Biochimica et biophysica acta. Molecular and cell biology of lipids最新文献

Background: The phenotypic switch of vascular smooth muscle cells (VSMCs) underlies the pathology of many cardiovascular diseases. Histone deacetylase 3 (HDAC3) is reported to upregulate in several cardiovascular diseases. RGFP966 is a highly selective HDAC3 inhibitor. This study aimed to explore the effects of RGFP966 on the phenotypic switch of VSMCs.

Method: First, we conducted an analysis of HDAC3 expression utilizing pertinent Gene Expression Omnibus (GEO) datasets. Then CCK-8, Edu, and wound healing assays were used to explore the effects of RGFP966 on the proliferation and migration of VSMCs and potential mechanisms at the cellular level.

Results: Our results showed that palmitic acid (PA) induced the accumulation of lipid droplets in VSMCs, downregulated Adipose triglyceride lipase (ATGL), and increased VSMC viability and migration, which were significantly reversed by RGFP966. Additionally, siRNA targeting ATGL dramatically enhanced the VSMCs injury induced by PA. The autophagy inhibitor 3-Methyladenine (3-MA) partially reversed the decreased ATGL expression caused by PA. Furthermore, the p-mTOR/mTOR ratio decreased under PA induction and rebounded after administration of RGFP966.

Conclusion: RGFP966 has a protective effect against VSMCs phenotype transitions, potentially related to the regulation of ATGL.

Carotenoids are naturally occurring pigments essential for both light-harvesting and photoprotection in photosynthetic processes. Among these, carbonyl-containing carotenoids exhibit distinctive excited state properties due to the presence of intramolecular charge transfer (ICT) in their excited states. In this study, we synthesized a novel family of carotenoid analogs with varying numbers of conjugated double bonds, denoted as the Ind series, and conducted femtosecond pump-probe spectroscopy on these molecules in both acetone and n-hexane. The objective was to elucidate how the excited-state dynamics depend on the conjugation length. The spectroscopic characterization of the Ind series revealed several unique features: the observation of stimulated emission from the ¹A_g^-/ICT state, the emergence of the ¹nπ^∗ state, triplet state formation mediated by the ¹nπ^∗ state, and an anomalous solvent dependence of the ¹A_g^-/ICT state lifetimes. The relationship between conjugation length and excited state dynamics, as well as the ICT character of the Ind series, are thoroughly discussed.

Lipid accumulation in hepatocytes in non-alcoholic steatohepatitis (NASH) is attributed partly to loss of insulin-responsiveness and/or an increased pro-inflammatory state. Since the rare sugar D-allulose has insulin mimetic and anti-inflammatory properties, its effects on lipid accumulation in liver-derived cells was tested. In HepG2 cells exposed to 200 μM oleic acid for 72 h, D-allulose treatment decreased intracellular lipid accumulation with an IC₅₀ = 0.45 ± 0.07 mM. A similar effect was observed in cells treated with 10 μM gemfibrozil. D-allulose and gemfibrozil treatment increased oleic acid β-oxidation. Both D-allulose and gemfibrozil increased peroxisome proliferator-activated receptor α (PPARα) expression (two-fold) relative to control cells, while retinoid X receptor was unchanged. D-allulose and gemfibrozil increased PPARα-dependent genes including those involved in fatty acid β-oxidation (acyl-coenzyme A oxidase 1, long-chain-fatty-acid-coenzyme A ligase 5, and carnitine palmitoyltransferase 1 A). D-allulose and gemfibrozil also increased PPARα reporter gene expression and phosphorylation (Serine 12) which were both inhibited by the mitogen-activated protein (MAP) kinase inhibitor PD098059. Other MAP kinase inhibitors, including SB203580, SP600125, and BIX10289 had no effect on reporter gene expression. Oleic acid treatment, but not D-allulose or gemfibrozil, decreased sterol response element binding protein 1 and sterol response element binding protein 2 expression relative to cells not exposed to oleic acid, while peroxisome proliferator-activated receptor γ expression did not change. These results indicate that D-alluose mimics gemfibrozil effects on lipid content in HepG2 cells by promoting fatty acid β-oxidation via PPARα .

Human paraoxonase 1 (PON1), an enzyme bound to high-density lipoprotein (HDL), hydrolyzes oxidized lipids and contributes to HDL atheroprotective functions. Decreased serum paraoxonase and arylesterase activities of PON1 have been reported in patients at increased atherosclerosis risk, such as rheumatoid arthritis patients, and associated with arthritis severity and cardiovascular risk. Agents that can modulate PON1 activity and HDL-mediated effects have not been discovered. Aiming to discover chemical tools that enhance PON1 activity, we screened a library of marketed drugs (956 compounds) to identify small molecules that can increase HDL-associated PON1 activity. Screening was performed by a kinetic absorbance assay using human HDL as a source of PON1, and paraoxon and phenyl acetate as substrates to measure paraoxonase and arylesterase activities, respectively. Screening identified the drug dantrolene as a potential PON1 activator, which was confirmed by enzymatic kinetic assays using recombinant wild-type PON1, as well as the PON1[L55M] variant displaying decreased enzyme activity in humans. Furthermore, we used the collagen-induced arthritis (CIA) mouse model to examine the effect of dantrolene on HDL properties and arthritis in vivo. Administration of dantrolene in CIA mice increased paraoxonase and arylesterase activities of PON1, as well as the antioxidant capacity of HDL, and reduced arthritis severity by inhibition of naïve CD4⁺ T cell differentiation to effector memory cells and generation of Th1 cells. Collectively, our in vitro and in vivo findings indicate using small molecules to enhance HDL-associated PON1 activity is a tractable approach that could lead to novel therapeutics targeting immune responses and atherosclerosis.

Terahertz (THz) radiation has gained attention due to technological advancements, but its biological effects remain unclear. We investigated the impact of 2.3 THz radiation on SK-MEL-28 cells using metabolomic and gene network analysis. Forty metabolites, primarily related to purine, pyrimidine synthesis and breakdown pathways, were significantly altered post-irradiation. Lipids, such as ceramides and phosphatidylcholines, were also affected. Gene network reconstruction and analysis identified key regulators of the enzymes involved in biosynthesis and degradation of significantly altered metabolites. Mitochondrial membrane components, such as the respiratory chain complex, the proton-transporting ATP synthase complex, and components of lipid rafts reacted to THz radiation. We propose that THz radiation induces reversible disruption of the lipid raft macromolecular structure, thereby altering mitochondrial molecule transport while maintaining protein integrity, which explains the high cell survival rate. Our findings enhance the understanding of THz biological effects and emphasize the role of membrane components in the cellular response to THz radiation.

The synthesis of n-3 and n-6 polyunsaturated acids (PUFAs) is associated with physiological functions in mammals, being catalyzed by Δ-5D and Δ-6D desaturases and elongases Elovl-2 and Elovl-5. In this context, we aimed to study the chief kinetic features of PUFA liver anabolism, looking upon (i) the time-dependency for the specific activity of Δ-6D, Δ-5D, Elovl2, Elovl2/5 and Elovl5, using n-3 and n-6 precursors between 0 and 240 min ex vivo in mouse liver.; and (ii) the specific activity-substrate (α-linolenic acid; ALA) concentration responses of Δ-6D in the absence and presence of linoleic acid (LA), arachidonic acid (ARA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), an enzyme regarded as the rate-limiting step in PUFA anabolism. Mouse liver was obtained from eight-week-old Balb/c mice fed a chow diet (expressed as % of total calories: 18 % fat, 24 % protein, and 58 % carbohydrate, with a caloric value of 3.1 kcal/g) for eight weeks, and used for preparation of the microsomal fraction. Enzymatic activities assayed under the addition of specific PUFA precursors or LA, ARA, EPA and DHA, identifying the respective PUFA products as fatty acid methyl esters by gas chromatographic analysis. Data described corroborate that (i) PUFA metabolism mainly occurs in the liver, with the participating enzymes preferring n-3 than n-6 substrates; and show that (ii) the rate-limiting step of PUFA metabolism relies on the second reaction of Δ-6D (24:5n-3 transformed to 24:6n-3); and (iii) LA, ARA, EPA and DHA act as non-competitive inhibitors with respect to ALA in the reaction catalyzed by Δ-6D. These results are relevant for future studies concerning the metabolic and nutritional implications of changes in desaturation and elongation of PUFAs.

DHHC-mediated protein-S-palmitoylation is recognized as a distinct and reversible lipid modification, playing a pivotal role in the progression and prevention of multiple diseases, including cancer and neurodegenerative disorders. Over the past decade, growing evidence indicated the crucial role of DHHC2 in preventing tumorigenesis by palmitoylation of various protein substrates. However, a comprehensive understanding of the specific impact of DHHC2 on cancer cell metabolic regulation remains unclear. To investigate the metabolic changes by DHHC2, we conducted untargeted metabolomic profiling on the HEK-293T cell line with DHHC2-Knockdown (DHHC2-KD), DHHC2-Overexpression (DHHC2-OE) and empty vector control (Ctrl) conditions via LC-MS/MS-based analysis. Our dataset revealed the identification of a total of 73 metabolites encompassing all the conditions, with only 22 showing significant differences in univariate analysis. Furthermore, we performed pathway analysis with metabolites having VIP ≥ 0.7, P value ≤ 0.05, and fold change (FC) > 2 in DHHC2-OE (upregulated) and FC < 0.5 in DHHC2-OE or FC > 2 in DHHC2-KD condition (downregulated). We unveiled significant expression of the pyrimidine metabolism, urea cycle, and aspartate metabolism due to the abundance of onco-metabolites such as glutamine, uridine, and glutamic acid in the DHHC2-KD condition. However, DHHC2 overexpression resulted in a higher expression of metabolites previously reported to be associated with anti-cancer activity, such as betaine and 5'-methylthioadenosine (5'-MTA). Overall, this study sheds light on the changes mediated by DHHC2 in a cancer cell metabolome and suggests avenues for further investigation into other DHHC isoforms and their metabolic aspects.

SREBP1 is a transcription factor that influences lipogenesis by regulating key genes associated with lipid biosynthesis, while AMPK, modulates lipid metabolism by regulating acetyl-CoA carboxylase. The exact role of these metabolic regulators in oleaginous microbes remains unclear. This study identified and manipulated the genes encoding SREBP1 (sre1) and α1 subunit of AMPK (ampk-α1) in Mucor circinelloides WJ11. Individual overexpression of sre1 yielded 32.5 % lipids and 21 g/L biomass, while ampk-α1 deletion combined with sre1 overexpression yielded 42.5 % lipids and 25 g/L biomass in mutant strains. This increase correlated with upregulated expression of key lipogenic genes and enzyme activity, enhancing lipid production and biomass. These surges were correlated with the increased mRNA levels of key genes (acl, acc1, acc2, cme1, fas1, g6pdh1, g6pdh2 and 6pgdh2). Enzyme activity analysis further showed that upregulation of ACL, ACC, ME, FAS, G6PDH and 6PGDH might provide more precursors and NADPH for lipid biosynthesis in sre1 overexpressing strains. Conversely, the activities of these genes and enzymes were markedly downregulated in sre1 deleted mutants consistent with lower lipid production and biomass than the control. These findings open new avenues for research by exploring the coordinated role of sre1 and ampk-α1 in lipid metabolism in M. circinelloides.

Sphingolipids are crucial components of cell membranes and serve as important signaling molecules. Ceramide, as the central hub of sphingolipid metabolism, plays a significant role in various biological processes, including the cell cycle, apoptosis, and cellular aging. Alterations in sphingolipid metabolism are implicated in cellular aging, however, the specific sphingolipid components and intrinsic mechanisms that mediate this process remain largely uncharacterized. In this study, we established a targeted sphingolipidomics approach and employed LC-MS/MS to quantitatively analyze changes in ceramide levels during chronological aging and in sur2Δ strains, aiming to elucidate the role of ceramides in regulating chronological lifespan. Our study revealed that in Saccharomyces cerevisiae, the C4 hydroxylase Sur2 and its product, phytoceramide, increase during chronological aging. While the loss of SUR2 function leads to a near-complete loss of phytoceramides and an accumulation of dihydroceramides, resulting in a significant reduction of total ceramide content to about half of that in wild-type cells. This ceramide profile alteration impairs both mitochondrial morphology and function, ultimately shortening the chronological lifespan. The knockout of SIT4 restores mitochondrial morphology and function, and rescues the chronological lifespan of SUR2-deficient yeast. Our findings highlight the critical role of dihydroceramide and phytoceramide in chronological aging in yeast and suggest that an imbalance between these two metabolites may trigger downstream ceramide signaling pathways. These insights could help elucidate potential mechanisms through which ceramide imbalance contributes to disease development in higher organisms.

Metabolic reprogramming occurs in cardiomyopathy and heart failure contributing to progression of the disease. Activation of cardiac Hippo pathway signaling has been implicated in mediating mitochondrial dysfunction and metabolic reprogramming in cardiomyopathy, albeit influence of Hippo pathway on lipid profile is unclear. Using a dual-omics approach, we determined alterations of cardiac lipids in a mouse model of cardiomyopathy due to enhanced Hippo signaling and explored molecular mechanisms. Lipidomic profiling discovered multiple alterations in lipid classes, notably reduction of triacylglycerol, diacylglycerol, phospholipids and ether lipids, and elevation of sphingolipids and lysophosphatidylcholine. Mechanistically, we found downregulated expression of PPARα and PGC-1α at mRNA and protein levels, and downregulated expression of PPARα-target genes, indicating attenuated transcriptional activity of PPARα/PGC-1α. Lipidomics-guided transcriptomic analysis revealed dysregulated expression of gene sets that were responsible for enhanced biosynthesis of ceramides, suppression of TG biosynthesis, storage, hydrolysis and mitochondrial fatty acid oxidation, and reduction of peroxisome-localized biosynthesis of ether lipids. Collectively, Hippo pathway activation with attenuated PPARα/PGC-1α signaling is the underlying mechanism for alterations in cardiac lipids in cardiomyopathy and failing heart.