title: Fluorescence-topographic NSOM directly visualizes peak-valley polarities of GM1/GM3 rafts in cell membrane fluctuations.
abstract: Simultaneous fluorescence-topographic nanoscale imaging of cell-surface molecules in the context of membrane ultra-structures has not been reported. Here, near-field scanning optical microscopy (NSOM)-based direct fluorescence-topographic imaging indicated that GM3 rafts/nanodomains (190.0 +/- 49.8 nm ranging 84.5-365.0 nm) were localized predominantly on the peaks of microvillus-like protrusions in the apical membrane of GM3 + Madin-Darby canine kidney cells, whereas GM1 rafts/nanodomains (159.5 +/- 63.8 nm ranging 42-360 nm) were distributed mainly on the slops of protrusions or the valleys between protrusions in the plasma membranes of GM1 + MDCK cells. The data demonstrated that gangliosides polarized not only in a well-known apical-basolateral manner but also in the more microscopic peak-valley manner, implicating unique distribution of GM1 or GM3 in cell-surface fluctuations on the apical membrane of polarized cells. The peak-valley polarities of gangliosides also implicated their different functions relevant to lipid rafts, microvilli, or cellular processes. Importantly, our study demonstrated for the first time that the NSOM-based direct fluorescence-topographic imaging is unique and powerful for elucidating nanoscale distribution of specific cell-surface molecules in membrane fluctuations.
authors.affiliation: Department of Microbiology and Immunology, Center for Primate Biomedical Research, University of Illinois College of Medicine, Chicago, Illinois, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Chen
authors.forename: Jie
authors.initials: J
authors.lastname: Qin
authors.forename: Zheng W
authors.initials: ZW
authors.lastname: Chen
mesh_terms: D000818:Animals; D002417:Cattle; D002460:Cell Line; D005453:Fluorescence; D005677:G(M1) Ganglioside / Q000737:chemistry*; D005679:G(M3) Ganglioside / Q000737:chemistry*; D018796:Immunoconjugates / Q000378:metabolism; D021962:Membrane Microdomains / Q000737:chemistry* / Q000378:metabolism; D051379:Mice; D008853:Microscopy; D018613:Microscopy, Confocal; D055095:Optics and Photonics; D010316:Particle Size; D045663:Quantum Dots; D013997:Time Factors
chemical_list: D005679:G(M3) Ganglioside; D018796:Immunoconjugates; D005677:G(M1) Ganglioside