Open AccessRegulation of S ‐adenosylmethionine decarboxylase in L1210 leukemia cells
Author(s) -
AUTELLI Riccardo,
STJERNBORG Louise,
KHOMUTOV Alex R.,
KHOMUTOV Radii M.,
PERSSON Lo
Publication year - 1991
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1991.tb15849.x
Subject(s) - spermidine , spermine , putrescine , adenosylmethionine decarboxylase , ornithine decarboxylase , polyamine , biochemistry , arginine decarboxylase , enzyme , ornithine decarboxylase antizyme , biology , l1210 cells , carboxy lyases , microbiology and biotechnology , chemistry , in vitro , cytotoxicity
A Potent irreversible inhibitor of S ‐adenosylmethionine (AdoMet) decarboxylase, S ‐(5′ ‐adenosyl)‐methylthio‐2‐aminooxyethane (AdoMeSaoe), was used to study the regulatory control of this key enzyme in the polyamine biosynthetic pathway. Treatment of L1210 cells with the inhibitor completely eradicated the growth‐induced rise in AdoMet decarboxylase activity, resulting in a marked decrease in cellular content of spermidine and spermine. The putrescine content, on the other hand, was greatly elevated. Although no detectable AdoMet decarboxylase activity was found in the L1210 cells after treatment with AdoMeSaoe, the cells contained 50‐fold higher amounts of AdoMet decarboxylase protein, compared to untreated cells during exponential growth. Part of this increase was shown to be due to elevated synthesis of the enzyme. This stimulation appeared to be related to the decrease in cellular spermidine and spermine content, since addition of either one of the polyamines counteracted the rise in AdoMet decarboxylase synthesis. The synthesis rate was determined by immunoprecipitation of labeled enzyme after a short pulse with [ 35 S]methionine. In addition to a protein that co‐migrated with pure rat AdoMet decarboxylase ( M r ∼ 32000), the antibody precipitated a somewhat larger labeled protein ( M r ∼ 37000) that most likely represents the proenzyme form. Treatment of the L1210 cells with AdoMetSaoe also gave rise to a marked stabilization of the decarboxylase which contributed to the increase in its cellular protein content. Addition of spermidine did not significantly affect this stabilization, whereas the addition of spermine reduced the half‐life of the enzyme to almost that of the control cells.