TY - JOUR
T1 - Sphingomyelinase activity in human platelets
AU - Simon, Carl G.
AU - Chatterjee, Subroto
AU - Gear, Adrian R.L.
N1 - Funding Information:
We thank Dr. Renata Polanowska-Grabowska and Steve Koh for help and advice. This work was supported by the Carman Trust, by NIH (DK-31722), and by NIH (HL-27014) for some of the original equipment.
PY - 1998/5/15
Y1 - 1998/5/15
N2 - The sphingolipid metabolites, ceramide, sphingosine, and sphingosine-1- phosphate, may be involved in several signalling pathways and may regulate cell functions such as cell growth, secretion, differentiation, and apoptosis. During activation of human platelets by thrombin, sphingosine-1- phosphate is released from platelets and can potentiate their aggregation. Thrombin also causes an increase in platelet sphingosine levels. Since these molecules can be derived from sphingomyelin, we have determined whether platelets possess sphingomyelinase and whether this enzyme is regulated during platelet function. Using radioactive sphingomyelin as substrate, we assayed sphingomyelinase activity over the range of pH 4 to 10 and observed optimal activity at pH 5.0-5.5. Little activity was found at neutral or alkaline pH, and the presence of Mg++, Ca++, Zn++, or EDTA in the reaction mixture had little effect on the pH profile. Activation of platelets by thrombin or ADP had no effect on sphingomyelinase activity, but thrombin caused secretion of the acid-sphingomyelinase activity into the media. Thus, human platelets contain an acid-sphingomyelinase which is secreted during thrombin-induced platelet activation.
AB - The sphingolipid metabolites, ceramide, sphingosine, and sphingosine-1- phosphate, may be involved in several signalling pathways and may regulate cell functions such as cell growth, secretion, differentiation, and apoptosis. During activation of human platelets by thrombin, sphingosine-1- phosphate is released from platelets and can potentiate their aggregation. Thrombin also causes an increase in platelet sphingosine levels. Since these molecules can be derived from sphingomyelin, we have determined whether platelets possess sphingomyelinase and whether this enzyme is regulated during platelet function. Using radioactive sphingomyelin as substrate, we assayed sphingomyelinase activity over the range of pH 4 to 10 and observed optimal activity at pH 5.0-5.5. Little activity was found at neutral or alkaline pH, and the presence of Mg++, Ca++, Zn++, or EDTA in the reaction mixture had little effect on the pH profile. Activation of platelets by thrombin or ADP had no effect on sphingomyelinase activity, but thrombin caused secretion of the acid-sphingomyelinase activity into the media. Thus, human platelets contain an acid-sphingomyelinase which is secreted during thrombin-induced platelet activation.
KW - Platelets
KW - Secretion
KW - Sphingomyelinase
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U2 - 10.1016/S0049-3848(98)00033-4
DO - 10.1016/S0049-3848(98)00033-4
M3 - Article
C2 - 9692614
AN - SCOPUS:0032524380
SN - 0049-3848
VL - 90
SP - 155
EP - 161
JO - Thrombosis research
JF - Thrombosis research
IS - 4
ER -