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1.
J Am Heart Assoc ; 11(12): e023386, 2022 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-35699182

RESUMO

Background Exercise is associated with a reduced risk of cardiovascular disease. Increased high-density lipoprotein cholesterol (HDL-C) levels are thought to contribute to these benefits, but much of the research in this area has been limited by lack of well-controlled subject selection and exercise interventions. We sought to study the effect of moderate and high-intensity exercise on HDL function, lipid/lipoprotein profile, and other cardiometabolic parameters in a homogeneous population where exercise, daily routine, sleep patterns, and living conditions were carefully controlled. Methods and Results Male Army recruits (n=115, age 22±0.3 years) completed a 12-week moderate-intensity exercise program. A subset of 51 subsequently completed a 15-week high-intensity exercise program. Fitness increased and body fat decreased after moderate- and high-intensity exercise (P<0.001). Moderate-intensity exercise increased HDL-C and apolipoprotein A-I levels (6.6%, 11.6% respectively), and decreased low-density lipoprotein cholesterol and apolipoprotein B levels (7.2%, 4.9% respectively) (all P<0.01). HDL-C and apolipoprotein A-I levels further increased by 8.2% (P<0.001) and 6.3% (P<0.05) after high-intensity exercise. Moderate-intensity exercise increased ABCA-1 (ATP-binding cassette transporter A1) mediated cholesterol efflux by 13.5% (P<0.001), which was sustained after high-intensity exercise. In a selected subset the ability of HDLs to inhibit ICAM-1 (intercellular adhesion molecule-1) expression decreased after the high (P<0.001) but not the moderate-intensity exercise program. Conclusions When controlling for exercise patterns, diet, and sleep, moderate-intensity exercise improved HDL function, lipid/lipoprotein profile, fitness, and body composition. A sequential moderate followed by high-intensity exercise program showed sustained or incremental benefits in these parameters. Improved HDL function may be part of the mechanism by which exercise reduces cardiovascular disease risk.


Assuntos
Apolipoproteína A-I , Doenças Cardiovasculares , Transportador 1 de Cassete de Ligação de ATP/metabolismo , Apolipoproteína A-I/metabolismo , Doenças Cardiovasculares/prevenção & controle , Colesterol/metabolismo , HDL-Colesterol/metabolismo , Humanos , Lipoproteínas , Lipoproteínas HDL/metabolismo , Masculino , Adulto Jovem
2.
Cancers (Basel) ; 14(8)2022 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-35454786

RESUMO

BACKGROUND: Epithelial ovarian cancer (EOC) is the most lethal gynaecological malignancy with over 80% of cases already disseminated at diagnosis and facing a dismal five-year survival rate of 35%. EOC cells often spread to the greater omentum where they take-up cholesterol. Excessive amounts of cholesterol can be cytocidal, suggesting that cholesterol efflux through transporters may be important to maintain homeostasis, and this may explain the observation that high expression of the ATP-binding cassette A1 (ABCA1) cholesterol transporter has been associated with poor outcome in EOC patients. METHODS: ABCA1 expression was silenced in EOC cells to investigate the effect of inhibiting cholesterol efflux on EOC biology through growth and migration assays, three-dimensional spheroid culture and cholesterol quantification. RESULTS: ABCA1 suppression significantly reduced the growth, motility and colony formation of EOC cell lines as well as the size of EOC spheroids, whilst stimulating expression of ABCA1 reversed these effects. In serous EOC cells, ABCA1 suppression induced accumulation of cholesterol. Lowering cholesterol levels using methyl-B-cyclodextrin rescued the effect of ABCA1 suppression, restoring EOC growth. Furthermore, we identified FDA-approved agents that induced cholesterol accumulation and elicited cytocidal effects in EOC cells. CONCLUSIONS: Our data demonstrate the importance of ABCA1 in maintaining cholesterol balance and malignant properties in EOC cells, highlighting its potential as a therapeutic target for this disease.

3.
Arterioscler Thromb Vasc Biol ; 40(11): 2728-2737, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32907370

RESUMO

OBJECTIVE: Patients with schizophrenia have increased long-term mortality attributable to cardiovascular disease and commonly demonstrate features of mixed dyslipidemia with low HDL-C (high-density lipoprotein cholesterol). The removal of cholesterol from cells by HDL via specific ATP-binding cholesterol transporters is a major functional property of HDL, and its measurement as cholesterol efflux capacity (CEC) can predict cardiovascular risk. Whether HDL function is impaired in patients with schizophrenia is unknown. Approach and Results: We measured basal and ABCA1 (ATP-binding cassette transporter A1)- and ABCG1 (ATP-binding cassette transporter G1)-dependent CEC, comparing patients with schizophrenia with age- and sex-matched healthy controls, and related our findings to nuclear magnetic resonance analysis of lipoprotein subclasses. Total plasma cholesterol and LDL-C (low-density lipoprotein cholesterol) were comparable between healthy controls (n=51) and patients (n=120), but patients with schizophrenia had increased total plasma triglyceride, low HDL-C and apo (apolipoprotein) A-I concentrations. Nuclear magnetic resonance analysis indicated a marked (15-fold) increase in large triglyceride-rich lipoprotein particle concentration, increased small dense LDL particles, and fewer large HDL particles. Despite lower HDL-C concentration, basal CEC was 13.7±1.6% higher, ABCA1-specific efflux was 35.9±1.6% higher, and ABCG1 efflux not different, in patients versus controls. In patients with schizophrenia, ABCA1-specific efflux correlated with the abundance of small 7.8 nm HDL particles but not with serum plasminogen or triglyceride levels. CONCLUSIONS: Patients with schizophrenia have increased concentrations of atherogenic apoB-containing lipoproteins, decreased concentrations of large HDL particles, but enhanced ABCA1-mediated CEC. In this population, preventative strategies should focus on reducing atherogenic lipoproteins rather than increasing CEC.


Assuntos
Transportador 1 de Cassete de Ligação de ATP/metabolismo , Colesterol/sangue , Dislipidemias/sangue , Lipoproteínas/sangue , Esquizofrenia/sangue , Transportador 1 de Cassete de Ligação de ATP/genética , Membro 1 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/genética , Membro 1 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/metabolismo , Adulto , Animais , Antipsicóticos/uso terapêutico , Biomarcadores/sangue , Células CHO , Estudos de Casos e Controles , Cricetulus , Dislipidemias/diagnóstico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Esquizofrenia/diagnóstico , Esquizofrenia/tratamento farmacológico , Triglicerídeos/sangue
4.
iScience ; 12: 41-52, 2019 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-30665196

RESUMO

Circulating tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) levels are reduced in patients with cardiovascular disease, and TRAIL gene deletion in mice exacerbates atherosclerosis and inflammation. How TRAIL protects against atherosclerosis and why levels are reduced in disease is unknown. Here, multiple strategies were used to identify the protective source of TRAIL and its mechanism(s) of action. Samples from patients with coronary artery disease and bone-marrow transplantation experiments in mice lacking TRAIL revealed monocytes/macrophages as the main protective source. Accordingly, deletion of TRAIL caused a more inflammatory macrophage with reduced migration, displaying impaired reverse cholesterol efflux and efferocytosis. Furthermore, interleukin (IL)-18, commonly increased in plasma of patients with cardiovascular disease, negatively regulated TRAIL transcription and gene expression, revealing an IL-18-TRAIL axis. These findings demonstrate that TRAIL is protective of atherosclerosis by modulating monocyte/macrophage phenotype and function. Manipulating TRAIL levels in these cells highlights a different therapeutic avenue in the treatment of cardiovascular disease.

5.
Biochim Biophys Acta Mol Cell Biol Lipids ; 1863(10): 1257-1273, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30305243

RESUMO

The 'cholesterol efflux capacity (CEC)' assay is a simple in vitro measure of the capacities of individual sera to promote the first step of the reverse cholesterol transport pathway, the delivery of cellular cholesterol to plasma HDL. This review describes the cell biology of this model and critically assesses its application as a marker of cardiovascular risk. We describe the pathways for cell cholesterol export, current cell models used in the CEC assay with their limitations and consider the contribution that measurement of serum CEC provides to our understanding of HDL function in vivo.


Assuntos
Biomarcadores/sangue , Doenças Cardiovasculares/sangue , Colesterol/sangue , Doenças Cardiovasculares/metabolismo , HDL-Colesterol/sangue , Humanos , Transporte Proteico , Transdução de Sinais
7.
Methods Mol Biol ; 1583: 287-298, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28205182

RESUMO

Reverse cholesterol transport (RCT) is one of the main processes that is thought to protect against cardiovascular disease. RCT constitutes the removal of cholesterol from peripheral sites, its transport through the plasma compartment for delivery to the liver for excretion. Here, we describe an in vivo RCT method that incorporates these steps, measuring movement of cholesterol from macrophages to the plasma, the liver, and finally to the feces in mice.


Assuntos
Colesterol/metabolismo , Macrófagos/metabolismo , Animais , Transporte Biológico Ativo/fisiologia , Linhagem Celular , Fezes , Fígado/metabolismo , Camundongos
8.
Biochem J ; 474(7): 1071-1092, 2017 03 08.
Artigo em Inglês | MEDLINE | ID: mdl-28104755

RESUMO

Sphingomyelin phosphodiesterase acid-like 3A (SMPDL3A) is a recently identified phosphodiesterase, which is a secreted N-linked glycoprotein. SMPDL3A is highly homologous to acid sphingomyelinase (aSMase), but unlike aSMase cannot cleave sphingomyelin. Rather, SMPDL3A hydrolyzes nucleotide tri- and diphosphates and their derivatives. While recent structural studies have shed light on these unexpected substrate preferences, many other aspects of SMPDL3A biology, which may give insight into its function in vivo, remain obscure. Here, we investigate the roles of N-glycosylation in the expression, secretion and activity of human SMPDL3A, using inhibitors of N-glycosylation and site-directed mutagenesis, with either THP-1 macrophages or CHO cells expressing human SMPDL3A. Tunicamycin (TM) treatment resulted in expression of non-glycosylated SMPDL3A that was not secreted, and was largely degraded by the proteasome. Proteasomal inhibition restored levels of SMPDL3A in TM-treated cells, although this non-glycosylated protein lacked phosphodiesterase activity. Enzymatic deglycosylation of purified recombinant SMPDL3A also resulted in significant loss of phosphodiesterase activity. Site-directed mutagenesis of individual N-glycosylation sites in SMPDL3A identified glycosylation of Asn69 and Asn222 as affecting maturation of its N-glycans and secretion. Glycosylation of Asn356 in SMPDL3A, an N-linked site conserved throughout the aSMase-like family, was critical for protection against proteasomal degradation and preservation of enzymatic activity. We provide the first experimental evidence for a predicted 22 residue N-terminal signal peptide in SMPDL3A, which is essential for facilitating glycosylation and is removed from the mature protein secreted from CHO cells. In conclusion, site-specific N-glycosylation is essential for the intracellular stability, secretion and activity of human SMPDL3A.


Assuntos
Monócitos/enzimologia , Proteínas Recombinantes de Fusão/química , Esfingomielina Fosfodiesterase/química , Sequência de Aminoácidos , Animais , Células CHO , Linhagem Celular , Cricetulus , Glicosilação/efeitos dos fármacos , Humanos , Indolizinas/farmacologia , Leupeptinas/farmacologia , Monócitos/citologia , Monócitos/efeitos dos fármacos , Mutagênese Sítio-Dirigida , Mutação , Peptídeo-N4-(N-acetil-beta-glucosaminil) Asparagina Amidase/química , Inibidores de Proteases/farmacologia , Complexo de Endopeptidases do Proteassoma/efeitos dos fármacos , Complexo de Endopeptidases do Proteassoma/metabolismo , Sinais Direcionadores de Proteínas , Estabilidade Proteica/efeitos dos fármacos , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Esfingomielina Fosfodiesterase/genética , Esfingomielina Fosfodiesterase/metabolismo , Swainsonina/farmacologia , Tunicamicina/farmacologia
9.
FASEB J ; 30(12): 4239-4255, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27630170

RESUMO

Apolipoprotein A-I (apoA-I) is the major component of HDL and central to the ability of HDL to stimulate ATP-binding cassette transporter A1 (ABCA1)-dependent, antiatherogenic export of cholesterol from macrophage foam cells, a key player in the pathology of atherosclerosis. Cell-mediated modifications of apoA-I, such as chlorination, nitration, oxidation, and proteolysis, can impair its antiatherogenic function, although it is unknown whether macrophages themselves contribute to such modifications. To investigate this, human monocyte-derived macrophages (HMDMs) were incubated with human apoA-I under conditions used to induce cholesterol export. Two-dimensional gel electrophoresis and Western blot analysis identified that apoA-I is cleaved (∼20-80%) by HMDMs in a time-dependent manner, generating apoA-I of lower MW and isoelectric point. Mass spectrometry analysis identified a novel C-terminal cleavage site of apoA-I between Ser228-Phe229 Recombinant apoA-I truncated at Ser228 demonstrated profound loss of capacity to solubilize lipid and to promote ABCA1-dependent cholesterol efflux. Protease inhibitors, small interfering RNA knockdown in HMDMs, mass spectrometry analysis, and cathepsin B activity assays identified secreted cathepsin B as responsible for apoA-I cleavage at Ser228 Importantly, C-terminal cleavage of apoA-I was also detected in human carotid plaque. Cleavage at Ser228 is a novel, functionally important post-translational modification of apoA-I mediated by HMDMs that limits the antiatherogenic properties of apoA-I.-Dinnes, D. L. M., White, M. Y., Kockx, M., Traini, M., Hsieh, V., Kim, M.-J., Hou, L., Jessup, W., Rye, K.-A., Thaysen-Andersen, M., Cordwell, S. J., Kritharides, L. Human macrophage cathepsin B-mediated C-terminal cleavage of apolipoprotein A-I at Ser228 severely impairs antiatherogenic capacity.


Assuntos
Apolipoproteína A-I/metabolismo , Aterosclerose/metabolismo , Catepsina B/metabolismo , Colesterol/metabolismo , Macrófagos/metabolismo , Transportadores de Cassetes de Ligação de ATP/genética , Transporte Biológico/fisiologia , Células Espumosas/metabolismo , Humanos , Processamento de Proteína Pós-Traducional/fisiologia , Proteólise , Serina/metabolismo
10.
Am Heart J ; 180: 54-63, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27659883

RESUMO

Epidemiologic studies have shown an inverse correlation between high-density lipoprotein (HDL) cholesterol (HDL-C) levels and cardiovascular disease outcomes. However, the hypothesis of a causal relationship between HDL-C and cardiovascular disease has been challenged by genetic and clinical studies. Serum cholesterol efflux capacity (CEC) is an important measure of HDL function in humans. Recent large clinical studies have shown a correlation between in vitro CEC and cardiovascular disease prevalence and incidence, which appears to be independent of HDL-C concentration. The present review summarizes recent large clinical studies and introduces important methodological considerations. Further studies are required to standardize and establish the reproducibility of this measure of HDL function and clarify whether modulating CEC will emerge as a useful therapeutic target.


Assuntos
Doenças Cardiovasculares/metabolismo , HDL-Colesterol/metabolismo , Colesterol/sangue , Doenças Autoimunes/metabolismo , Transporte Biológico , Doenças Cardiovasculares/sangue , Células Cultivadas , Diabetes Mellitus/metabolismo , Humanos , Técnicas In Vitro
12.
Arterioscler Thromb Vasc Biol ; 36(7): 1338-49, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-27150391

RESUMO

OBJECTIVE: Cyclosporin A (CsA) is an immunosuppressant commonly used to prevent organ rejection but is associated with hyperlipidemia and an increased risk of cardiovascular disease. Although studies suggest that CsA-induced hyperlipidemia is mediated by inhibition of low-density lipoprotein receptor (LDLr)-mediated lipoprotein clearance, the data supporting this are inconclusive. We therefore sought to investigate the role of the LDLr in CsA-induced hyperlipidemia by using Ldlr-knockout mice (Ldlr(-/-)). APPROACH AND RESULTS: Ldlr(-/-) and wild-type (wt) C57Bl/6 mice were treated with 20 mg/kg per d CsA for 4 weeks. On a chow diet, CsA caused marked dyslipidemia in Ldlr(-/-) but not in wt mice. Hyperlipidemia was characterized by a prominent increase in plasma very low-density lipoprotein and intermediate-density lipoprotein/LDL with unchanged plasma high-density lipoprotein levels, thus mimicking the dyslipidemic profile observed in humans. Analysis of specific lipid species by liquid chromatography-tandem mass spectrometry suggested a predominant effect of CsA on increased very low-density lipoprotein-IDL/LDL lipoprotein number rather than composition. Mechanistic studies indicated that CsA did not alter hepatic lipoprotein production but did inhibit plasma clearance and hepatic uptake of [(14)C]cholesteryl oleate and glycerol tri[(3)H]oleate-double-labeled very low-density lipoprotein-like particles. Further studies showed that CsA inhibited plasma lipoprotein lipase activity and increased levels of apolipoprotein C-III and proprotein convertase subtilisin/kexin type 9. CONCLUSIONS: We demonstrate that CsA does not cause hyperlipidemia via direct effects on the LDLr. Rather, LDLr deficiency plays an important permissive role for CsA-induced hyperlipidemia, which is associated with abnormal lipoprotein clearance, decreased lipoprotein lipase activity, and increased levels of apolipoprotein C-III and proprotein convertase subtilisin/kexin type 9. Enhancing LDLr and lipoprotein lipase activity and decreasing apolipoprotein C-III and proprotein convertase subtilisin/kexin type 9 levels may therefore provide attractive treatment targets for patients with hyperlipidemia receiving CsA.


Assuntos
Ciclosporina , Hiperlipidemias/metabolismo , Metabolismo dos Lipídeos , Receptores de LDL/metabolismo , Animais , Apolipoproteína C-III/sangue , Biomarcadores/sangue , Ésteres do Colesterol/metabolismo , Modelos Animais de Doenças , Feminino , Predisposição Genética para Doença , Hiperlipidemias/sangue , Hiperlipidemias/induzido quimicamente , Hiperlipidemias/genética , Lipase Lipoproteica/sangue , Lipoproteínas HDL/sangue , Lipoproteínas IDL/sangue , Lipoproteínas VLDL/sangue , Fígado/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fenótipo , Pró-Proteína Convertase 9/sangue , Receptores de LDL/deficiência , Receptores de LDL/genética , Fatores de Tempo , Trioleína/metabolismo
14.
Cardiovasc Res ; 108(1): 111-23, 2015 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-26092098

RESUMO

AIMS: Macrophage apoptosis is a prominent feature of atherosclerosis, yet whether cell death-protected macrophages would favour the resolution of already established atherosclerotic lesions, and thus hold therapeutic potential, remains unknown. METHODS AND RESULTS: We irradiated then transplanted into Apoe(-/-) or LDLr(-/-) recipient mice harbouring established atherosclerotic lesions, bone marrow cells from mice displaying enhanced macrophage survival through overexpression of the antiapoptotic gene hBcl-2 (Mø-hBcl2 Apoe(-/-) or Mø-hBcl2 Apoe(+/+) LDLr(-/-)). Both recipient mice exhibited decreased lesional apoptotic cell content and reduced necrotic areas when repopulated with Mø-hBcl2 mouse-derived bone marrow cells. In contrast, only LDLr(-/-) recipients showed a reduction in plasma cholesterol levels and in atherosclerotic lesions. The absence of significant reduction of plasma cholesterol levels in the context of apoE deficiency highlighted macrophage-derived apoE as key in both the regulation of plasma and tissue cholesterol levels and the progression of pre-existing lesion. Accordingly, hBcl2 expression in macrophages was associated with larger pools of Kupffer cells and Ly-6C(low) monocytes, both high producers of apoE. Additionally, increased Kupffer cells population was associated with improved clearance of apoptotic cells and modified lipoproteins. CONCLUSION: Collectively, these data show that promoting macrophage survival provides a supplemental source of apoE, which hinders pre-existing plaque progression.


Assuntos
Apolipoproteínas E/fisiologia , Aterosclerose/etiologia , Macrófagos/fisiologia , Animais , Antígenos Ly/fisiologia , Apoptose , Sobrevivência Celular , Colesterol/metabolismo , Progressão da Doença , Masculino , Camundongos , Proteínas Proto-Oncogênicas c-bcl-2/análise , Receptores de LDL/fisiologia
15.
Circ Res ; 116(7): 1133-42, 2015 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-25589556

RESUMO

RATIONALE: High-density lipoprotein (HDL) is a heterogeneous population of particles. Differences in the capacities of HDL subfractions to remove cellular cholesterol may explain variable correlations between HDL-cholesterol and cardiovascular risk and inform future targets for HDL-related therapies. The ATP binding cassette transporter A1 (ABCA1) facilitates cholesterol efflux to lipid-free apolipoprotein A-I, but the majority of apolipoprotein A-I in the circulation is transported in a lipidated state and ABCA1-dependent efflux to individual HDL subfractions has not been systematically studied. OBJECTIVE: Our aims were to determine which HDL particle subfractions are most efficient in mediating cellular cholesterol efflux from foam cell macrophages and to identify the cellular cholesterol transporters involved in this process. METHODS AND RESULTS: We used reconstituted HDL particles of defined size and composition, isolated subfractions of human plasma HDL, cell lines stably expressing ABCA1 or ABCG1, and both mouse and human macrophages in which ABCA1 or ABCG1 expression was deleted. We show that ABCA1 is the major mediator of macrophage cholesterol efflux to HDL, demonstrating most marked efficiency with small, dense HDL subfractions (HDL3b and HDL3c). ABCG1 has a lesser role in cholesterol efflux and a negligible role in efflux to HDL3b and HDL3c subfractions. CONCLUSIONS: Small, dense HDL subfractions are the most efficient mediators of cholesterol efflux, and ABCA1 mediates cholesterol efflux to small dense HDL and to lipid-free apolipoprotein A-I. HDL-directed therapies should target increasing the concentrations or the cholesterol efflux capacity of small, dense HDL species in vivo.


Assuntos
Transportador 1 de Cassete de Ligação de ATP/fisiologia , HDL-Colesterol/metabolismo , Colesterol/metabolismo , Lipoproteínas HDL/metabolismo , Macrófagos/metabolismo , Transportador 1 de Cassete de Ligação de ATP/antagonistas & inibidores , Transportador 1 de Cassete de Ligação de ATP/deficiência , Transportador 1 de Cassete de Ligação de ATP/genética , Membro 1 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Transportadores de Cassetes de Ligação de ATP/deficiência , Transportadores de Cassetes de Ligação de ATP/fisiologia , Animais , Apolipoproteína A-I/metabolismo , Transporte Biológico , Células CHO , Linhagem Celular , Cricetinae , Cricetulus , Células Espumosas/metabolismo , Inativação Gênica , Humanos , Lipoproteínas/deficiência , Lipoproteínas/fisiologia , Lipoproteínas HDL2/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Tamanho da Partícula , Proteínas Recombinantes de Fusão/metabolismo , Doença de Tangier/enzimologia , Doença de Tangier/genética
16.
Biochim Biophys Acta ; 1841(12): 1741-51, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25462452

RESUMO

Vitamin E membrane transport has been shown to involve the cholesterol transporters SR-BI, ABCA1 and NPC1L1. Our aim was to investigate the possible participation of another cholesterol transporter in cellular vitamin E efflux: ABCG1. In Abcgl-deficient mice, vitamin E concentration was reduced in plasma lipoproteins whereas most tissues displayed a higher vitamin E content compared to wild-type mice. α- and γ-tocopherol efflux was increased in CHO cells overexpressing human ABCG1 compared to control cells. Conversely, α- and γ- tocopherol efflux was decreased in ABCG1-knockdown human cells (Hep3B hepatocytes and THP-1 macro- phages). Interestingly, α- and γ-tocopherol significantly downregulated ABCG1 and ABCA1 expression levels in Hep3B and THP-1, an effect confirmed in vivo in rats given vitamin E for 5 days. This was likely due to reduced LXR activation by oxysterols, as Hep3B cells and rat liver treated with vitamin E displayed a significantly reduced content in oxysterols compared to their respective controls. Overall, the present study reveals for the first time that ABCG1 is involved in cellular vitamin E efflux.


Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Lipoproteínas/metabolismo , Vitamina E/metabolismo , Transportador 1 de Cassete de Ligação de ATP/genética , Transportador 1 de Cassete de Ligação de ATP/metabolismo , Membro 1 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Transportadores de Cassetes de Ligação de ATP/deficiência , Transportadores de Cassetes de Ligação de ATP/genética , Animais , Transporte Biológico , Células CHO , Cromanos/metabolismo , Cricetinae , Cricetulus , Regulação para Baixo , Humanos , Lipoproteínas/deficiência , Fígado/metabolismo , Receptores X do Fígado , Macrófagos/metabolismo , Camundongos Endogâmicos C57BL , Especificidade de Órgãos , Receptores Nucleares Órfãos/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Interferente Pequeno/metabolismo , Ratos , Transfecção
17.
J Biol Chem ; 289(47): 32895-913, 2014 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-25288789

RESUMO

Cholesterol-loaded foam cell macrophages are prominent in atherosclerotic lesions and play complex roles in both inflammatory signaling and lipid metabolism, which are underpinned by large scale reprogramming of gene expression. We performed a microarray study of primary human macrophages that showed that transcription of the sphingomyelin phosphodiesterase acid-like 3A (SMPDL3A) gene is up-regulated after cholesterol loading. SMPDL3A protein expression in and secretion from primary macrophages are stimulated by cholesterol loading, liver X receptor ligands, and cyclic AMP, and N-glycosylated SMPDL3A protein is detectable in circulating blood. We demonstrate for the first time that SMPDL3A is a functional phosphodiesterase with an acidic pH optimum. We provide evidence that SMPDL3A is not an acid sphingomyelinase but unexpectedly is active against nucleotide diphosphate and triphosphate substrates at acidic and neutral pH. SMPDL3A is a major source of nucleotide phosphodiesterase activity secreted by liver X receptor-stimulated human macrophages. Extracellular nucleotides such as ATP may activate pro-inflammatory responses in immune cells. Increased expression and secretion of SMPDL3A by cholesterol-loaded macrophage foam cells in lesions may decrease local concentrations of pro-inflammatory nucleotides and potentially represent a novel anti-inflammatory axis linking lipid metabolism with purinergic signaling in atherosclerosis.


Assuntos
Colesterol/metabolismo , Macrófagos/metabolismo , Nucleotídeos/metabolismo , Diester Fosfórico Hidrolases/metabolismo , Esfingomielina Fosfodiesterase/metabolismo , Animais , Western Blotting , Células CHO , Linhagem Celular Tumoral , Células Cultivadas , Colesterol/farmacologia , Cricetinae , Cricetulus , AMP Cíclico/farmacologia , Células Espumosas/efeitos dos fármacos , Células Espumosas/metabolismo , Complexo de Golgi/metabolismo , Células HEK293 , Humanos , Receptores X do Fígado , Macrófagos/efeitos dos fármacos , Microscopia Confocal , Nucleotídeos/farmacologia , Análise de Sequência com Séries de Oligonucleotídeos , Receptores Nucleares Órfãos/metabolismo , Diester Fosfórico Hidrolases/genética , Interferência de RNA , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Esfingomielina Fosfodiesterase/sangue , Esfingomielina Fosfodiesterase/genética , Transcriptoma/efeitos dos fármacos , Transcriptoma/genética
18.
PLoS One ; 9(10): e111186, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25347775

RESUMO

Dynamins are fission proteins that mediate endocytic and exocytic membrane events and are pharmacological therapeutic targets. These studies investigate whether dynamin II regulates constitutive protein secretion and show for the first time that pharmacological inhibition of dynamin decreases secretion of apolipoprotein E (apoE) and several other proteins constitutively secreted from primary human macrophages. Inhibitors that target recruitment of dynamin to membranes (MiTMABs) or directly target the GTPase domain (Dyngo or Dynole series), dose- and time- dependently reduced the secretion of apoE. SiRNA oligo's targeting all isoforms of dynamin II confirmed the involvement of dynamin II in apoE secretion. Inhibition of secretion was not mediated via effects on mRNA or protein synthesis. 2D-gel electrophoresis showed that inhibition occurred after apoE was processed and glycosylated in the Golgi and live cell imaging showed that inhibited secretion was associated with reduced post-Golgi movement of apoE-GFP-containing vesicles. The effect was not restricted to macrophages, and was not mediated by the effects of the inhibitors on microtubules. Inhibition of dynamin also altered the constitutive secretion of other proteins, decreasing the secretion of fibronectin, matrix metalloproteinase 9, Chitinase-3-like protein 1 and lysozyme but unexpectedly increasing the secretion of the inflammatory mediator cyclophilin A. We conclude that pharmacological inhibitors of dynamin II modulate the constitutive secretion of macrophage apoE as a class effect, and that their capacity to modulate protein secretion may affect a range of biological processes.


Assuntos
Apolipoproteínas E/metabolismo , Dinamina II/antagonistas & inibidores , Exocitose/efeitos dos fármacos , Macrófagos/metabolismo , Acrilamidas/farmacologia , Animais , Células CHO , Células Cultivadas , Cricetinae , Cricetulus , Dinamina II/genética , Dinamina II/metabolismo , Células Hep G2 , Humanos , Indóis/farmacologia , Macrófagos/efeitos dos fármacos , Via Secretória
19.
J Biol Chem ; 289(11): 7524-36, 2014 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-24500716

RESUMO

The objective of this study was to examine the influence of cholesterol in post-translational control of ABCA1 and ABCG1 protein expression. Using CHO cell lines stably expressing human ABCA1 or ABCG1, we observed that the abundance of these proteins is increased by cell cholesterol loading. The response to increased cholesterol is rapid, is independent of transcription, and appears to be specific for these membrane proteins. The effect is mediated through cholesterol-dependent inhibition of transporter protein degradation. Cell cholesterol loading similarly regulates degradation of endogenously expressed ABCA1 and ABCG1 in human THP-1 macrophages. Turnover of ABCA1 and ABCG1 is strongly inhibited by proteasomal inhibitors and is unresponsive to inhibitors of lysosomal proteolysis. Furthermore, cell cholesterol loading inhibits ubiquitination of ABCA1 and ABCG1. Our findings provide evidence for a rapid, cholesterol-dependent, post-translational control of ABCA1 and ABCG1 protein levels, mediated through a specific and sterol-sensitive mechanism for suppression of transporter protein ubiquitination, which in turn decreases proteasomal degradation. This provides a mechanism for acute fine-tuning of cholesterol transporter activity in response to fluctuations in cell cholesterol levels, in addition to the longer term cholesterol-dependent transcriptional regulation of these genes.


Assuntos
Transportador 1 de Cassete de Ligação de ATP/metabolismo , Transportadores de Cassetes de Ligação de ATP/metabolismo , Colesterol/metabolismo , Ubiquitinação , Membro 1 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Animais , Aterosclerose/metabolismo , Transporte Biológico , Células CHO , Linhagem Celular , Cricetulus , Humanos , Macrófagos/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Inibidores de Proteassoma , Ubiquitina/metabolismo
20.
Atherosclerosis ; 232(2): 346-60, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24468148

RESUMO

OBJECTIVE: This EAS Consensus Panel critically appraised evidence relevant to the benefit to risk relationship of functional foods with added plant sterols and/or plant stanols, as components of a healthy lifestyle, to reduce plasma low-density lipoprotein-cholesterol (LDL-C) levels, and thereby lower cardiovascular risk. METHODS AND RESULTS: Plant sterols/stanols (when taken at 2 g/day) cause significant inhibition of cholesterol absorption and lower LDL-C levels by between 8 and 10%. The relative proportions of cholesterol versus sterol/stanol levels are similar in both plasma and tissue, with levels of sterols/stanols being 500-/10,000-fold lower than those of cholesterol, suggesting they are handled similarly to cholesterol in most cells. Despite possible atherogenicity of marked elevations in circulating levels of plant sterols/stanols, protective effects have been observed in some animal models of atherosclerosis. Higher plasma levels of plant sterols/stanols associated with intakes of 2 g/day in man have not been linked to adverse effects on health in long-term human studies. Importantly, at this dose, plant sterol/stanol-mediated LDL-C lowering is additive to that of statins in dyslipidaemic subjects, equivalent to doubling the dose of statin. The reported 6-9% lowering of plasma triglyceride by 2 g/day in hypertriglyceridaemic patients warrants further evaluation. CONCLUSION: Based on LDL-C lowering and the absence of adverse signals, this EAS Consensus Panel concludes that functional foods with plant sterols/stanols may be considered 1) in individuals with high cholesterol levels at intermediate or low global cardiovascular risk who do not qualify for pharmacotherapy, 2) as an adjunct to pharmacologic therapy in high and very high risk patients who fail to achieve LDL-C targets on statins or are statin- intolerant, 3) and in adults and children (>6 years) with familial hypercholesterolaemia, in line with current guidance. However, it must be acknowledged that there are no randomised, controlled clinical trial data with hard end-points to establish clinical benefit from the use of plant sterols or plant stanols.


Assuntos
Anticolesterolemiantes/uso terapêutico , Doenças Cardiovasculares/terapia , Dislipidemias/terapia , Fitosteróis/uso terapêutico , Sitosteroides/uso terapêutico , Animais , Doenças Cardiovasculares/sangue , Doenças Cardiovasculares/prevenção & controle , Colesterol/sangue , Colesterol/metabolismo , LDL-Colesterol/sangue , Humanos , Inflamação/tratamento farmacológico , Lipídeos/sangue , Triglicerídeos/sangue
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