0000000000188441
AUTHOR
Gabrielle Maume
High-performance liquid chromatographic study of the regulation of phospholipid metabolism in cultured adrenocortical cells
Abstract A rapid high-performance liquid chromatographic (HPLC) method for the separation of phospholipids was developed for minute samples of total lipids (ca. 200 μg). The method was applied to the study of the phospholipid metabolism in adrenocortical cell cultures. A complete separation of the different cellular phospholipid classes was achieved in 40 min. Good resolution of the phospholipid peaks was obtained, which allowed the collection of each individual class of phospholipids for further analysis of radioactivity and fatty acid composition by gas chromatography. When cells were incubated with [U-14C]glycerol or [U-14C]palmitate the bulk of the radioactivity was found in cellular ph…
Geranylgeranyl as well as farnesyl moiety is transferred to Ras p21 overproduced in adrenocortical cells transformed by c-Ha-rasEJ oncogene.
The ras-transformed newborn rat adrenocortical (RTAC) cells were obtained by transfection with the mutated c-Ha-rasEJ oncogene. They are proliferative and tumorigenic cells characterized by expression of the c-Ha-rasEJ oncogene and overexpression of a wild-type ras oncogene. The overproduced Ras p21 was identified here as Ki-Ras p21 by western blotting using a specific anti-Ki-Ras monoclonal antibody. Radioactivity derived from [14C]mevalonolactone was strongly incorporated into Ras p21 overproduced in RTAC cells. RTAC cells pretreated with lovastatin and labeled with either [3H]geranylgeranyl-pyrophosphate or [3H]farnesyl-pyrophosphate incorporated also radioactivity into Ras p21. These re…
Aldosterone biosynthesis induced by ACTH and angiotensin II in newborn rat adrenocortical cells transfected by c-EJ-Ha-ras oncogene
Abstract Adrenocortical cells were obtained by fractionated trypsination of newborn rat adrenal glands and transfected with a plasmid containing the EJ T24 -Ha-ras oncogene. Isolation of adhesive cells led to a proliferative cell line with an overexpression of 21 kDa ras protein. These cells incubated with corticosterone or deoxycorticosterone as the precursor produced a high level of 18-hydroxycorticosterone and aldosterone as identified by gas chromatography- mass spectrometry. ACTH and angiotensin II increased the basal production of aldosterone nineteen-fold and six-fold respectively. Under ACTH stimulation the ratio between aldosterone and 18-hydroxycorticosterone production was 1:3. T…
INHIBITION OF CELLULAR GROWTH AND STEROID 11β-HYDROXYLATION INRAS-TRANSFORMED ADRENOCORTICAL CELLS BY THE FUNGAL TOXINS BETICOLINS
Abstract The proliferation of GM16 and 4CDTras-transformed newborn rat adrenocortical (RTAC) cells and Y1 mouse adrenal tumor cells was inhibited by beticolins, the fungal toxins extracted fromCercospora beticola, at submicromolar concentrations in a dose-dependent manner. Inhibitory concentrations for half the maximum inhibition were 150, 75 and 25 n M for beticolin-1 and 230, 150 and 50 n M for beticolin-2 in GM16, 4CDT and Y1 cells respectively. Beticolins strongly inhibited the production of 11β-hydroxysteroids on the second and third days of treatment in a dose-dependent manner between 0.1 and 1 μ M . Beticolins were shown by confocal microscopy to be localized in cytoplasmic organelle…
Combination of the novel farnesyltransferase inhibitor RPR130401 and the geranylgeranyltransferase-1 inhibitor GGTI-298 disrupts MAP kinase activation and G(1)-S transition in Ki-Ras-overexpressing transformed adrenocortical cells.
To test the Kirsten-Ras (Ki-Ras) alternative prenylation hypothesis in malignant transformation, we used a novel farnesyltransferase inhibitor competitive to farnesyl-pyrophosphate, RPR130401, and a CaaX peptidomimetic geranylgeranyltransferase-1 inhibitor GGTI-298. In Ki-Ras-overexpressing transformed adrenocortical cells, RPR130401 at 1-10 microM inhibited very efficiently the [(3)H]farnesyl but not [(3)H]geranylgeranyl transfer to Ras. However, proliferation of these cells was only slightly sensitive to RPR130401 (IC(50)=30 microM). GGTI-298 inhibited the growth of these cells with an IC(50) of 11 microM but cell lysis was observed at 15 microM. The combination of 10 microM RPR130401 and…
Effect of rat plasma high density lipoprotein with or without apolipoprotein E on the cholesterol uptake and on the induction of the corticosteroid biosynthetic pathway in newborn rat adrenocortical cell cultures
Abstract High density lipoprotein (HDL) has been shown to induce the cellular accumulation of cholesterol esters and the biosynthesis of 21-hydroxysteroids (corticosteroids) newborn rat adrenocortical cells cultivated in serum-free medium. In order to identify the component(s) of HDL responsible for these effects, we investigated the ability of rat HDL subfractions and HDL with or without apolipoprotein E to deliver cholesterol to cells and to stimulate the steroid biosynthetic pathways in adrenal cultured cells. The total cholesterol uptake from HDL 2 was greater than that observed with HDL rich in apolipoprotein E (HDL 1 and HDL c ). Furthermore, the increase of the ratio between 21-hydro…