Search results for "Cholesterol"

A critical role for the cholesterol-associated proteolipids PLP and M6B in myelination of the central nervous system.

2012

The formation of central nervous system myelin by oligodendrocytes requires sterol synthesis and is associated with a significant enrichment of cholesterol in the myelin membrane. However, it is unknown how oligodendrocytes concentrate cholesterol above the level found in nonmyelin membranes. Here, we demonstrate a critical role for proteolipids in cholesterol accumulation. Mice lacking the most abundant myelin protein, proteolipid protein (PLP), are fully myelinated, but PLP-deficient myelin exhibits a reduced cholesterol content. We therefore hypothesized that "high cholesterol" is not essential in the myelin sheath itself but is required for an earlier step of myelin biogenesis that is f…

Human neuroblastoma SH-SY5Y cell line: neurosteroid-producing cell line relying on cytoskeletal organization.

2000

Pregnenolone, the precursor of all steroids, is synthesized by CNS structures. The synthesis requires an obligatory step involving cholesterol transport to mitochondrial cytochrome P450-cholesterol side chain cleavage (cytP450scc), although the underlying mechanism(s) are still mostly unknown. We used the human neuroblastoma SH-SY5Y cell line to investigate cytP450scc expression and activity and to establish a role of cytoskeleton in pregnenolone synthesis. Immunocytochemical and biochemical approaches revealed that undifferentiated as well as differentiated cells either by retinoic acid (RA) or phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), possess cytP450scc and rapidly synthes…

Oligomerization of Vibrio cholerae cytolysin yields a pentameric pore and has a dual specificity for cholesterol and sphingolipids in the target memb…

1999

Vibrio cholerae cytolysin permeabilizes animal cell membranes. Upon binding to the target lipid bilayer, the protein assembles into homo-oligomeric pores of an as yet unknown stoichiometry. Pore formation has been observed with model liposomes consisting of phosphatidylcholine and cholesterol, but the latter were much less susceptible to the cytolysin than were erythrocytes or intestinal epithelial cells. We here show that liposome permeabilization is strongly promoted if cholesterol is combined with sphingolipids, whereby the most pronounced effects are observed with monohexosylceramides and free ceramide. These two lipid species are prevalent in mammalian intestinal brush border membranes…

Sterols and Steroids

1994

Sterols and steroids, like the terpenes and carotinoids, are isoprene derivatives. The sterols are components of the membranes of all eukaryotic cells and they bind and condense the phospholipid bilayer. The outer cell membrane is particularly rich in sterols, with a molar ratio of sterols to phospholipids of 0.8–0.1, compared with the usual value of 0.1–0.3 for intracellular membranes. The parent substance of all sterols is cholesterol (Fig. 16.1). The sterols are classified with the steroid hormones and bile salts as steroids because they also have the gonan (formerly steran) four-ring system and have their biosynthetic origin in cholesterol. Steroids with hormonal functions are known fro…

Lp(a): a genetic cause of clinical FH in children

2022

No abstract available

Coupling of Cholesterol and Cone-shaped Lipids in Bilayers Augments Membrane Permeabilization by the Cholesterol-specific Toxins Streptolysin O and V…

2001

Abstract Vibrio cholerae cytolysin (VCC) forms oligomeric pores in lipid bilayers containing cholesterol. Membrane permeabilization is inefficient if the sterol is embedded within bilayers prepared from phosphatidylcholine only but is greatly enhanced if the target membrane also contains ceramide. Although the enhancement of VCC action is stereospecific with respect to cholesterol, we show here that no such specificity applies to the two stereocenters in ceramide; all four stereoisomers of ceramide enhanced VCC activity in cholesterol-containing bilayers. A wide variety of ceramide analogs were as effective asd-erythro-ceramide, as was diacylglycerol, suggesting that the effect of ceramide …

Il calcio coronarico è indipendentemente associato alla rigidità arteriosa e al cholesterol burden nei pazienti con ipercolesterolemia familiare

2021

Determination of cholesterol in human milk: an alternative to chromatographic methods

2015

Introduction: human milk (HM) is considered the best option for feeding healthy infants. Cholesterol (CHOL) is important for proper development of the nervous system, and for hormone and vitamin synthesis in growing infants. Breastfeeding and dietary CHOL intake during infancy have been suggested to affect blood lipid levels and the risk of cardiovascular disease in adulthood. Gas chromatography is the technique most widely used to determine CHOL in HM. Chromatographic methods are specific for the determination of CHOL and other sterols present in HM, but are extremely time consuming, and the costs and equipment requirements mean that they are not accessible to all laboratories. Aim: the pr…

Cholesterol reporter molecules.

2007

Cholesterol is a major constituent of the membranes in most eukaryotic cells where it fulfills multiple functions. Cholesterol regulates the physical state of the phospholipid bilayer, affects the activity of several membrane proteins, and is the precursor for steroid hormones and bile acids. Cholesterol plays a crucial role in the formation of membrane microdomains such as “lipid rafts” and caveolae. However, our current understanding on the membrane organization, intracellular distribution and trafficking of cholesterol is rather poor. This is mainly due to inherent difficulties to label and track this small lipid. In this review, we describe different approaches to detect cholesterol in …

Plasma non-cholesterol sterols: a useful diagnostic tool in pediatric hypercholesterolemia.

2010

Current guidelines strongly recommend the identification of genetic forms of hypercholesterolemia (HC) during childhood. The usefulness of non–cholesterol sterols (NCS) in the diagnosis of genetic HC has not been fully explored. Plasma NCS were measured by gas chromatography/mass spectrometry (GC/MS) in 113 children with hypercholesterolemia affected by: autosomal dominant hypercholesterolemia (ADH), familial combined hyperlipidemia (FCHL), polygenic hypercholesterolemia (PHC), and in 79 controls to evaluate: i) plasma NCS profile in different genetic HC and ii) the usefulness of NCS for the diagnosis of HC beyond current clinical criteria. ADH was characterized by raised lathosterol/total …