Search results for " Class B"
showing 10 items of 12 documents
Cholesterol trafficking and raft-like membrane domain composition mediate scavenger receptor class B type 1-dependent lipid sensing in intestinal epi…
2018
IF 5.547; International audience; Scavenger receptor Class B type 1 (SR-B1) is a lipid transporter and sensor. In intestinal epithelial cells, SR-B1-dependent lipid sensing is associated with SR-B1 recruitment in raft-like/ detergent-resistant membrane domains and interaction of its C-terminal transmembrane domain with plasma membrane cholesterol. To clarify the initiating events occurring during lipid sensing by SR-B1, we analyzed cholesterol trafficking and raft-like domain composition in intestinal epithelial cells expressing wild-type SR-B1 or the mutated form SR-B1-Q445A, defective in membrane cholesterol binding and signal initiation. These features of SR-B1 were found to influence bo…
Expression of host defense scavenger receptors in spondylarthropathy
2001
Objective Reactive arthritis (ReA) is postulated to be caused by a defective host defense against gram-negative bacteria. HLA–B27 could play a role in this process, but does not account for the many HLA–B27 negative patients. The objective of this study was to test the expression of 3 macrophage scavenger receptors (SRs) that are responsible for innate immunity against gram-negative bacteria: SR class A type I (SR-AI), SR-AII, and the macrophage receptor with collagenous structure (MARCO). We postulate that defects in such receptors might also contribute to the host risk factors that increase the predisposition to ReA and perhaps other subtypes of spondylarthropathy (SpA). Methods Periphera…
Intestinal Scavenger Receptors Are Involved in Vitamin K 1 Absorption
2014
International audience; Vitamin K-1 (phylloquinone) intestinal absorption is thought to be mediated by a carrier protein that still remains to be identified. Apical transport of vitamin K-1 was examined using Caco-2 TC-7 cell monolayers as a model of human intestinal epithelium and in transfected HEK cells. Phylloquinone uptake was then measured ex vivo using mouse intestinal explants. Finally, vitamin K-1 absorption was compared between wild-type mice and mice overexpressing scavenger receptor class B type I (SR-BI) in the intestine and mice deficient in cluster determinant 36 (CD36). Phylloquinone uptake by Caco-2 cells was saturable and was significantly impaired by co-incubation with al…
Upregulation of liver VLDL receptor and FAT/CD36 expressions in LDLR-/- apoB100/100 mice fed trans-10,cis-12 conjugated linoleic acid
2006
International audience; This study explores the mechanisms responsible for the fatty liver setup in mice fed trans-10,cis-12 conjugated linoleic acid (t10c12 CLA), hypothesizing that an induction of low density lipoprotein receptor (LDLR) expression is associated with lipid accumulation. To this end, the effects of t10c12 CLA treatment on lipid parameters, serum lipoproteins, and expression of liver lipid receptors were measured in LDLR(-/-) apoB(100/100) mice as a model of human familial hypercholesterolemia itself depleted of LDLR. Mice were fed t10c12 CLA over 2 or 4 weeks. We first observed that the treatment induced liver steatosis, even in the absence of LDLR. Mice treated for 2 weeks…
A novel member of an ancient superfamily: sponge (Geodia cydonium, Porifera) putative protein that features scavenger receptor cysteine-rich repeats
1997
Proteins featuring scavenger receptor cysteine-rich (SRCR) domains are prominent receptors known from vertebrates and from one phylum of invertebrates, the echinoderms. In the present study we report the first putative SRCR protein from the marine sponge Geodia cydonium (Porifera), a member of the lowest phylum of contemporary Metazoans. Two forms of SRCR molecules were characterized, which apparently represent alternative splicing of the same transcript. The long putative SRCR protein, of 1536 aa, features twelve SRCR repeats, a C-terminal transmembrane domain and a cytoplasmic tail. The sequence of the short form is identical with the long form except that it lacks a coding region near th…
Incidence of Hepatocellular Carcinoma in Patients With HCV-Associated Cirrhosis Treated With Direct-Acting Antiviral Agents.
2018
Background & Aims: Studies have produced conflicting results of the incidence of hepatocellular carcinoma (HCC) in patients with hepatitis C virus–associated cirrhosis treated with direct-acting antivirals (DAAs). Data from clinics are needed to accurately assess the occurrence rate of HCC in patients with cirrhosis in the real world. Methods: We collected data from a large prospective study of 2,249 consecutive patients (mean age = 65.4 years, 56.9% male) with hepatitis C virus–associated cirrhosis (90.5% with Child-Pugh class A and 9.5% with Child-Pugh class B) treated with DAAs from March 2015 through July 2016 at 22 academic and community liver centers in Sicily, Italy. HCC occurren…
The putative sponge aggregation receptor. Isolation and characterization of a molecule composed of scavenger receptor cysteine-rich domains and short…
1998
Porifera (sponges) are the oldest extant metazoan phylum. Dissociated sponge cells serve as a classic system to study processes of cell reaggregation. The reaggregation of dissociated cells is mediated by an extracellularly localized aggregation factor (AF), based on heterophilic interactions of the third order; the AF bridges two cells by ligating a cell-surface-bound aggregation receptor (AR). In the present study we report cloning, expression and immunohistochemical localization of a polypeptide from the marine sponge Geodia cydonium, which very likely represents the AR. The presumed AR gene gives rise to at least three forms of alternatively spliced transcripts of 6.5, 4.9 and 3.9 kb, a…
Lipid and apoprotein composition of HDL in partial or complete CETP deficiency
2012
Hyperalphalipoproteinemia, as observed in patients who are either homozygous or heterozygous for cholesteryl ester transfer protein (CETP) deficiency, has been shown to be associated with striking changes in apolipoprotein size distribution, namely, of high-density lipoprotein (HDL) and HDL-like particles. We compared the effect of varying degrees of CETP activity on the HDL apolipoprotein profile in Caucasian CETP-deficient subjects and following pharmacological decrease in CETP activity, using Size Exclusion Chromatography followed by Reverse Phase Protein Array (SEC RPA). The main HDL-associated apolipoproteins (Apo), i.e. ApoA-I, ApoA-II, ApoC-I, and ApoC-III, co-eluted with the HDL pea…
On the pathogenesis of atherosclerosis: enzymatic transformation of human low density lipoprotein to an atherogenic moiety.
1995
Combined treatment with trypsin, cholesterol esterase, and neuraminidase transforms LDL, but not HDL or VLDL, to particles with properties akin to those of lipid extracted from atherosclerotic lesions. Single or double enzyme modifications, or treatment with phospholipase C, or simple vortexing are ineffective. Triple enzyme treatment disrupts the ordered and uniform structure of LDL particles, and gives rise to the formation of inhomogeneous lipid droplets 10-200 nm in diameter with a pronounced net negative charge, but lacking significant amounts of oxidized lipid. Enzymatically modified LDL (E-LDL), but not oxidatively modified LDL (ox-LDL), is endowed with potent complement-activating c…
Iron Induces Proliferation and Morphogenesis in Primmorphs from the Marine SpongeSuberites domuncula
2002
Dissociated cells from marine demosponges retain their proliferation capacity if they are allowed to form special aggregates, the primmorphs. On the basis of incorporation studies and septin gene expression, we show that Fe3+ ions are required for the proliferation of cells in primmorphs from Suberites domuncula. In parallel, Fe3+ induced the expression of ferritin and strongly stimulated the synthesis of spicules. This result is supported by the finding that the enzymatic activity of silicatein, converting organosilicon to silicic acid, depends on Fe3+. Moreover, the expression of a scavenger receptor molecule, possibly involved in the morphology of spicules, depends on the presence of Fe3…