RESUMO
Two new azaphilones, namely muyocopronones A (1) and B (2), were isolated from the cultures of an endophytic fungus Muyocopron laterale ECN279. Their structures were elucidated by extensive spectroscopic analysis. Their absolute configurations were determined using the modified Mosher's method and through comparisons of experimental and calculated electronic circular dichroism data. In addition, muyocopronone B (2) was found to exhibit a weak antibacterial activity against some Gram-positive bacteria.
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BACKGROUND: Coagulant factor Xa inhibitors (XaIs) are prescribed for patients with atrial fibrillation for years. METHODS: Human umbilical venous endothelial cells (HUVECs) were cultured with or without (w/wo) a XaI (rivaroxaban) under high glucose (HG: 22 mM). Endothelial senescence was investigated by assessing senescence-associated-ß-galactosidase (SA-ß-gal), p53, and telomere length. Endothelial function and atherosclerosis were examined by nitric oxide-related-products (NOx: NO2- and NO3-), O2-, endothelial NO synthase (eNOS), NADPH oxidase (p22phox), and ICAM1. PAR1 (protease-activated receptor 1) and PAR2, which were reported to regulate eNOS phosphorylation, were inhibited by small interfering RNAs (siRNAs). Thirty-two male dyslipidemic type 2 diabetic rats (ZFDM LepRfa/fa) were fed a high-cholesterol diet w/wo XaI (50 µg/day/kg) for 1-4 weeks. RESULTS: SA-ß-gal, p53, p21, and p16INK4a were increased by HG and restored by XaI (50 nM) in HUVECs. XaI restored telomerase activity and preserved telomere length. XaI suppressed O2-, p22phox, and ICAM1 and restored NOx and eNOS. XaI decreased PAR1 following elevation by HG, which was confirmed by PAR1 siRNA and PAR2 siRNA. In in vivo experiments, plasma glucose, total cholesterol, and triglycerides were increased for 4 weeks but were not changed by XaI. XaI decreased SA-ß-gal and telomerase and preserved telomere length in the aortic endothelium. XaI activated eNOS, inhibited p22phox, increased plasma NOx, and decreased O2-. CONCLUSION: Rivaroxaban prevents replicative senescence in HUVECs and aortic endothelial cells in dyslipidemic diabetic mice. It restores endothelial function and prevents the progression of atherosclerosis.
Assuntos
Doenças da Aorta/prevenção & controle , Aterosclerose/prevenção & controle , Proliferação de Células/efeitos dos fármacos , Senescência Celular/efeitos dos fármacos , Diabetes Mellitus Tipo 2/tratamento farmacológico , Dislipidemias/tratamento farmacológico , Inibidores do Fator Xa/farmacologia , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Rivaroxabana/farmacologia , Animais , Doenças da Aorta/sangue , Doenças da Aorta/etiologia , Doenças da Aorta/patologia , Aterosclerose/sangue , Aterosclerose/etiologia , Aterosclerose/patologia , Glicemia/metabolismo , Proteínas de Ciclo Celular/metabolismo , Células Cultivadas , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/complicações , Dieta Hiperlipídica , Modelos Animais de Doenças , Dislipidemias/sangue , Dislipidemias/complicações , Feminino , Células Endoteliais da Veia Umbilical Humana/metabolismo , Células Endoteliais da Veia Umbilical Humana/patologia , Humanos , Lipídeos/sangue , Óxido Nítrico/metabolismo , Ratos Zucker , Espécies Reativas de Oxigênio/metabolismo , Receptores Ativados por Proteinase/metabolismo , Transdução de Sinais , Telomerase/metabolismoRESUMO
We previously synthesized two retinoid X receptor (RXR) agonists, 4'-hydroxy-3'-propyl-[1,1'-biphenyl]-3-propanoic acid ethyl ester (4'OHE) and 6-hydroxy-3'-propyl-[1,1'-biphenyl]-3-propanoic acid ethyl ester (6OHE), based on the structure of magnaldehyde B, a natural product obtained from Magnolia obovata. 4'OHE and 6OHE exhibited different selectivities for peroxisome proliferator-activated receptor (PPAR)/RXR heterodimers. To examine the regulatory effects of these compounds in adipogenesis, 3T3-L1 mouse preadipocytes were treated with a differentiation cocktail with or without test compounds to induce differentiation, and subsequently treated with test compounds in insulin-containing medium every alternate day. Lipid droplets were stained with Oil Red O to examine lipid accumulation. In addition, adipogenesis-related gene expression was measured using RT-qPCR and immunoblotting. The results showed that a PPARγ agonist, 4'OHE, which exerts agonistic effects on PPARγ and RXRα, enhanced adipogenesis similar to rosiglitazone. However, unlike GW501516, a PPARδ agonist, 6OHE and its hydrolysis product (6OHA), which exert agonistic effects on PPARδ and RXRα, suppressed adipogenesis. In a manner similar to 6OHE and 6OHA, bexarotene, an RXR agonist, suppressed adipocyte differentiation, and its anti-adipogenic effect was reversed by an RXR antagonist. Furthermore, 6OHA and bexarotene inhibited the increase in Pparγ2 and Cebpa mRNA levels 2 days after the induction of differentiation. We demonstrated the adipogenic effect of 4'OHE and anti-adipogenic effects of 6OHE and 6OHA in 3T3-L1 cells. Previously, RXR agonists have been reported to positively regulate the differentiation of mesenchymal stem cells into adipocytes, but our current data showed that they inhibited the differentiation of preadipocytes, at least 3T3-L1 cells, into adipocytes.
Assuntos
Lignanas , PPAR delta , Animais , Camundongos , Adipogenia , PPAR gama/farmacologia , Receptores X de Retinoides/farmacologia , Células 3T3-L1 , Propionatos/farmacologia , Bexaroteno/farmacologia , PPAR delta/farmacologia , Diferenciação Celular , Lignanas/farmacologiaRESUMO
Background and aims: Sichuan dark tea (ST), Zangcha, is a traditional fermented Chinese tea found in Sichuan and Tibet and claimed for beneficial effects against lifestyle-related metabolic disorders. We examined the effects of ST on lipid metabolism and atherosclerosis. Methods and results: Sichuan dark tea was given to fat-rich diet-induced atherosclerosis model rats in comparison with dark-fermented Chinese Pu-erh tea (PT) and Japanese green tea (GT). After 8 weeks of feeding, ST and PT induced an increase in high-density lipoprotein (HDL)-cholesterol and a decrease in glucose, and ST decreased triglyceride in plasma. ST also induced low pH in the cecum. There was no significant change in their body weight among the fat-feeding groups but a decrease was found in the visceral fat and liver weight in the ST group. Accordingly, ST reduced lipid deposition in the aorta in comparison with PT and GT. ST increased mRNA of LXRα, PPARα, PPARγ, and ABCA1 in the rat liver. The extract of ST stimulated the AMPK pathway to increase the expression of ABCA1 in J774 cells and increased expression of lipoprotein lipase and hormone-sensitive lipase in 3T3L1 cells, consistent with its anti-atherogenic effects in rats. High-performance liquid chromatography analysis showed unique spectra of original specific compounds of caffeine and catechins in each tea extract, but none of them was likely responsible for these effects. Conclusion: Sichuan dark tea increases plasma HDL and reduces plasma triglyceride to decrease atherosclerosis through AMPK activation. Further study is required to identify specific components for the effects of this tea preparation.
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AIM: We previously revealed that Caï¼ï¼-activated calmodulin binds to ABCA1 by the region near the PEST sequence and retards its calpain-mediated degradation to increase HDL biogenesis. Calmodulin activity is reportedly modulated also by other nutritional divalent cations; thus, we attempted to determine whether Znï¼ï¼ is involved in the regulation of ABCA1 stability through the modulation of calmodulin activity. METHODS: The effects of Znï¼ï¼ on ABCA1 expression was investigated in J774 mouse macrophage cell-line cells and HepG2 human hepatoma cell-line cells. RESULTS: Znï¼ï¼ increased ABCA1 expression, not by increasing the mRNA but by attenuating its decay rate, more prominently in the presence of cAMP. Accordingly, it enhanced cell cholesterol release with extracellular apolipoprotein A-I. Calmodulin binding to ABCA1 was increased by Znï¼ï¼ and Caï¼ï¼. Znï¼ï¼ suppressed calpain-mediated hydrolysis of the peptide of ABCA1 cytosolic loop, including the PEST sequence and the calmodulin-binding site, in a calmodulin- dependent fashion, in the presence of the minimum amount of Caï¼ï¼ to activate calpain, but not calmodulin. Calpain activity was not directly inhibited by Znï¼ï¼ at the concentration for enhancing calmodulin binding to ABCA1. CONCLUSION: Nutritional divalent cation Znï¼ï¼ is involved in the regulation of ABCA1 activity and biogenesis of HDL through the modulation of calmodulin activity. The results were consistent with previous clinical findings that Znï¼ï¼ increased plasma HDL in the conditions of sympathetic activation, such as type 2 diabetes and chronic hemodialysis.
Assuntos
Transportador 1 de Cassete de Ligação de ATP/metabolismo , Calmodulina/efeitos dos fármacos , Macrófagos/efeitos dos fármacos , Proteólise/efeitos dos fármacos , Zinco/farmacologia , Animais , Apolipoproteína A-I/metabolismo , Calmodulina/metabolismo , Calpaína/metabolismo , Técnicas de Cultura de Células , Linhagem Celular , Colesterol/metabolismo , AMP Cíclico , Humanos , Hidrólise , Macrófagos/metabolismo , Camundongos , RNA MensageiroRESUMO
BACKGROUND AND AIMS: Nobiletin (NOB), a functional ingredient found in citrus peel, is said to act against diabetes, obesity, and atherosclerosis. It has been reported to activate AMPK pathway, as well as increase SREBP1c, PPARα and PPARγ expression. However, no molecular mechanism has been elucidated to be able to integrate these sporadic findings with some controversies to lead to concrete outcomes. In this study, regulation of HDL biogenesis by NOB was investigated modulating ABCA1 and ABCG1 expression. METHODS AND RESULTS: Regulation of ABCA1/G1 by NOB was investigated in mouse macrophages J774.1. NOB increased mRNA and protein levels of ABCA1/G1, and cell cholesterol release by these factors. It also increased mRNA of PPARγ and LXRα but not PPARα. The increase in ABCA1/G1 mRNA levels by NOB was suppressed by antagonists of PPARγ and LXRα. The increase in PPARγ mRNA levels by NOB was suppressed by an LXRα antagonist, and the increase in LXRα mRNA levels was suppressed by a PPARγ antagonist. NOB increased CD36 mRNA and this was suppressed by an LXRα antagonist. The increase in ABCA1 mRNA by a PPARγ agonist was also suppressed by an LXRα antagonist. NOB did not influence LPL1 mRNA expression levels. NOB stimulated AMPK phosphorylation, and the increase in ABCA1/G1, LXRα and PPARγ mRNA levels and ABCA1/G1 protein levels by NOB was reversed by an AMPK inhibitor. AMPK siRNA suppressed ABCA1 expression. CONCLUSIONS: NOB activates AMPK and subsequently LXRα to promote the expression of ABCA1 and ABCG1, and an LXRα - PPARγ loop pathway amplifies these signals.
Assuntos
Transportador 1 de Cassete de Ligação de ATP/metabolismo , Membro 1 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/metabolismo , Flavonas/farmacologia , Hipolipemiantes/farmacologia , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Proteínas Quinases Ativadas por AMP/metabolismo , Transportador 1 de Cassete de Ligação de ATP/genética , Membro 1 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/genética , Animais , Linhagem Celular , Ativação Enzimática , Receptores X do Fígado/genética , Receptores X do Fígado/metabolismo , Camundongos , PPAR gama/genética , PPAR gama/metabolismo , Fosforilação , Regulação para CimaRESUMO
L-citrulline and L-arginine supplementation has been shown to have several beneficial effects on the cardiovascular system. Nitric oxide (NO) protects against the progression of atherosclerosis and is synthesized by nitric oxide synthase (NOS), which converts L-arginine (L-Arg) into L-citrulline (L-Cit). Our previous study revealed that chronic administration of a combination of L-Cit and L- Arg has a better therapeutic effect on high cholesterol-induced atherosclerosis in rabbits. We investigated how L-Arg and L-Cit affect endothelial function, aging and atherosclerosis. Following a 3-day stimulation of human umbilical venous endothelial cells (HUVECs) with high glucose (HG: 22 mM) and L-Arg (300 µM), L-Cit (300 µM) or L-Arg plus L-Cit (LALC: each 150 µM) supplementation, endothelial senescence and function were evaluated. These amino acids were also administered to dyslipidemic type 2 diabetic (ZDFM) rats fed a high cholesterol diet. They were fed L-Arg or L-Cit or LALC for four weeks. Aortic senescence was investigated by measuring senescence-associated ß-galactosidase (SA-ß-gal), telomerase activity, DNA damage and p16INK4a protein expression. Only L-Cit and LALC supplementation retarded the HG-induced endothelial senescence, as evaluated by SA-ß-gal activity, a widely used marker of cellular senescence, p16INK4a expression, a senescence-related protein, and DNA damage. Under HG conditions, L-Cit and LCLA restored telomerase activity to levels observed under normal glucose (NG) conditions. Under HG conditions, L-Cit decreased ROS production, as measured by CM-H2DCFDA and the expression of p67phox, a major component of NADPH oxidase. Under HG conditions, L-Cit and LALC increased NO production, as measured by DAF-2AM. Endothelial NO synthase (eNOS) and phosphorylated eNOS were decreased under HG conditions and L-Cit and LALC significantly increased these levels. Arginase 2 protein expression increased under the HG conditions, and L-Cit and LALC significantly attenuated this effect. In ZDFM rats, SA-ß-gal activity was detected on the aortic endothelial surface; however, L-Cit and LALC reduced these levels. L-Cit and LALC both decreased the proportion of senescent cells. Furthermore, treatment with LALC for 4 weeks increased plasma NO production. Therefore conclusively, L-citrulline supplementation rescued NO levels better than L-arginine supplementation by inhibiting ROS production and arginase 2 protein expression. Consequently, L-Cit and LCLA supplementation retaeded HG-induced endothelial senescence.
Assuntos
Arginina/administração & dosagem , Senescência Celular/efeitos dos fármacos , Citrulina/administração & dosagem , Endotélio Vascular/efeitos dos fármacos , Animais , Arginina/farmacologia , Citrulina/farmacologia , Endotélio Vascular/citologia , Células Endoteliais da Veia Umbilical Humana , Humanos , Ratos , Ratos ZuckerRESUMO
AIM: To study atherosclerosis risk in diabetes, we investigated ATP-binding cassette transporter A1 (ABCA1) expression and high-density lipoprotein (HDL) biogenesis in the liver and hepatocytes under hyperglycemic conditions. METHODS AND RESULTS: In streptozotocin-induced diabetic mice, plasma HDL decreased while ABCA1 protein increased without changing its mRNA in the liver, only in the animals that responded to the treatment to show hypoinsulinemia and fasting hyperglycemia but not in the poor responders not showing those. To study the mechanism for this finding, hepatocytes were isolated from the control and diabetic mice, and they showed no difference in expression of ABCA1 protein, its mRNA, and HDL biogenesis in 1 g/l d-glucose but showed decreased HDL biogenesis in 4.5 g/l d-glucose although ABCA1 protein increased without change in its mRNA. Similar findings were confirmed in HepG2 cells with d-glucose but not with l-glucose. Thus, these cell models reproduced the in vivo findings in hyperglycemia. Labeling of cell surface protein revealed that surface ABCA1 decreased in high concentration of d-glucose in HepG2 cells despite the increase of cellular ABCA1 while not with l-glucose. Immunostaining of ABCA1 in HepG2 cells demonstrated the decrease of surface ABCA1 but increase of intracellular ABCA1 with high d-glucose. Clearance of ABCA1 was retarded both in primary hepatocytes and HepG2 cells exposed to high d-glucose but not to l-glucose, being consistent with the decrease of surface ABCA1. CONCLUSIONS: It is suggested that localization of ABCA1 to the cell surface is decreased in hepatocytes in hyperglycemic condition to cause decrease of HDL biogenesis.
Assuntos
Transportador 1 de Cassete de Ligação de ATP/metabolismo , Diabetes Mellitus Experimental/patologia , Regulação da Expressão Gênica/efeitos dos fármacos , Glucose/farmacologia , Hepatócitos/patologia , Lipoproteínas HDL/biossíntese , Animais , Células Cultivadas , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/metabolismo , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Edulcorantes/farmacologiaRESUMO
BACKGROUND AND AIMS: Expression of ATP binding cassette transporter (ABC) A1, a key membrane protein for biogenesis of high-density lipoprotein (HDL), is regulated not only by its gene transcription but also by its intracellular degradation to modulate plasma HDL concentration. We previously showed that inhibition of ABCA1 degradation by probucol oxidative products, spiroquinone (SQ) and diphenoquinone (DQ), increased HDL biogenesis and reverse cholesterol transport, and achieved reduction of atherosclerosis in animal models. The background mechanism has thus been investigated. METHODS: Involvement of caveolin-1, a protein of multiple functions in cell biology, particularly in cholesterol trafficking, has been examined for its roles in ABCA1 degradation as well as the effects of SQ and DQ on the reaction. RESULTS: ABCA1 protein was increased in caveolin-1-deficient mouse embryonic fibroblasts, not by increase of transcription but by decrease in its internalization and degradation. Transfection and expression of caveolin-1 normalized the protein level and the rate of degradation of ABCA1. Immunoprecipitation experiments demonstrated association between ABCA1 and caveolin-1 and SQ and DQ disrupted this interaction. The effects of SQ and DQ to increase ABCA1 and cell cholesterol release induced by apolipoprotein A-I were dependent on expression of caveolin-1. Fluorescence imaging of ABCA1 and caveolin-1 in cultured cells demonstrated their co-localization as well as its disruption by SQ and DQ, being consistent with the biochemical findings. CONCLUSIONS: Caveolin-1 enhances internalization and degradation of ABCA1 by its association with ABCA1. Interference of this interaction by probucol oxidative products suppresses ABCA1 degradation and increase HDL biogenesis.