Oxygenation of desmosterol and cholesterol in cell cultures.
In order to determine whether hydration of the delta 24 bond of desmosterol contributes to the formation of the regulatory oxysterol, 25-hydroxycholesterol, [3H]desmosterol was incubated with two cultured cell lines and the labeled products were analyzed. Small amounts of 25-hydroxycholesterol were formed with Chinese hamster lung (Dede) cell cultures, but not with mouse fibroblast (L) cell cultures. Apparently, desmosterol was converted into cholesterol, a process that does not occur in L cells, before 25-hydroxycholesterol takes place. No reliable evidence could be obtained for hydration of the delta 24 bond or for the reverse reaction upon incubation of [3H]25-hydroxycholesterol. Oxygenation of desmosterol occurred in both Dede and L cell cultures to give a mixture of 24(R)- and 24(S)-25-epoxy-cholesterol. This reaction, along with the production of 7-oxygenated sterols, may account for low levels of HMG-CoA reductase repressor activity previously found to be associated with delta 24 sterols.
Saucier
S E
SE
Jackson Laboratory, Bar Harbor, ME 04609.
Kandutsch
A A
AA
Gayen
A K
AK
Nelson
J A
JA
Spencer
T A
TA
D000818:Animals; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D006224:Cricetinae; D003897:Desmosterol / Q000378:metabolism*; D005347:Fibroblasts; D006888:Hydroxycholesterols / Q000378:metabolism; D008168:Lung / Q000166:cytology / Q000378:metabolism; D051379:Mice; D010100:Oxygen / Q000378:metabolism*; D013997:Time Factors
D006888:Hydroxycholesterols; D003897:Desmosterol; C007997:25-hydroxycholesterol; D002784:Cholesterol; D010100:Oxygen