title: Plasma membrane cholesterol content affects nitric oxide diffusion dynamics and signaling.
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.
authors.affiliation: Department of Chemistry and Biochemistry University of Windsor, Windsor Ontario N9B 3P4, Canada.
authors.forename: Shane
authors.initials: S
authors.lastname: Miersch
authors.forename: Michael Graham
authors.initials: MG
authors.lastname: Espey
authors.forename: Ruchi
authors.initials: R
authors.lastname: Chaube
authors.forename: Arzu
authors.initials: A
authors.lastname: Akarca
authors.forename: Rodney
authors.initials: R
authors.lastname: Tweten
authors.forename: Sirinart
authors.initials: S
authors.lastname: Ananvoranich
authors.forename: Bulent
authors.initials: B
authors.lastname: Mutus
mesh_terms: D001792:Blood Platelets / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000378:metabolism; D045744:Cell Line, Tumor; D002784:Cholesterol / Q000378:metabolism*; D004058:Diffusion; D004563:Electrochemistry; D004912:Erythrocytes / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism* / Q000473:pathology; D006162:Guanylate Cyclase / Q000378:metabolism; D006801:Humans; D008560:Membrane Fluidity; D021962:Membrane Microdomains / Q000378:metabolism* / Q000473:pathology; D008840:Microfilament Proteins / Q000378:metabolism; D009542:Niemann-Pick Diseases / Q000378:metabolism / Q000473:pathology; D009569:Nitric Oxide / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D015398:Signal Transduction; D000098662:Vasodilator-Stimulated Phosphoprotein
chemical_list: D015815:Cell Adhesion Molecules; D008840:Microfilament Proteins; D010750:Phosphoproteins; D000098662:Vasodilator-Stimulated Phosphoprotein; D009569:Nitric Oxide; D002784:Cholesterol; D006162:Guanylate Cyclase