Lipid-Conjugated Rigidochromic Probe Discloses Membrane Alteration in Model Cells of Krabbe Disease

Gerardo Abbandonato, Barbara Storti, Ilaria Tonazzini, Martin Stöckl, Vinod Subramaniam, Costanza Montis, Riccardo Nifosì, Marco Cecchini, Giovanni Signore*, Ranieri Bizzarri

*Corresponding author for this work

    Research output: Contribution to JournalArticle

    Abstract

    The plasma membrane of cells has a complex architecture based on the bidimensional liquid-crystalline bilayer arrangement of phospho- and sphingolipids, which in turn embeds several proteins and is connected to the cytoskeleton. Several studies highlight the spatial membrane organization into more ordered (L o or lipid raft) and more disordered (L d ) domains. We here report on a fluorescent analog of the green fluorescent protein chromophore that, when conjugated to a phospholipid, enables the quantification of the L o and L d domains in living cells on account of its large fluorescence lifetime variation in the two phases. The domain composition is straightforwardly obtained by the phasor approach to confocal fluorescence lifetime imaging, a graphical method that does not require global fitting of the fluorescence decay in every spatial position of the sample. Our imaging strategy was applied to recover the domain composition in human oligodendrocytes at rest and under treatment with galactosylsphingosine (psychosine). Exogenous psychosine administration recapitulates many of the molecular fingerprints of a severe neurological disease, globoid cell leukodystrophy, better known as Krabbe disease. We found out that psychosine progressively destabilizes plasma membrane, as witnessed by a shrinking of the L o fraction. The unchanged levels of galactosyl ceramidase, i.e., the enzyme lacking in Krabbe disease, upon psychosine treatment suggest that psychosine alters the plasma membrane structure by direct physical effect, as also recently demonstrated in model membranes.

    Original languageEnglish
    Pages (from-to)477-486
    Number of pages10
    JournalBiophysical Journal
    Volume116
    Issue number3
    Early online date25 Dec 2018
    DOIs
    Publication statusPublished - 5 Feb 2019

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