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1.
Int Heart J ; 61(5): 1034-1040, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32999190

RESUMO

Low-density lipoprotein (LDL) particles are known to be atherogenic agents in coronary artery diseases. They adjust to other electronegative forms and can be the subject for the enhancement of inflammatory events in vessel subendothelial spaces. The LDL uptake is related to the membrane scavenger receptors, including LDL receptor (LDLR). The LDLR expression is closely associated with LDL uptake and occurrence of diseases, such as atherosclerotic cardiovascular diseases. Our findings identified USP16 as a novel regulator of LDLR due to its ability to prevent ubiquitylation-dependent LDLR degradation, further promoting the uptake of LDL. The enhancement of USP16-mediated deubiquitination andthe suppressive degradation of the LDLR cause the presentation of a potential strategy to increase LDL cholesterol clearance.


Assuntos
Receptores de LDL/metabolismo , Ubiquitina Tiolesterase/metabolismo , Ubiquitinação , Células HeLa , Humanos , Lipoproteínas LDL/metabolismo , Processamento de Proteína Pós-Traducional
2.
N Engl J Med ; 383(8): 711-720, 2020 08 20.
Artigo em Inglês | MEDLINE | ID: mdl-32813947

RESUMO

BACKGROUND: Homozygous familial hypercholesterolemia is characterized by premature cardiovascular disease caused by markedly elevated levels of low-density lipoprotein (LDL) cholesterol. This disorder is associated with genetic variants that result in virtually absent (null-null) or impaired (non-null) LDL-receptor activity. Loss-of-function variants in the gene encoding angiopoietin-like 3 (ANGPTL3) are associated with hypolipidemia and protection against atherosclerotic cardiovascular disease. Evinacumab, a monoclonal antibody against ANGPTL3, has shown potential benefit in patients with homozygous familial hypercholesterolemia. METHODS: In this double-blind, placebo-controlled, phase 3 trial, we randomly assigned in a 2:1 ratio 65 patients with homozygous familial hypercholesterolemia who were receiving stable lipid-lowering therapy to receive an intravenous infusion of evinacumab (at a dose of 15 mg per kilogram of body weight) every 4 weeks or placebo. The primary outcome was the percent change from baseline in the LDL cholesterol level at week 24. RESULTS: The mean baseline LDL cholesterol level in the two groups was 255.1 mg per deciliter, despite the receipt of maximum doses of background lipid-lowering therapy. At week 24, patients in the evinacumab group had a relative reduction from baseline in the LDL cholesterol level of 47.1%, as compared with an increase of 1.9% in the placebo group, for a between-group least-squares mean difference of -49.0 percentage points (95% confidence interval [CI], -65.0 to -33.1; P<0.001); the between-group least-squares mean absolute difference in the LDL cholesterol level was -132.1 mg per deciliter (95% CI, -175.3 to -88.9; P<0.001). The LDL cholesterol level was lower in the evinacumab group than in the placebo group in patients with null-null variants (-43.4% vs. +16.2%) and in those with non-null variants (-49.1% vs. -3.8%). Adverse events were similar in the two groups. CONCLUSIONS: In patients with homozygous familial hypercholesterolemia receiving maximum doses of lipid-lowering therapy, the reduction from baseline in the LDL cholesterol level in the evinacumab group, as compared with the small increase in the placebo group, resulted in a between-group difference of 49.0 percentage points at 24 weeks. (Funded by Regeneron Pharmaceuticals; ELIPSE HoFH ClinicalTrials.gov number, NCT03399786.).


Assuntos
Proteínas Semelhantes a Angiopoietina/antagonistas & inibidores , Anticorpos Monoclonais/uso terapêutico , Anticolesterolemiantes/uso terapêutico , LDL-Colesterol/sangue , Hiperlipoproteinemia Tipo II/tratamento farmacológico , Adolescente , Adulto , Idoso , Anticorpos Monoclonais/efeitos adversos , Anticorpos Monoclonais/sangue , Anticolesterolemiantes/efeitos adversos , Anticolesterolemiantes/sangue , Criança , Método Duplo-Cego , Feminino , Homozigoto , Humanos , Hiperlipoproteinemia Tipo II/sangue , Hiperlipoproteinemia Tipo II/genética , Infusões Intravenosas , Análise dos Mínimos Quadrados , Masculino , Pessoa de Meia-Idade , Mutação , Receptores de LDL/metabolismo , Adulto Jovem
3.
PLoS One ; 15(8): e0235551, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32833964

RESUMO

VPS34 is a key regulator of endomembrane dynamics and cargo trafficking, and is essential in cultured cell lines and in mice. To better characterize the role of VPS34 in cell growth, we performed unbiased cell line profiling studies with the selective VPS34 inhibitor PIK-III and identified RKO as a VPS34-dependent cellular model. Pooled CRISPR screen in the presence of PIK-III revealed endolysosomal genes as genetic suppressors. Dissecting VPS34-dependent alterations with transcriptional profiling, we found the induction of hypoxia response and cholesterol biosynthesis as key signatures. Mechanistically, acute VPS34 inhibition enhanced lysosomal degradation of transferrin and low-density lipoprotein receptors leading to impaired iron and cholesterol uptake. Excess soluble iron, but not cholesterol, was sufficient to partially rescue the effects of VPS34 inhibition on mitochondrial respiration and cell growth, indicating that iron limitation is the primary driver of VPS34-dependency in RKO cells. Loss of RAB7A, an endolysosomal marker and top suppressor in our genetic screen, blocked transferrin receptor degradation, restored iron homeostasis and reversed the growth defect as well as metabolic alterations due to VPS34 inhibition. Altogether, our findings suggest that impaired iron mobilization via the VPS34-RAB7A axis drive VPS34-dependence in certain cancer cells.


Assuntos
Classe III de Fosfatidilinositol 3-Quinases/metabolismo , Ferro/metabolismo , Neoplasias/metabolismo , Hipóxia Celular , Linhagem Celular Tumoral , Proliferação de Células , Colesterol/biossíntese , Colesterol/genética , Classe III de Fosfatidilinositol 3-Quinases/genética , Endossomos/metabolismo , Células HEK293 , Humanos , Lisossomos/metabolismo , Receptores de LDL/metabolismo , Transferrina/metabolismo , Proteínas rab de Ligação ao GTP/genética , Proteínas rab de Ligação ao GTP/metabolismo
4.
Life Sci ; 258: 118030, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32739470

RESUMO

The risk of atherosclerosis (AS) ascends among post-menopausal women, while current hormone replacement therapy exerts several adverse effects. Alisol B 23-acetate (AB23A), a tetracyclic triterpenoid isolated from the rhizome of Alisma orientale, was reported to show multiple physiological activities, including regulating lipid metabolism. According to molecular docking analysis, it was predicted to bind with estrogen receptor α (ERα). In this study, we aimed to observe the effect of AB23A on preventing post-menopausal AS and explore whether the mechanism was mediated by ERα. In vitro, free fatty acid (FFA) was applied to induce the abnormal lipid metabolism of L02 cells. In vivo, the ApoE-/- mice were ovariectomized to mimic the cessation of estrogen. The high-fat diet was also given to induce post-menopausal AS. We demonstrated AB23A attenuated the accumulation of total cholesterol and triglyceride induced by free fatty acids in hepatocytes. In high-fat diet-ovariectomy-treated ApoE-/- mice, AB23A eliminated lipids in blood and liver. AB23A not only reduced the synthesis of proprotein convertase subtilisin/kexin type 9 (PCSK9) through sterol-regulatory element binding proteins (SREBPs) but also suppressed the secretion of PCSK9 through silent information regulator 1 (SIRT1). Notably, AB23A promoted the expression of ERα in vivo and in vitro. The both ERα inhibitor and ERα siRNA were also applied in confirming whether the hepatic protective effect of AB23A was mediated by ERα. We found that AB23A significantly promoted the expression of ERα. AB23A could inhibit the synthesis and secretion of PCSK9 through ERα, lower the accumulation of triglyceride and cholesterol, and prevent post-menopausal AS.


Assuntos
Aterosclerose/patologia , Colestenonas/farmacologia , Receptor alfa de Estrogênio/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Pós-Menopausa/efeitos dos fármacos , Animais , Aterosclerose/genética , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Colestenonas/química , Dieta Hiperlipídica , Ácidos Graxos/metabolismo , Feminino , Lipoproteínas LDL/metabolismo , Camundongos , Ovariectomia , Regiões Promotoras Genéticas/genética , Pró-Proteína Convertase 9/genética , Pró-Proteína Convertase 9/metabolismo , Receptores de LDL/genética , Receptores de LDL/metabolismo , Sirtuína 1/metabolismo , Proteínas de Ligação a Elemento Regulador de Esterol/genética , Proteínas de Ligação a Elemento Regulador de Esterol/metabolismo , Regulação para Cima/efeitos dos fármacos
5.
Proc Natl Acad Sci U S A ; 117(28): 16401-16408, 2020 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-32601215

RESUMO

Proteins have evolved by incorporating several structural units within a single polypeptide. As a result, multidomain proteins constitute a large fraction of all proteomes. Their domains often fold to their native structures individually and vectorially as each domain emerges from the ribosome or the protein translocation channel, leading to the decreased risk of interdomain misfolding. However, some multidomain proteins fold in the endoplasmic reticulum (ER) nonvectorially via intermediates with nonnative disulfide bonds, which were believed to be shuffled to native ones slowly after synthesis. Yet, the mechanism by which they fold nonvectorially remains unclear. Using two-dimensional (2D) gel electrophoresis and a conformation-specific antibody that recognizes a correctly folded domain, we show here that shuffling of nonnative disulfide bonds to native ones in the most N-terminal region of LDL receptor (LDLR) started at a specific timing during synthesis. Deletion analysis identified a region on LDLR that assisted with disulfide shuffling in the upstream domain, thereby promoting its cotranslational folding. Thus, a plasma membrane-bound multidomain protein has evolved a sequence that promotes the nonvectorial folding of its upstream domains. These findings demonstrate that nonvectorial folding of a multidomain protein in the ER of mammalian cells is more coordinated and elaborated than previously thought. Thus, our findings alter our current view of how a multidomain protein folds nonvectorially in the ER of living cells.


Assuntos
Retículo Endoplasmático/metabolismo , Receptores de LDL/química , Receptores de LDL/genética , Retículo Endoplasmático/química , Retículo Endoplasmático/genética , Células HeLa , Humanos , Biossíntese de Proteínas , Conformação Proteica , Domínios Proteicos , Dobramento de Proteína , Receptores de LDL/metabolismo
6.
Arterioscler Thromb Vasc Biol ; 40(9): 2108-2113, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32640904

RESUMO

OBJECTIVE: Renin cleavage of angiotensinogen has species specificity. As the residues at positions 11 and 12 are different between human angiotensinogen and mouse angiotensinogen, we determined whether these 2 residues in angiotensinogen affect renin cleavage and angiotensin II-mediated blood pressure regulation and atherosclerosis using an adenoassociated viral approach for manipulating angiotensinogen in vivo. Approach and Results: Hepatocyte-specific angiotensinogen deficient (hepAGT-/-) mice in an LDL receptor-deficient background were infected with adenoassociated virals containing a null insert, human angiotensinogen, or mouse angiotensinogen expressing the same residues of the human protein at positions 11 and 12 (mouse angiotensinogen [L11V;Y12I]). Expression of human angiotensinogen in hepAGT-/- mice led to high plasma human angiotensinogen concentrations without changes in plasma endogenous mouse angiotensinogen, plasma renin concentrations, blood pressure, or atherosclerosis. This is consistent with human angiotensinogen not being cleaved by mouse renin. To determine whether the residues at positions 11 and 12 in human angiotensinogen lead to the inability of mouse renin to cleave human angiotensinogen, hepAGT-/- mice were injected with adenoassociated viral vector encoding mouse angiotensinogen (L11V;Y12I). Expression of mouse angiotensinogen (L11V;Y12I) in hepAGT-/- mice resulted in increased plasma mouse angiotensinogen concentrations, reduced renin concentrations, and increased renal AngII concentrations that were comparable to their concentrations in hepAGT+/+ mice. This mouse angiotensinogen variant increased blood pressure and atherosclerosis in hepAGT-/- mice to the magnitude of hepAGT+/+ mice. CONCLUSIONS: Replacement of L11 and Y12 to V11 and I12, respectively, in mouse angiotensinogen does not affect renin cleavage, blood pressure, and atherosclerosis in LDL receptor-deficient mice.


Assuntos
Angiotensina II/metabolismo , Angiotensinogênio/metabolismo , Aterosclerose/metabolismo , Pressão Sanguínea , Hepatócitos/metabolismo , Hipertensão/metabolismo , Renina/metabolismo , Substituição de Aminoácidos , Angiotensinogênio/deficiência , Angiotensinogênio/genética , Animais , Aterosclerose/genética , Aterosclerose/patologia , Modelos Animais de Doenças , Feminino , Humanos , Hipertensão/genética , Hipertensão/fisiopatologia , Masculino , Camundongos Knockout , Placa Aterosclerótica , Receptores de LDL/genética , Receptores de LDL/metabolismo , Especificidade da Espécie
7.
Arterioscler Thromb Vasc Biol ; 40(9): 2084-2094, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32673528

RESUMO

OBJECTIVE: Increased postprandial lipemia (PPL) is an independent risk factor for atherosclerotic cardiovascular diseases. PCSK9 (Proprotein convertase subtilisin kexin type 9) is an endogenous inhibitor of the LDLR (low-density lipoprotein receptor) pathway. We previously showed that PCSK9 inhibition in mice reduces PPL. However, the relative contribution of intracellular intestinal PCSK9 or liver-derived circulating PCSK9 to this effect is still unclear. Approach and Results: To address this issue, we generated the first intestine-specific Pcsk9-deficient (i-Pcsk9-/-) mouse model. PPL was measured in i-Pcsk9-/- as well as in wild-type and streptozotocin-induced diabetic mice following treatment with a PCSK9 monoclonal antibody (alirocumab). Blocking the circulating form of PCSK9 with alirocumab significantly reduced PPL, while overexpressing human PCSK9 in the liver of full Pcsk9-/- mice had the opposite effect. Alirocumab regulated PPL in a LDLR-dependent manner as this effect was abolished in Ldlr-/- mice. In contrast, i-Pcsk9-/- mice did not exhibit alterations in plasma lipid parameters nor in PPL. Finally, PPL was highly exacerbated by streptozotocin-induced diabetes mellitus in Pcsk9+/+ but not in Pcsk9-/- mice, an effect that was mimicked by the use of alirocumab in streptozotocin-treated Pcsk9+/+ mice. CONCLUSIONS: Taken together, our data demonstrate that PPL is significantly altered by full but not intestinal PCSK9 deficiency. Treatment with a PCSK9 monoclonal antibody mimics the effect of PCSK9 deficiency on PPL suggesting that circulating PCSK9 rather than intestinal PCSK9 is a critical regulator of PPL. These data validate the clinical relevance of PCSK9 inhibitors to reduce PPL, especially in patients with type 2 diabetes mellitus.


Assuntos
Diabetes Mellitus Experimental/sangue , Diabetes Mellitus Tipo 2/sangue , Hiperlipidemias/sangue , Intestinos/enzimologia , Lipídeos/sangue , Pró-Proteína Convertase 9/sangue , Animais , Anticorpos Monoclonais Humanizados/farmacologia , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/enzimologia , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/enzimologia , Hiperlipidemias/enzimologia , Hiperlipidemias/genética , Hiperlipidemias/prevenção & controle , Hipolipemiantes/farmacologia , Intestinos/efeitos dos fármacos , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Período Pós-Prandial , Pró-Proteína Convertase 9/antagonistas & inibidores , Pró-Proteína Convertase 9/deficiência , Pró-Proteína Convertase 9/genética , Receptores de LDL/genética , Receptores de LDL/metabolismo
8.
Gene ; 749: 144720, 2020 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-32360840

RESUMO

AIMS: The purpose of present study was to examine the correlations of LDL (LDLR) and HDL (SR-B1) receptors with lipoproteins, miR-199a-5p, miR-199b-5p, miR-455-5p in the malignant and benign breast tumors. METHODS: Total cholesterol-rich-lipoproteins and the receptors were determined using enzymatic-homogeneous and ELISA methods. The expression levels of miRNAs were detected by qRT-PCR. RESULTS: Receptor expressions and lipoproteins concentration were significantly higher in the malignant tumors (p < 0.05). Positive correlation was found for LDLR with Ki67% and Her2+. HDL-C content of TNBC tumors was higher than those of Non-TNBC (p < 0.05). The expression level of miR-199a-5p was found to be downregulated significantly in the malignant tumors of <2 cm, TNBC, HER2- or stage3. The expression of miR-199b-5p was downregulated in the malignant tumors and was negatively associated with TNBC, stage and Her2+. The expression of miR-455-5p was significantly correlated with Her2- (p < 0.05). A positive correlation was observed for SR-B1 or LDLR with HDL-C or LDL-C and also for SR-B1 with LDLR, although a reverse association was detected for the expression of miR-199b-5p with LDLR in the malignant tumors (p < 0.05). No significant correlations were found for miR-199a-5p or miR-455-5p with LDLR or SR-B1 expressions and also for LDL-C and SR-B1 with clinicopathological features (p ≥ 0.05). CONCLUSIONS: Mechanisms potentially involved in the present findings may be due to the lipid internalization and lipoprotein consumption through LDLR and SR-B1 over expression. It is noteworthy that the expression of miR-199b-5p is negatively correlated with LDLR which may suggest it as a suppressor for LDLR expression in the breast cancer.


Assuntos
Neoplasias da Mama/metabolismo , MicroRNAs/metabolismo , Receptores de LDL/metabolismo , Receptores Depuradores Classe B/metabolismo , Adulto , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Colesterol/metabolismo , Feminino , Humanos , Lipoproteínas/metabolismo , Pessoa de Meia-Idade
9.
Life Sci ; 254: 117756, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32389832

RESUMO

Polydatin (PD) is a monocrystalline metabolite from the underground parts of Polygonum cuspidatum Sieb. et Zucc., a member of the Polygonaceae family, which has been traditionally used in Asian countries as both foodstuffs and medicine. PD, also reckoned as pieceid, 3,4',5-trihydroxystilbene-3-ß-D-glucoside, (E)-piceid, (E)-polydatin, and trans-polydatin. It possesses potent biological activities i.e. analgesic, anti-inflammatory, antidiabetic, anticancer, and anti-atherosclerotic properties. The initial part of this report specifically explains distinct sequential mechanisms underlying the initiation and development of atherosclerotic plaques and later part deals with the pharmacological efficacy of PD in the management of major cardiac event i.e. atherosclerotic cardiovascular diseases (ASCVD) via modulation of a set of molecular mechanisms i.e. antioxidant potential, lipid and lipoprotein metabolism including total cholesterol (TC) and low density lipoprotein (LDL) levels, ß-hydroxy-ß-methyl-glutaryl-CoA reductase (HMG-R) expression and functionality, SIRT signalling, LDL-receptor (LDL-R), LDL oxidation status (Ox-LDL), effects on endothelial cells (ECs), smooth muscle cells (SMCs), macrophage, foam cell formation and plaque stabilization, inflammatory signalling pathways and hypertension. In contrast, one of the major insight into the potential cardioprotective molecular mechanism is the PD-mediated targeting of proprotein convertase subtilisin/kexin type-9 (PCSK-9) and LDL-R pathway, both at transcriptional and protein functional level, which makes it a better alternative therapeutic medicinal candidate to treat hypercholesterolemia, especially for the patients facing inadequate lipid lowering with classical HMG-R inhibitors (statins) and statin intolerance. Finally, to sum up the whole, we concluded that PD may be promoted from alternative to mainstream medicine in targeting risk factors mediated ASCVD.


Assuntos
Aterosclerose/tratamento farmacológico , Glucosídeos/farmacologia , Estilbenos/farmacologia , Anticolesterolemiantes/uso terapêutico , LDL-Colesterol/metabolismo , Células Endoteliais/metabolismo , Fallopia japonica/metabolismo , Glucosídeos/uso terapêutico , Humanos , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Hipercolesterolemia/tratamento farmacológico , Hiperlipidemias/tratamento farmacológico , Lipoproteínas LDL , Placa Aterosclerótica/tratamento farmacológico , Receptores de LDL/metabolismo , Fatores de Risco , Estilbenos/uso terapêutico
10.
PLoS One ; 15(5): e0225356, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32437440

RESUMO

High plasma LDL cholesterol (LDL-c) concentration is a major risk factor for atherosclerosis. Hepatic LDL receptor (LDLR) regulates LDL metabolism, and thereby plasma LDL-c concentration. Recently, we have identified the (pro)renin receptor [(P)RR] as a novel regulator of LDL metabolism, which regulates LDLR degradation and hence its protein abundance and activity. In silico analysis suggests that the (P)RR is a target of miR-148a. In this study we determined whether miR-148a could regulate LDL metabolism by regulating (P)RR expression in HepG2 and Huh7 cells. We found that miR-148a suppressed (P)RR expression by binding to the 3'-untranslated regions (3'-UTR) of the (P)RR mRNA. Mutating the binding sites for miR-148a in the 3'-UTR of (P)RR mRNA completely abolished the inhibitory effects of miR-148a on (P)RR expression. In line with our recent findings, reduced (P)RR expression resulted in decreased cellular LDL uptake, likely as a consequence of decreased LDLR protein abundance. Overexpressing the (P)RR prevented miR-148a-induced reduction in LDLR abundance and cellular LDL uptake. Our study supports a new concept that miR-148a is a regulator of (P)RR expression. By reducing (P)RR abundance, miR-148a decreases LDLR protein abundance and consequently cellular LDL uptake.


Assuntos
Lipoproteínas LDL/metabolismo , MicroRNAs/fisiologia , Receptores de Superfície Celular/metabolismo , Receptores de LDL/metabolismo , ATPases Vacuolares Próton-Translocadoras/metabolismo , Células HEK293 , Células Hep G2 , Humanos
11.
Arterioscler Thromb Vasc Biol ; 40(5): 1311-1324, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32188273

RESUMO

OBJECTIVE: TMEM55B (transmembrane protein 55B) is a phosphatidylinositol-(4,5)-bisphosphate (PI[4,5]P2) phosphatase that regulates cellular cholesterol, modulates LDLR (low-density lipoprotein receptor) decay, and lysosome function. We tested the effects of Tmem55b knockdown on plasma lipids in mice and assessed the roles of LDLR lysosomal degradation and change in (PI[4,5]P2) in mediating these effects. Approach and Results: Western diet-fed C57BL/6J mice were treated with antisense oligonucleotides against Tmem55b or a nontargeting control for 3 to 4 weeks. Hepatic Tmem55b transcript and protein levels were reduced by ≈70%, and plasma non-HDL (high-density lipoprotein) cholesterol was increased ≈1.8-fold (P<0.0001). Immunoblot analysis of fast protein liquid chromatography (FPLC) fractions revealed enrichment of ApoE-containing particles in the LDL size range. In contrast, Tmem55b knockdown had no effect on plasma cholesterol in Ldlr-/- mice. In primary hepatocytes and liver tissues from Tmem55b knockdown mice, there was decreased LDLR protein. In the hepatocytes, there was increased lysosome staining and increased LDLR-lysosome colocalization. Impairment of lysosome function (incubation with NH4Cl or knockdown of the lysosomal proteins LAMP1 or RAB7) abolished the effect of TMEM55B knockdown on LDLR in HepG2 (human hepatoma) cells. Colocalization of the recycling endosome marker RAB11 (Ras-related protein 11) with LDLR in HepG2 cells was reduced by 50% upon TMEM55B knockdown. Finally, knockdown increased hepatic PI(4,5)P2 levels in vivo and in HepG2 cells, while TMEM55B overexpression in vitro decreased PI(4,5)P2. TMEM55B knockdown decreased, whereas overexpression increased, LDL uptake in HepG2 cells. Notably, the TMEM55B overexpression effect was reversed by incubation with PI(4,5)P2. Conclusions: These findings indicate a role for TMEM55B in regulating plasma cholesterol levels by affecting PI(4,5)P2-mediated LDLR lysosomal degradation.


Assuntos
Colesterol/sangue , Hepatócitos/metabolismo , Fígado/metabolismo , Lisossomos/metabolismo , Fosfatidilinositol 4,5-Difosfato/metabolismo , Fosfatases de Fosfoinositídeos/metabolismo , Receptores de LDL/metabolismo , Animais , Dieta Hiperlipídica , Regulação para Baixo , Feminino , Células Hep G2 , Humanos , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fosfatases de Fosfoinositídeos/genética , Transporte Proteico , Proteólise , Receptores de LDL/genética , Proteínas de Transporte Vesicular/genética , Proteínas de Transporte Vesicular/metabolismo
12.
Ecotoxicol Environ Saf ; 193: 110318, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32105945

RESUMO

The current study aimed to examine, for the first time, the relationship between exposure to deltamethrin (DLM) and atherogenic lipid profile disorders in adult Wistar rats, as well as, to verify the mechanism of the beneficial role of Zygophyllum album leaves extracts (ZALE). The experimental study was assessed using DLM (4 mg/kg b.w) either alone or co administered with ZALE (400 mg/kg b.w) orally for 90 days in rats. RP-HPLC-DAD-ESI-QTOF-MS was used to identify the bioactive metabolites present in ZALE. Plasmatic and aortic total cholesterol (TC), LDL-cholesterol (LDL-C), native LDL (LDL-apo B-100) and oxidized LDL (ox-LDL) were evaluated using auto-analyzer and a sandwich ELISA, respectively. The protein expressions of LDLR (native LDL receptor) and CD36 (Scavenger receptor class B) were evaluated in aorta or liver with a Western blot. The pathology has been confirmed with lipid stain (Oil Red O). Phytochemicals analysis revealed the presence of fifteen saponins in ZALE. Rats intoxicated with DLM revealed a significant increase in plasmatic and aortic lipid profile (TC, LDL-C, LDL-apo B-100 and ox-LDL), as well as, the concentration of the plasmatic cytokines include TNF-α, IL-2 and IL-6, compared to control. Hepatic native LDL and aortic CD36 receptor expression were increased in DLM treated group, however aortic LDL-R does not present any modification, when compared to control. The detected disturbances in lipid parameters were supported by Oil Red O applied. Due to their antioxidant activity, the bioactive compounds in ZALE as powerful agents able to prevent the pro-atherogenic effect observed in DLM-treated animals. These metabolites modulated most of inflammatory markers, prevented accumulation of lipid and lipoprotein biomarkers, regulated the major receptor regulators of hepatic cholesterol metabolism, as well as normalize lipid distribution in liver and aorta tissue.


Assuntos
Aorta/efeitos dos fármacos , Aterosclerose/prevenção & controle , Poluentes Ambientais/toxicidade , Lipoproteínas LDL/sangue , Nitrilos/toxicidade , Piretrinas/toxicidade , Saponinas/farmacologia , Zygophyllum/química , Animais , Aorta/imunologia , Aorta/metabolismo , Aterosclerose/imunologia , Aterosclerose/metabolismo , Antígenos CD36/metabolismo , Colesterol/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/imunologia , Fígado/metabolismo , Masculino , Folhas de Planta/química , Ratos , Ratos Wistar , Receptores de LDL/metabolismo , Saponinas/isolamento & purificação , Fator de Necrose Tumoral alfa/metabolismo
13.
Nanotoxicology ; 14(3): 355-371, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31909645

RESUMO

The use of indium oxide (In2O3) and indium-metal hybrids for various applications, including the manufacture of batteries and liquid crystal displays, increases the chances of human exposure to In2O3 via inhalation, especially in occupational settings. However, there is little information available on the toxic effects of In2O3 nanoparticles (NPs) on secondary organs following pulmonary exposure. In this study, we evaluated the effect of In2O3 NPs on atherosclerotic plaque formation and the related mechanisms after pulmonary exposure in low-density lipoprotein receptor knockout (Ldlr-/-) mice. At 10 weeks after a single pharyngeal aspiration, In2O3 NPs caused chronic active inflammation, pulmonary alveolar proteinosis, and accumulation of inflammatory cells in the peribronchial and perivascular areas of the lungs. The expression of pro-inflammatory cytokines in the lung tissue, including TNF-α and MCP-1, was markedly increased by treatment with In2O3 NPs. In the In2O3 NP-treated groups, the levels of total cholesterol and low-density lipoprotein in the plasma were increased, whereas HDL cholesterol showed no significant changes compared to vehicle control. The formation of atherosclerotic lesions was increased by treatment with In2O3 NPs. Real-time PCR analysis of the aorta showed that IL-6 and MCP-1 expression was up-regulated upon treatment with In2O3 NPs. These results suggested that the pulmonary inflammation induced by In2O3 NPs aggravates the progression of atherosclerotic plaque formation, possibly by the alteration of the plasma lipid profile and enhancement of the aortic inflammatory processes.


Assuntos
Aterosclerose/induzido quimicamente , Índio/toxicidade , Nanopartículas/toxicidade , Placa Aterosclerótica/induzido quimicamente , Pneumonia/induzido quimicamente , Receptores de LDL/metabolismo , Animais , Aterosclerose/sangue , Aterosclerose/metabolismo , Citocinas/metabolismo , Índio/química , Exposição por Inalação , Lipoproteínas LDL/sangue , Pulmão/efeitos dos fármacos , Pulmão/metabolismo , Masculino , Camundongos , Camundongos Knockout , Nanopartículas/química , Placa Aterosclerótica/sangue , Placa Aterosclerótica/metabolismo , Pneumonia/sangue , Pneumonia/metabolismo , Receptores de LDL/genética
14.
Arterioscler Thromb Vasc Biol ; 40(3): 638-655, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31893948

RESUMO

OBJECTIVE: Although often studied independently, little is known about how aortic valve endothelial cells and valve interstitial cells interact collaborate to maintain tissue homeostasis or drive valve calcific pathogenesis. Inflammatory signaling is a recognized initiator of valve calcification, but the cell-type-specific downstream mechanisms have not been elucidated. In this study, we test how inflammatory signaling via NFκB (nuclear factor κ-light-chain enhancer of activated B cells) activity coordinates unique and shared mechanisms of valve endothelial cells and valve interstitial cells differentiation during calcific progression. Approach and Results: Activated NFκB was present throughout the calcific aortic valve disease (CAVD) process in both endothelial and interstitial cell populations in an established mouse model of hypercholesterolemia-induced CAVD and in human CAVD. NFκB activity induces endothelial to mesenchymal transformation in 3-dimensional cultured aortic valve endothelial cells and subsequent osteogenic calcification of transformed cells. Similarly, 3-dimensional cultured valve interstitial cells calcified via NFκB-mediated osteogenic differentiation. NFκB-mediated endothelial to mesenchymal transformation was directly demonstrated in vivo during CAVD via genetic lineage tracking. Genetic deletion of NFκB in either whole valves or valve endothelium only was sufficient to prevent valve-specific molecular and cellular mechanisms of CAVD in vivo despite the persistence of a CAVD inducing environment. CONCLUSIONS: Our results identify NFκB signaling as an essential molecular regulator for both valve endothelial and interstitial participation in CAVD pathogenesis. Direct demonstration of valve endothelial cell endothelial to mesenchymal transformation transmigration in vivo during CAVD highlights a new cellular population for further investigation in CAVD morbidity. The efficacy of valve-specific NFκB modulation in inhibiting hypercholesterolemic CAVD suggests potential benefits of multicell type integrated investigation for biological therapeutic development and evaluation for CAVD.


Assuntos
Valva Aórtica/metabolismo , Calcinose/metabolismo , Diferenciação Celular , Células Endoteliais/metabolismo , Doenças das Valvas Cardíacas/metabolismo , NF-kappa B/metabolismo , Osteogênese , Animais , Valva Aórtica/patologia , Calcinose/etiologia , Calcinose/patologia , Células Cultivadas , Microambiente Celular , Modelos Animais de Doenças , Células Endoteliais/patologia , Doenças das Valvas Cardíacas/etiologia , Doenças das Valvas Cardíacas/genética , Doenças das Valvas Cardíacas/patologia , Humanos , Hipercolesterolemia/complicações , Hipercolesterolemia/genética , Hipercolesterolemia/metabolismo , Quinase I-kappa B/genética , Quinase I-kappa B/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , NF-kappa B/genética , Fatores de Transcrição NFATC/genética , Fatores de Transcrição NFATC/metabolismo , Receptores de LDL/genética , Receptores de LDL/metabolismo , Transdução de Sinais , Fator de Transcrição RelA/genética , Fator de Transcrição RelA/metabolismo
15.
J Biol Chem ; 295(8): 2285-2298, 2020 02 21.
Artigo em Inglês | MEDLINE | ID: mdl-31949048

RESUMO

Proprotein convertase subtilisin/kexin type-9 (PCSK9) is a ligand of low-density lipoprotein (LDL) receptor (LDLR) that promotes LDLR degradation in late endosomes/lysosomes. In human plasma, 30-40% of PCSK9 is bound to LDL particles; however, the physiological significance of this interaction remains unknown. LDL binding in vitro requires a disordered N-terminal region in PCSK9's prodomain. Here, we report that peptides corresponding to a predicted amphipathic α-helix in the prodomain N terminus adopt helical structure in a membrane-mimetic environment. This effect was greatly enhanced by an R46L substitution representing an atheroprotective PCSK9 loss-of-function mutation. A helix-disrupting proline substitution within the putative α-helical motif in full-length PCSK9 lowered LDL binding affinity >5-fold. Modeling studies suggested that the transient α-helix aligns multiple polar residues to interact with positively charged residues in the C-terminal domain. Gain-of-function PCSK9 mutations associated with familial hypercholesterolemia (FH) and clustered at the predicted interdomain interface (R469W, R496W, and F515L) inhibited LDL binding, which was completely abolished in the case of the R496W variant. These findings shed light on allosteric conformational changes in PCSK9 required for high-affinity binding to LDL particles. Moreover, the initial identification of FH-associated mutations that diminish PCSK9's ability to bind LDL reported here supports the notion that PCSK9-LDL association in the circulation inhibits PCSK9 activity.


Assuntos
Lipoproteínas LDL/metabolismo , Pró-Proteína Convertase 9/química , Pró-Proteína Convertase 9/metabolismo , Substituição de Aminoácidos , Células HEK293 , Células Hep G2 , Humanos , Interações Hidrofóbicas e Hidrofílicas , Mutação/genética , Peptídeos/metabolismo , Prolina/genética , Pró-Proteína Convertase 9/genética , Ligação Proteica , Domínios Proteicos , Estrutura Secundária de Proteína , Receptores de LDL/metabolismo , Relação Estrutura-Atividade , Tirosina/metabolismo
16.
Mol Cell Biol ; 40(8)2020 03 30.
Artigo em Inglês | MEDLINE | ID: mdl-31964754

RESUMO

Brain lipoprotein receptors have been shown to regulate the metabolism of ApoE and ß-amyloid (Aß) and are potential therapeutic targets for Alzheimer's disease (AD). Previously, we identified E3 ubiquitin ligase IDOL as a negative regulator of brain lipoprotein receptors. Genetic ablation of Idol increases low-density lipoprotein receptor protein levels, which facilitates Aß uptake and clearance by microglia. In this study, we utilized an antisense oligonucleotide (ASO) to reduce IDOL expression therapeutically in the brains of APP/PS1 male mice. ASO treatment led to decreased Aß pathology and improved spatial learning and memory. Single-cell transcriptomic analysis of hippocampus revealed that IDOL inhibition upregulated lysosomal/phagocytic genes in microglia. Furthermore, clustering of microglia revealed that IDOL-ASO treatment shifted the composition of the microglia population by increasing the prevalence of disease-associated microglia. Our results suggest that reducing IDOL expression in the adult brain promotes the phagocytic clearance of Aß and ameliorates Aß-dependent pathology. Pharmacological inhibition of IDOL activity in the brain may represent a therapeutic strategy for the treatment of AD.


Assuntos
Amiloidose/metabolismo , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismo , Doença de Alzheimer/metabolismo , Doença de Alzheimer/fisiopatologia , Peptídeos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Amiloidose/patologia , Animais , Apolipoproteínas E/metabolismo , Encéfalo/metabolismo , Cognição/fisiologia , Modelos Animais de Doenças , Hipocampo/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microglia/metabolismo , Microglia/patologia , Oligodesoxirribonucleotídeos Antissenso/farmacologia , Receptores de LDL/metabolismo
17.
Am J Physiol Gastrointest Liver Physiol ; 318(2): G211-G224, 2020 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-31709830

RESUMO

Nonalcoholic steatohepatitis (NASH) has increased in Western countries due to the prevalence of obesity. Current interests are aimed at identifying the type and function of immune cells that infiltrate the liver and key factors responsible for mediating their recruitment and activation in NASH. We investigated the function and phenotype of CD8+ T cells under obese and nonobese NASH conditions. We found an elevation in CD8 staining in livers from obese human subjects with NASH and cirrhosis that positively correlated with α-smooth muscle actin, a marker of hepatic stellate cell (HSC) activation. CD8+ T cells were elevated 3.5-fold in the livers of obese and hyperlipidemic NASH mice compared with obese hepatic steatosis mice. Isolated hepatic CD8+ T cells from these mice expressed a cytotoxic IL-10-expressing phenotype, and depletion of CD8+ T cells led to significant reductions in hepatic inflammation, HSC activation, and macrophage accumulation. Furthermore, hepatic CD8+ T cells from obese and hyperlipidemic NASH mice activated HSCs in vitro and in vivo. Interestingly, in the lean NASH mouse model, depletion and knockdown of CD8+ T cells did not impact liver inflammation or HSC activation. We demonstrated that under obese/hyperlipidemia conditions, CD8+ T cell are key regulators of the progression of NASH, while under nonobese conditions they play a minimal role in driving the disease. Thus, therapies targeting CD8+ T cells may be a novel approach for treatment of obesity-associated NASH.NEW & NOTEWORTHY Our study demonstrates that CD8+ T cells are the primary hepatic T cell population, are elevated in obese models of NASH, and directly activate hepatic stellate cells. In contrast, we find CD8+ T cells from lean NASH models do not regulate NASH-associated inflammation or stellate cell activation. Thus, for the first time to our knowledge, we demonstrate that hepatic CD8+ T cells are key players in obesity-associated NASH.


Assuntos
Linfócitos T CD8-Positivos/patologia , Hepatopatia Gordurosa não Alcoólica/patologia , Obesidade/patologia , Animais , Células Estreladas do Fígado/efeitos dos fármacos , Hepatite/patologia , Humanos , Hiperlipidemias/patologia , Interleucina-10/biossíntese , Fígado/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Obesos , Hepatopatia Gordurosa não Alcoólica/complicações , Obesidade/etiologia , Receptores de LDL/genética , Receptores de LDL/metabolismo
18.
Am J Physiol Endocrinol Metab ; 318(2): E249-E261, 2020 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-31846369

RESUMO

Hepatic fat-specific protein 27 [cell death-inducing DNA fragmentation effector protein C (Cidec)/Fsp27] mRNA levels have been associated with hepatic lipid droplet extent under certain circumstances. To address its hepatic expression under different dietary conditions and in both sexes, apolipoprotein E (Apoe)-deficient mice were subjected to different experimental conditions for 11 wk to test the influence of cholesterol, Western diet, squalene, oleanolic acid, sex, and surgical castration on Cidec/Fsp27 mRNA expression. Dietary cholesterol increased hepatic Cidec/Fsp27ß expression, an effect that was suppressed when cholesterol was combined with saturated fat as represented by Western diet feeding. Using the latter diet, neither oleanolic acid nor squalene modified its expression. Females showed lower levels of hepatic Cidec/Fsp27ß expression than males when they were fed Western diets, a result that was translated into a lesser amount of CIDEC/FSP27 protein in lipid droplets and microsomes. This was also confirmed in low-density lipoprotein receptor (Ldlr)-deficient mice. Incubation with estradiol resulted in decreased Cidec/Fsp27ß expression in AML12 cells. Whereas male surgical castration did not modify the expression, ovariectomized females did show increased levels compared with control females. Females also showed increased expression of peroxisome proliferator-activated receptor-γ coactivator 1-α (Pgc1a), suppressed by ovariectomy, and the values were significantly and inversely associated with those of Cidec/Fsp27ß. When Pgc1a-deficient mice were used, the sex differences in Cidec/Fsp27ß expression disappeared. Therefore, hepatic Cidec/Fsp27ß expression has a complex regulation influenced by diet and sex hormonal milieu. The mRNA sex differences are controlled by Pgc1a.


Assuntos
Dieta Ocidental/efeitos adversos , Fígado/metabolismo , Hepatopatia Gordurosa não Alcoólica/metabolismo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Proteínas/genética , Animais , Linhagem Celular , Colesterol na Dieta/farmacologia , Feminino , Gotículas Lipídicas/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Hepatopatia Gordurosa não Alcoólica/genética , Orquiectomia , Ovariectomia , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/genética , RNA Mensageiro/biossíntese , Receptores de LDL/genética , Receptores de LDL/metabolismo , Caracteres Sexuais
19.
J Med Genet ; 57(1): 11-17, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31391289

RESUMO

BACKGROUND: Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors are novel therapeutics for reducing low-density lipoprotein cholesterol (LDLc). While serious side-effects have not been observed in short-term clinical trials, there remain concerns that long-term PCSK9 inhibition may cause neurocognitive side-effects. METHODS AND RESULTS: An adult male with childhood-onset global developmental delay, cerebellar atrophy and severe hypolipidaemia underwent extensive biochemical and genetic investigations. Initial testing revealed low circulating PCSK9 levels and a common loss-of-function PCSK9 polymorphism, but these findings did not fully account for severe hypolipidaemia. Whole-exome sequencing was subsequently performed and identified two pathogenic phosphomannose mutase 2 (PMM2) variants (p.Arg141His and p.Pro69Ser) known to cause PMM2-associated congenital disorder of glycosylation (PMM2-CDG). A diagnosis of PMM2-CDG was consistent with the proband's neurological symptoms and severe hypolipidaemia. Given that PMM2-CDG is characterised by defective protein N-glycosylation and that PCSK9 is a negative regulator of LDLc, we postulated that loss of PCSK9 N-glycosylation mediates hypolipidaemia among patients with PMM2-CDG. First, in an independent cohort of patients with PMM2-CDG (N=8), we verified that circulating PCSK9 levels were significantly lower in patients than controls (p=0.0006). Second, we conducted in vitro experiments in hepatocyte-derived cells to evaluate the effects of PCSK9 N-glycosylation loss on LDL receptor (LDLR) activity. Experimental results suggest that defective PCSK9 N-glycosylation reduces the ability of circulating PCSK9 to degrade LDLR. CONCLUSION: Life-long exposure to genetically lower PCSK9 per se is unlikely to cause neurocognitive impairment. Both observational and experimental findings suggest that hypolipidaemia in PMM2-CDG may be partially mediated by loss of PCSK9 N-glycosylation and/or its regulators.


Assuntos
Defeitos Congênitos da Glicosilação/genética , Dislipidemias/metabolismo , Fosfotransferases (Fosfomutases)/deficiência , Pró-Proteína Convertase 9/sangue , Receptores de LDL/metabolismo , Adulto , Estudos de Coortes , Defeitos Congênitos da Glicosilação/complicações , Defeitos Congênitos da Glicosilação/metabolismo , Análise Mutacional de DNA , Dislipidemias/etiologia , Regulação da Expressão Gênica , Glicosilação , Células Hep G2 , Humanos , Mutação com Perda de Função , Masculino , Linhagem , Fosfotransferases (Fosfomutases)/genética , Fosfotransferases (Fosfomutases)/metabolismo , Polimorfismo Genético , Pró-Proteína Convertase 9/genética , Pró-Proteína Convertase 9/metabolismo , Processamento de Proteína Pós-Traducional , Proteólise , Receptores de LDL/genética , Sequenciamento Completo do Exoma
20.
Crit Care Med ; 48(1): 41-48, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31651422

RESUMO

OBJECTIVES: Obese patients have lower sepsis mortality termed the "obesity paradox." We hypothesized that lipopolysaccharide, known to be carried within lipoproteins such as very low density lipoprotein, could be sequestered in adipose tissue during sepsis; potentially contributing a survival benefit. DESIGN: Retrospective analysis. SETTING: University research laboratory. SUBJECTS AND PATIENTS: Vldlr knockout mice to decrease very low density lipoprotein receptors, Pcsk9 knockout mice to increase very low density lipoprotein receptor, and Ldlr knockout mice to decrease low density lipoprotein receptors. Differentiated 3T3-L1 adipocytes. Caucasian septic shock patients. INTERVENTIONS: We measured lipopolysaccharide uptake into adipose tissue 6 hours after injection of fluorescent lipopolysaccharide into mice. Lipopolysaccharide uptake and very low density lipoprotein receptor protein expression were measured in adipocytes. To determine relevance to humans, we genotyped the VLDLR rs7852409 G/C single-nucleotide polymorphism in 519 patients and examined the association of 28-day survival with genotype. MEASUREMENTS AND MAIN RESULTS: Lipopolysaccharide injected into mice was found in adipose tissue within 6 hours and was dependent on very low density lipoprotein receptor but not low density lipoprotein receptors. In an adipocyte cell line decreased very low density lipoprotein receptor expression resulted in decreased lipopolysaccharide uptake. In septic shock patients, the minor C allele of VLDLR rs7852409 was associated with increased survival (p = 0.010). Previously published data indicate that the C allele is a gain-of-function variant of VLDLR which may increase sequestration of very low density lipoprotein (and lipopolysaccharide within very low density lipoprotein) into adipose tissue. When body mass index less than 25 this survival effect was accentuated and when body mass index greater than or equal to 25 this effect was diminished suggesting that the effect of variation in very low density lipoprotein receptor function is overwhelmed when copious adipose tissue is present. CONCLUSIONS: Lipopolysaccharide may be sequestered in adipose tissue via the very low density lipoprotein receptor and this sequestration may contribute to improved sepsis survival.


Assuntos
Tecido Adiposo/metabolismo , Lipopolissacarídeos/metabolismo , Receptores de LDL/metabolismo , Sepse/metabolismo , Adipócitos/metabolismo , Adulto , Idoso , Animais , Células Cultivadas , Feminino , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , Estudos Retrospectivos
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