scholarly journals Endocytosis of hyaluronic acid by rat liver endothelial cells. Evidence for receptor recycling

1989 ◽  
Vol 257 (3) ◽  
pp. 875-884 ◽  
Author(s):  
C T McGary ◽  
R H Raja ◽  
P H Weigel
Keyword(s):  
Endothelial Cells ◽  
Hyaluronic Acid ◽  
Rat Liver ◽  
Chondroitin Sulphate ◽  
Binding Capacity ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Receptor Recycling ◽  
Density Lipoprotein Receptor ◽  
Liver Endothelial Cells

Hyaluronic acid (HA) is cleared from the blood by liver endothelial cells through receptor-mediated endocytosis [Eriksson, Fraser, Laurent, Pertoft & Smedsrod (1983) Exp. Cell Res. 144, 223-238]. We have measured the capacity of cultured rat liver endothelial cells to endocytose and degrade 125I-HA (Mr approximately 44,000) at 37 degrees C. Endocytosis was linear for 3 h and then reached a plateau. The rate of endocytosis was concentration-dependent and reached a maximum of 250 molecules/s per cell. Endocytosis of 125I-HA was inhibited more than 92% by a 150-fold excess of non-radiolabelled HA. HA, chondroitin sulphate and heparin effectively competed for endocytosis of 125I-HA, whereas glucuronic acid, N-acetylglucosamine, DNA, RNA, polygalacturonic acid and dextran did not compete. In the absence of cycloheximide, endothelial cells processed 13 times more 125I-HA in 6 h than their total (cell-surface and intracellular) specific HA-binding capacity. This result was not due to degradation and rapid replacement of receptors, because, even in the presence of cycloheximide, these cells processed 6 times more HA than their total receptor content in 6 h. Also, in the presence of cycloheximide, no decrease in 125I-HA-binding capacity was seen in cells processing or not processing HA for 6 h, indicating that receptors are not degraded after the endocytosis of HA. During endocytosis of HA at 37 degrees C, at least 65% of the intracellular HA receptors became occupied with HA within 30 min. This indicates that the intracellular HA receptors (75% of the total) function during continuous endocytosis. Hyperosmolarity inhibits endocytosis and receptor recycling in the asialoglycoprotein and low-density-lipoprotein receptor systems by disrupting the coated-pit pathway [Heuser & Anderson (1987) J. Cell Biol. 105, 230a; Oka & Weigel (1988) J. Cell. Biochem. 36, 169-183]. Hyperosmolarity inhibited 125I-HA endocytosis in liver endothelial cells by more than 90%, suggesting use of a coated-pit pathway by this HA receptor. We conclude that liver endothelial cell HA receptors are recycled during the continuous endocytosis and processing of HA.

scholarly journals Theranostic Design of Angiopep-2 Conjugated Hyaluronic Acid Nanoparticles (Thera-ANG-cHANPs) for Dual Targeting and Boosted Imaging of Glioma Cells

Cancers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 503
Author(s):  
Angela Costagliola di Polidoro ◽  
Giorgia Zambito ◽  
Joost Haeck ◽  
Laura Mezzanotte ◽  
Martine Lamfers ◽  
...  
Keyword(s):  
Hyaluronic Acid ◽  
Clinical Care ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Glioma Cells ◽  
Drug Molecules ◽  
Dual Targeting ◽  
Density Lipoprotein Receptor ◽  
Targeting Peptide

Glioblastoma multiforme (GBM) has a mean survival of only 15 months. Tumour heterogeneity and blood-brain barrier (BBB) mainly hinder the transport of active agents, leading to late diagnosis, ineffective therapy and inaccurate follow-up. The use of hydrogel nanoparticles, particularly hyaluronic acid as naturally occurring polymer of the extracellular matrix (ECM), has great potential in improving the transport of drug molecules and, furthermore, in facilitatating the early diagnosis by the effect of hydrodenticity enabling the T1 boosting of Gadolinium chelates for MRI. Here, crosslinked hyaluronic acid nanoparticles encapsulating gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) and the chemotherapeutic agent irinotecan (Thera-cHANPs) are proposed as theranostic nanovectors, with improved MRI capacities. Irinotecan was selected since currently repurposed as an alternative compound to the poorly effective temozolomide (TMZ), generally approved as the gold standard in GBM clinical care. Also, active crossing and targeting are achieved by theranostic cHANPs decorated with angiopep-2 (Thera-ANG-cHANPs), a dual-targeting peptide interacting with low density lipoprotein receptor related protein-1(LRP-1) receptors overexpressed by both endothelial cells of the BBB and glioma cells. Results showed preserving the hydrodenticity effect in the advanced formulation and internalization by the active peptide-mediated uptake of Thera-cHANPs in U87 and GS-102 cells. Moreover, Thera-ANG-cHANPs proved to reduce ironotecan time response, showing a significant cytotoxic effect in 24 h instead of 48 h.

scholarly journals Endocytosis of formaldehyde-treated serum albumin via scavenger pathway in liver endothelial cells

1984 ◽  
Vol 218 (1) ◽  
pp. 81-86 ◽  
Author(s):  
R Blomhoff ◽  
W Eskild ◽  
T Berg
Keyword(s):  
Endothelial Cells ◽  
Low Density Lipoprotein ◽  
Scavenger Receptor ◽  
Density Lipoprotein ◽  
Low Density ◽  
Surface Culture ◽  
Rat Liver Cells ◽  
Liver Endothelial Cells ◽  
Isolated Liver

Denatured or modified proteins (including albumin and low-density lipoprotein) are catabolized in vitro via scavenger receptors. We have studied the distribution of formaldehyde-denatured albumin in rat liver cells after intravenous injection of tracer doses of the protein. At 12 min after injection, most of the formaldehyde-denatured albumin (about 70% of the injected dose) was recovered in liver endothelial cells. Furthermore, isolated liver endothelial cells in suspension and in surface culture took up formaldehyde-denatured albumin by receptor-mediated endocytosis. Our data indicate that the scavenger receptor in liver is mainly located on the endothelial cells. Implications for the catabolism of low-density lipoproteins are discussed.

Upregulation of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) in endothelial cells by nitric oxide deficiency

2004 ◽  
Vol 287 (1) ◽  
pp. F25-F32 ◽  
Author(s):  
I. V. Smirnova ◽  
T. Sawamura ◽  
M. S. Goligorsky
Keyword(s):  
Nitric Oxide ◽  
Renal Failure ◽  
Endothelial Cells ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Common Denominator ◽  
Low Density ◽  
Lipoprotein Receptor ◽  
Low Density Lipoprotein Receptor ◽  
Density Lipoprotein Receptor

Endothelial cell dysfunction (ECD) is emerging as a common denominator for diverse cardiovascular abnormalities associated with inhibition of endothelial nitric oxide (NO) synthase (eNOS). Elevated levels of asymmetric dimethylarginine (ADMA), a potent eNOS inhibitor, are common in renal failure and may contribute to ECD. Through DNA microarray screening of genes modulated in human umbilical vein endothelial cells (HUVEC) by NG-nitro-l-arginine methyl ester (l-NAME), we found a 1.8-fold increase in low-density lipoprotein receptor-1 (LOX-1) expression. LOX-1 is a major endothelial receptor for oxidized low-density lipoproteins (OxLDL) and is assumed to play a role in the initiation and progression of atherosclerosis. Here, we confirmed the upregulation of LOX-1 mRNA and protein level by quantitative RT-PCR and Western blot analysis. Increased expression of LOX-1 was associated with the accumulation of DiI-labeled OxLDL (DiI-OxLDL) in ADMA- and l-NAME-pretreated HUVEC. To evaluate the contribution of LOX-1 in ADMA-induced accumulation of OxLDL by HUVEC, we used the competitive receptor inhibitor, soluble LOX-1. Treatment of HUVEC with soluble LOX-1 was associated with an approximately two- to threefold inhibition of DiI-OxLDL uptake in l-NAME- or ADMA-treated HUVEC. In conclusion, ADMA- or l-NAME-induced NO deficiency leads to the increased expression of LOX-1 mRNA and protein in HUVEC, which in turn results in the accumulation of OxLDL. Competition with LOX-1-soluble extracellular domain reduces OxLDL accumulation. In summary, elevated ADMA levels, i.e., in patients with renal failure, may be responsible for endothelial accumulation of OxLDL via upregulated LOX-1 receptor, thus contributing to endothelial lipidosis and dysfunction.

scholarly journals HIV-1 Tat Regulates Occludin and AβTransfer Receptor Expression in Brain Endothelial Cells via Rho/ROCK Signaling Pathway

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Yanlan Chen ◽  
Wen Huang ◽  
Wenlin Jiang ◽  
Xianghong Wu ◽  
Biao Ye ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Signaling Pathway ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Receptor Expression ◽  
Immunofluorescent Staining ◽  
Mrna Levels ◽  
Protein Levels ◽  
Density Lipoprotein Receptor ◽  
Hiv 1

HIV-1 transactivator protein (Tat) has been shown to play an important role in HIV-associated neurocognitive disorders. The aim of the present study was to evaluate the relationship between occludin and amyloid-beta (Aβ) transfer receptors in human cerebral microvascular endothelial cells (hCMEC/D3) in the context of HIV-1-related pathology. The protein expressions of occludin, receptor for advanced glycation end products (RAGE), and low-density lipoprotein receptor-related protein 1 (LRP1) in hCMEC/D3 cells were examined using western blotting and immunofluorescent staining. The mRNA levels of occludin, RAGE, and LRP1 were measured using quantitative real-time polymerase chain reaction. HIV-1 Tat at 1 µg/mL and the Rho inhibitor hydroxyfasudil (HF) at 30 µmol/L, with 24 h exposure, had no significant effect on hCMEC/D3 cell viability. Treatment with HIV-1 Tat protein decreased mRNA and protein levels of occludin and LRP1 and upregulated the expression of RAGE; however, these effects were attenuated by HF. These data suggest that the Rho/ROCK signaling pathway is involved in HIV-1 Tat-mediated changes in occludin, RAGE, and LRP1 in hCMEC/D3 cells. HF may have a beneficial influence by protecting the integrity of the blood-brain barrier and the expression of Aβtransfer receptors.

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