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Endocrinology and Metabolism (Seoul,... Feb 2022Dulaglutide, a long-acting glucagon-like peptide-1 receptor agonist (GLP-1RA), has been shown to reduce body weight and liver fat content in patients with type 2...
BACKGROUND
Dulaglutide, a long-acting glucagon-like peptide-1 receptor agonist (GLP-1RA), has been shown to reduce body weight and liver fat content in patients with type 2 diabetes. Family with sequence similarity 3 member A (FAM3A) plays a vital role in regulating glucose and lipid metabolism. The aim of this study was to determine the mechanisms by which dulaglutide protects against hepatic steatosis in HepG2 cells treated with palmitic acid (PA).
METHODS
HepG2 cells were pretreated with 400 μM PA for 24 hours, followed by treatment with or without 100 nM dulaglutide for 24 hours. Hepatic lipid accumulation was determined using Oil red O staining and triglyceride (TG) assay, and the expression of lipid metabolism-associated factor was analyzed using quantitative real time polymerase chain reaction and Western blotting.
RESULTS
Dulaglutide significantly decreased hepatic lipid accumulation and reduced the expression of genes associated with lipid droplet binding proteins, de novo lipogenesis, and TG synthesis in PA-treated HepG2 cells. Dulaglutide also increased the expression of proteins associated with lipolysis and fatty acid oxidation and FAM3A in PA-treated cells. However, exendin-(9-39), a GLP-1R antagonist, reversed the expression of FAM3A, and fatty acid oxidation-associated factors increased due to dulaglutide. In addition, inhibition of FAM3A by siRNA attenuated the reducing effect of dulaglutide on TG content and its increasing effect on regulation of fatty acid oxidation.
CONCLUSION
These results suggest that dulaglutide could be used therapeutically for improving nonalcoholic fatty liver disease, and its effect could be mediated in part via upregulation of FAM3A expression through a GLP-1R-dependent pathway.
Topics: Diabetes Mellitus, Type 2; Glucagon-Like Peptides; Humans; Immunoglobulin Fc Fragments; Non-alcoholic Fatty Liver Disease; Palmitic Acid; Recombinant Fusion Proteins; Signal Transduction
PubMed: 35144334
DOI: 10.3803/EnM.2021.1293 -
Molecular Medicine Reports Oct 2023The present study aimed to establish a model of palmitic acid (PA)‑induced insulin resistance (IR) in C2C12 cells and to determine the mechanism underlying how...
The present study aimed to establish a model of palmitic acid (PA)‑induced insulin resistance (IR) in C2C12 cells and to determine the mechanism underlying how resveratrol (RSV) improves IR. C2C12 cells were divided into the control (CON), PA, PA + RSV, PA + RSV + DNA damage‑inducible transcript 4 (DDIT4)‑small interfering (si)RNA and PA + RSV + MHY1485 (mTOR agonist) groups. Glucose contents in culture medium and triglyceride contents in cells were determined. Oil red O staining was performed to observe the pathological changes in the cells. Reverse transcription‑quantitative PCR and western blotting were conducted to evaluate the mRNA and protein expression levels, respectively, of DDIT4, mTOR, p70 ribosomal protein S6 kinase (p70S6K), insulin receptor substrate (IRS)‑1, PI3K, AKT and glucose transporter 4 (GLUT4). Compared with in the CON group, glucose uptake was decreased, cellular lipid deposition was increased, phosphorylated (p)‑IRS‑1, p‑mTOR and p‑p70S6K protein expression levels were increased, and p‑PI3K, p‑AKT, GLUT4 and DDIT4 protein expression levels were decreased in the PA group. By contrast, compared with in the PA group, culture medium glucose content and cellular lipid deposition were decreased, p‑PI3K, p‑AKT, GLUT4 and DDIT4 protein expression levels were increased, p‑IRS‑1 protein expression levels were decreased, and mTOR and p70S6K mRNA and protein expression levels were decreased in the PA + RSV group. Compared with in the PA + RSV group, DDIT4 protein and mRNA expression levels were reduced in the PA + RSV + DDIT4‑siRNA group, but showed no change in the PA + RSV + MHY1485 group. Following transfection with DDIT4‑siRNA or treatment with MHY1485, the effects of RSV on improving IR and lipid metabolism were weakened, mTOR and p70S6K protein expression levels were upregulated, p‑PI3K, p‑AKT and GLUT4 protein expression levels were down‑regulated, p‑IRS‑1 protein expression levels were upregulated, and culture medium glucose content and cellular lipid deposition were increased. In conclusion, RSV may improve PA‑induced IR in C2C12 cells through the DDIT4/mTOR/IRS‑1/PI3K/AKT/GLUT4 signaling pathway, as well as via improvements in glucose and lipid metabolism.
Topics: Humans; Palmitic Acid; Resveratrol; Ribosomal Protein S6 Kinases, 70-kDa; Insulin Resistance; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; TOR Serine-Threonine Kinases; RNA, Messenger; Culture Media; Transcription Factors
PubMed: 37594055
DOI: 10.3892/mmr.2023.13068 -
Journal of Neurochemistry Apr 2022While brain glucose metabolism is known to contribute the carbons to support brain saturated and monounsaturated fatty biosynthesis de novo in the developing brains of...
While brain glucose metabolism is known to contribute the carbons to support brain saturated and monounsaturated fatty biosynthesis de novo in the developing brains of young rodents, such a contribution to fatty acid biosynthesis in the adult brain is poorly understood. Recent work from the Bazinet laboratory illuminates the role of brain glucose metabolism in providing a carbon source from which palmitic acid is synthesized. In "The Majority of Brain Palmitic Acid is Maintained by Lipogenesis from Dietary Sugars and is Augmented in Offspring fed low Palmitic Acid Levels from Birth", the Bazinet lab demonstrates the importance of glucose as a key contributing source of carbon for brain palmitic synthesis and that a low palmitate diet exacerbates its utilization for brain palmitate synthesis de novo. Further, this impact is found in male mice rather than female mice, which adds an additional layer of importance. Mammals are known to conserve carbon and the brain has the ability to convert a variety of carbon sources to needed molecules, depending on the physiological needs of the brain. Overall, this paper contributes an important missing piece of the puzzle regarding carbon recycling in the brain and is a key piece of evidence that indeed the adult mammalian brain can convert glucose to carbons for use in saturated fatty acid synthesis.
Topics: Animals; Brain; Carbon; Fatty Acids; Female; Glucose; Male; Mice; Palmitates; Palmitic Acid; Rodentia
PubMed: 35224738
DOI: 10.1111/jnc.15592 -
The Journal of Infectious Diseases Jul 2021Neisseria gonorrhoeae is a bacterial pathogen that colonizes mucosal epithelia that are rich in antimicrobial molecules such as long-chain fatty acids. Here we studied...
Neisseria gonorrhoeae is a bacterial pathogen that colonizes mucosal epithelia that are rich in antimicrobial molecules such as long-chain fatty acids. Here we studied the mechanisms involved in palmitic acid resistance and their impact on in vivo biological fitness in a murine genital tract infection model. A stable palmitic acid-resistant derivative was obtained by serial passage with incremental palmitic acid concentrations. This derivative outcompeted its parent strain for colonization and survival in the murine infection model. Subsequent whole-genome sequencing resulted in the identification of the 3 resistance-related SNPs ihfAC5T, fadDC772T, and farAG-52T (promoter) that were verified for resistance against palmitic acid. Subsequent characterization of the associated resistance determinants showed that ihfAC5T and farAG-52T induced gene expression of the FarAB efflux pump, whereas fadDC772T increased the maximum enzyme activity of the FadD long-chain fatty acid-coenzyme A ligase. Our results highlight the mechanisms involved in gonococcal adaptation to the murine host environment.
Topics: Animals; Bacterial Proteins; Coenzyme A Ligases; Disease Models, Animal; Female; Gonorrhea; HeLa Cells; Humans; Mice; Mice, Inbred BALB C; Mutation; Neisseria gonorrhoeae; Palmitic Acid; Reproductive Tract Infections; Vaginal Diseases
PubMed: 33170275
DOI: 10.1093/infdis/jiaa701 -
Biochimica Et Biophysica Acta.... Jan 2023Palmitic acid (PA), the most common statured fatty acid in diets, is involved in peripheral as well as central inflammation. The M1 polarization of microglia plays an...
Palmitic acid (PA), the most common statured fatty acid in diets, is involved in peripheral as well as central inflammation. The M1 polarization of microglia plays an important role in PA-induced neuroinflammation. However, it is still unclear on the key factor and molecule mechanism of microglial polarization among it. Thus, we investigated whether the release of self-DNA into the cytoplasm of microglia was a consequence of PA treatment, as in aortic endothelial cells and adipocytes. RT-qPCR and immunofluorescence were performed to detect the status of cytosolic DNA and microglial polarization after PA treatment. We found that the content of cytosolic nDNA rather than mtDNA increased after PA treatment and the M1 polarization of microglia was associated with this. Moreover, the knockdown of cGAS in BV2 microglial cells demonstrated that the cGAS-STING pathway is involved in polarization process. Our results revealed that nDNA and cGAS-STING pathway are critically involved in PA-induced microglial M1 polarization. This mechanism may pose a new insight on targeting microglia may be a promising way to mitigate diet-induced early neuroinflammation.
Topics: Microglia; Palmitic Acid; Endothelial Cells; Cytosol; Signal Transduction; Nucleotidyltransferases; DNA, Mitochondrial
PubMed: 36302463
DOI: 10.1016/j.bbamcr.2022.119385 -
European Review For Medical and... Jan 2022Diabetic peripheral neuropathy (DPN) is a common long-term complication of diabetes mellitus accompanied with hyperglycemia and hyperlipidemia. Both high blood glucose...
OBJECTIVE
Diabetic peripheral neuropathy (DPN) is a common long-term complication of diabetes mellitus accompanied with hyperglycemia and hyperlipidemia. Both high blood glucose and high blood lipids are key pathogenies for DPN. This research aims to investigate whether the combination of glucose (Glu) and palmitic acid (PA) played a synergistic role in the pathogenesis of DPN.
MATERIALS AND METHODS
The proliferation rate of Rat Schwann cell line RSC96 cells stimulated by different concentrations of Glu and PA were analyzed by CCK-8 assay. After the IC50 was detected for each drug, the RSC96 cells were divided into control, Glu, Glu+PA, PA, and BSA groups. The apoptosis of RSC96 cells in different groups were detected by flow cytometry. The effects of Glu and/or PA on endoplasmic reticulum (ER) stress-associated apoptotic signaling pathways were determined by Western blot and qPCR.
RESULTS
Both Glu and PA showed similar inhibition on the proliferation of RSC96 cells in a dose-dependent manner. However, PA induced stronger apoptosis of RSC96 cells than glucose and significantly increased the levels of X-box-binding protein-1 (XBP1), C/EBP homologous protein (CHOP), and eIF2α phosphorylation, which are key proteins regulating endoplasmic reticulum (ER) stress-associated apoptotic signaling pathways. The combination of Glu and PA induced the strongest apoptosis in RSC96 cells and also activated ER stress-associated apoptotic signaling pathways. These results verified the synergistic effect of Glu and PA on inducing ER stress-associated apoptosis in RSC96 cells, and PA even induced stronger apoptosis in RSC96 cells than Glu.
CONCLUSIONS
The present research indicated that hyperglycemia and hyperlipidemia might exert a synergistic damage during the pathogenesis of DPN, suggesting that blood lipid control is as important as blood glucose control for DPN patients.
Topics: Animals; Apoptosis; Diabetic Neuropathies; Endoplasmic Reticulum Stress; Glucose; Humans; Palmitic Acid; Rats; Schwann Cells
PubMed: 35049031
DOI: 10.26355/eurrev_202201_27761 -
Cell Stress & Chaperones Mar 2021Diabetic retinopathy (DR) is a serious microvascular complication of diabetes. Gambogic acid has been reported to have anti-inflammatory effect. However, the effect of...
Diabetic retinopathy (DR) is a serious microvascular complication of diabetes. Gambogic acid has been reported to have anti-inflammatory effect. However, the effect of GA on inflammatory response of ARPE-19 cells remains unclear. In our study, ARPE-19 cells were stimulated by palmitic acid (PA) induction in the presence of 30 mM glucose and then treated with 0.5, 1, 2, 5, 10, or 20 μM GA. CCK-8 assay showed that cell viability was increased by GA treatment at doses of 0.5, 1, and 2 μM instead of higher doses. ELISA analysis found that GA dose-dependently reduced the production of pro-inflammatory mediators TNF-α and IL-1β. Western blot indicated that GA downregulated the expression of NLRP3 inflammasome components including TXNIP, NLRP3, ASC, cleaved-caspase-1, and cleaved-IL-1β in a dose-dependent manner. In addition, Western blot and immunofluorescence analysis suggested that GA effectively increased the protein level of nuclear factor E2-related factor-2 (Nrf2). RT-qPCR showed that GA significantly increased the mRNA levels of Heme oxygenase-1 (HO-1) and NADPH:quinone oxidoreductase1 (NQO1). Furthermore, Nrf2 siRNA transfection confirmed the above effects of GA. In total, subtoxic doses of GA significantly flattened the inflammatory response induced by HG and PA in ARPE-19 cells via modulating the Nrf2 signaling pathway.
Topics: Cell Line; Diabetic Retinopathy; Humans; Inflammation; NF-E2-Related Factor 2; Palmitic Acid; Xanthones
PubMed: 33245515
DOI: 10.1007/s12192-020-01182-1 -
Theriogenology Jan 2020The concentration of fatty acids in follicular fluid reflect the physical condition of donors, and palmitic acid (PA) is a major component of follicular fluid. The...
The concentration of fatty acids in follicular fluid reflect the physical condition of donors, and palmitic acid (PA) is a major component of follicular fluid. The present study examined the effect of PA on in vitro oocyte growth and investigated the molecular backgrounds of the PA induced-low quality oocytes. Oocyte-granulosa cell complexes (OGCs) were collected from early antral follicles of gilts. The OGCs were cultured for 14 days in a medium containing 0.5 mM PA or vehicle (BSA). PA was found to reduce granulosa cell (GCs) proliferation (0.73 fold) and viability (93.9% vs. 85.8%) and increase lipid content in oocytes and GCs. Oocytes developed in the presence of PA had low developmental ability to the blastocyst stage. In addition, PA affected developmental and epigenetic markers of histone modifications in oocytes; levels of H4K12 acetylation and H3K9 demethylation. PA affected cellular proliferation, apoptosis and endoplasmic reticulum stress markers along with reducing the phosphor-AKT/AKT levels and increasing the expression levels of caspase-3 and CHOP in GCs. Incubation of OGCs with PA increased ceramide content in the GC, and addition of ceramide to the culture medium inhibited GC proliferation. In conclusion, it is suggested that high PA content in the medium reduces viability and proliferation through ceramide accumulation, and PA impaires the developmental ability of oocytes grown in vitro. In addition, high-fat conditions induce changes in the histone modifications of oocytes grown in vitro.
Topics: Animals; Apoptosis; Cell Proliferation; Cell Survival; Endoplasmic Reticulum; Female; Granulosa Cells; In Vitro Oocyte Maturation Techniques; Oocytes; Palmitic Acid; Swine
PubMed: 31518729
DOI: 10.1016/j.theriogenology.2019.09.006 -
Molecules (Basel, Switzerland) Mar 2022Diabetic nephropathy (DN) is a leading cause of end-stage renal disease. An elevated fatty acid plasma concentration leads to podocyte injury and DN progression. This...
Diabetic nephropathy (DN) is a leading cause of end-stage renal disease. An elevated fatty acid plasma concentration leads to podocyte injury and DN progression. This study aimed to identify and characterize cellular mechanisms of natural compounds that inhibit palmitic acid (PA)-induced human podocyte injury. By screening 355 natural compounds using a cell viability assay, 3-hydroxyterphenyllin (3-HT) and candidusin A (CDA), isolated from the marine-derived fungus PSU-AMF169, were found to protect against PA-induced podocyte injury, with half-maximal inhibitory concentrations (IC) of ~16 and ~18 µM, respectively. Flow cytometry revealed that 3-HT and CDA suppressed PA-induced podocyte apoptosis. Importantly, CDA significantly prevented PA-induced podocyte barrier impairment as determined by 70 kDa dextran flux. Reactive oxygen species (ROS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) direct scavenging assays indicated that both compounds exerted an anti-oxidative effect via direct free radical-scavenging activity. Moreover, 3-HT and CDA upregulated the anti-apoptotic Bcl2 protein. In conclusion, 3-HT and CDA represent fungus-derived bioactive compounds that have a novel protective effect on PA-induced human podocyte apoptosis via mechanisms involving free radical scavenging and Bcl2 upregulation.
Topics: Apoptosis; Diabetic Nephropathies; Fungi; Humans; Palmitic Acid; Podocytes; Proto-Oncogene Proteins c-bcl-2; Reactive Oxygen Species; Terphenyl Compounds
PubMed: 35408508
DOI: 10.3390/molecules27072109 -
The Journal of Nutritional Biochemistry Nov 2021Electronegative LDL (LDL(-)) and free fatty acids (FFAs) are circulating risk factors for cardiovascular diseases (CVDs) and have been associated with inflammation....
Synergistic effects of electronegative-LDL- and palmitic-acid-triggered IL-1β production in macrophages via LOX-1- and voltage-gated-potassium-channel-dependent pathways.
Electronegative LDL (LDL(-)) and free fatty acids (FFAs) are circulating risk factors for cardiovascular diseases (CVDs) and have been associated with inflammation. Interleukin-1 beta (IL-1β) represents a key cytokine in the development of CVD; however, the initial trigger of IL-1β in CVD remains to be explored. In this study, we investigated the combined effects of LDL(-) from the plasma of ST-segment elevation myocardial infarction (STEMI) patients or diet-induced hypercholesterolemic rabbits and bovine serum albumin bound palmitic acid (PA-BSA) on IL-1β production in macrophages. Macrophages derived from THP-1 cells or human peripheral blood mononuclear cells were independently treated with LDL(-), PA-BSA or cotreated with LDL(-) and PA-BSA. The results showed that nLDL and/or PA-BSA had no effect on IL-1β, and LDL(-) slightly increased IL-1β; however, cotreatment with LDL(-) and PA-BSA resulted in abundant secretion of IL-1β in macrophages. Rabbit LDL(-) induced the elevation of cellular pro-IL-1β and p-Iκ-Bα, but PA-BSA had no effect on pro-IL-1β or p-Iκ-Bα. In potassium-free buffer, LDL(-)-induced IL-1β reached a level similar to that induced by cotreatment with LDL(-) and PA-BSA. Moreover, LDL(-) and PA-BSA-induced IL-1β was inhibited in lectin-type oxidized LDL receptor-1 (LOX-1) knockdown cells and by blockers of voltage-gated potassium (Kv) channels. LDL(-) from diet-induced hypercholesterolemic rabbit had a similar effect as STEMI LDL(-) on IL-1β in macrophages. These results show that PA-BSA cooperates with LDL(-) to trigger IL-1β production in macrophages via a mechanism involving the LOX-1 and Kv channel pathways, which may play crucial roles in the regulation of inflammation in CVD.
Topics: Animals; Cell Line, Tumor; Humans; Hypercholesterolemia; Interleukin-1beta; Lipoproteins, LDL; Macrophages; Male; Palmitic Acid; Potassium Channels, Voltage-Gated; Rabbits; ST Elevation Myocardial Infarction; Scavenger Receptors, Class E; Signal Transduction; THP-1 Cells
PubMed: 34052311
DOI: 10.1016/j.jnutbio.2021.108767