Cutting edge: optical microspectrophotometry supports the existence of gel phase lipid rafts at the lamellipodium of neutrophils: apparent role in calcium signaling.
Although much progress has been made in elucidating the biochemical properties of lipid rafts, there has been less success in identifying these structures within living cell membranes, which has led to some concern regarding their existence. One difficulty in analyzing lipid rafts using optical microscopy is their small size. We now test the existence of lipid rafts in polarized neutrophils, which redistribute lipid raft markers into comparatively large lamellipodia. Optical microspectrophotometry of Laurdan-labeled neutrophils revealed a large blue shift at lamellipodia relative to cell bodies. This blue shift disappeared after exposure to methyl-beta-cyclodextrin (m beta CD), which disrupts lipid rafts. The Ca(2+) channel transient receptor potential-like channel-1, a lipid raft marker, traffics to lamellipodia, but redistributes uniformly about cells after exposure to m beta CD. This is accompanied by disruption of Ca(2+) waves normally initiated at lamellipodia. Thus, m beta CD-sensitive lipid-ordered domains are present at and participate in signaling from the lamellipodia of living neutrophils.
Kindzelskii
Andrei L
AL
Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, Ann Arbor, MI 48105, USA.
Sitrin
Robert G
RG
Petty
Howard R
HR
D015415:Biomarkers / Q000097:blood; D015220:Calcium Channels / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D016764:Cell Polarity / Q000502:physiology; D003505:Cyclodextrins / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000378:metabolism; D005679:G(M3) Ganglioside / Q000378:metabolism; D005782:Gels; D021962:Membrane Microdomains / Q000187:drug effects / Q000502:physiology*; D008856:Microscopy, Fluorescence / Q000379:methods; D015591:Microspectrophotometry / Q000379:methods; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D009904:Optical Rotation; D044367:Phase Transition; D011554:Pseudopodia / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D050052:TRPC Cation Channels; D047392:beta-Cyclodextrins
D015415:Biomarkers; D015220:Calcium Channels; D003505:Cyclodextrins; D005456:Fluorescent Dyes; D005679:G(M3) Ganglioside; D005782:Gels; D050052:TRPC Cation Channels; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; C096351:transient receptor potential cation channel, subfamily C, member 1