Abstract
ABSTRACTLipid phase heterogeneity in plasma membranes is thought to play a key role in targeting cellular signaling, but efforts to test lipid raft and related hypotheses are limited by the spatially dynamic nature of these phase-based structures in cells and by experimental characterization tools. We suggest that perturbation of plasma membrane structure by lipid derivatives offers a general method for assessing functional roles for ordered lipid regions in membrane and cell biology. We previously reported that short chain ceramides with either C2 or C6 acyl chains inhibit antigen-stimulated Ca2+ mobilization (Gidwani et al., 2003). We now show that these short chain ceramides inhibit liquid order (Lo)-liquid disorder (Ld) phase separation in giant plasma membrane vesicles that normally occurs at low temperatures. Furthermore, they are effective inhibitors of tyrosine phosphorylation stimulated by antigen, as well as store-operated Ca2+ entry. In Jurkat T cells, C6-ceramide is also effective at inhibiting Ca2+ mobilization stimulated by either anti-TCR or thapsigargin, consistent with the view that these short chain ceramides effectively interfere with functional responses that depend on ordered lipid regions in the plasma membrane.
Highlights
The biological relevance of lipid phase-like properties in the plasma membrane, including ordered lipid domains (‘lipid rafts’), has been controversial (Munro, 2003), strong evidence supports the general consensus that such lipid-based heterogeneity participates in many aspects of cell biology involving the plasma membrane
We previously showed that C2- and C6- short chain ceramides decrease the degree of lipid order, as measured by fluorescence anisotropy, in plasma membrane vesicles derived from rat basophilic leukemia (RBL) mast cells, and increase the distance between liquid order (Lo)-preferring proteins, as measured by fluorescence resonance energy transfer (FRET) in intact cells
Because our previous results suggested that the short chain ceramides, C2- and C6- (Fig. 1), inhibit Ca2+ mobilization by interfering with ordered lipid membrane structure, we examined their effects on the Lo/liquid disorder (Ld)-like phase separation that occurs in giant plasma membrane vesicles (GPMVs) derived from RBL mast cells following treatment to induce their formation and detachment from the plasma membrane skeleton (Baumgart et al, 2007)
Summary
The biological relevance of lipid phase-like properties in the plasma membrane, including ordered lipid domains (‘lipid rafts’), has been controversial (Munro, 2003), strong evidence supports the general consensus that such lipid-based heterogeneity participates in many aspects of cell biology involving the plasma membrane (for recent review see Sezgin et al, 2017). Using a wide range of experimental approaches in a mast cell model system, we established a consistent mechanism by which antigen-crosslinked IgE/FcεRI complexes associate with liquid order (Lo)-preferring lipids, thereby stabilizing raft-like structures that preferentially include membrane-anchored Lyn tyrosine kinase and exclude transmembrane tyrosine phosphatases (Holowka et al, 2005).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
