scholarly journals Characterization of SID-1-dependent and independent intergenerational RNA transport pathways in Caenorhabditis elegans

2017 ◽  
Author(s):  
Eddie Wang ◽  
Craig P. Hunter
Keyword(s):  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Epigenetic Inheritance ◽  
Transport Pathways ◽  
C Elegans ◽  
Early Embryos ◽  
Systemic Rna

AbstractSystemic RNA interference (RNAi) in C. elegans is dependent on sid-1 (Winstonet al. 2002), sid-3 (Joseet al. 2012) and sid-5 (Hinaset al. 2012). After injection, expression, or ingestion, double-stranded RNA (dsRNA) is transported between cells throughout the animal to enable RNAi in most tissues, including the germline and progeny. Here, we characterize the role of the Sid genes in transport of dsRNA to progeny. We previously reported that dsRNA injected directly in the germline unexpectedly requires sid-1 activity in the progeny to initiate RNAi (Winstonet al. 2002). We now show that germline injected dsRNA can travel by three independent pathways to silence gene expression in embryos. First, germline injected dsRNA is delivered, presumably by bulk flow, into oocytes and embryos. This means of delivery, which does not require sid-1, is limited by the amount and location of injected dsRNA. Second, maternal sid-1 transports extracellular dsRNA into the germline where it can silence maternal deposited mRNAs and segregate to embryos to silence embryonically expressed mRNAs. Third, extracellular dsRNA is also endocytosed into oocytes by the low-density lipoprotein (LDL) receptor superfamily homolog RME-2. The endocytosed dsRNA then requires sid-1 and sid-5 in embryos to silence embryonically expressed genes. Extracellular fluorescent dsRNA, once endocytosed into oocytes, does not co-localize with VIT2::GFP and it does not require sid-1 activity to segregate from the late endocytosis marker GFP::RAB-7 in early embryos. In conclusion, we identify genes and pathways that function redundantly for intergenerational RNA transfer that may represent mechanisms for transgenerational epigenetic inheritance.

scholarly journals Oxidized LDL but not angiotensin II induces the interaction between LOX-1 and AT1 receptors

2020 ◽  
Author(s):  
Li Lin ◽  
Ning Zhou ◽  
Le Kang ◽  
Qi Wang ◽  
Jian Wu ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Direct Interaction ◽  
Cardiomyocyte Hypertrophy ◽  
Oxidized Low Density Lipoprotein ◽  
Protein Activation

Oxidized low-density lipoprotein (Ox-LDL) can induce cardiac hypertrophy, but the mechanism is still unclear. Here we elucidate the role of angiotensin II (AngII) receptor (AT1-R) in Ox-LDL-induced cardiomycyte hypertrophy. Inhibition of Ox-LDL receptor LOX-1 and AT1-R rather than AngII abolished Ox-LDL-induced hypertrophic responses. Similar results were obtained from the heart of mice lacking endogenous Ang II and their cardiomyocytes. Ox-LDL but not AngII induced binding of LOX-1 to AT1-R, and the inhibition of LOX-1 or AT1-R rather than AngII abolished the association of these two receptors. Ox-LDL-induced ERKs phosphorylation in LOX-1 and AT1-R-overexpression cells and the binding of both receptors were suppressed by the mutants of LOX-1 (Lys266Ala/Lys267Ala) or AT1-R (Glu257Ala), however, the AT1-R mutant lacking Gq protein-coupling ability only abolished the ERKs phosphorylation. The phosphorylation of ERKs induced by Ox-LDL in LOX-1 and AT1-R-overexpression cells was abrogated by Gq protein inhibitor but not by Jak2, Rac1 and RhoA inhibitors. Therefore, the direct interaction between LOX-1 and AT1-R and the downstream Gq protein activation are important mechanisms for Ox-LDL- but not AngII-induced cardiomyocyte hypertrophy

scholarly journals Role of Lectin-Like Oxidized Low Density Lipoprotein-1 in Fetoplacental Vascular Dysfunction in Preeclampsia

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Felipe A. Zuniga ◽  
Valeska Ormazabal ◽  
Nicolas Gutierrez ◽  
Valeria Aguilera ◽  
Claudia Radojkovic ◽  
...  
Keyword(s):  
Endothelial Dysfunction ◽  
Vascular Dysfunction ◽  
Pathological Condition ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Fetal Loss ◽  
Density Lipoprotein ◽  
Placental Tissue

The bioavailability of nitric oxide (NO) represents a key marker in vascular health. A decrease in NO induces a pathological condition denominated endothelial dysfunction, syndrome observed in different pathologies, such as obesity, diabetes, kidney disease, cardiovascular disease, and preeclampsia (PE). PE is one of the major risks for maternal death and fetal loss. Recent studies suggest that the placenta of pregnant women with PE express high levels of lectin-like oxidized LDL receptor-1 (LOX-1), which induces endothelial dysfunction by increasing reactive oxygen species (ROS) and decreasing intracellular NO. Besides LOX-1 activation induces changes in migration and apoptosis of syncytiotrophoblast cells. However, the role of this receptor in placental tissue is still unknown. In this review we will describes the physiological roles of LOX-1 in normal placenta development and the potential involvement of this receptor in the pathophysiology of PE.

Characterization of the LDL receptor in rat promegakaryoblasts in culture

1991 ◽  
Vol 11 (1) ◽  
pp. 15-21 ◽  
Author(s):  
Tracy J. Budd ◽  
Frank W. Hemming ◽  
Bruce Middleton
Keyword(s):  
Cell Biology ◽  
Receptor Cell ◽  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Classical Type ◽  
Lysosomal Degradation ◽  
High Affinity ◽  
Ldl Binding

Rat promegakaryoblasts (RPM, a precursor platelet cell line) in culture exhibited a capacity to bind, take up and degrade125I-LDL. The low density lipoprotein (LDL) binding showed the following characteristics: (a) high affinity, (b) saturability, (c) specificity, (d) down-regulation, after exposure to 25 hydroxycholesterol. Furthermore the proteolytic degradation of125I-LDL by RPMs was inhibited by chloroquine which interferes with the lysosomal degradation processes. These findings show LDL receptor cell biology of RPM to be of the classical type and to differ from that of platelets.

Abstract 437: Lipoprotein(a) Internalization in HepG2 Cells is Regulated by Proprotein Convertase Subtilisin Kexin Type 9 Through the Low-Density Lipoprotein Receptor

2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
Rocco Romagnuolo ◽  
Nabil G Seidah ◽  
Marlys L Koschinsky
Keyword(s):  
Heavy Chain ◽  
Hepg2 Cells ◽  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Proprotein Convertase ◽  
Human Hepatoma Cells ◽  
Lipoprotein A ◽  
Clathrin Heavy Chain

Elevated levels of lipoprotein(a) (Lp(a)) have been identified as an independent and causal risk factor for coronary heart disease. Lp(a) consists of an LDL-like moiety covalently linked to the unique glycoprotein apolipoprotein(a) (apo(a)). The mechanism by which Lp(a) is catabolized is currently unknown, but may form the basis for the development of drug therapy to reduce high levels of plasma Lp(a). Although the role of the LDL receptor (LDLR) in Lp(a) catabolism is controversial, recent evidence has shown that Lp(a) levels are significantly reduced with an antibody against proprotein convertase subtilisin kexin type 9 (PCSK9) in patients with hypercholesterolemia receiving statin therapy. Therefore, we explored the role of PCSK9 in Lp(a)/apo(a) internalization by hepatic cells. Lp(a) or apo(a) internalization is significantly reduced in HepG2 (human hepatoma) cells either by overexpressing PCSK9 or by treatment with purified PCSK9. The ability of Lp(a) and apo(a) to be internalized was significantly reduced in the presence of the lysine analogue, ε-ACA, indicating lysine-dependent interactions with cellular receptors. Mutation of the strong lysine binding site in a recombinant apo(a) variant resulted in a reduced ability to be internalized. While LDL can bind to PCSK9 and inhibit its ability to degrade the LDLR, we found that Lp(a) lacked these properties. Interestingly, overexpressing the LDLR on HepG2 cells significantly increased the ability of Lp(a) to be internalized, an effect that was partially reduced by the addition of PCSK9. This indicates a potential key role for the LDLR in regulating Lp(a) catabolism. Furthermore, knockdown of clathrin heavy chain resulted in a significant decrease in apo(a) internalization and apo(a) internalization was not further reduced by pre-treatment of PCSK9 in the context of clathrin heavy chain knockdown. Treatment of HepG2 cells with a lysosomal inhibitor, but not a proteosomal inhibitor, resulted in accumulation of Lp(a) in HepG2 cells indicating that Lp(a) is potentially targeted for degradation through lysosomes. Taken together, these results indicate that Lp(a)/apo(a) uptake can be regulated in HepG2 cells by PCSK9 and the LDLR through clathrin-mediated endocytosis and lysosomal degradation.

Abstract 15833: LRP1 is a Novel Receptor of Bmper and Required for Pathological Angiogenesis

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Xi Li ◽  
Xinchun Pi
Keyword(s):  
Endothelial Cells ◽  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Bmp Signaling ◽  
Functional Roles ◽  
Oxygen Induced Retinopathy ◽  
Morphogenetic Protein ◽  
Density Lipoprotein Receptor

Low density lipoprotein receptor-related protein 1 (LRP1) is a multifunctional member of the LDL receptor family, impacting a variety of biological processes such as lipid metabolism, endocytosis and signal transduction. However, the role of LRP1 in endothelium was almost unknown. Until recently we discovered that LRP1 is a novel regulator of bone morphogenetic protein (Bmp) signaling through its association with the extracellular modulator-Bmper (Bmp-binding endothelial cell precursor-derived regulator) and regulates zebrafish vascular development. Here we studied the functional roles of LRP1 in mammalian system by performing cell culture studies with endothelial cells (ECs) and analyzing angiogenic defects in oxygen-induced retinopathy model with LRP1flox/flox;Tie2-Cre+/- mice (EC-LRP1 KO). In MECs, we observed that the activation of Src, ERK and tyrosine phosphorylation of multiple proteins were induced by Bmper and this activation was LRP1-dependent since LRP1 knockdown inhibited their activation. However, this Bmper-induced activation was not blocked by Bmp4 neutralized antibody, which suggests that LRP1 is required for Bmp4-independent signaling for Bmper. These data also indicate that Bmper and LRP1 is a novel ligand receptor pair. Moreover, we observed that LRP1 protein was induced in response to 1% hypoxia in both mouse ECs (MECs) and human retinal microvascular endothelial cells, suggesting that LRP1 is required for hypoxia induced endothelial function. In hypoxia condition, EC-LRP1 KO mice resulted in accelerated angiogenesis in retinal endothelial cells, similar to the pattern of Bmper deleted mice. Therefore, we identify that the Bmper/LRP1 signaling is a novel signaling pathway in endothelial cells and their activity regulates angiogenic responses during oxygen-induced retinopathy. This study provides mechanistic insights for angiogenesis-related pathophysiologic conditions.

scholarly journals Role of the Low-Density Lipoprotein Receptor in Entry of Bovine Viral Diarrhea Virus

2006 ◽  
Vol 80 (21) ◽  
pp. 10862-10867 ◽  
Author(s):  
Thomas Krey ◽  
Etienne Moussay ◽  
Heinz-Jürgen Thiel ◽  
Till Rümenapf
Keyword(s):  
Bovine Viral Diarrhea Virus ◽  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Bovine Viral Diarrhea ◽  
Low Density ◽  
Diarrhea Virus ◽  
Viral Diarrhea ◽  
Viral Diarrhea Virus

ABSTRACT Among several proposed cellular receptors for bovine viral diarrhea virus (BVDV), the low-density lipoprotein (LDL) receptor is of special interest because it is also considered a receptor for the related hepatitis C virus. It has been reported that an anti-LDL receptor monoclonal antibody blocked the infection of bovine cells by BVDV and that the resistance of bovine CRIB cells (cells resistant to infection with BVDV) (E. F. Flores and R. O. Donis, Virology 208:565-575, 1995) to BVDV infection was due to a lack of the LDL receptor (V. Agnello et al., Proc. Natl. Acad. Sci. USA 96:12766-12771, 1999). In connection with our studies on BVDV entry, we reevaluated the putative role of the LDL receptor as a cellular receptor for BVDV. It was first clearly demonstrated that neither of two monoclonal antibodies against the LDL receptor inhibited BVDV infection of two bovine cell lines. Furthermore, the LDL receptor was detected on the surface of CRIB cells. The functionality of the LDL receptor on CRIB cells was demonstrated by the internalization of fluorescently labeled LDL. In conclusion, at present no experimental evidence supports an involvement of the LDL receptor in BVDV invasion.

scholarly journals Role of the Low Density Lipoprotein (LDL) Receptor Pathway in the Metabolism of Chylomicron Remnants

1996 ◽  
Vol 271 (37) ◽  
pp. 22422-22427 ◽  
Author(s):  
Shun Ishibashi ◽  
Stéphane Perrey ◽  
Zhong Chen ◽  
Jun-ichi Osuga ◽  
Masako Shimada ◽  
...  
Keyword(s):  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Low Density ◽  
Chylomicron Remnants
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