scholarly journals Age-Associated Mitochondrial Dysfunction Accelerates Atherogenesis

2020 ◽  
Vol 126 (3) ◽  
pp. 298-314 ◽  
Author(s):  
Daniel J. Tyrrell ◽  
Muriel G. Blin ◽  
Jianrui Song ◽  
Sherri C. Wood ◽  
Min Zhang ◽  
...  
Keyword(s):  
Mitochondrial Dysfunction ◽  
Mitochondrial Function ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Aortic Tissue ◽  
Wild Type ◽  
Il Interleukin ◽  
Age Related ◽  
Density Lipoprotein Receptor ◽  
Young Mice

Rationale: Aging is one of the strongest risk factors for atherosclerosis. Yet whether aging increases the risk of atherosclerosis independently of chronic hyperlipidemia is not known. Objective: To determine if vascular aging before the induction of hyperlipidemia enhances atherogenesis. Methods and Results: We analyzed the aortas of young and aged normolipidemic wild type, disease-free mice and found that aging led to elevated IL (interleukin)-6 levels and mitochondrial dysfunction, associated with increased mitophagy and the associated protein Parkin. In aortic tissue culture, we found evidence that with aging mitochondrial dysfunction and IL-6 exist in a positive feedback loop. We triggered acute hyperlipidemia in aged and young mice by inducing liver-specific degradation of the LDL (low-density lipoprotein) receptor combined with a 10-week western diet and found that atherogenesis was enhanced in aged wild-type mice. Hyperlipidemia further reduced mitochondrial function and increased the levels of Parkin in the aortas of aged mice but not young mice. Genetic disruption of autophagy in smooth muscle cells of young mice exposed to hyperlipidemia led to increased aortic Parkin and IL-6 levels, impaired mitochondrial function, and enhanced atherogenesis. Importantly, enhancing mitophagy in aged, hyperlipidemic mice via oral administration of spermidine prevented the increase in aortic IL-6 and Parkin, attenuated mitochondrial dysfunction, and reduced atherogenesis. Conclusions: Before hyperlipidemia, aging elevates IL-6 and impairs mitochondrial function within the aorta, associated with enhanced mitophagy and increased Parkin levels. These age-associated changes prime the vasculature to exacerbate atherogenesis upon acute hyperlipidemia. Our work implies that novel therapeutics aimed at improving vascular mitochondrial bioenergetics or reducing inflammation before hyperlipidemia may reduce age-related atherosclerosis.

scholarly journals Lipocalin 2 Deficiency Alters Estradiol Production and Estrogen Receptor Signaling in Female Mice

Endocrinology ◽  
2012 ◽  
Vol 153 (3) ◽  
pp. 1183-1193 ◽  
Author(s):  
Hong Guo ◽  
Yuanyuan Zhang ◽  
David A. Brockman ◽  
Wendy Hahn ◽  
David A. Bernlohr ◽  
...  
Keyword(s):  
Estrogen Receptor ◽  
Adipose Tissue ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Low Density ◽  
Lipocalin 2 ◽  
Wild Type ◽  
Female Mice ◽  
Estrogen Receptor Signaling ◽  
Age Related

We have previously characterized lipocalin 2 (Lcn2) as a new adipokine having a critical role in energy and lipid metabolism in male mice. Previous studies by others have suggested that Lcn2 is a putative target gene of estrogens. In this study, we reported the effect of Lcn2 deficiency on estradiol biosynthesis and estrogen receptor signaling in female Lcn2-deficient (Lcn2−/−) mice. We found that Lcn2 expression in white adipose tissue is gender, depot, and age dependent. In female mice, Lcn2 is predominantly expressed in inguinal adipose tissue but at relatively very low levels in perigonadal depot and ovary. After 22 wk of high-fat diet (HFD) feeding or at old age, Lcn2−/− female mice had significantly reduced levels of serum 17β-estradiol and down-regulated expression of estrogen receptor α in multiple metabolic tissues. Consistently, the expression of estrogen-regulated genes involved in cholesterol homeostasis, such as liver X receptor β and low-density lipoprotein receptor was also down-regulated in the adipose tissue of Lcn2−/− mice. These changes were in line with the development of atherogenic dyslipidemia in response to HFD feeding; female Lcn2−/− mice had significantly elevated levels of total cholesterol and low-density lipoprotein cholesterol, whereas reduced high-density lipoprotein cholesterol levels compared with wild-type female mice. Interestingly, when compared with wild-type controls, HFD-fed female Lcn2−/− mice had significantly reduced expression levels of aromatase, a key enzyme regulating estradiol biosynthesis, in adipose tissue. Moreover, Lcn2 deficiency markedly blunted age-related increase in adipose aromatase expression but had no significant impact on age-related reduction in ovarian aromatase expression. Our findings suggest that Lcn2 has a tissue-specific role in adipose estradiol biosynthesis, which may link Lcn2 to obesity- and age-related estradiol production and metabolic complications in females.

Structural and Functional Characterization of a Codon Optimized Coagulation Factor VIII

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3765-3765
Author(s):  
Svetlana A Shestopal ◽  
James H Kurasawa ◽  
Jian-Jiang Hao ◽  
Elena Karnaukhova ◽  
Yideng Liang ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Specific Activity ◽  
Codon Optimization ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Wild Type ◽  
Density Lipoprotein Receptor ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Lipoprotein Receptor Related Protein

Abstract Background. Production of recombinant factor VIII (FVIII) is challenging due to its low expression. Previously, it was shown that codon optimization of a B domain-deleted (BDD) FVIII resulted in its increased expression (Ward et al, Blood 2011; 117: 798-807). However, in some cases, synonymous mutations are known to affect the protein's post-translation modifications, conformation, fidelity of amino acid sequence, and functions. Thus, for each particular codon optimization of a given protein, confirmation of its biochemical characteristics is necessary. Recently, we established conditions for expression and purification of a codon optimized BDD-FVIII (CO), in parallel, testing the BDD-FVIII (WT) expressed from the wild-type cDNA sequence (Shestopal et al, ISTH-2015 meeting, Abstract PO196-WED). In present work, we verified if the characteristics of the CO remain unchanged upon modification of its coding sequence. Objective. To characterize structural and functional properties of the BDD-FVIII encoded by either a codon-optimized or wild-type cDNA sequence (CO and WT, respectively). Experimental Approach. Several preparations of each WT and CO, purified from independent CHO cells clonal lines, were analyzed by: polyacrylamide gel electrophoresis (PAGE), before and after thrombin treatment; Western-blot analysis; ELISA; mass-spectrometry upon specific protein fragmentation; circular dichroism; chromogenic, clotting and thrombin generation assays to test the FVIII activity; and by surface plasmon resonance to test the binding to von Willebrand factor and a fragment of the low-density lipoprotein receptor-related protein 1 (LRP). Results. The average purification yield of CO was approximately 7-fold higher than that of WT. The proteins were identical in the amino acid sequences, covered by 99% by mass-spectrometry, and were very similar in: i) patterns of the molecular fragments, including those produced upon thrombin cleavage by PAGE, ii) recognition by anti-FVIII antibodies by both Western-blot and ELISA, iii) glycosylation and tyrosine sulfation by mass spectrometry, iv) secondary structures by circular dichroism and v) binding to von Willebrand factor, and vi) to a fragment of the low-density lipoprotein receptor-related protein 1 by surface plasmon resonance. By chromogenic, clotting and thrombin generation assays, the CO had about 1.5-fold higher FVIII specific activity (activity normalized to protein mass) than WT. Conclusions. The higher specific activity of CO was attributed to better preservation of its structure due to consistently higher concentrations than WT at all steps of the production. Thus, we concluded that the codon optimization of the BDD-FVIII resulted in a significant increase of its expression, while did not affect the protein's properties. Disclosures No relevant conflicts of interest to declare.

scholarly journals Melatonin Attenuates ox-LDL-Induced Endothelial Dysfunction by Reducing ER Stress and Inhibiting JNK/Mff Signaling

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Peng Li ◽  
Changlian Xie ◽  
Jiankai Zhong ◽  
Zhongzhou Guo ◽  
Kai Guo ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Endothelial Dysfunction ◽  
Er Stress ◽  
Mitochondrial Dysfunction ◽  
Signaling Pathway ◽  
Mitochondrial Function ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Mitochondrial Ros ◽  
Er Homeostasis

Endothelial dysfunction, which is characterized by damage to the endoplasmic reticulum (ER) and mitochondria, is involved in a variety of cardiovascular disorders. Here, we explored whether mitochondrial damage and ER stress are associated with endothelial dysfunction. We also examined whether and how melatonin protects against oxidized low-density lipoprotein- (ox-LDL-) induced damage in endothelial cells. We found that CHOP, GRP78, and PERK expressions, which are indicative of ER stress, increased significantly in response to ox-LDL treatment. ox-LDL also induced mitochondrial dysfunction as evidenced by decreased mitochondrial membrane potential, increased mitochondrial ROS levels, and downregulation of mitochondrial protective factors. In addition, ox-LDL inhibited antioxidative processes, as evidenced by decreased antioxidative enzyme activity and reduced Nrf2/HO-1 expression. Melatonin clearly reduced ER stress and promoted mitochondrial function and antioxidative processes in the presence of ox-LDL. Molecular investigation revealed that ox-LDL activated the JNK/Mff signaling pathway, and melatonin blocked this effect. These results demonstrate that ox-LDL induces ER stress and mitochondrial dysfunction and activates the JNK/Mff signaling pathway, thereby contributing to endothelial dysfunction. Moreover, melatonin inhibited JNK/Mff signaling and sustained ER homeostasis and mitochondrial function, thereby protecting endothelial cells against ox-LDL-induced damage.

scholarly journals A low-carbohydrate ketogenic diet induces the expression of very-low-density lipoprotein receptor in liver and affects its associated metabolic abnormalities

2019 ◽  
Vol 3 (1) ◽  
Author(s):  
Tetsuya Okuda
Keyword(s):  
Ketogenic Diet ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Lipoprotein Receptor ◽  
Wild Type ◽  
Low Density Lipoprotein Receptor ◽  
Low Carbohydrate ◽  
Density Lipoprotein Receptor

AbstractA low-carbohydrate ketogenic diet (LCKD) promotes the progression of hepatic steatosis in C57BL/6 wild-type mice, but improves the condition in leptin-deficient obese (ob/ob) mice. Here, we show a novel effect of LCKD associated with the conflicting effects on these mice. Gene expression microarray analyses showed that expression of the Vldlr gene, which encodes the very-low-density lipoprotein receptor (VLDLR), was induced in LCKD-fed ob/ob mice. Although the VLDLR is not normally expressed in the liver, the LCKD led to VLDLR expression in both ob/ob and wild-type mice. To clarify this effect on VLDL dynamics, we analyzed the lipid content of serum lipoproteins and found a marked decrease in VLDL-triglycerides only in LCKD-fed wild-type mice. Further analyses suggested that transport of triglycerides via VLDL from the liver to extrahepatic tissues was inhibited by LCKD-induced hepatic VLDLR expression, but rescued under conditions of leptin deficiency.

scholarly journals Canonical Wnt signaling in megakaryocytes regulates proplatelet formation

Blood ◽  
2013 ◽  
Vol 121 (1) ◽  
pp. 188-196 ◽  
Author(s):  
Iain C. Macaulay ◽  
Jonathan N. Thon ◽  
Marloes R. Tijssen ◽  
Brian M. Steele ◽  
Bryan T. MacDonald ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Fetal Liver ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Wild Type ◽  
Density Lipoprotein Receptor ◽  
Proplatelet Formation ◽  
And Function ◽  
Canonical Wnt ◽  
Whole Genome Expression

Abstract Wnt signaling is involved in numerous aspects of vertebrate development and homeostasis, including the formation and function of blood cells. Here, we show that canonical and noncanonical Wnt signaling pathways are present and functional in megakaryocytes (MKs), with several Wnt effectors displaying MK-restricted expression. Using the CHRF288-11 cell line as a model for human MKs, the canonical Wnt3a signal was found to induce a time and dose-dependent increase in β-catenin expression. β-catenin accumulation was inhibited by the canonical antagonist dickkopf-1 (DKK1) and by the noncanonical agonist Wnt5a. Whole genome expression analysis demonstrated that Wnt3a and Wnt5a regulated distinct patterns of gene expression in MKs, and revealed a further interplay between canonical and noncanonical Wnt pathways. Fetal liver cells derived from low-density-lipoprotein receptor-related protein 6-deficient mice (LRP6−/−), generated dramatically reduced numbers of MKs in culture of lower ploidy (2N and 4N) than wild-type controls, implicating LRP6-dependent Wnt signaling in MK proliferation and maturation. Finally, in wild-type mature murine fetal liver-derived MKs, Wnt3a potently induced proplatelet formation, an effect that could be completely abrogated by DKK1. These data identify novel extrinsic regulators of proplatelet formation, and reveal a profound role for Wnt signaling in platelet production.

scholarly journals Reversal of hyperlipidaemia in apolipoprotein C1 transgenic mice by adenovirus-mediated gene delivery of the low-density-lipoprotein receptor, but not by the very-low-density-lipoprotein receptor

1999 ◽  
Vol 338 (2) ◽  
pp. 281-287 ◽  
Author(s):  
Miek C. JONG ◽  
Ko WILLEMS Van DIJK ◽  
Vivian E.H. DAHLMANS ◽  
Hans Van Der BOOM ◽  
Kunisha KOBAYASHI ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Lipoprotein Receptor ◽  
Wild Type ◽  
Low Density Lipoprotein Receptor ◽  
Lipoprotein Particles ◽  
Density Lipoprotein Receptor

We have shown previously that human apolipoprotein (apo)C1 transgenic mice exhibit hyperlipidaemia, due primarily to an impaired clearance of very-low-density lipoprotein (VLDL) particles from the circulation. In the absence of at least the low-density-lipoprotein receptor (LDLR), it was shown that APOC1 overexpression in transgenic mice inhibited the hepatic uptake of VLDL via the LDLR-related protein. In the present study, we have now examined the effect of apoC1 on the binding of lipoproteins to both the VLDL receptor (VLDLR) and the LDLR. The binding specificity of the VLDLR and LDLR for apoC1-enriched lipoprotein particles was examined in vivo through adenovirus-mediated gene transfer of the VLDLR and the LDLR [giving rise to adenovirus-containing (Ad)-VLDLR and Ad-LDLR respectively] in APOC1 transgenic mice, LDLR-deficient (LDLR-/-) mice and wild-type mice. Remarkably, Ad-VLDLR treatment did not reduce hyperlipidaemia in transgenic mice overexpressing human APOC1, irrespective of both the level of transgenic expression and the presence of the LDLR, whereas Ad-VLDLR treatment did reverse hyperlipidaemia in LDLR-/- and wild-type mice. On the other hand, Ad-LDLR treatment strongly decreased plasma lipid levels in these APOC1 transgenic mice. These results suggest that apoC1 inhibits the clearance of lipoprotein particles via the VLDLR, but not via the LDLR. This hypothesis is corroborated by in vitro binding studies. Chinese hamster ovary (CHO) cells expressing the VLDLR (CHO-VLDLR) or LDLR (CHO-LDLR) bound less APOC1 transgenic VLDL than wild-type VLDL. Intriguingly, however, enrichment with apoE enhanced dose-dependently the binding of wild-type VLDL to CHO-VLDLR cells (up to 5-fold), whereas apoE did not enhance the binding of APOC1 transgenic VLDL to these cells. In contrast, for binding to CHO-LDLR cells, both wild-type and APOC1 transgenic VLDL were stimulated upon enrichment with apoE. From these studies, we conclude that apoC1 specifically inhibits the apoE-mediated binding of triacylglycerol-rich lipoprotein particles to the VLDLR, whereas apoC1-enriched lipoproteins can still bind to the LDLR. The variability in specificity of these lipoprotein receptors for apoC1-containing lipoprotein particles provides further evidence for a regulatory role of apoC1 in the delivery of lipoprotein constituents to different tissues on which these receptors are located.

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