonged the lifespan, reduced the level of ROS, and alleviated oxidative damage in Caenorhabditis elegans. A. muciniphila cell-free supernatant supported resistance to increases in glucose and triglyceride induced by a high-glucose diet and downregulated the expression of key genes of glucose metabolism, such as gsy-1, pygl-1, pfk-1.1, and pyk-1, while upregulating the expression of key genes of lipid metabolism, such as acs-2, cpt-4, sbp-1, and tph-1, as well as down-regulating the expression of the fat-7 gene to inhibit fatty acid biosynthesis. These findings indicated that A. muciniphila cell-free supernatant, as a postbiotic, has the potential to prevent obesity and improve glucose metabolism disorders and other diseases.

Astaxanthin-loaded nanoparticles enhance its cell uptake, antioxidant and hypolipidemic activities in multiple cell lines

Astaxanthin is a natural carotenoid pigment, which provides many benefits to human health and nutrition. However, the human body has a low bioavailability of astaxanthin due to its poor solubility in the water phase. This study aimed to prepare astaxanthin nanoparticles using an emulsification/solvent evaporation method and then to evaluate bioavailability of nano-astaxanthin for biomedical applications. The results showed that the combinative use of cremophor RH40 as surfactants and polyethylene glycol–polylactic acid copolymer as an encapsulation agent generated well-defined astaxanthin nanoparticles with 5% astaxanthin content. These nanoparticles exhibited spherical morphology with average particle diameters of 90 nm. Nanoastaxanthin had high DPPH free radical scavenging activity and significantly improved cell uptake compared to the free astaxanthin. Astaxanthin nanoparticles showed no cytotoxicity against HT29, HepG2 and RAW264.7 cells up to a concentration of 500 μg/mL and event showed a more powerful cytoprotective effect on H2O2-induced oxidative HepG2 cell damage at concentrations of 50 and 100 μg/mL. Besides that, the activity of antioxidant enzymes (catalase and glutathione peroxidase) and gene expressions of Nrf2, HO-1 and NQO1 increased concentration-dependently, while the mRNA level of Keap1 significantly decreased in cells incubated with nanoastaxanthin compared to astaxanthin and control groups. Moreover, hepatocytes and murine RAW264.7 macrophages treated with nanoastaxanthin, but not with free astaxanthin, displayed to reduce cellular lipid accumulation compared with control cells via altering the expression of key genes in lipid metabolism (LDLR, CYP7A1, FAS, PPARα, CPT-1 and LXRα in HepG2 cells and ABCA1 and G1 in RAW264.7 cells). Our results highlight the great potential of nanoastaxanthin for applications in human health and nutrition.

Identification of the hub genes related to adipose tissue metabolism of bovine.

Due to the demand for high-quality animal protein, there has been consistent interest in how to obtain more high-quality beef. As well-known, the adipose content of beef has a close connection with the taste and quality of beef, and cattle with different energy or protein diet have corresponding effects on the lipid metabolism of beef. Thus, we performed weighted gene co-expression network analysis (WGCNA) with subcutaneous adipose genes from Norwegian red heifers fed different diets to identify hub genes regulating bovine lipid metabolism. For this purpose, the RNA sequencing data of subcutaneous adipose tissue of 12-month-old Norwegian red heifers (n = 48) with different energy or protein levels were selected from the GEO database, and 7,630 genes with the largest variation were selected for WGCNA analysis. Then, three modules were selected as hub genes candidate modules according to the correlation between modules and phenotypes, including pink, magenta and grey60 modules. GO and KEGG enrichment analysis showed that genes were related to metabolism, and participated in Rap, MAPK, AMPK, VEGF signaling pathways, and so forth. Combined gene interaction network analysis using Cytoscape software, eight hub genes of lipid metabolism were identified, including TIA1, LOC516108, SNAPC4, CPSF2, ZNF574, CLASRP, MED15 and U2AF2. Further, the expression levels of hub genes in the cattle tissue were also measured to verify the results, and we found hub genes in higher expression in muscle and adipose tissue in adult cattle. In summary, we predicted the key genes of lipid metabolism in the subcutaneous adipose tissue that were affected by the intake of various energy diets to find the hub genes that coordinate lipid metabolism, which provide a theoretical basis for regulating beef quality.

Broken Xinyang Maojian tea supplementation in a high-fat diet improves the growth performance, flesh quality and lipid metabolism of Yellow River carp (Cyprinus carpio)

This study explored the protective effect of broken tea on growth, antioxidant capacity, nutritional composition and lipid metabolism in fish fed a high-fat (HF) diet. A total of 450 Cyprinus carpio (18.79 ± 3.16 g) were divided into five groups and fed for 8 weeks: the control diet group (C), HF diet group (HF), and the HF diet plus 1 %, 2 % and 3 % broken Xinyang Maojian tea (BTMaojian) groups (HF+1%BT, HF+2 %BT and HF+3 %BT). We found that the weight gain rate (WGR) of carp was increased significantly in the HF+ 3 %BT group compared with the control group (P < 0.05). The elevated hepatic malondialdehyde (MDA), alanine aminotransaminase (ALT), aspartate aminotransferase (AST), and triglyceride (TG) in the HF group were attenuated by BTMaojian treatment (P < 0.05). Moreover, the low total antioxidant capacity (T-AOC) and superoxide dismutase (T-SOD) content in serum and hepatopancreas in the HF group were significantly increased by the addition of BTMaojian (P < 0.05). The total essential amino acid content in muscle was significantly increased in the HF+ 2%BT group compared with the HF group (P < 0.05). Additionally, the highest linoleic acid content in muscle was found in the HF+ 3%BT group. The excessive hepatopancreas fat accumulation caused by the HF diet was alleviated in the 2 % and 3 % BTMaojian supplementation groups. The mRNA level of most key lipid metabolism genes in the hepatopancreas, intestinal tract, muscle and adipose tissue tended to be increased in the HF group and decreased in the BTMaojian treatment groups. Taken together, these results indicated that the addition of 2 % or 3 % BTMaojian likely positively affected growth performance, enhanced flesh quality, and alleviated harmful symptoms, including low antioxidant capacity and excessive hepatic fat accumulation in carp fed a HF diet. Thus, BTMaojian can be used as a green feed additive in C. carpio feed.

MEDB-73. Lipid metabolism as a therapeutic vulnerability in BET inhibitor-resistant medulloblastoma

MYC-driven medulloblastomas are a particularly devastating group of pediatric brain tumors that exhibit resistance and continued progression despite standard of care treatments. Our preclinical work identified BET-bromodomain inhibitors as a potentially promising new class of drugs for children with medulloblastoma and other MYC-driven cancers, providing rationale to evaluate these agents in clinical trials. However, treatment with BET inhibitor (BETi) alone is unlikely to be sufficient to cure, with most tumors evolving to acquire resistance to single-agent targeted therapies. We applied an integrative genomics approach to identify genes and pathways mediating BETi response in medulloblastoma. These studies revealed that MYC-driven medulloblastoma cells with acquired resistance to BETi reinstate transcription of essential genes suppressed by drug and exhibit changes in cell state and new vulnerabilities not present in drug-sensitive cells. We now have a growing body of evidence showing that BET inhibition downregulates the expression of key lipid metabolism genes and metabolism-related signaling pathways, and that medulloblastoma cells with adaptive resistance to drug differentially express and exhibit preferential dependency on specific lipid metabolic genes and transcriptional regulators. Our studies explore the possibility of exploiting these metabolic vulnerabilities to overcome BETi resistance and provide a more efficacious upfront therapy.

The specific glycerolipid composition is responsible for maintaining the membrane stability of Physcomitrella patens under dehydration stress

Land colonization is a major event in plant evolution. Little is known about the evolutionary characteristics of lipids during this process. Here, we proved that Physcomitrella patens, a bryophyte that appeared in the early evolution of terrestrial plants, has short-term desiccation resistance. The maintenance of membrane integrity is related to its specific glycerolipid composition and key genes for lipid metabolism. We analyzed 414 types of lipid molecules, and found that phospholipids accounted for 61.7%, mainly PC and PI; glycolipids accounted for only 26.5%, with a special MGDG molecular map. The most abundant MDGD, that is, MGDG34:6, contained rare 15- and 19-carbon acyl chains; the level of neutral lipids was higher. This was consistent with the results observed by TEM, with fewer lamellae and obvious lipid droplets. Slight dehydration accumulated a large number of TAG molecules, and severe dehydration degraded phospholipids and caused membrane leakage, but PA and MGDG fluctuated less. The key genes of lipid metabolism, DGAT and PAP, were actively transcribed, suggesting that PA was one of the main DAG sources for TAG synthesis. This work proves that Physcomitrella patens adopts high-constitutive PC and PI similar to plant seeds, abundant TAG, and its own specific MGDG to resist extreme dehydration. This result provides a new insight into the lipid evolution of early terrestrial plants against unfavorable terrestrial environments.

TAMI-75. LIPID METABOLISM AS A THERAPEUTIC VULNERABILITY IN BET INHIBITOR-RESISTANT MEDULLOBLASTOMA

Abstract MYC-driven medulloblastomas are a particularly devastating group of pediatric brain tumors that exhibit resistance and continued progression despite standard of care treatments. Our preclinical work identified BET-bromodomain inhibitors as a potentially promising new class of drugs for children with medulloblastoma and other MYC-driven cancers, providing rationale to evaluate these agents in clinical trials. However, treatment with BET inhibitor (BETi) alone is unlikely to be sufficient for a cure, with most tumors evolving to acquire resistance to single-agent targeted therapies. We applied an integrative genomics approach to identify genes and pathways mediating BETi response in medulloblastoma. These studies revealed that MYC-driven medulloblastoma cells with acquired resistance to BETi reinstate transcription of essential genes suppressed by drug, and exhibit changes in cell state and new vulnerabilities not present in drug-sensitive cells. We now have a growing body of evidence showing that BET inhibition downregulates the expression of key lipid metabolism genes and metabolism-related signaling pathways, and that medulloblastoma cells with adaptive resistance to drug differentially express and exhibit preferential dependency on specific lipid metabolic genes and transcriptional regulators. Our studies explore the possibility of exploiting these novel metabolic vulnerabilities in order to overcome BETi resistance and provide a more efficacious upfront therapy.

Use of human PBMC to analyse the impact of obesity on lipid metabolism and metabolic status: a proof-of-concept pilot study

Peripheral blood mononuclear cells (PBMC) are widely used as a biomarker source in nutrition/obesity studies because they reflect gene expression profiles of internal tissues. In this pilot proof-of-concept study we analysed in humans if, as we previously suggested in rodents, PBMC could be a surrogate tissue to study overweight/obesity impact on lipid metabolism. Pre-selected key lipid metabolism genes based in our previous preclinical studies were analysed in PBMC of normoglycemic normal-weight (NW), and overweight-obese (OW-OB) subjects before and after a 6-month weight-loss plan. PBMC mRNA levels of CPT1A, FASN and SREBP-1c increased in the OW-OB group, according with what described in liver and adipose tissue of humans with obesity. This altered expression pattern was related to increased adiposity and early signs of metabolic impairment. Greater weight loss and/or metabolic improvement as result of the intervention was related to lower CPT1A, FASN and SREBP-1c gene expression in an adjusted linear mixed-effects regression analysis, although no gene expression recovery was observed when considering mean comparisons. Thus, human PBMC reflect lipid metabolism expression profile of energy homeostatic tissues, and early obesity-related alterations in metabolic at-risk subjects. Further studies are needed to understand PBMC usefulness for analysis of metabolic recovery in weigh management programs.

Increased toxicity and retention of perflourooctane sulfonate (PFOS) in humanized CYP2B6-Transgenic mice compared to Cyp2b-null mice is relieved by a high-fat diet (HFD)

PFOS is a persistent, fluorosurfactant used in multiple products. Murine Cyp2b's are induced by PFOS and high-fat diets (HFD) and therefore we hypothesized that human CYP2B6 may alleviate PFOS-induced steatosis. Cyp2b-null and hCYP2B6-Tg mice were treated with 0, 1, or 10 mg/kg/day PFOS by oral gavage for 21-days while provided a chow diet (ND) or HFD. Similar to murine Cyp2b10, CYP2B6 is inducible by PFOS. Furthermore, three ND-fed hCYP2B6-Tg females treated with 10 mg/kg/day PFOS died during the exposure period; neither Cyp2b-null nor HFD-fed mice died. hCYP2B6-Tg mice retained more PFOS in serum and liver than Cyp2b-null mice presumably causing the observed toxicity. In contrast, serum PFOS retention was reduced in the HFD-fed hCYP2B6-Tg mice; the opposite trend observed in HFD-fed Cyp2b-null mice. Hepatotoxicity biomarkers, ALT and ALP, were higher in PFOS-treated mice and repressed by a HFD. However, PFOS combined with a HFD exacerbated steatosis in all mice, especially in the hCYP2B6-Tg mice with significant disruption of key lipid metabolism genes such as Srebp1, Pparg, and Hmgcr. In conclusion, CYP2B6 is induced by PFOS but does not alleviate PFOS toxicity presumably due to increased retention. CYP2B6 protects from PFOS-mediated steatosis in ND-fed mice, but increases steatosis when co-treated with a HFD.

Delphinidin-3-sambubioside from Hibiscus sabdariffa. L attenuates hyperlipidemia in high fat diet-induced obese rats and oleic acid-induced steatosis in HepG2 cells

ABSTRACT Hibiscus sabdariffa. L is folk medicine that is often used for its hypolipidemic and antihypertensive effects; however, the active compound responsible for its anti-obesity effect is presently unknown. Delphinidin-3-sambubioside (Dp3-Sam) is an anthocyanin, was extracted from Hibiscus sabdariffa L. The present research aimed to investigate the role of Dp3-Sam in the prevention of hyperlipidemia in vivo and in vitro. Rats were fed with a standard chow diet (Control group) or high-fat diet (HFD and DP group) for eight weeks. Besides, HepG2 cells were stimulated with 0.2 mM oleic acid, with or without Dp3-Sam (100–200 µg/ml). Lipid profiles were measured by commercial kits. Oil Red O staining was performed to measure the hepatic and intracellular lipid levels. The key genes of lipid metabolism were measured by RT-PCR. In HFD-fed rats, Dp3-Sam reduced the body weight gain, visceral fat, and abdominal fat and decreased hepatic lipid deposits. Dp3-Sam decreased intracellular TG levels and lipid accumulation in oleic acid-treated HepG2 cells. Besides, Dp3-Sam downregulated the mRNA expression of HMG-CoA reductase (HMGCR), sterol regulatory element-binding protein-1 c (SREBP-1 C), fatty acid synthase (FASN), and acetyl-CoA carboxylase (ACC) and upregulated the mRNA expression of cholesterol 7α-hydroxylase (CYP7A1), carnitine palmitoyltransferase1 (CPT1), acyl-coenzyme A oxidase (ACOX), and peroxisome proliferator-activated receptor alpha (PPARα). Dp3-Sam up-regulated the expression of phosphorylation of AMP-activated protein kinase (pAMPK) in HFD-fed rats. Our findings indicated that Dp3-Sam possesses the potential to improve lipid metabolism dysfunction and our results offered evidence for the use of Dp3-Sam as therapy for the prevention of obesity and dyslipidemia.

Transcription profiling of cadmium-exposed livers reveals alteration of lipid metabolism and predisposition to hepatic steatosis

Cadmium is a ubiquitous environmental toxicant that can cause liver steatosis and nonalcoholic fatty liver disease (NAFLD) on long-term exposure. Sixteen Sprague Dawley rats were randomly divided into two groups, and were administered normal saline and 5mg/(kg·d) cadmium chloride by gavage. In vitro, BRL3A cells, a rat normal liver cell line, were treated with different concentrations of cadmium to verify the sequencing results. The RNA-seq revealed 146 upregulated genes and 127 downregulated genes in the cadmium intervention group. The key genes of lipid metabolism were significantly overexpressed, such as Cyp1a1 and Pla2g2d. The GO enrichment analysis showed that the "sterol biosynthetic process" was the most obvious difference. The KEGG analysis showed that 6 of the top 10 differential pathways were related to lipid metabolism. The expression of the essential genes in BRL3A was consistent with the sequencing results. The protein-protein interaction (PPI) yielded that Cyp1a1 is in the central region of the differentially expressed gene network. In conclusion, the chronic cadmium exposure is still an important environmental health problem with a probable tendency to cause NAFLD. It may possibly act by affecting the lipid metabolism in the liver, especially the synthesis and decomposition of unsaturated fatty acids.

Modulation of Proinflammatory Bacteria- and Lipid-Coupled Intracellular Signaling Pathways in a Transwell Triple Co-Culture Model by Commensal Bifidobacterium Animalis R101-8.

Following a fat-rich diet, alterations in gut microbiota contribute to enhanced gut permeability, metabolic endotoxemia, and low grade inflammation-associated metabolic disorders. To better understand whether commensal bifidobacteria influence the expression of key metaflammation-related biomarkers (chemerin, MCP-1, PEDF) and modulate the pro-inflammatory bacteria- and lipid-coupled intracellular signaling pathways, we aimed at i) investigating the influence of the establishment of microbial signaling molecules-based cell-cell contacts on the involved intercellular communication between enterocytes, immune cells, and adipocytes, and ii) assessing their inflammatory mediators' expression profiles within an inflamed adipose tissue model. Bifidobacterium animalis R101-8 and Escherichia coli TG1, respectively, were added to the apical side of a triple co-culture model consisting of intestinal epithelial HT-29/B6 cell line, human monocyte-derived macrophage cells, and adipose-derived stem cell line in the absence or presence of LPS or palmitic acid. mRNA expression levels of key lipid metabolism genes HILPDA, MCP-1/CCL2, RARRES2, SCD, SFRP2 and TLR4 were determined using TaqMan qRT-PCR. Protein expression levels of cytokines (IL-1β, IL-6, and TNF-α), key metaflammation-related biomarkers including adipokines (chemerin and PEDF), chemokine (MCP- 1) as well as cellular triglycerides were assessed by cell-based ELISA, while those of p-ERK, p-JNK, p-p38, NF-κB, p-IκBα, pc-Fos, pc-Jun, and TLR4 were assessed by Western blotting. B. animalis R101-8 inhibited LPS- and palmitic acid-induced protein expression of inflammatory cytokines IL-1β, IL-6, TNF-α concomitant with decreases in chemerin, MCP-1, PEDF, and cellular triglycerides, and blocked NF-kB and AP-1 activation pathway through inhibition of p- IκBα, pc-Jun, and pc-Fos phosphorylation. B. animalis R101-8 downregulated mRNA and protein levels of HILPDA, MCP-1/CCL2, RARRES2, SCD and SFRP2 and TLR4 following exposure to LPS and palmitic acid. B. animalis R101-8 improves biomarkers of metaflammation through at least two molecular/signaling mechanisms triggered by pro-inflammatory bacteria/lipids. First, B. animalis R101-8 modulates the coupled intracellular signaling pathways via metabolizing saturated fatty acids and reducing available bioactive palmitic acid. Second, it inhibits NF-kB's and AP-1's transcriptional activities, resulting in the reduction of pro-inflammatory markers. Thus, the molecular basis may be formed by which commensal bifidobacteria improve intrinsic cellular tolerance against excess pro-inflammatory lipids and participate in homeostatic regulation of metabolic processes in vivo.