Plasma membrane cholesterol content affects nitric oxide diffusion dynamics and signaling

Department of Chemistry and Biochemistry University of Windsor, Windsor Ontario N9B 3P4, Canada.
Journal of Biological Chemistry (Impact Factor: 4.6). 08/2008; 283(27):18513-21. DOI: 10.1074/jbc.M800440200
Source: PubMed

ABSTRACT Nitric oxide (NO) signaling is inextricably linked to both its physical and chemical properties. Due to its preferentially hydrophobic solubility, NO molecules tend to partition from the aqueous milieu into biological membranes. We hypothesized that plasma membrane ordering provided by cholesterol further couples the physics of NO diffusion with cellular signaling. Fluorescence lifetime quenching studies with pyrene liposome preparations showed that the presence of cholesterol decreased apparent diffusion coefficients of NO approximately 20-40%, depending on the phospholipid composition. Electrochemical measurements indicated that the diffusion rate of NO across artificial bilayer membranes were inversely related to cholesterol content. Sterol transport-defective Niemann-Pick type C1 (NPC1) fibroblasts exhibited increased plasma membrane cholesterol content but decreased activation of both intracellular soluble guanylyl cyclase and vasodilator-stimulated phosphoprotein (VASP) phosphorylation at Ser(239) induced by exogenous NO exposure relative to their normal human fibroblast (NHF) counterparts. Augmentation of plasma membrane cholesterol in NHF diminished production of both cGMP and VASP phosphorylation elicited by NO to NPC1-comparable levels. Conversely, decreasing membrane cholesterol in NPC1 resulted in the augmentation in both cGMP and VASP phosphorylation to a level similar to those observed in NHF. Increasing plasma membrane cholesterol contents in NHF, platelets, erythrocytes and tumor cells also resulted in an increased level of extracellular diaminofluorescein nitrosation following NO exposure. These findings suggest that the impact of cholesterol on membrane fluidity and microdomain structure contributes to the spatial heterogeneity of NO diffusion and signaling.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A number of experimental studies has documented that S-nitrosoglutathione (GSNO), the main endogenous low-molecular-weight S-nitrosothiol, can exert modulatory effects on inflammatory processes, thus supporting its potential employment in medicine for the treatment of important disease conditions. At molecular level, GSNO effects have been shown to modulate the activity of a series of transcription factors (notably NF-κB, AP-1, CREB and others) as well as other components of signal transduction chains (e.g. IKK-β, caspase 1, calpain and others), resulting in the modulation of several cytokines and chemokines expression (TNFα, IL-1β, IFN-γ, IL-4, IL-8, RANTES, MCP-1 and others). Results reported to date are however not univocal, and a single main mechanism of action for the observed anti-inflammatory effects of GSNO has not been identified. Conflicting observations can be explained by differences among the various cell types studies as to the relative abundance of enzymes in charge of GSNO metabolism (GSNO reductase, γ-glutamyltransferase, protein disulfide isomerase and others), as well as by variables associated with the individual experimental models employed. Altogether, anti-inflammatory properties of GSNO seem however to prevail, and exploration of the therapeutic potential of GSNO and analogues appears therefore warranted.
    Archives of Biochemistry and Biophysics 08/2014; 562. DOI:10.1016/ · 3.04 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Purpose: To investigate the effects of Bruch's membrane (BrM) neutral lipid deposition in mouse models and its significance to aging and age-related macular degeneration it is essential to reliable detect small quantities of neutral lipids including esterified cholesterol (EC). In chorioretinal sections and BrM wholemounts we tested a novel fluorescent cholesterol marker based on the bacterial toxin Perfringolysin O (PFO) and compared results to those obtained with the classic cholesterol dye filipin. Methods: An engineered plasmid containing the specific cholesterol binding domain (D4) of PFO fused to green fluorescent protein (GFP) was expressed in cultured E. coli, isolated, purified, and concentrated. A total of 150 BrM-choroid wholemounts and chorioretinal sections of 11 to 13-month-old ApoEnull mice were prepared and stained with PFO/D4-GFP or filipin for EC. Samples were examined by epifluorescence microscopy. Results: The fluorescence intensity of PFO/D4-GFP was strong, stable, and if small quantities of EC were present superior to filipin. In all specimens we could sharply locate the PFO/D4-GFP signal to BrM. A semi-quantitative evaluation of BrM lipid deposition is possible by measuring PFO/D4-GFP fluorescence intensity. Conclusions: PFO/D4-GFP allowed a robust and direct detection of EC in aged murine BrM. In wholemount samples its strong and stable fluorescence facilitated a semi-quantitative evaluation of BrM's EC content over a large area. The patterns of EC deposition in murine BrM wholemounts are comparable to findings in human BrM wholemounts. PFO/D4-GFP could be an important tool for investigating the effects of BrM lipid deposition in mouse models.
    Investigative Ophthalmology &amp Visual Science 07/2014; 55(8). DOI:10.1167/iovs.14-14311 · 3.66 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Cholesterol (CH) is a vital component of cell membranes and of their function. It is entirely justified to warn against haphazard aggressive CH lowering, especially now, when more effective CH-modifying medications are entering the market. Enormous success in lowering the human toll of atherosclerosis and cardiovascular disease (CVD) by treating abnormally elevated lipids may be off set by the therapeutic risk. There are warning reports that low cholesterol is associated with malignity. There is a pressing need to evaluate all reports related to the risk of low CH body stores. New cholesterol management guidelines presented by American professional cardiology societies in November 2013 have reinforced the need to critically evaluate the management with statins and with other CH lowering medications (Tab. 1, Fig. 3, Ref. 58). Keywords: total cholesterol (CH), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), cardiovascular disease (CVD), hydroxy-methylglutaryl coenzyme A reductase (HMGCR), randomized control trial (RCT), cancer, statin, low cholesterol risk, lipid treatment guideline.
    Bratislavske lekarske listy 01/2014; 115(2):59-65. DOI:10.4149/BLL_2014_013 · 0.45 Impact Factor


Available from
Sep 10, 2014