Pathological levels of glucosylceramide change the biophysical properties of artificial and cell membranes

Abstract

Glucosylceramide (GlcCer) plays an active role in the regulation of various cellular events. Moreover, GlcCer is also a key modulator of membrane biophysical properties, which might be linked to the mechanism of its biological action. In order to understand the biophysical implications of GlcCer on membranes of living cells, we first studied the effect of GlcCer on artificial membranes containing 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), sphingomyelin (SM) and cholesterol (Chol). Using an array of biophysical methods, we demonstrate that at lower GlcCer/Chol ratios, GlcCer stabilizes SM/Chol-enriched liquid-ordered domains. However, upon decreasing the Chol content, GlcCer significantly increased membrane order through the formation of gel domains. Changes in pH disturbed the packing properties of GlcCer-containing membranes, leading to an increase in membrane fluidity and reduced membrane electronegativity. To address the biophysical impact of GlcCer in biological membranes, studies were performed in wild type and in fibroblasts treated with conduritol-B-epoxide (CBE), which causes intracellular GlcCer accumulation, and in fibroblasts from patients with type I Gaucher disease (GD). Decreased membrane fluidity was observed in cells containing higher levels of GlcCer, such as in CBE-treated and GD cells. Together, we demonstrate that elevated GlcCer levels change the biophysical properties of cellular membranes, which might compromise membrane-associated cellular events and be of relevance for understanding the pathology of diseases, such as GD, in which GlcCer accumulates at high levels.

CHO/LY-B cell growth under limiting sphingolipid supply: correlation between lipid composition and biophysical properties of sphingolipid-restricted cell membranes+

“…S12B, C). Both Cer and HexCer are known to increase membrane lipid order [72][73][74] GPMV have been shown to be permeable to hydrophilic macromolecules 71 , and this could again be related to the increased Cer, and partly HexCer, since these SL happen to increase membrane permeability 72,73 . The observed increases in GP and breakthrough forces could be secondary to the use of dithiothreitol in GPMV formation.…”

The role of glucocerebrosidase in Parkinson disease pathogenesis

“…GlcCer has been reported to accumulate in this fraction . GlcCer can stabilize sphingomyelin/cholesterol‐enriched liquid domains, however, as the proportion of GlcCer rises membrane order is increased . Indeed membrane fluidity is decreased in CBE‐treated fibroblasts or GD type 1 fibroblasts .…”

“…GlcCer can stabilize sphingomyelin/cholesterol‐enriched liquid domains, however, as the proportion of GlcCer rises membrane order is increased . Indeed membrane fluidity is decreased in CBE‐treated fibroblasts or GD type 1 fibroblasts . Should this occur in PD brains, given that membrane dynamics are required for both macroautophagy and CMA (see below) this could greatly affect α‐synuclein degradation.…”

Alterations in the properties of the cell membrane due to glycosphingolipid accumulation in a model of Gaucher disease

“…In the context of our experimental system raft-like microdomains correspond to obstacles. An increase in the size of raft-like microdomains and the consequent formation of a continuous raft phase have already been reported upon glucosylceramide loading or changes in temperature 40 , 61 . While the diffusion of non-raft lipids and proteins was found to be significantly inhibited due to the corralling effect of the percolating raft phase, the movement of raft components was not significantly affected.…”