scholarly journals BLOS1 mediates kinesin switch during endosomal recycling of LDL receptor

2020 ◽  
Author(s):  
Chang Zhang ◽  
Chanjuan Hao ◽  
Guanghou Shui ◽  
Wei Li
Keyword(s):  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Cholesterol Homeostasis ◽  
Whole Body ◽  
Cellular Mechanisms ◽  
Anterograde Transport ◽  
Recycling Endosomes ◽  
Endosomal Recycling ◽  
Density Lipoprotein Receptor

AbstractLow-density lipoprotein receptor (LDLR) in hepatocytes plays a key role in normal clearance of circulating LDL and in whole body cholesterol homeostasis. The trafficking of LDLR is highly regulated in clathrin-dependent endocytosis, endosomal recycling and lysosomal degradation. Current studies have been focusing on its endocytosis and degradation. However, the detailed molecular and cellular mechanisms underlying its endosomal recycling are largely unknown. We found that BLOS1, a shared subunit of BLOC-1 and BORC, is involved in LDLR endosomal recycling. Loss of BLOS1 leads to less membrane LDLR and impairs LDL clearance from plasma in hepatocyte-specific BLOS1 knockout mice. BLOS1 interacts with kinesin-3, and that BLOS1 acts as a new adaptor for kinesin-2 to coordinate kinesin-3 and kinesin-2 during the long-range transport of recycling endosomes (REs) to plasma membrane along microtubule tracks to overcome hurdles at microtubule intersections. These findings provide new insights into RE’s anterograde transport and the pathogenesis of dyslipidemia.

scholarly journals BLOS1 mediates kinesin switch during endosomal recycling of LDL receptor

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Chang Zhang ◽  
Chanjuan Hao ◽  
Guanghou Shui ◽  
Wei Li
Keyword(s):  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Cholesterol Homeostasis ◽  
Whole Body ◽  
Cellular Mechanisms ◽  
Anterograde Transport ◽  
Recycling Endosomes ◽  
Endosomal Recycling ◽  
Density Lipoprotein Receptor

Low-density lipoprotein receptor (LDLR) in hepatocytes plays a key role in plasma clearance of circulating LDL and in whole body cholesterol homeostasis. The trafficking of LDLR is highly regulated in clathrin-dependent endocytosis, endosomal recycling and lysosomal degradation. Current studies focus on its endocytosis and degradation. However, the detailed molecular and cellular mechanisms underlying its endosomal recycling are largely unknown. We found that BLOS1, a shared subunit of BLOC-1 and BORC, is involved in LDLR endosomal recycling. Loss of BLOS1 leads to less membrane LDLR and impairs LDL clearance from plasma in hepatocyte-specific BLOS1 knockout mice. BLOS1 interacts with kinesin-3 motor KIF13A, and BLOS1 acts as a new adaptor for kinesin-2 motor KIF3 to coordinate kinesin-3 and kinesin-2 during the long-range transport of recycling endosomes (REs) to plasma membrane along microtubule tracks to overcome hurdles at microtubule intersections. This provides new insights into RE’s anterograde transport and the pathogenesis of dyslipidemia.

scholarly journals Detection of the low-density-lipoprotein receptor with biotin-low-density lipoprotein. A rapid new method for ligand blotting

1985 ◽  
Vol 229 (3) ◽  
pp. 785-790 ◽  
Author(s):  
D P Wade ◽  
B L Knight ◽  
A K Soutar
Keyword(s):  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
High Sensitivity ◽  
Receptor Protein ◽  
Low Density ◽  
Very Low Density Lipoproteins ◽  
Cell Extracts ◽  
Density Lipoprotein Receptor ◽  
A New Technique

A new technique has been developed to identify low-density-lipoprotein (LDL) receptors on nitrocellulose membranes, after transfer from SDS/polyacrylamide gels, by ligand blotting with biotin-modified LDL. Modification with biotin hydrazide of periodate-oxidized lipoprotein sugar residues does not affect the ability of the lipoprotein to bind to the LDL receptor. Bound lipoprotein is detected with high sensitivity by a streptavidin-biotin-peroxidase complex, and thus this method eliminates the need for specific antibodies directed against the ligand. The density of the bands obtained is proportional to the amount of pure LDL receptor protein applied to the SDS/polyacrylamide gel, so that it is possible to quantify LDL receptor protein in cell extracts. Biotin can be attached to other lipoproteins, for example very-low-density lipoproteins with beta-mobility, and thus the method will be useful in the identification and isolation of other lipoprotein receptors.

scholarly journals Effect of dietary eicosapentaenoic and docosahexaenoic acid on expression of rat liver genes controlling cholesterol homeostasis and on plasma cholesterol level

2014 ◽  
Vol 59 (No. 9) ◽  
pp. 391-398 ◽  
Author(s):  
T. Komprda ◽  
G. Zorníková ◽  
A. Knoll ◽  
Z. Vykoukalová ◽  
V. Rozíková ◽  
...  
Keyword(s):  
Docosahexaenoic Acid ◽  
Plasma Cholesterol ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Cholesterol Homeostasis ◽  
Ldlr Gene ◽  
Expression Of Genes ◽  
Density Lipoprotein Receptor ◽  
Lower Plasma Cholesterol ◽  
Coa Reductase

A hypothesis that eicosapentaenoic acid + docosahexaenoic acid (EPA+DHA) lower plasma cholesterol via increased expression of the Insig-1 gene with ensuing decrease of expression of genes coding for 3-hydroxy-3-methyl-glutaryl-CoA reductase (Hmgcr) and low density lipoprotein receptor (Ldlr) was tested in rats fed a diet with 3% of fish oil (FO). Expression of the Insig-1 gene in the liver of the FO-fed rats was 730% (P < 0.05) of the control. However, contrary to the hypothesis, expression of the Hmgcr gene and Ldlr gene was 165% and 210% of the control (P > 0.05). Nevertheless, FO in the diet decreased (P < 0.05) plasma cholesterol of rats by 10% (from 1.19 to 1.07 mmol/l); it was therefore concluded that the cholesterol-lowering effect of EPA+DHA is at least partly based on mechanisms other than tested in the present experiment.  

scholarly journals Significance of Soluble Lectin-Like Oxidized LDL Receptor-1 Levels in Systemic and Coronary Circulation in Acute Coronary Syndrome

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Tomofumi Misaka ◽  
Satoshi Suzuki ◽  
Nobuo Sakamoto ◽  
Takayoshi Yamaki ◽  
Koichi Sugimoto ◽  
...  
Keyword(s):  
Acute Coronary Syndrome ◽  
Coronary Circulation ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
High Sensitivity ◽  
Coronary Intervention ◽  
Coronary Syndrome ◽  
Density Lipoprotein Receptor

Background.Soluble lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) level is a novel biomarker for diagnosis of acute coronary syndrome (ACS); however, this level in the coronary circulation has yet to be examined.Methods.Twenty-seven consecutive patients with ACS and 40 patients with effort angina pectoris (EAP) undergoing percutaneous coronary intervention (PCI) had levels of soluble LOX-1 and LOX-1 index measured in paired blood samples from aorta (Ao) and coronary sinus (CS) just prior to the PCI.Results.We found positive correlations between soluble LOX-1 levels in the Ao and CS in both ACS and EAP patients (P<0.01, for both). The soluble LOX-1 levels in the Ao and CS were higher in ACS than in EAP patients (P<0.01, for both). The levels of soluble LOX-1 and LOX-1 index of the CS were significantly greater than those of the Ao in both ACS and EAP patients (P<0.01, for both). Receiver operating characteristic curves for ACS detection demonstrated high sensitivity and specificity for the soluble LOX-1 and LOX-1 index with no differences between the Ao and CS.Conclusions.The present study showed that circulating soluble LOX-1 originates from coronary circulation and soluble LOX-1 and LOX-1 index are useful biomarkers for ACS.

scholarly journals The low-density lipoprotein receptor-related protein 1 (LRP1) mediates the endocytosis of the cellular prion protein

2007 ◽  
Vol 402 (1) ◽  
pp. 17-23 ◽  
Author(s):  
David R. Taylor ◽  
Nigel M. Hooper
Keyword(s):  
Prion Protein ◽  
Low Density Lipoprotein ◽  
Neuronal Cells ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Adaptor Protein ◽  
Cellular Prion Protein ◽  
Low Density ◽  
Related Protein ◽  
Density Lipoprotein Receptor

PrPC (cellular prion protein) is located at the surface of neuronal cells in detergent-insoluble lipid rafts, yet is internalized by clathrin-dependent endocytosis. As PrPC is glycosyl-phosphatidylinositol-anchored, it requires a transmembrane adaptor protein to connect it to the clathrin endocytosis machinery. Using receptor-associated protein and small interfering RNA against particular LDL (low-density lipoprotein) family members, in combination with immunofluorescence microscopy and surface biotinylation assays, we show that the transmembrane LRP1 (LDL receptor-related protein 1) is required for the Cu2+-mediated endocytosis of PrPC in neuronal cells. We show also that another LRP1 ligand that can cause neurodegenerative disease, the Alzheimer's amyloid precursor protein, does not modulate the endocytosis of PrPC.

LDL Receptor Mediates Effective Endocytosis of Activated Factor V.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1766-1766 ◽  
Author(s):  
Alexander B. Meijer ◽  
Sigrid D. Roosendaal ◽  
Vincent Limburg ◽  
Carmen van der Zwaan ◽  
Kees W. Rodenburg ◽  
...  
Keyword(s):  
Cho Cells ◽  
Fluorescent Protein ◽  
Low Density Lipoprotein ◽  
Yellow Fluorescent Protein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Functional Expression ◽  
Factor V ◽  
Early Endosomes ◽  
Density Lipoprotein Receptor

Abstract The platelet α-granules contain a unique pool of partially activated factor V, which has been suggested to originate form megakaryocyte endocytosis of factor V (FV) from plasma. The presence of activated FV (FVa) in plasma itself should be tightly controlled as dysfunction therein may predispose to thrombotic disorders. Previously, we have reported that FVa but not FV can bind the low-density lipoprotein receptor related protein (LRP). This multifunctional receptor can bind a multitude of ligands including FV’s homologue factor VIII (FVIII). We now investigated whether FV or FVa can, like FVIII, also bind the more restricted LDL receptor (LDLR). To this end, the endocytosis of FV and FVa by CHO cells expressing LDLR (CHO-LDLR+ cells) was assessed utilizing confocal microscopy. In the experimental setup, FV and FVa were visualized employing immuno-fluorescence staining techniques. The results showed that within 10 minutes after addition of FVa, fluorescent spots appeared inside the CHO-LDLR+ cells. In contrast, no fluorescent spots were observed after 10 minutes of incubation with FV. These observations suggest that FVa but not FV effectively interacts with the LDLR expressing CHO cells. We then assessed whether FVa can compete with FVIII for endocytosis by CHO-LDLR+ cells. In the presence of an equimolar amount of FVa and a FVIII derivative (FVIIIYFP) containing yellow fluorescent protein, both proteins were detected within the same vesicles inside the CHO-LDLR+ cells. Employing co-localization studies, we established that these vesicles represented early endosomes. In the presence of an access of FVa, however, the yellow fluorescence of FVIIIYFP was no longer observed. These results demonstrate that FVa can block the FVIII endocytosis by CHO-LDLR+ cells. The observations together suggest that LDLR can not only bind FVIII but also FVa. In line with this notion, we established that CHO-ldlA cells, which lack functional expression of LDLR, were unable to internalize neither FVa nor FVIIIYFP. In addition, the ligand-binding clusters II and cluster IV of LRP effectively inhibited the endocytic uptake of FVa by CHO-LDLR+ cells. This implies that structural elements of FVa involved in LRP binding may overlap with those required for LDLR dependent internalization. Our results suggest a so far unidentified role for members of the LDL receptor family in the regulation of FVa in plasma.

scholarly journals Three types of low density lipoprotein receptor-deficient mutant have pleiotropic defects in the synthesis of N-linked, O-linked, and lipid-linked carbohydrate chains.

1986 ◽  
Vol 102 (5) ◽  
pp. 1576-1585 ◽  
Author(s):  
D M Kingsley ◽  
K F Kozarsky ◽  
M Segal ◽  
M Krieger
Keyword(s):  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Genetic Defects ◽  
Low Density ◽  
Viral Glycoprotein ◽  
Essentially Normal ◽  
Density Lipoprotein Receptor ◽  
Glycolipid Synthesis ◽  
Carbohydrate Chains

Biochemical, immunological, and genetic techniques were used to investigate the genetic defects in three types of low density lipoprotein (LDL) receptor-deficient hamster cells. The previously isolated ldlB, ldlC, and ldlD mutants all synthesized essentially normal amounts of a 125,000-D precursor form of the LDL receptor, but were unable to process this receptor to the mature form of 155,000 D. Instead, these mutants produced abnormally small, heterogeneous receptors that reached the cell surface but were rapidly degraded thereafter. The abnormal sizes of the LDL receptors in these cells were due to defective processing of the LDL receptor's N- and O-linked carbohydrate chains. Processing defects in these cells appeared to be general since the ldlB, ldlC, and ldlD mutants also showed defective glycosylation of a viral glycoprotein, alterations in glycolipid synthesis, and changes in resistance to several toxic lectins. Preliminary structural studies suggested that these cells had defects in multiple stages of the Golgi-associated processing reactions responsible for synthesis of glycolipids and in the N-linked and O-linked carbohydrate chains of glycoproteins. Comparisons between the ldl mutants and a large number of previously isolated CHO glycosylation defective mutants showed that the genetic defects in ldlB, ldlC, and ldlD cells were unique and that only very specific types of carbohydrate alteration could dramatically affect LDL receptor function.

scholarly journals A novel peroxisome proliferator response element modulates hepatic low-density lipoprotein receptor gene transcription in response to PPARδ activation

2015 ◽  
Vol 472 (3) ◽  
pp. 275-286 ◽  
Author(s):  
Vikram R. Shende ◽  
Amar Bahadur Singh ◽  
Jingwen Liu
Keyword(s):  
Gene Transcription ◽  
Receptor Gene ◽  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Peroxisome Proliferator ◽  
Density Lipoprotein Receptor ◽  
Peroxisome Proliferator Response Element

PPARδ activation beneficially regulates lipid metabolism. We have now identified a novel function of PPARδ that increases LDL receptor gene transcription in hepatic cells in vitro and in vivo through direct binding to a PPRE motif on LDLR promoter.

scholarly journals Whole-Body Prolyl Hydroxylase Domain (PHD) 3 Deficiency Increased Plasma Lipids and Hematocrit Without Impacting Plaque Size in Low-Density Lipoprotein Receptor Knockout Mice

2021 ◽  
Vol 9 ◽  
Author(s):  
Jasper A. F. Demandt ◽  
Kim van Kuijk ◽  
Thomas L. Theelen ◽  
Elke Marsch ◽  
Sean P. Heffron ◽  
...  
Keyword(s):  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Prolyl Hydroxylase ◽  
The Body ◽  
Whole Body ◽  
Low Density ◽  
Lipoprotein Receptor ◽  
Plaque Size ◽  
Low Density Lipoprotein Receptor ◽  
Density Lipoprotein Receptor

Background and aims: Atherosclerosis is an important cause of clinical cardiovascular events. Atherosclerotic plaques are hypoxic, and reoxygenation improves plaque phenotype. Central players in hypoxia are hypoxia inducible factors (HIF) and their regulators, HIF-prolyl hydroxylase (PHD) isoforms 1, 2, and 3. PHD inhibitors, targeting all three isoforms, are used to alleviate anemia in chronic kidney disease. Likewise, whole-body PHD1 and PHD2ko ameliorate hypercholesterolemia and atherogenesis. As the effect of whole-body PHD3 is unknown, we investigated the effects of germline whole-body PHD3ko on atherosclerosis.Approach and Results: To initiate hypercholesterolemia and atherosclerosis low-density lipoprotein receptor knockout (LDLrko) and PHD3/LDLr double knockout (PHD3dko), mice were fed a high-cholesterol diet. Atherosclerosis and hypoxia marker pimonidazole were analyzed in aortic roots and brachiocephalic arteries. In contrast to earlier reports on PHD1- and PHD2-deficient mice, a small elevation in the body weight and an increase in the plasma cholesterol and triglyceride levels were observed after 10 weeks of diet. Dyslipidemia might be explained by an increase in hepatic mRNA expression of Cyp7a1 and fatty acid synthase, while lipid efflux of PHD3dko macrophages was comparable to controls. Despite dyslipidemia, plaque size, hypoxia, and phenotype were not altered in the aortic root or in the brachiocephalic artery of PHD3dko mice. Additionally, PHD3dko mice showed enhanced blood hematocrit levels, but no changes in circulating, splenic or lymphoid immune cell subsets.Conclusion: Here, we report that whole-body PHD3dko instigated an unfavorable lipid profile and increased hematocrit, in contrast to other PHD isoforms, yet without altering atherosclerotic plaque development.

scholarly journals Dietary-Induced Elevations of Triglyceride-Rich Lipoproteins Promote Atherosclerosis in the Low-Density Lipoprotein Receptor Knockout Syrian Golden Hamster

2021 ◽  
Vol 8 ◽  
Author(s):  
Xiao Lin ◽  
Ping Ma ◽  
Chun Yang ◽  
Jinjie Wang ◽  
Kunxiang He ◽  
...  
Keyword(s):  
Golden Hamster ◽  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Syrian Golden Hamster ◽  
Low Density ◽  
Lipoprotein Receptor ◽  
Low Density Lipoprotein Receptor ◽  
Large Particles ◽  
Density Lipoprotein Receptor

Elevated triglycerides are associated with an increased risk of cardiovascular disease (CVD). Therefore, it is very important to understand the metabolism of triglyceride-rich lipoproteins (TRLs) and their atherogenic role in animal models. Using low-density lipoprotein receptor knockout (LDLR−/−) Syrian golden hamsters, this study showed that unlike LDLR−/− mice, when LDLR−/− hamsters were fed a high cholesterol high-fat diet (HFD), they had very high plasma levels of triglycerides and cholesterol. We found that LDLR−/− hamsters exhibited increased serum TRLs and the ApoB100 and 48 in these particles after being fed with HFD. Treatment with ezetimibe for 2 weeks decreased these large particles but not the LDL. In addition, ezetimibe simultaneously reduced ApoB48 and ApoE in plasma and TRLs. The expression of LRP1 did not change in the liver. These findings suggested that the significantly reduced large particles were mainly chylomicron remnants, and further, the remnants were mainly cleared by the LDL receptor in hamsters. After 40 days on an HFD, LDLR−/− hamsters had accelerated aortic atherosclerosis, accompanied by severe fatty liver, and ezetimibe treatment reduced the consequences of hyperlipidemia. Compared with the serum from LDLR−/− hamsters, that from ezetimibe-treated LDLR−/− hamsters decreased the expression of vascular adhesion factors in vascular endothelial cells and lipid uptake by macrophages. Our results suggested that in the LDLR−/− hamster model, intestinally-derived lipoprotein remnants are highly atherogenic and the inflammatory response of the endothelium and foam cells from macrophages triggered atherosclerosis. The LDL receptor might be very important for chylomicrons remnant clearance in the Syrian golden hamster, and this may not be compensated by another pathway. We suggest that the LDLR−/− hamster is a good model for the study of TRLs-related diseases as it mimics more complex hyperlipidemia.

Sign in / Sign up

Export Citation Format

Share Document