Open AccessRepression by dexamethasone of epinephrine‐induced modulation of the fatty acyl‐CoA desaturase system in Tetrahymena microsomes
Author(s) -
UMEKI Shigenobu,
NOZAWA Yoshinori
Publication year - 1984
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1984.tb08294.x
Subject(s) - epinephrine , endocrinology , medicine , microsome , dexamethasone , stimulation , chemistry , fatty acid , stearoyl coa desaturase , biology , biochemistry , enzyme , gene expression , gene
Epinephrine modulation of the fatty acyl‐CoA desaturase activities in Tetrahymena microsomes, namely the stimulation of Δ 9 desaturase activity with a decreased activity of Δ 12 desaturase, was markedly inhibited by dexamethasone administered 30min prior to epinephrine addition. This effect by dexamethasone was dose‐dependent. With epinephrine or dexamethasone prior to epinephrine administration, the activities of Δ 9 ‐terminal and Δ 12 ‐terminal components were found to change in parallel with those of Δ 9 and Δ 12 desaturase activities respectively. Furthermore, addition of dexamethasone as early as 30 min before epinephrine repressed the epinephrine‐mediated stimulation of cyclic AMP production and of adenylate cyclase activity. Therefore, it is suggested that dexamethasone may inhibit the modulation by epinephrine of the terminal component activity, which plays a crucial role in microsomal fatty acyl‐CoA desaturase system, through the reduction of cyclic AMP accumulation by decreased responsiveness to epinephrine of Tetrahymena cells.