Lysosphingolipids and mitochondrial function. II. Deleterious effects of sphingosylphosphorylcholine

Psychosine, sphingosylphosphorylcholine (52-104 microM), and other glycosphingolipids stimulate mitochondrial respiration (up to 500%) and inhibit oxidative phosphorylation to varying degrees. Above 104 microM these functions as well as uptake of Ca2+ are prevented. At 104 microM sphingosylphosphorylcholine inhibits the mitochondrial ATPase reaction in submitochondrial particles by 48%. Both sphingosylphosphorylcholine and psychosine enhance the active phosphate-dependent swelling of mitochondria. Passive swelling occurs in the presence of rotenone (when swelling does not normally occur) and under hypotonic conditions. A direct interaction of sphingosylphosphorylcholine with membranes is demonstrated by a discharge of the proton gradient across mitochondrial membranes, hemolysis of red blood cells, and binding to inner and outer mitochondrial membranes. Thus lysosphingolipids bind strongly to mitochondrial membranes and markedly alter mitochondrial function. This alteration would affect the ATP levels, thereby altering a wide range of ATP-dependent cellular functions. These results offer a partial explanation for the pathogenesis of representative lysosomal storage diseases.