Relief of temperature sensitivity in a concanavalin A resistant Chinese hamster ovary cell line auxotrophic for cholesterol.
The concanavalin A resistant, glycosylation-deficient, Chinese hamster ovary cell variant CR-7 is auxotrophic for cholesterol owing to an inability to adequately convert lanosterol to cholesterol. It is also temperature sensitive for growth, being unable to proliferate at 39 degrees C. Temperature sensitivity was relieved by addition of mevalonolactone, dolichol, or dolichyl-P to the growth medium, provided that cholesterol was also present in amounts sufficient to overcome cholesterol auxotrophy at 34 degrees C. Other metabolites of mevalonolactone (squalene, ubiquinone, lanosterol, and isopentenyladenine) were inactive in this regard. Measurement of dolichol levels in CR-7 and wild-type cells at 34 degrees C and after exposure to 39 degrees C showed that dolichol increased at 39 degrees C to an approximately equal extent in both cell types. Dolichol, dolichyl-P, ubiquinone, and isopentenyladenine had no effect on the sensitivity of either wild-type or CR-7 cells to the cytotoxic effects of concanavalin A. Mevalonolactone or lanosterol markedly increased the resistance of CR-7 to the lectin, but had no effect on wild-type cells. This raises the possibility that the presence of unusually large amounts of lanosterol, coupled with low amounts of cholesterol, in the membranes of CR-7 may be related to its concanavalin A resistance and other characteristic phenotypic abnormalities.
Hurta
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RA
Department of Microbiology, University of Manitoba, Winnipeg, Canada.
Burton
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DN
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002784:Cholesterol / Q000378:metabolism*; D003208:Concanavalin A / Q000494:pharmacology*; D004286:Dolichols / Q000378:metabolism / Q000494:pharmacology; D004351:Drug Resistance; D007700:Kinetics; D008798:Mevalonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D013696:Temperature
D004286:Dolichols; D003208:Concanavalin A; C015367:mevalonolactone; D002784:Cholesterol; D008798:Mevalonic Acid