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1.
Chemphyschem ; : e202300961, 2024 Jun 08.
Article in English | MEDLINE | ID: mdl-38850107

ABSTRACT

Efficient nitrogen (N2) fixation and activation under mild conditions are crucial for modern society. External electric fields (Felectric) can significantly affect N2 activation. In this work, the effect of Felectric on N2 activation by Nb3 clusters supported in a sumanene bowl was studied by density functional theory calculations. Four typical systems at different stages of N-N activation were studied, including two intermediates and two transition states. The impact of Felectric on various properties related to N2 activation was investigated, including the N-N bond length, overlap population density of states (OPDOS), total energy of the system, adsorption energy of N2, decomposition of energy changes, and electron transfer. The sumanene not only functions as a support and protective substrate, but also serves as a donor or acceptor under different Felectric conditions. Negative Felectric is beneficial to N-N bond activation because it promotes electron transfer to the N-N region and improves the d-π* orbital hybridization between metals and N2 in the activation process. Positive Felectric improves d-π* orbital hybridization only when the N-N is nearly dissociated. The microscopic mechanism of Felectric's effects provides insight into N2 activation and theoretical guidance for the design of catalytic reaction conditions for nitrogen reduction reactions (NRR).

2.
Nat Metab ; 6(1): 39-49, 2024 Jan.
Article in English | MEDLINE | ID: mdl-38167726

ABSTRACT

Proteins activate small intestinal calcium sensing receptor (CaSR) and/or peptide transporter 1 (PepT1) to increase hormone secretion1-8, but the effect of small intestinal protein sensing and the mechanistic potential of CaSR and/or PepT1 in feeding and glucose regulation remain inconclusive. Here we show that, in male rats, CaSR in the upper small intestine is required for casein infusion to increase glucose tolerance and GLP1 and GIP secretion, which was also dependent on PepT1 (ref. 9). PepT1, but not CaSR, is required for casein infusion to lower feeding. Upper small intestine casein sensing fails to regulate feeding, but not glucose tolerance, in high-fat-fed rats with decreased PepT1 but increased CaSR expression. In the ileum, a CaSR-dependent but PepT1-independent pathway is required for casein infusion to lower feeding and increase glucose tolerance in chow-fed rats, in parallel with increased PYY and GLP1 release, respectively. High fat decreases ileal CaSR expression and disrupts casein sensing on feeding but not on glucose control, suggesting an ileal CaSR-independent, glucose-regulatory pathway. In summary, we discover small intestinal CaSR- and PepT1-dependent and -independent protein sensing mechanisms that regulate gut hormone release, feeding and glucose tolerance. Our findings highlight the potential of targeting small intestinal CaSR and/or PepT1 to regulate feeding and glucose tolerance.


Subject(s)
Gastrointestinal Hormones , Receptors, Calcium-Sensing , Animals , Male , Rats , Caseins/metabolism , Gastrointestinal Hormones/metabolism , Glucose/metabolism , Intestine, Small/metabolism , Receptors, Calcium-Sensing/metabolism
3.
Diabetes ; 73(3): 426-433, 2024 Mar 01.
Article in English | MEDLINE | ID: mdl-38064571

ABSTRACT

GDF15 regulates energy balance and glucose homeostasis in rodents by activating its receptor GFRAL, expressed in the area postrema of the brain. However, whether GDF15-GFRAL signaling in the area postrema regulates glucose tolerance independent of changes in food intake and weight and contributes to the glucose-lowering effect of metformin remain unknown. Herein, we report that direct, acute GDF15 infusion into the area postrema of rats fed a high-fat diet increased intravenous glucose tolerance and insulin sensitivity to lower hepatic glucose production independent of changes in food intake, weight, and plasma insulin levels under conscious, unrestrained, and nonstressed conditions. In parallel, metformin infusion concurrently increased plasma GDF15 levels and glucose tolerance. Finally, a knockdown of GFRAL expression in the area postrema negated administration of GDF15, as well as metformin, to increase glucose tolerance independent of changes in food intake, weight, and plasma insulin levels. In summary, activation of GFRAL in the area postrema contributes to glucose regulation of GDF15 and metformin in vivo.


Subject(s)
Insulins , Metformin , Rats , Animals , Area Postrema/metabolism , Glucose/metabolism , Metformin/pharmacology , Brain , Insulins/metabolism
4.
Cell Metab ; 35(5): 875-886.e5, 2023 05 02.
Article in English | MEDLINE | ID: mdl-37060902

ABSTRACT

Metformin, the most widely prescribed medication for obesity-associated type 2 diabetes (T2D), lowers plasma glucose levels, food intake, and body weight in rodents and humans, but the mechanistic site(s) of action remain elusive. Metformin increases plasma growth/differentiation factor 15 (GDF15) levels to regulate energy balance, while GDF15 administration activates GDNF family receptor α-like (GFRAL) that is highly expressed in the area postrema (AP) and the nucleus of the solitary tract (NTS) of the hindbrain to lower food intake and body weight. However, the tissue-specific contribution of plasma GDF15 levels after metformin treatment is still under debate. Here, we found that metformin increased plasma GDF15 levels in high-fat (HF) fed male rats through the upregulation of GDF15 synthesis in the kidney. Importantly, the kidney-specific knockdown of GDF15 expression as well as the AP-specific knockdown of GFRAL expression negated the ability of metformin to lower food intake and body weight gain. Taken together, we unveil the kidney as a target of metformin to regulate energy homeostasis through a kidney GDF15-dependent AP axis.


Subject(s)
Diabetes Mellitus, Type 2 , Metformin , Humans , Male , Rats , Animals , Metformin/pharmacology , Area Postrema/metabolism , Weight Loss , Diabetes Mellitus, Type 2/metabolism , Body Weight/physiology , Eating , Kidney/metabolism , Growth Differentiation Factor 15/metabolism
5.
J Biol Chem ; 299(5): 104633, 2023 05.
Article in English | MEDLINE | ID: mdl-36963496

ABSTRACT

The area postrema (AP) of the brain is exposed to circulating metabolites and hormones. However, whether AP detects glucose changes to exert biological responses remains unknown. Its neighboring nuclei, the nucleus tractus solitarius (NTS), responds to acute glucose infusion by inhibiting hepatic glucose production, but the mechanism also remains elusive. Herein, we characterized AP and NTS glucose-sensing mechanisms. Infusion of glucose into the AP, like the NTS, of chow rats suppressed glucose production during the pancreatic (basal insulin)-euglycemic clamps. Glucose transporter 1 or pyruvate kinase lentiviral-mediated knockdown in the AP negated AP glucose infusion to lower glucose production, while the glucoregulatory effect of NTS glucose infusion was also negated by knocking down glucose transporter 1 or pyruvate kinase in the NTS. Furthermore, we determined that high-fat (HF) feeding disrupts glucose infusion to lower glucose production in association with a modest reduction in the expression of glucose transporter 1, but not pyruvate kinase, in the AP and NTS. However, pyruvate dehydrogenase activator dichloroacetate infusion into the AP or NTS that enhanced downstream pyruvate metabolism and recapitulated the glucoregulatory effect of glucose in chow rats still failed to lower glucose production in HF rats. We discovered that a glucose transporter 1- and pyruvate kinase-dependent glucose-sensing mechanism in the AP (as well as the NTS) lowers glucose production in chow rats and that HF disrupts the glucose-sensing mechanism that is downstream of pyruvate metabolism in the AP and NTS. These findings highlight the role of AP and NTS in mediating glucose to regulate hepatic glucose production.


Subject(s)
Area Postrema , Glucose Transporter Type 1 , Glucose , Pyruvate Kinase , Animals , Rats , Area Postrema/metabolism , Glucose/metabolism , Glucose Transporter Type 1/genetics , Glucose Transporter Type 1/metabolism , Solitary Nucleus/metabolism , Pyruvate Kinase/metabolism , Gene Knockdown Techniques , Lentivirus/metabolism , Pyruvic Acid/metabolism , Male , Diet, High-Fat
6.
Gut ; 72(3): 460-471, 2023 03.
Article in English | MEDLINE | ID: mdl-36008102

ABSTRACT

OBJECTIVE: Bariatric surgery is an effective treatment for type 2 diabetes (T2D) that changes gut microbial composition. We determined whether the gut microbiota in humans after restrictive or malabsorptive bariatric surgery was sufficient to lower blood glucose. DESIGN: Women with obesity and T2D had biliopancreatic diversion with duodenal switch (BPD-DS) or laparoscopic sleeve gastrectomy (LSG). Faecal samples from the same patient before and after each surgery were used to colonise rodents, and determinants of blood glucose control were assessed. RESULTS: Glucose tolerance was improved in germ-free mice orally colonised for 7 weeks with human microbiota after either BPD-DS or LSG, whereas food intake, fat mass, insulin resistance, secretion and clearance were unchanged. Mice colonised with microbiota post-BPD-DS had lower villus height/width and crypt depth in the distal jejunum and lower intestinal glucose absorption. Inhibition of sodium-glucose cotransporter (Sglt)1 abrogated microbiota-transmissible improvements in blood glucose control in mice. In specific pathogen-free (SPF) rats, intrajejunal colonisation for 4 weeks with microbiota post-BPD-DS was sufficient to improve blood glucose control, which was negated after intrajejunal Sglt-1 inhibition. Higher Parabacteroides and lower Blautia coincided with improvements in blood glucose control after colonisation with human bacteria post-BPD-DS and LSG. CONCLUSION: Exposure of rodents to human gut microbiota after restrictive or malabsorptive bariatric surgery improves glycaemic control. The gut microbiota after bariatric surgery is a standalone factor that alters upper gut intestinal morphology and lowers Sglt1-mediated intestinal glucose absorption, which improves blood glucose control independently from changes in obesity, insulin or insulin resistance.


Subject(s)
Bariatric Surgery , Diabetes Mellitus, Type 2 , Gastrointestinal Microbiome , Insulin Resistance , Obesity, Morbid , Humans , Female , Rats , Mice , Animals , Glucose , Diabetes Mellitus, Type 2/surgery , Obesity/surgery , Gastrectomy , Obesity, Morbid/surgery
7.
Acta Pharm Sin B ; 12(4): 1899-1912, 2022 Apr.
Article in English | MEDLINE | ID: mdl-35847503

ABSTRACT

Atherosclerosis is a chronic multifactorial cardiovascular disease. Western diets have been reported to affect atherosclerosis through regulating adipose function. In high cholesterol diet-fed ApoE -/- mice, adipocyte HIF-1α deficiency or direct inhibition of HIF-1α by the selective pharmacological HIF-1α inhibitor PX-478 alleviates high cholesterol diet-induced atherosclerosis by reducing adipose ceramide generation, which lowers cholesterol levels and reduces inflammatory responses, resulting in improved dyslipidemia and atherogenesis. Smpd3, the gene encoding neutral sphingomyelinase, is identified as a new target gene directly regulated by HIF-1α that is involved in ceramide generation. Injection of lentivirus-SMPD3 in epididymal adipose tissue reverses the decrease in ceramides in adipocytes and eliminates the improvements on atherosclerosis in the adipocyte HIF-1α-deficient mice. Therefore, HIF-1α inhibition may constitute a novel approach to slow atherosclerotic progression.

9.
iScience ; 24(4): 102366, 2021 Apr 23.
Article in English | MEDLINE | ID: mdl-33870148

ABSTRACT

Hypothalamic regulation of lipid and glucose homeostasis is emerging, but whether the dorsal vagal complex (DVC) senses nutrients and regulates hepatic nutrient metabolism remains unclear. Here, we found in rats DVC oleic acid infusion suppressed hepatic secretion of triglyceride-rich very-low-density lipoprotein (VLDL-TG), which was disrupted by inhibiting DVC long-chain fatty acyl-CoA synthetase that in parallel disturbed lipid homeostasis during intravenous lipid infusion. DVC glucose infusion elevated local glucose levels similarly as intravenous glucose infusion and suppressed hepatic glucose production. This was independent of lactate metabolism as inhibiting lactate dehydrogenase failed to disrupt glucose sensing and neither could DVC lactate infusion recapitulate glucose effect. DVC oleic acid and glucose infusion failed to lower VLDL-TG secretion and glucose production in high-fat fed rats, while inhibiting DVC farnesoid X receptor enhanced oleic acid but not glucose sensing. Thus, an impairment of DVC nutrient sensing may lead to the disruption of lipid and glucose homeostasis in metabolic syndrome.

10.
Gut ; 70(9): 1675-1683, 2021 09.
Article in English | MEDLINE | ID: mdl-33087489

ABSTRACT

OBJECTIVE: Conjugated bile acids are metabolised by upper small intestinal microbiota, and serum levels of taurine-conjugated bile acids are elevated and correlated with insulin resistance in people with type 2 diabetes. However, whether changes in taurine-conjugated bile acids are necessary for small intestinal microbiome to alter insulin action remain unknown. DESIGN: We evaluated circulating and specifically brain insulin action using the pancreatic-euglycaemic clamps in high-fat (HF) versus chow fed rats with or without upper small intestinal healthy microbiome transplant. Chemical and molecular gain/loss-of-function experiments targeting specific taurine-conjugated bile acid-induced changes of farnesoid X receptor (FXR) in the brain were performed in parallel. RESULTS: We found that short-term HF feeding increased the levels of taurochenodeoxycholic acid (TCDCA, an FXR ligand) in the upper small intestine, ileum, plasma and dorsal vagal complex (DVC) of the brain. Transplantation of upper small intestinal healthy microbiome into the upper small intestine of HF rats not only reversed the rise of TCDCA in all reported tissues but also enhanced the ability of either circulating hyperinsulinaemia or DVC insulin action to lower glucose production. Further, DVC infusion of TCDCA or FXR agonist negated the enhancement of insulin action, while genetic knockdown or chemical inhibition of FXR in the DVC of HF rats reversed insulin resistance. CONCLUSION: Our findings indicate that FXR in the DVC is sufficient and necessary for upper small intestinal microbiome-mediated changes of TCDCA to alter insulin action in rats, and highlight a previously unappreciated TCDCA-FXR axis linking gut microbiome and host insulin action.


Subject(s)
Brain Stem/physiology , Gastrointestinal Microbiome/physiology , Insulin Resistance , Intestine, Small/microbiology , Receptors, Cytoplasmic and Nuclear/metabolism , Taurochenodeoxycholic Acid/metabolism , Animals , Brain/metabolism , Brain Chemistry , Brain Stem/metabolism , Diet, High-Fat , Fecal Microbiota Transplantation , Gene Knockdown Techniques , Glucose Clamp Technique , Insulin Resistance/physiology , Intestine, Small/metabolism , Rats , Receptors, Cytoplasmic and Nuclear/analysis , Taurochenodeoxycholic Acid/analysis
11.
Mol Metab ; 44: 101132, 2021 02.
Article in English | MEDLINE | ID: mdl-33264656

ABSTRACT

OBJECTIVE: The mechanism of nutrient sensing in the upper small intestine (USI) and ileum that regulates glucose homeostasis remains elusive. Short-term high-fat (HF) feeding increases taurochenodeoxycholic acid (TCDCA; an agonist of farnesoid X receptor (FXR)) in the USI and ileum of rats, and the increase of TCDCA is prevented by transplantation of microbiota obtained from the USI of healthy donors into the USI of HF rats. However, whether changes of TCDCA-FXR axis in the USI and ileum alter nutrient sensing remains unknown. METHODS: Intravenous glucose tolerance test was performed in rats that received USI or ileal infusion of nutrients (i.e., oleic acids or glucose) via catheters placed toward the lumen of USI and/or ileum, while mechanistic gain- and loss-of-function studies targeting the TCDCA-FXR axis or bile salt hydrolase activity in USI and ileum were performed. RESULTS: USI or ileum infusion of nutrients increased glucose tolerance in healthy but not HF rats. Transplantation of healthy microbiome obtained from USI into the USI of HF rats restored nutrient sensing and inhibited FXR via a reduction of TCDCA in the USI and ileum. Further, inhibition of USI and ileal FXR enhanced nutrient sensing in HF rats, while inhibiting USI (but not ileal) bile salt hydrolase of HF rats transplanted with healthy microbiome activated FXR and disrupted nutrient sensing in the USI and ileum. CONCLUSIONS: We reveal a TCDCA-FXR axis in both the USI and ileum that is necessary for the upper small intestinal microbiome to govern local nutrient-sensing glucoregulatory pathways in rats.


Subject(s)
Intestine, Small/metabolism , Nutrients , Taurochenodeoxycholic Acid/metabolism , Animals , Bile Acids and Salts , Gastrointestinal Microbiome , Glucose/metabolism , Glucose Tolerance Test , Homeostasis , Ileum/metabolism , Male , Rats , Rats, Sprague-Dawley
12.
Mol Metab ; 39: 101011, 2020 09.
Article in English | MEDLINE | ID: mdl-32416314

ABSTRACT

BACKGROUND: In response to energy abundant or deprived conditions, nutrients and hormones activate hypothalamic pathways to maintain energy and glucose homeostasis. The underlying CNS mechanisms, however, remain elusive in rodents and humans. SCOPE OF REVIEW: Here, we first discuss brain glucose sensing mechanisms in the presence of a rise or fall of plasma glucose levels, and highlight defects in hypothalamic glucose sensing disrupt in vivo glucose homeostasis in high-fat fed, obese, and/or diabetic conditions. Second, we discuss brain leptin signalling pathways that impact glucose homeostasis in glucose-deprived and excessed conditions, and propose that leptin enhances hypothalamic glucose sensing and restores glucose homeostasis in short-term high-fat fed and/or uncontrolled diabetic conditions. MAJOR CONCLUSIONS: In conclusion, we believe basic studies that investigate the interaction of glucose sensing and leptin action in the brain will address the translational impact of hypothalamic glucose sensing in diabetes and obesity.


Subject(s)
Brain/physiology , Glucose/metabolism , Leptin/metabolism , Signal Transduction , Animals , Disease Susceptibility , Energy Metabolism , Homeostasis , Humans , Insulin/metabolism , Neurons/metabolism
13.
Cell Metab ; 30(5): 937-951.e5, 2019 11 05.
Article in English | MEDLINE | ID: mdl-31668872

ABSTRACT

Obesity-induced adipose dysfunction is a major contributor to atherosclerosis. Cold exposure has been reported to affect atherosclerosis through regulation of adipose function, but the mechanism has not been well clarified. Here, adipocyte hypoxia-inducible factor 2α (HIF-2α) was upregulated after mild cold exposure at 16°C and mediated cold-induced thermogenesis. Adipocyte HIF-2α deficiency exacerbated Western-diet-induced atherosclerosis by increasing adipose ceramide levels, which blunted hepatocyte cholesterol elimination and thermogenesis. Mechanistically, Acer2, the gene encoding alkaline ceramidase 2, was identified as a novel target gene of HIF-2α, triggering ceramide catabolism. Adipose overexpression of ACER2 rescued adipocyte HIF-2α-deficiency-induced exacerbation of atherosclerosis. Furthermore, activation of adipose HIF-2α by the HIF prolyl hydroxylase inhibitor FG-4592 had protective effects on atherosclerosis, accompanied by a reduction in adipose and plasma ceramide and plasma cholesterol levels. This study highlights adipocyte HIF-2α as a putative drug target against atherosclerosis.


Subject(s)
Adipocytes/metabolism , Adipose Tissue/metabolism , Atherosclerosis/metabolism , Basic Helix-Loop-Helix Transcription Factors/metabolism , Ceramides/metabolism , Alkaline Ceramidase/genetics , Alkaline Ceramidase/metabolism , Animals , Atherosclerosis/drug therapy , Atherosclerosis/etiology , Basic Helix-Loop-Helix Transcription Factors/genetics , Cholesterol/metabolism , Cold Temperature , Diet, Western/adverse effects , Gene Knockout Techniques , Glycine/analogs & derivatives , Glycine/pharmacology , Glycine/therapeutic use , Hypoxia-Inducible Factor-Proline Dioxygenases/antagonists & inhibitors , Hypoxia-Inducible Factor-Proline Dioxygenases/metabolism , Isoquinolines/pharmacology , Isoquinolines/therapeutic use , Mice , Mice, Inbred C57BL , Mice, Knockout, ApoE , Signal Transduction/drug effects , Thermogenesis , Up-Regulation/genetics
14.
Cell Cycle ; 18(16): 1882-1892, 2019 08.
Article in English | MEDLINE | ID: mdl-31208278

ABSTRACT

Long non-coding RNAs (lncRNAs) have been confirmed to be aberrantly expressed and involved in the progression of neuroblastoma. This study aimed to explore the expression profile of lncRNA X-inactive specific transcript (XIST) and its functional involvement in neuroblastoma. In this study, the relative level of XIST in neuroblastoma tissues and cell lines was detected by qPCR, and DKK1 protein expression was determined using western blot. The effect of XIST on cell growth, invasion and migration in vitro and in tumorigenesis of neuroblastoma was assessed. The level of H3K27me3 in DKK1 promoter was analyzed with ChIP-qPCR. Interaction between XIST and EZH2 was verified by RNA immunoprecipitation (RIP) and RNA pull-down assay. XIST was significantly upregulated in neuroblastoma tissues (n = 30) and cells lines, and it was statistically associated with the age and International Neuroblastoma Staging System (INSS) staging in neuroblastoma patients. Downregulation of XIST suppressed the growth, migration and invasion of neuroblastoma cells. EZH2 inhibited DKK1 expression through inducing H3 histone methylation in its promoter. XIST increased the level of H3K27me3 in DKK1 promoter via interacting with EZH2. Downregulation of XIST increased DKK1 expression to suppress neuroblastoma cell growth, invasion, and migration, which markedly restrained the tumor progression. In conclusion, XIST downregulated DKK1 by inducing H3 histone methylation via EZH2, thereby facilitating the growth, migration and invasion of neuroblastoma cells and retarding tumor progression.


Subject(s)
Cell Movement/genetics , Cell Proliferation/genetics , Histones/metabolism , Intercellular Signaling Peptides and Proteins/metabolism , Neuroblastoma/metabolism , Neuroblastoma/pathology , RNA, Long Noncoding/metabolism , Animals , Cell Line, Tumor , Down-Regulation/genetics , Enhancer of Zeste Homolog 2 Protein/metabolism , Gene Expression Regulation, Neoplastic/genetics , HEK293 Cells , Heterografts , Humans , Male , Methylation , Mice , Mice, Inbred BALB C , Mice, Nude , Neoplasm Invasiveness/genetics , RNA, Long Noncoding/genetics , Transfection , Up-Regulation/genetics
15.
Nat Commun ; 10(1): 714, 2019 02 12.
Article in English | MEDLINE | ID: mdl-30755615

ABSTRACT

Glucose homeostasis is partly controlled by the energy sensor mechanistic target of rapamycin (mTOR) in the muscle and liver. However, whether mTOR in the small intestine affects glucose homeostasis in vivo remains unknown. Here, we first report that delivery of rapamycin or an adenovirus encoding the dominant negative acting mTOR-mutated protein into the upper small intestine is sufficient to inhibit small intestinal mTOR signaling and lower glucose production in rodents with high fat diet-induced insulin resistance. Second, we found that molecular activation of small intestinal mTOR blunts the glucose-lowering effect of the oral anti-diabetic agent metformin, while inhibiting small intestinal mTOR alone lowers plasma glucose levels by inhibiting glucose production in rodents with diabetes as well. Thus, these findings illustrate that inhibiting upper small intestinal mTOR is sufficient and necessary to lower glucose production and enhance glucose homeostasis, and thereby unveil a previously unappreciated glucose-lowering effect of small intestinal mTOR.


Subject(s)
Blood Glucose/metabolism , Glucose/biosynthesis , Intestine, Small/metabolism , TOR Serine-Threonine Kinases/antagonists & inhibitors , Adenoviridae/genetics , Animals , Diet, High-Fat , Homeostasis , Insulin Resistance , Intestine, Small/drug effects , Male , Metformin/pharmacology , Rats , Rats, Sprague-Dawley , Signal Transduction , Sirolimus/pharmacology , TOR Serine-Threonine Kinases/genetics , TOR Serine-Threonine Kinases/metabolism
16.
EBioMedicine ; 31: 202-216, 2018 May.
Article in English | MEDLINE | ID: mdl-29735414

ABSTRACT

The adipose Nod-like receptor protein 3 (NLRP3) inflammasome senses danger-associated molecular patterns (DAMPs) and initiates insulin resistance, but the mechanisms of adipose inflammasome activation remains elusive. In this study, Homocysteine (Hcy) is revealed to be a DAMP that activates adipocyte NLRP3 inflammasomes, participating in insulin resistance. Hcy-induced activation of NLRP3 inflammasomes were observed in both adipocytes and adipose tissue macrophages (ATMs) and mediated insulin resistance. Lysophosphatidylcholine (lyso-PC) acted as a second signal activator, mediating Hcy-induced adipocyte NLRP3 inflammasome activation. Hcy elevated adipocyte lyso-PC generation in a hypoxia-inducible factor 1 (HIF1)-phospholipase A2 group 16 (PLA2G16) axis-dependent manner. Lyso-PC derived from the Hcy-induced adipocyte also activated ATM NLRP3 inflammasomes in a paracrine manner. This study demonstrated that Hcy activates adipose NLRP3 inflammasomes in an adipocyte lyso-PC-dependent manner and highlights the importance of the adipocyte NLRP3 inflammasome in insulin resistance.


Subject(s)
Adipocytes/metabolism , Homocysteine/pharmacology , Inflammasomes/metabolism , Insulin Resistance , Lysophosphatidylcholines/pharmacology , Macrophage Activation/drug effects , Macrophages/metabolism , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism , Adipocytes/chemistry , Adipocytes/cytology , Animals , Female , Humans , Inflammasomes/genetics , Lysophosphatidylcholines/chemistry , Macrophages/cytology , Male , Mice, Knockout , NLR Family, Pyrin Domain-Containing 3 Protein/genetics
17.
Br J Pharmacol ; 175(8): 1230-1240, 2018 04.
Article in English | MEDLINE | ID: mdl-28407200

ABSTRACT

Adrenomedullin (ADM) 2/intermedin (IMD) is a short peptide that belongs to the CGRP superfamily. Although it shares receptors with CGRP, ADM and amylin, ADM2 has significant and unique functions in the cardiovascular system. In the past decade, the cardiovascular effect of ADM2 has been carefully analysed. In this review, progress in understanding the effects of ADM2 on the cardiovascular system and its protective role in cardiometabolic diseases are summarized. LINKED ARTICLES: This article is part of a themed section on Spotlight on Small Molecules in Cardiovascular Diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.8/issuetoc.


Subject(s)
Cardiovascular Diseases/drug therapy , Metabolic Diseases/drug therapy , Peptide Hormones/therapeutic use , Animals , Cardiovascular Diseases/metabolism , Humans , Metabolic Diseases/metabolism , Peptide Hormones/pharmacology , Receptors, Peptide/metabolism
18.
Acta Pharmacol Sin ; 38(12): 1601-1610, 2017 Dec.
Article in English | MEDLINE | ID: mdl-28933423

ABSTRACT

Hyperhomocysteinemia (HHcy) is a key risk factor in hepatic steatosis. In this study, we applied a metabolomic approach to investigate the changes in the metabolite profile due to HHcy-induced hepatic steatosis and the effects of omega-3 PUFA (polyunsaturated fatty acid) supplementation in mice. HHcy was induced in mice by giving DL-Hcy (1.8 g/L) in drinking water for 6 weeks, then the mice were sacrificed, and the metabolic profiles of the liver and plasma were analyzed through UPLC-ESI-QTOFMS-based lipidomics. Hepatic triglycerides and cholesterol were further assayed. The expression of ceramide metabolism-related genes was measured by quantitative PCR. Compared with control mice, HHcy mice exhibited hepatic steatosis with a notable increase in ceramide-related metabolites and subsequent upregulation of ceramide synthesis genes such as Sptlc3, Degs2, Cer4 and Smpd4. Omega-3 PUFA was simultaneously administered in HHcy mice through chow diet containing 3.3% omega-3 PUFA supplement for 6 weeks, which significantly ameliorated Hcy-induced hepatic steatosis. The decrease in hepatic lipid accumulation was mainly due to reduced hepatic levels of ceramides, which was partly the result of the lower expression of ceramide synthesis genes, Sptlc3 and Degs2. Similar beneficial effects of DHA were observed in Hcy-stimulated primary hepatocytes in vitro. In summary, Hcy-induced ceramide elevation in hepatocytes might contribute to the development of hepatic steatosis. Furthermore, downregulation of ceramide levels through omega-3 PUFA supplementation ameliorates hepatic lipid accumulation. Thus, ceramide is a potential therapeutic target for the treatment of hepatic steatosis.


Subject(s)
Ceramides/biosynthesis , Fatty Acids, Omega-3/pharmacology , Fatty Acids, Omega-3/therapeutic use , Fatty Liver/drug therapy , Fatty Liver/etiology , Hepatocytes/drug effects , Hyperhomocysteinemia/complications , Animals , Cells, Cultured , Hepatocytes/metabolism , Mice , Mice, Inbred C57BL
19.
Redox Biol ; 13: 459-469, 2017 10.
Article in English | MEDLINE | ID: mdl-28715731

ABSTRACT

Particulate matter with an aerodynamic diameter less than 2.5µM (PM2.5) is one of the major environmental pollutants in China. In this study, we carried out a metabolomics profile study on PM2.5-induced inflammation. PM2.5 from Beijing, China, was collected and given to rats through intra-tracheal instillation in vivo. Acute pulmonary injury were observed by pulmonary function assessment and H.E. staining. The lipid metabolic profile was also altered with increased phospholipid and sphingolipid metabolites in broncho-alveolar lavage fluid (BALF) after PM2.5 instillation. Organic component analysis revealed that benzo[a]pyrene (BaP) is one of the most abundant and toxic components in the PM2.5 collected on the fiber filter. In vitro, BaP was used to treat A549 cells, an alveolar type II cell line. BaP (4µM, 24h) induced inflammation in the cells. Metabolomics analysis revealed that BaP (4µM, 6h) treatment altered the cellular lipid metabolic profile with increased phospholipid metabolites and reduced sphingolipid metabolites and free fatty acids (FFAs). The proportion of ω-3 polyunsaturated fatty acid (PUFA) was also decreased. Mechanically, BaP (4µM) increased the phospholipase A2 (PLA2) activity at 4h as well as the mRNA level of Pla2g2a at 12h. The pro-inflammatory effect of BaP was reversed by the cytosolic PLA2 (cPLA2) inhibitor and chelator of intracellular Ca2+. This study revealed that BaP, as a component of PM2.5, induces pulmonary injury by activating PLA2 and elevating lysophosphatidylcholine (LPC) in a Ca2+-dependent manner in the alveolar type II cells.


Subject(s)
Benzo(a)pyrene/toxicity , Lipid Metabolism , Lung Injury/etiology , Metabolome , Particulate Matter/toxicity , Animals , Benzo(a)pyrene/analysis , Bronchoalveolar Lavage Fluid/chemistry , Cell Line, Tumor , Humans , Lung/drug effects , Lung/metabolism , Lung Injury/metabolism , Male , Particulate Matter/chemistry , Phospholipases A2/metabolism , Rats , Rats, Wistar
20.
Mediators Inflamm ; 2017: 9029327, 2017.
Article in English | MEDLINE | ID: mdl-29386753

ABSTRACT

Hypoxia-inducible factor (HIF) 1α is a metabolic regulator that plays an important role in immunologic responses. Previous studies have demonstrated that HIF1α participates in the M1 polarization of macrophages. To clarify the mechanism of HIF1α-induced polarization of M1 macrophage, myeloid-specific HIF1α overexpression (Lysm HIF1α lsl) mice were employed and the bone marrow-derived and peritoneal macrophages were isolated. RT-PCR results revealed that HIF1α overexpression macrophage had a hyperinflammatory state characterized by the upregulation of M1 markers. Cellular bioenergetics analysis showed lower cellular oxygen consumption rates in the Lysm HIF1α lsl mice. Metabolomics studies showed that HIF1α overexpression led to increased glycolysis and pentose phosphate pathway intermediates. Further results revealed that macrophage M1 polarization, induced by HIF1α overexpression, was via upregulating the mRNA expression of the genes related to the glycolysis metabolism. Our results indicate that HIF1α promoted macrophage glycolysis metabolism, which induced M1 polarization in mice.


Subject(s)
Glycolysis , Hypoxia-Inducible Factor 1, alpha Subunit/physiology , Inflammation/etiology , Macrophage Activation , Macrophages/metabolism , Animals , Cell Polarity , Mice , Mice, Inbred C57BL , Pentose Phosphate Pathway
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