Effects of dimethylsulfoxide on sphingomyelinase activities in normal and Niemann-Pick type A, B and C fibroblasts.
The effects of dimethylsulfoxide (DMSO) on sphingomyelinase activity measured at pH range 3.5-8.0 were examined in normal and Niemann-Pick disease type A, B and C fibroblasts culture. In normal cells, a minor activity was observed at pH 7.5, which was 3- to 4-fold lower than a major one at pH 5.0. Both activities at pH 5.0 and 7.5 were Mg2+-independent and localized to lysosomes. Niemann-Pick type C cells had 30-50% residual sphingomyelinase activity at both pH 5.0 and 7.5, as compared to normal control cells, whereas type A and B cells exhibited virtually no activity over the entire pH range examined. Treatment with 2% DMSO caused a marked increase in sphingomyelinase activities at pH 5.0 and 7.5 in normal and Niemann-Pick disease type C cells, while in type A and B cells, both activities remained virtually unchanged after DMSO treatment. The increase in sphingomyelinase activity at pH 5.0 induced in normal cells by DMSO resulted in an increase in the Vmax without a substantial change in the Km and was inhibited by the simultaneous addition of 10 micrograms/ml of cycloheximide. By comparison, a less than 2-fold increase in other lysosomal hydrolase activities was observed after DMSO treatment in all cell lines examined.
Sato
M
M
Division of Mental Retardation and Birth Defect Research, National Institute of Neural Science, Tokyo, Japan.
Yoshida
Y
Y
Sakuragawa
N
N
Arima
M
M
D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D004121:Dimethyl Sulfoxide / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007424:Intracellular Fluid / Q000187:drug effects / Q000201:enzymology; D008247:Lysosomes / Q000187:drug effects / Q000201:enzymology; D009542:Niemann-Pick Diseases / Q000145:classification / Q000201:enzymology* / Q000473:pathology; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D013108:Sphingomyelin Phosphodiesterase / Q000037:antagonists & inhibitors / Q000378:metabolism*
D003513:Cycloheximide; D010727:Phosphoric Diester Hydrolases; D013108:Sphingomyelin Phosphodiesterase; D004121:Dimethyl Sulfoxide