The Transport of Steroids into Animal Cells in Culture

Giorgi, Eleonora P.; Stein, Wilfred D.

doi:10.1210/endo-108-2-688

Cited by 88 publications

(41 citation statements)

References 27 publications

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“…Since it has been found that the permeability coefficient for cortisol can vary easily 2-fold between different cell lines (Giorgi & Stein, 1981), differences in composition of the plasmamembrane might play a role in this finding.…”

Section: Discussionmentioning

confidence: 93%

“…The order of lipophilicity of the most important steroids studied here is progesterone > testosterone > cortisol > aldosterone. The octanol/water partition coefficient for these steroids are 124, 61, 12.6 and not studied resp., according to Giorgi and Stein (1981).…”

Section: Resultsmentioning

confidence: 99%

“…For aldosterone no significant difference in cellular accumulation between sensitive and Pgp/MDR cells was found (not shown). Another steroid hormone, that might be actively transported by Pgp is cortisol, because it is more hydrophilic than progesterone, but less hydrophilic than aldosterone (Giorgi & Stein, 1981). We therefore studied the energy-dependence of cortisol transport in the highly Pgp expressing cell line, DC3-F/ADX (resistance factor for actinomycin D is 10,000; Biedler et al, 1988).…”

Section: Cortisolmentioning

confidence: 99%

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Cortisol is transported by the multidrug resistance gene product P-glycoprotein

Kalken

Broxterman²,

Pinedo³

et al. 1993

Br J Cancer

133

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Section: Discussionmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 99%

Section: Cortisolmentioning

confidence: 99%

See 1 more Smart Citation

Cortisol is transported by the multidrug resistance gene product P-glycoprotein

Kalken

Broxterman²,

Pinedo³

et al. 1993

Br J Cancer

133

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“…This model is based on the lipophilic nature of steroid molecules and on their affinity for lipid constituents of the plasma membranes (Giorgi & Stein, 1981). However, other investigations in this field of transmembrane movement suggest that there exists another possible process of steroid transport into the target cells.…”

Section: Introductionmentioning

confidence: 99%

Evidence for the presence of specific binding sites for corticoids in mouse liver plasma membranes

et al. 1989

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The specific binding of [3H]cortisol to plasma membranes purified from mouse liver, studied by the ultrafiltration method, shows the existence of specific binding sites for cortisol. The kinetic parameters of this binding are KD = 4.4 nM and Bmax = 685 fmol/mg protein in presence of 1 microM of corticosterone. With respect to the binding of 4 nM [3H]cortisol to the membrane, the affinities of the steroids decreased in the following order: deoxycorticosterone greater than corticosterone greater than progesterone greater than cortisol greater than prednisolone greater than testosterone greater than 20 beta-hydroxyprogesterone greater than cortisone. Estradiol, dexamethasone, ouabain and triamcinolone acetonide do not have affinity for this binding site. Neither Ca2+ nor Mg2+ affected the binding of [3H]cortisol to the plasma membranes. Likewise, the presence of agonists and antagonists of alpha and beta-adrenergic receptors did not modify the binding of [3H]cortisol. The results suggest that the plasma membrane binding site characterized is more specific for corticoids and is different from nuclear glucocorticoid and progesterone receptors.

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“…Such an experiment is feasible due to the fast transport and the practically immediate equilibrium (15-30 sec) of added steroids with the inner cytoplasmic environment of the intact cells (33,34). Based on these observations, we monitored the activity of newly synthesized 5a-reductase in mRNA-injected oocytes by measuring the metabolism of [3H]testosterone added to intact eggs.…”

Section: Discussionmentioning

confidence: 99%

Biosynthesis of catalytically active rat testosterone 5 alpha-reductase in microinjected Xenopus oocytes: evidence for tissue-specific differences in translatable mRNA.

Farkash

Soreq²,

Orly³

1988

Proc. Natl. Acad. Sci. U.S.A.

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The enzyme 4-ene-3-ketosteroid-5a-oxidoreductase [5a-reductase; 3-oxo-5a-steroid A4-dehydrogenase, 3-oxo-5a-steroid: (acceptor) EC 1.3.99.5] plays a key role in androgen-dependent target tissues, where it catalyzes the conversion of testosterone to the biologically active dihydrotestosterone. The regulation of 5a-reductase expression has not been studied at the molecular level as the enzyme is a membrane protein that is labile in cell-free homogenates. We developed a sensitive bioassay of the enzyme activity expressed in Xenopus oocytes microinjected with rat liver and prostate mRNA. After microinjection, incubation of intact oocytes in the presence of [3H]testosterone revealed the in ovo appearance of active 5a-reductase. Polyadenylylated RNA was fractionated by sucrose gradient centrifugation, and the enzymatic activity was shown to be encoded by a 1600-to 2000-base-pair fraction of hepatic poly(A) + RNA. 5a-Reductase mRNA was most efficiently translated when up to 80 ng of RNA was injected per oocyte. In the injected oocytes, 5a-reductase mRNA was found to be a short-lived molecule (til2 = 2 hr), whereas its in ovo translatable 5a-reductase protein exhibited stable enzymatic activity for over 40 hr. Moreover, the levels oftranslatable tissue-specific 5a-reductase mRNAs as monitored in the Xenopus oocytes correlated with the variable 5a-reductase activities in female rat liver, male rat liver, and prostate homogenates; the ratio of their specific activities was of 2500:630:1, respectively. Altogether, these results provide supporting evidence in favor of the transcriptional control of 5a-reductase expression in rat tissues.ical inactivation of 4-ene-3-ketosteroids, mainly adrenal corticosteroids (19).Previous biochemical studies of 5a-reductase have revealed kinetic parameters, such as affinity constants to steroid hormones, as well as the enzyme subcellular distribution in the rough endoplasmic reticulum and/or nuclei of various tissues (1,(20)(21)(22)(23)(24). Because the activity of Sareductase is extremely unstable in cell-free preparations (1, 20), it has not been purified, and therefore the regulation of its expression could not be studied at the molecular level. To approach this issue, we pursued an experimental model in which 5a-reductase biosynthesis can be studied in intact living cells. Toward this aim, we designed a bioassay for the detection of newly synthesized 5a-reductase produced in mRNA-microinjected Xenopus oocytes. The oocytes efficiently translate microinjected heterologous mRNA, perform correct posttranslational processing and, most importantly for 5a-reductase, direct newly synthesized proteins into the correct subcellular compartments (for review, see ref. 25).Here, we report that Xenopus oocytes are able to synthesize catalytically active 5a-reductase, directed by microinjected poly(A) + RNA prepared from female and male rat liver. For yet unknown reasons, there are remarkable differences between the specific activities of 5a-reductase in female liver, male liver (16, 17)...

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The Transport of Steroids into Animal Cells in Culture

Cited by 88 publications

References 27 publications

Cortisol is transported by the multidrug resistance gene product P-glycoprotein

Cortisol is transported by the multidrug resistance gene product P-glycoprotein

Evidence for the presence of specific binding sites for corticoids in mouse liver plasma membranes

Biosynthesis of catalytically active rat testosterone 5 alpha-reductase in microinjected Xenopus oocytes: evidence for tissue-specific differences in translatable mRNA.

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