Sphingomyelinase activity is enhanced in cerebral cortex of senescence-accelerated mouse-P/10 with advancing age.
The cerebral cortical sphingomyelinase (SMase) activities were detected in the cytosolic and the membrane fractions of cerebral cortex, hippocampus, cerebellum, brainstem, and thalamus/midbrain of senescence-accelerated mouse-prone/10 (SAM-P/10) and SAM-resistant/1 (SAM-R/1) with advancing age, respectively. The SMase activity was increased uniquely in the membrane fraction of the cerebral cortex of SAM-P/10 in an age-dependent manner; The enzyme activities of 10 and 17 months of age were about 25 and 30% higher than those of 2 months of age, respectively. This observation implicates that the membrane-associated SMase activity might be related with accelerated senescence. The cerebral cortical SMase was eluted in a molecular mass of approximately 400 kDa on a gel filtration chromatography and was active in a broad range of pH from 4 to 9. It was also suggested that phosphorylation may be one of the mechanisms regulating the enzyme activity, but not responsible for the increased activity with advancing age.
Kim
S S
SS
Department of Pharmacology, College of Medicine, Seoul National University, South Korea.
Kang
M S
MS
Choi
Y M
YM
Suh
Y H
YH
Kim
D K
DK
D000375:Aging / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000201:enzymology* / Q000254:growth & development; D002462:Cell Membrane / Q000201:enzymology; D002540:Cerebral Cortex / Q000201:enzymology* / Q000254:growth & development; D002850:Chromatography, Gel; D003600:Cytosol / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D051379:Mice; D008817:Mice, Mutant Strains; D008970:Molecular Weight; D009928:Organ Specificity; D013108:Sphingomyelin Phosphodiesterase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*
D013108:Sphingomyelin Phosphodiesterase