The production of very low density lipoprotein and high density lipoprotein particles by the liver is a tightly regulated process, which begins with synthesis and assembly of core protein components in the rough endoplasmic reticulum. Factors influencing the production and metabolism of these particles are of immediate medical relevance, as their malfunction or hyperactivity can lead to an assortment of disease states. Hepatic lipase is a secreted liver enzyme, with many previously described roles in the metabolism and clearance of both high and low density lipoproteins. Increased production and assembly of this enzyme is an indicator of metabolic dysfunction, while its absence or insufficiency leads to pre-mature atherosclerosis and death. The present study shows that this enzyme’s role in lipoprotein metabolism is not confined to the degradation and clearance of these particles after they have been secreted. Experiments using co-immunoprecipitation targeted at hepatic lipase demonstrate that this protein interacts with ApoA1 and ApoB100, the core protein components of HDL and VLDL respectively, at the ER level in hepatocytes, as part of an enormous multi-subunit protein complex. This interaction with ApoA1 leads to decreased competence of hepatocytes to secrete HDL, which confers a pro-atherogenic phenotype. Analysis of ER to Golgi VLDL transport vesicles, produced with a cell-free in vitro budding assay, has revealed that hepatic lipase is co-secreted between these compartments with immature VLDL particles. Further analysis of cytosol isolated from hepatocytes demonstrates an interaction between hepatic lipase and the LDL-receptor related protein in a post-Golgi vesicle; the significance of which will be investigated in future studies.

Dyslipidemia can be a comorbidity of both insulin-resistance and atherosclerosis. Hypertriglyceridemia is common in hyperglycemia and is associated with hypoalphalipoproteinemia (low HDL) and with altered nucleotide or purinergic signaling. We therefore hypothesized that extracellular nucleotides may affect hepatic lipoprotein metabolism. Our studies confirm this view and show that nucleotides regulate cellular proteolytic pathways in liver cells and thereby control lipoprotein secretion and their metabolism by hepatic lipase (HL). Treatment of liver cells with the nucleotide, adenosine diphosphate (ADP), stimulates VLDL-apoB100 and apoE secretion, but blocks HDL-apoA-I and HL secretion. ADP functions like a proteasomal inhibitor to block proteasomal degradation and stimulate apoB100 secretion. Blocking the proteosome is known to activate autophagic pathways. The nucleotide consequently stimulates autophagic degradation in liver cells and increases cellular levels of the autophagic proteins, LC3 and p62. Confocal studies show that ADP increases cellular LC3 levels and promotes co-localization of LC3 and apoA-I in an autophagosomal degradation compartment. ADP acts through the G-protein coupled receptor, P2Y13, to stimulate autophagy and block both HDL and HL secretion. Overexpression of P2Y13 increases cellular LC3 levels and blocks the induction of both HDL and HL secretion, while P2Y13 siRNA reduce LC3 protein levels and cause up to a ten-fold stimulation in HDL and HL secretion. P2Y13 gene expression regulates autophagy through the insulin receptor (IR-β). A reduction in P2Y13 expression increases the phosphorylation of IR-β and protein kinase B (Akt) >3-fold, while increasing P2Y13 expression inhibits the activation of IR-β and Akt. Experiments with epitope-labeled apoA-I and HL show that activation of purinergic pathways has no effect on the internalization and degradation of extracellular apoA-I and HL, which confirms the view that nucleotides primarily impact intracellular protein transport and degradation. In conclusion, elevated blood glucose levels may promote dyslipidemia by stimulating purinergic signaling through P2Y13 and IR-β and perturbing the intracellular degradation and secretion of both HDL and VLDL.

Made available in DSpace on 2015-07-22T20:49:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-01. Added 1 bitstream(s) on 2015-08-11T03:26:17Z : No. of bitstreams: 1 Publico-13210a.pdf: 2089186 bytes, checksum: 4bd9af1812c538db03b2120cffdc516f (MD5). Added 1 bitstream(s) on 2015-08-11T03:26:17Z : No. of bitstreams: 2 Publico-13210a.pdf: 2089186 bytes, checksum: 4bd9af1812c538db03b2120cffdc516f (MD5) Publico-13210b.pdf: 2054432 bytes, checksum: c717885187f0d071e0c0fb8d4bbfe281 (MD5). Added 1 bitstream(s) on 2015-08-11T03:26:17Z : No. of bitstreams: 3 Publico-13210a.pdf: 2089186 bytes, checksum: 4bd9af1812c538db03b2120cffdc516f (MD5) Publico-13210b.pdf: 2054432 bytes, checksum: c717885187f0d071e0c0fb8d4bbfe281 (MD5) Publico-13210c.pdf: 540730 bytes, checksum: fba8c62dcb0177a09d2fde3ef4bace9d (MD5) / A lípase hepática (HL) é uma enzima presente nos sinusoides hepáticos, responsável pela lipólise de lipoproteínas. Contém quatro sítios polimórficos: G-250A, T-710C, 763G-A, e C-514T single-nucleotide polymorphism (SNPs). O último polimorfismo é o foco do presente estudo. Os genótipos associados com o polimorfismo C-514T são CC (homozigoto normal - W), CT (heterozigoto - H) e TT (alelo homozigoto menor - M). A atividade da HL é, significativamente, diminuída nos indivíduos dos genótipos TT e CT. Um total de 58 mulheres pós-menopausas foi estudado. As participantes eram histerectomizadas e submetidas à terapia de reposição hormonal, consistindo de 0,625 mg de estrogênio equino conjugado, uma vez ao dia. Os critérios de inclusão foram: menopausa de até há três anos, resultados de exames de sangue, radiografias, citologia cérvico-vaginal e densitometria óssea normais. O DNA foi extraído a partir de células da mucosa bucal e de células de sangue periférico de todas as pacientes, utilizando-se um conjunto comercialmente disponível (GFX ® - Amersham-Pharmacia, EUA). Resultados: foram encontradas reduções estatisticamente significativas nos triglicérides (t = 2,16; n = 58, p = 0,03), mas não nos níveis de colesterol total (t = 0,14; n = 58, p = 0,89) após o tratamento. Este grupo de bons respondedores eram portadores do alelo T; os genótipos CT e TT estavam presentes com frequência significativamente maior do que no grupo de nãorespondedores (p = 0,02 ou p = 0,07, respectivamente). No entanto, nenhuma diferença significativa nos níveis de HDL-C (t = 0,94; n = 58, p = 0,35) ou LDL-C (t =- 0,83; n = 58, p = 0,41) foi encontrada nestas pacientes. Conclusões: as variações no perfil lipídico associadas ao polimorfismo C-514T são significativas e o alelo T é associado à melhor resposta à TRE. / Background: Hepatic lipase (HL), an enzyme present in the hepatic sinusoids, is responsible for the lipolysis of lipoproteins. Human HL contains four polymorphic sites: G-250A, T-710C, A-763G, and C-514T single-nucleotide polymorphism (SNPs). The last polymorphism is the focus of the current study. The genotypes associated with the C-514T polymorphism are CC (normal homozygous – W), CT (heterozygous – H), and TT (minor-allele homozygous – M). HL activity is significantly impaired in individuals of the TT and CT genotypes. A total of 58 postmenopausal women were studied. The subjects were hysterectomized women receiving hormone replacement therapy consisting of 0.625 mg of conjugated equine estrogen once a day. The inclusion criteria were menopause of up to three years and normal blood tests, radiographs, cervical-vaginal cytology, and densitometry. DNA was extracted from the buccal and blood cells of all 58 patients using a commercially available kit (GFX® - Amersham-Pharmacia, USA). Results: Statistically significant reductions in triglycerides (t=2.16; n=58; p=0.03) but not in total cholesterol (t=0.14; n=58; p=0.89) were found after treatment. This group of good responders were carriers of the T allele; the CT and TT genotypes were present significantly more frequently than in the group of non-responders (p=0.02 or p=0.07, respectively). However, no significant difference in HDL-C (t=0.94; n=58; p=0.35) or LDL-C (t=- 0.83; n=58; p=0.41) was found in these patients. Conclusions: The variation in lipid profile associated with the C-514T polymorphism is significant, and the T allele is associated with the best response to ERT. / TEDE

Submitted by Ana Maria Fiscina Sampaio (fiscina@bahia.fiocruz.br) on 2016-02-15T14:03:58Z No. of bitstreams: 1 Juliana Stolze Efeito...2015.pdf: 1337321 bytes, checksum: 6fdad9cde6d0cc06bd37fdbe677450ae (MD5) / Approved for entry into archive by Ana Maria Fiscina Sampaio (fiscina@bahia.fiocruz.br) on 2016-02-15T14:04:13Z (GMT) No. of bitstreams: 1 Juliana Stolze Efeito...2015.pdf: 1337321 bytes, checksum: 6fdad9cde6d0cc06bd37fdbe677450ae (MD5) / Made available in DSpace on 2016-02-15T14:04:13Z (GMT). No. of bitstreams: 1 Juliana Stolze Efeito...2015.pdf: 1337321 bytes, checksum: 6fdad9cde6d0cc06bd37fdbe677450ae (MD5) Previous issue date: 2015 / Fundação Oswaldo Cruz, Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / Introdução: as doenças cardiovasculares acometem milhares de pessoas no mundo. Destas, a doença arterosclerótica está entre as de maior morbimortalidade. Para a avaliação da necessidade de intervenções hemodinâmicas e/ou revascularização miocárdica, há a necessidade da realização do cateterismo (CATE), procedimento de imagem indicado para evidenciar pontos de obstrução e determinar a melhor estratégia cirúrgica. Para a realização do CATE utiliza-se heparina sódica (5000 UI) in bolus. Atualmente, sabe-se que a heparina interfere no remodelamento de partículas lipoproteicas por liberação da lipoproteína lipase (LPL) e da lipase hepática (LH), essa ação pode alterar o transporte reverso do colesterol (TRC), em função de modificações no metabolismo das lipoproteínas. Métodos: foram selecionados por conveniência 20 pacientes, 10 do sexo masculino e 10 do sexo feminino, ambos os sexos, entre 45 e 73 anos, admitidos no Hospital Ana Neri, submetidos à cineangiocoronariografia (CATE). Todas as determinações laboratoriais foram realizadas antes e depois do CATE. Resultados: houve aumento significativo da atividade da lipase e diminuição da concentração dos triglicérides depois do CATE na análise geral e estratificada pelo sexo (p<0,05; Teste t pareado). A razão HDL-C/apoA aumentou significativamente depois do CATE, já a razão LDL-C/apoB não aumentou, nem diminuiu nas análises geral e estratificada por sexo. Enquanto a razão de risco cardiovascular TG/HDL-C diminuiu significativamente, a ApoB/apoA aumentou significativamente na análise geral e estratificada por sexo depois do CATE. As análises de correlações tiveram comportamentos diferentes, sendo a significância estatística encontrada dependente do grupo analisado (geral, masculino e feminino). A concentração do não-HDL-C, semelhante à determinação da haptoglobina, tiveram diminuição significativa na análise geral e no sexo masculino depois do CATE (p<0,05; Teste t pareado), o grupo feminino não mostrou significância. As taxas de incorporação de colesterol livre e fosfolípides não foram significativas depois do CATE. Conclusão: A administração in bolus de heparina sódica interfere no remodelamento de partículas lipoproteicas, sendo este fato evidenciado pelas variações das razões de risco, tais como, HDL-C/apoA, TG/HDL-C. O percentual de incorporação dos fosfolípides e colesterol livre na HDL mostrou-se influenciado em relação ao sexo, o que o torna relevante dado aos resultados encontrados. A utilização de razões de risco e ainda suas correlações mostraram-se melhores indicadores de desfecho sugestivo de doença cardiovascular nessa casuística do que quando avaliados apenas os marcadores séricos do perfil lipídico isoladamente. / Introduction: cardiovascular diseases affect thousands of people worldwide. Of these, the atherosclerotic disease is one of the most morbidity and mortality. To evaluate the need for hemodynamic interventions and / or CABG, the catheterization (CATE) is performed, an imaging procedure to evidence obstruction and to determine the best surgical strategy. To perform CATE, is necessary to use in bolus sodium heparin (5000 IU). Currently, it is known that heparin interferes with the remodeling of the lipoprotein particles by releasing lipoprotein lipase (LPL) and hepatic lipase (HL), this action may alter the reverse cholesterol transport (TRC), by changes in lipoprotein metabolism. Methods: were selected by convenience 20 patients, 10 male and 10 female, both gender, between 45 and 73 years old, admitted to the Hospital Ana Neri, who underwent coronary angiography (CATE). All laboratory measurements were performed before and after CATE. Results: were significant increase in lipase activity and decreased concentration of triglycerides after CATE, in the overall analysis and stratified by sex (p<0.05, paired t test). The HDL-C/apoA ratio increased significantly after CATE, since the LDL-C/apoB ratio has not increased or decreased in the general analysis, and stratified by gender. While TG/HDL-C cardiovascular risk ratio decreased significantly, ApoB/apoA increased significantly in the overall analysis, and stratified by sex after CATE. The correlation analysis had different behaviors, and the statistic significance found, were dependent of the group analyzed (generally male and female). The concentration of non-HDL-C, similar to the determination of haptoglobin, had a significant decrease in the overall analysis and in males after CATE (p<0.05, paired t-test), the female group do not show significance. The free cholesterol and phospholipids incorporation rates were not significant after the CATE. Conclusion: The administration of in bolus sodium heparin interferes in lipoprotein particles remodeling, by evidences from risk ratios variations, such as HDL-C/apoA, and TG/HDL-C. The percentage of phospholipids and free cholesterol incorporation in HDL shows sex influences, which makes it relevant to the obtained results. The use of hazard ratios and their correlations were better surrogate markers at these casuistic of cardiovascular disease than when serum markers of lipid profile were evaluated alone.

Dyslipidemia can be a comorbidity of both insulin-resistance and atherosclerosis. Hypertriglyceridemia is common in hyperglycemia and is associated with hypoalphalipoproteinemia (low HDL) and with altered nucleotide or purinergic signaling. We therefore hypothesized that extracellular nucleotides may affect hepatic lipoprotein metabolism. Our studies confirm this view and show that nucleotides regulate cellular proteolytic pathways in liver cells and thereby control lipoprotein secretion and their metabolism by hepatic lipase (HL). Treatment of liver cells with the nucleotide, adenosine diphosphate (ADP), stimulates VLDL-apoB100 and apoE secretion, but blocks HDL-apoA-I and HL secretion. ADP functions like a proteasomal inhibitor to block proteasomal degradation and stimulate apoB100 secretion. Blocking the proteosome is known to activate autophagic pathways. The nucleotide consequently stimulates autophagic degradation in liver cells and increases cellular levels of the autophagic proteins, LC3 and p62. Confocal studies show that ADP increases cellular LC3 levels and promotes co-localization of LC3 and apoA-I in an autophagosomal degradation compartment. ADP acts through the G-protein coupled receptor, P2Y13, to stimulate autophagy and block both HDL and HL secretion. Overexpression of P2Y13 increases cellular LC3 levels and blocks the induction of both HDL and HL secretion, while P2Y13 siRNA reduce LC3 protein levels and cause up to a ten-fold stimulation in HDL and HL secretion. P2Y13 gene expression regulates autophagy through the insulin receptor (IR-β). A reduction in P2Y13 expression increases the phosphorylation of IR-β and protein kinase B (Akt) >3-fold, while increasing P2Y13 expression inhibits the activation of IR-β and Akt. Experiments with epitope-labeled apoA-I and HL show that activation of purinergic pathways has no effect on the internalization and degradation of extracellular apoA-I and HL, which confirms the view that nucleotides primarily impact intracellular protein transport and degradation. In conclusion, elevated blood glucose levels may promote dyslipidemia by stimulating purinergic signaling through P2Y13 and IR-β and perturbing the intracellular degradation and secretion of both HDL and VLDL.