Psychosine enhances the shedding of membrane microvesicles: Implications in demyelination in Krabbe's disease

Area of Science:

• Neuroscience
• Cell Biology
• Biochemistry

Background:

• Krabbe disease is characterized by psychosine accumulation, which was previously shown to disrupt lipid rafts and signaling pathways crucial for oligodendrocyte survival.
• The precise mechanism by which psychosine causes demyelination, beyond lipid raft disruption, remained unclear.
• Understanding the direct impact of psychosine on membrane biophysics is essential for elucidating its role in Krabbe disease pathogenesis.

Purpose of the Study:

• To investigate how psychosine, a cationic lipid, affects the fluidity, stability, and structure of myelin and plasma membranes.
• To elucidate the role of direct membrane destabilization and microvesiculation in psychosine-induced demyelination in Krabbe disease.

Main Methods:

• Utilized advanced imaging techniques on red blood cell (non-myelinating) and oligodendrocyte (myelinating) cell models.
• Analyzed myelin membranes from Twitcher mice, a model organism for Krabbe disease.
• Measured membrane rigidity, psychosine levels, and microvesiculation.

Main Results:

• Psychosine disrupts sphingomyelin-enriched domains and increases localized plasma membrane rigidity.
• Psychosine promotes the shedding of membranous microvesicles from cells.
• Similar membrane rigidification and microvesiculation were observed in myelin from Twitcher mice, correlating with psychosine levels.

Conclusions:

• Psychosine's toxicity in Krabbe disease involves direct destabilization and fragmentation of cell membranes via microvesiculation, in addition to lipid raft disruption.
• This membrane disruption mechanism creates focal weak points in the myelin sheath, leading to demyelination.
• The findings propose a novel pathogenic mechanism for demyelination in Krabbe disease with potential implications for other leukodystrophies.