TY - JOUR
T1 - Sphingomyelin metabolism in rat liver after chronic dietary replacement of choline by N-aminodeanol
AU - Nikolova-Karakashian, Mariana N.
AU - Russell, Roger W.
AU - Booth, Ruth A.
AU - Jenden, Donald J.
AU - Merrill, Alfred H.
N1 - Copyright:
Copyright 2007 Elsevier B.V., All rights reserved.
PY - 1997/9
Y1 - 1997/9
N2 - Sphingomyelin (SM) is a structural element of cell membranes and lipoproteins, and participates in signal transduction. To determine whether a choline analog (N-amino-N,N-dimethylaminoethanol, N-aminodeanol, NADe) can be substituted for choline in the SM of liver, rats (male, Sprague-Dawley- derived) were fed a diet that was low in choline and methionine, and contained 35.5 mmol of NADe/kg. After 18 months, liver plasma membranes and microsomes contained 48.9 ± 3.6 and 93.6 ± 6.9 nmol/mg protein of phosphatidyl-NADe, respectively, and 3.2 ± 0.2 and 3.5 ± 0.1 nmol/mg protein of ceramide phospho-NADe. The SM content of microsomes from NADe-fed rats was about one-third lower than for the control, and phosphatidylcholine (PC) was reduced by <10%; there was also a small decrease in PC, but not SM, in plasma membranes. In vitro assays of enzymes involved in SM metabolism found no change in PC:ceramide choline-phosphotransferase, but the NADe-fed animals had higher phosphatidylethanolamine: ceramide ethanolaminephosphotransferase activity, greater incorporation of methyl groups from [methyl-3H]-S-adenosyl methionine into SM, and a lower neutral sphingomyelinase activity. These results show that NADe-fed rats form considerable amounts of ceramide phospho- and phosphatidyl-NADe; however, liver plasma membranes retain relatively normal levels of PC and SM, perhaps due to increases in the de novo pathway for SM synthesis and decreases in SM turnover.
AB - Sphingomyelin (SM) is a structural element of cell membranes and lipoproteins, and participates in signal transduction. To determine whether a choline analog (N-amino-N,N-dimethylaminoethanol, N-aminodeanol, NADe) can be substituted for choline in the SM of liver, rats (male, Sprague-Dawley- derived) were fed a diet that was low in choline and methionine, and contained 35.5 mmol of NADe/kg. After 18 months, liver plasma membranes and microsomes contained 48.9 ± 3.6 and 93.6 ± 6.9 nmol/mg protein of phosphatidyl-NADe, respectively, and 3.2 ± 0.2 and 3.5 ± 0.1 nmol/mg protein of ceramide phospho-NADe. The SM content of microsomes from NADe-fed rats was about one-third lower than for the control, and phosphatidylcholine (PC) was reduced by <10%; there was also a small decrease in PC, but not SM, in plasma membranes. In vitro assays of enzymes involved in SM metabolism found no change in PC:ceramide choline-phosphotransferase, but the NADe-fed animals had higher phosphatidylethanolamine: ceramide ethanolaminephosphotransferase activity, greater incorporation of methyl groups from [methyl-3H]-S-adenosyl methionine into SM, and a lower neutral sphingomyelinase activity. These results show that NADe-fed rats form considerable amounts of ceramide phospho- and phosphatidyl-NADe; however, liver plasma membranes retain relatively normal levels of PC and SM, perhaps due to increases in the de novo pathway for SM synthesis and decreases in SM turnover.
KW - Ceramide
KW - Methylation
KW - Sphingomyelin synthase
KW - Sphingomyelinase
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U2 - 10.1016/s0022-2275(20)37151-0
DO - 10.1016/s0022-2275(20)37151-0
M3 - Article
C2 - 9323586
AN - SCOPUS:0030771333
SN - 0022-2275
VL - 38
SP - 1764
EP - 1770
JO - Journal of Lipid Research
JF - Journal of Lipid Research
IS - 9
ER -