scholarly journals Why Is Very High Cholesterol Content Beneficial for the Eye Lens but Negative for Other Organs?

Nutrients ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 1083 ◽  
Author(s):  
Justyna Widomska ◽  
Witold K. Subczynski
Keyword(s):  
Cell Membranes ◽  
Plasma Membranes ◽  
Pathological Condition ◽  
Cholesterol Content ◽  
Phospholipid Bilayer ◽  
Human Lens ◽  
Lens Fiber Cell ◽  
Cholesterol Crystals ◽  
Pure Cholesterol ◽  
Cholesterol Solubility

The plasma membranes of the human lens fiber cell are overloaded with cholesterol that not only saturates the phospholipid bilayer of these membranes but also leads to the formation of pure cholesterol bilayer domains. Cholesterol level increases with age, and for older persons, it exceeds the cholesterol solubility threshold, leading to the formation of cholesterol crystals. All these changes occur in the normal lens without too much compromise to lens transparency. If the cholesterol content in the cell membranes of other organs increases to extent where cholesterol crystals forma, a pathological condition begins. In arterial cells, minute cholesterol crystals activate inflammasomes, induce inflammation, and cause atherosclerosis development. In this review, we will indicate possible factors that distinguish between beneficial and negative cholesterol action, limiting cholesterol actions to those performed through cholesterol in cell membranes and by cholesterol crystals.

scholarly journals Proteomics and Phosphoproteomics Analysis of Human Lens Fiber Cell Membranes

2013 ◽  
Vol 54 (2) ◽  
pp. 1135 ◽  
Author(s):  
Zhen Wang ◽  
Jun Han ◽  
Larry L. David ◽  
Kevin L. Schey
Keyword(s):  
Cell Membranes ◽  
Fiber Cell ◽  
Human Lens ◽  
Lens Fiber ◽  
Lens Fiber Cell

Stability of shark and human lens fiber cell membranes

1982 ◽  
Vol 73 (4) ◽  
pp. 791-796
Author(s):  
Seymour Zigman ◽  
Teresa Paxhia ◽  
Blenda Antonellis
Keyword(s):  
Cell Membranes ◽  
Fiber Cell ◽  
Human Lens ◽  
Lens Fiber ◽  
Lens Fiber Cell

scholarly journals Cholesterol Bilayer Domains in the Eye Lens Health: A Review

2017 ◽  
Vol 75 (3-4) ◽  
pp. 387-398 ◽  
Author(s):  
Justyna Widomska ◽  
Witold K. Subczynski ◽  
Laxman Mainali ◽  
Marija Raguz
Keyword(s):  
Physical Properties ◽  
Age Groups ◽  
Phospholipid Composition ◽  
Cholesterol Content ◽  
Fiber Cell ◽  
Cholesterol Concentration ◽  
Human Lens ◽  
Eye Lens ◽  
Lens Fiber Cell ◽  
Age Related

Abstract The most unique biochemical characteristic of the eye lens fiber cell plasma membrane is its extremely high cholesterol content, the need for which is still unclear. It is evident, however, that the disturbance of Chol homeostasis may result in damages associated with cataracts. Electron paramagnetic resonance methods allow discrimination of two types of lipid domains in model membranes overloaded with Chol, namely, phospholipid-cholesterol domains and pure Chol bilayer domains. These domains are also detected in human lens lipid membranes prepared from the total lipids extracted from lens cortices and nuclei of donors from different age groups. Independent of the age-related changes in phospholipid composition, the physical properties of phospholipid-Chol domains remain the same for all age groups and are practically identical for cortical and nuclear membranes. The presence of Chol bilayer domains in these membranes provides a buffering capacity for cholesterol concentration in the surrounding phospholipid-Chol domains, keeping it at a constant saturating level and thus keeping the physical properties of the membrane consistent with and independent of changes in phospholipid composition. It seems that the presence of Chol bilayer domains plays an integral role in the regulation of cholesterol-dependent processes in fiber cell plasm membranes and in the maintenance of fiber cell membrane homeostasis.

Lipids of human lens fiber cell membranes

1984 ◽  
Vol 3 (7) ◽  
pp. 887-896 ◽  
Author(s):  
S. Zigman ◽  
T. Paxhia ◽  
G. Marinetti ◽  
S. Girsch
Keyword(s):  
Cell Membranes ◽  
Fiber Cell ◽  
Human Lens ◽  
Lens Fiber ◽  
Lens Fiber Cell

Regional variation in HDL metabolism in human fat cells: effect of cell size

1987 ◽  
Vol 252 (5) ◽  
pp. E654-E659 ◽  
Author(s):  
J. P. Despres ◽  
B. S. Fong ◽  
P. Julien ◽  
J. Jimenez ◽  
A. Angel
Keyword(s):  
Cell Size ◽  
Cellular Uptake ◽  
Plasma Membranes ◽  
Cholesterol Content ◽  
Cholesterol Concentration ◽  
Fat Cells ◽  
Obese Patients ◽  
Adipocyte Size ◽  
Fat Cell ◽  
Omental Fat

Abdominal obesity is related to reduced plasma high-density lipoprotein (HDL) cholesterol, and both are associated with cardiovascular disease risk. We have observed that plasma membranes from abdominal subcutaneous adipocytes have a greater HDL binding capacity than omental fat cell plasma membranes. The present study examined whether these binding characteristics could be due to differences in fat cell size or cholesterol concentration between the two adipose depots. Abdominal subcutaneous and deep omental fat were obtained from massively obese patients at surgery. Subcutaneous abdominal fat cells were significantly larger and their cellular cholesterol content greater than omental adipocytes. The uptake of HDL by collagenase-isolated fat cells was studied by incubating the cells for 2 h at 37 degrees C with 10 micrograms/ml 125I-HDL2 or 125I-HDL3. In both depots, the cellular uptake of 125I-HDL2 and 125I-HDL3 was specifically inhibited by addition of 25-fold excess unlabeled HDL and a close correlation was observed between the cellular uptake of 125I-HDL2 and 125I-HDL3. In obese patients, the uptake of 125I-HDL was higher in subcutaneous cells than in omental cells [5.85 +/- 0.53 vs. 2.74 +/- 0.30 pmol X 2 h-1. (10(6) cells)-1]. The cellular 125I-HDL uptake was significantly correlated with adipocyte size and fat cell cholesterol content but not with adipocyte cholesterol concentration. These results suggest that the higher HDL uptake observed in subcutaneous cells compared with omental cells in obesity is the result of differences in adipocyte size rather than differences in the cholesterol concentration (cholesterol-to-triglyceride ratio).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Identification of the glucose transporter in mammalian cell membranes with a125I-forskolin photoaffinity label

1988 ◽  
Vol 255 (3) ◽  
pp. 983-990 ◽  
Author(s):  
B E Wadzinski ◽  
M F Shanahan ◽  
R B Clark ◽  
A E Ruoho
Keyword(s):  
Smooth Muscle ◽  
Molecular Mass ◽  
Mammalian Cell ◽  
Cell Membranes ◽  
Plasma Membranes ◽  
Glucose Transporter ◽  
Apparent Molecular Mass ◽  
Synaptic Membranes ◽  
Placental Membranes ◽  
Adipocyte Plasma Membranes

The glucose transporter has been identified in a variety of mammalian cell membranes using a photoactivatable carrier-free radioiodinated derivative of forskolin, 3-[125I]iodo-4-azidophenethylamido-7-O-succinyldeacetylforskoli n ([125I]IAPS-forskolin) at 1-3 nM. The membranes that were photolabelled with [125I]IAPS-forskolin were human placental membranes, rat cortical and cerebellar synaptic membranes, rat cardiac sarcolemmal membranes, rat adipocyte plasma membranes, smooth-muscle membranes, and S49 wild-type (WT) lymphoma-cell membranes. The glucose transporter in plasma membranes prepared from the insulin-responsive rat cardiac sarcolemmal cells, rat adipocytes and smooth-muscle cells were determined to be approx. 45 kDa by SDS/polyacrylamide-gel electrophoresis (PAGE). Photolysis of human placental membranes, rat cortical and cerebellar synaptic membranes, and WT lymphoma membranes with [125I]-IAPS-forskolin, followed by SDS/PAGE, indicated specific derivatization of a broad band (43-55 kDa) in placental membranes and a narrower band (approx. 45 kDa) in synaptic membranes and WT lymphoma membranes. Digestion of the [125I]IAPS-forskolin-labelled placental and WT lymphoma membranes with endo-beta-galactosidase showed a reduction in the apparent molecular mass of the radiolabelled band to approx. 40 kDa. The membranes that were photolabelled with [125I]IAPS-forskolin and trypsin-treated produced a radiolabelled proteolytic fragment with an apparent molecular mass of 18 kDa. [125I]IAPS-forskolin is a highly effective probe for identifying low levels of glucose transporters in mammalian tissues.

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