ABSTRACT
Intracrinology mechanism involves the metabolism of steroids in peripheral tissues, such as DHEA, to molecules with estrogenic or androgenic activity. Proliferation rate of endometria from Polycystic Ovary Syndrome women (PCOS) is increased, favoring hyperplasia development. Besides, in endometria from PCOS-women the synthesis of androst-5-ene-3ß,17ß-diol (androstenediol), an estrogenic molecule, is enhanced concomitantly to increased cellular proliferation. DHEA, the major intracrinological precursor, circulates mainly in its sulfated form and requires transporters for cell intake, that belong to the families of organic anion transporting polypeptides (OATP) and organic anion transporters (OAT). The aim of this study was to determine protein levels and activity of sulfated steroid transporters OATP2B1, OATP3A1, OATP4A1 and OAT4 in endometria from control and PCOS-women and to evaluate the activity of the enzyme 3ß-HSD. Levels of transporters were done by RT-PCR (OAT4 only) and Western-blot (WB). Additionally, in primary culture cells stimulated with steroids, protein levels by WB and uptake of tritiated DHEAS, were evaluated; 3ß-HSD activity was assessed using radiolabel substrate. PCOS-endometrium had higher levels of OATP2B1 and OATP4A1 than CE (p<0.05); decreased OATP4A1 levels were found in androstenediol or testosterone-stimulated cells. Accordingly, the entry of DHEAS to cells was lower in cells stimulated with testosterone (p<0.05); 3ß-HSD-activity was similar in control and PCOS-endometria. Therefore, this study describes that steroids can modulate the expression and activity of transporters of OATPs-family in human endometria and that some transporter levels are increased in PCOS-endometria, suggesting a potential role in the pathogenesis of endometrial hyperplasia of these patients.
Subject(s)
3-Hydroxysteroid Dehydrogenases/metabolism , Endometrium/metabolism , Organic Anion Transporters/metabolism , Polycystic Ovary Syndrome/metabolism , Adult , Cells, Cultured , Endometrium/enzymology , Enzyme Activation , Female , Gene Expression Profiling , Humans , Organic Anion Transporters/biosynthesis , Organic Anion Transporters/genetics , Polycystic Ovary Syndrome/enzymology , Polycystic Ovary Syndrome/geneticsABSTRACT
In yeasts, several sensing systems localized to the plasma membrane which transduce information regarding the availability and quality of nitrogen and carbon sources and work in parallel with the intracellular nutrient-sensing systems, regulate the expression and activity of proteins involved in nutrient uptake and utilization. The aim of this work was to establish whether the cellular signals triggered by amino acids modify the expression of the UGA4 gene which encodes the delta-aminolevulinic (ALA) and gamma-aminobutyric (GABA) acids permease. In the present paper, we demonstrate that extracellular amino acids regulate UGA4 expression and that this effect seems to be mediated by the amino acid sensor complex SPS (SSY1, PTR3, SSY5).
Subject(s)
Amino Acid Transport Systems/biosynthesis , Gene Expression Regulation, Fungal , Organic Anion Transporters/biosynthesis , Amino Acid Transport Systems/genetics , Aminolevulinic Acid/metabolism , Carrier Proteins/physiology , GABA Plasma Membrane Transport Proteins , Intracellular Signaling Peptides and Proteins , Membrane Proteins/physiology , Organic Anion Transporters/genetics , Saccharomyces cerevisiae Proteins/physiology , gamma-Aminobutyric Acid/metabolismABSTRACT
BACKGROUND AND AIMS: biological processes in all organisms are controlled by environmental conditions, however, information concerning the molecular responses to external pH is scarce. In this work we studied the pH response of UGA4 gene encoding delta-aminolevulinic acid and gamma-aminobutyric acid permease in Saccharomyces cerevisiae. METHODS: we analyzed the effect of pH on the expression of UGA4 gene measuring beta-galactosidase activity in cells carrying a UGA4::lacZ fusion gene. RESULTS: results indicate that UGA4 expression is higher at acidic pH. The expression of UGA3 and UGA35 genes, which encode two positive transcription factors, is not regulated by external pH, while the expression of UGA43 gene encoding a repressor of UGA4 transcription is dependent on pH. Using a strain lacking Uga43p we clearly showed that the effect of ambient pH on UGA4 expression is not a secondary effect of the pH regulation on UGA43. We have also demonstrated that the effect of pH can only be detected when UGA4 gene is not subject to a strong repression by Uga43p nor to GABA induction. CONCLUSION: here, we demonstrate that UGA4 is an acid-expressed gene. This regulation is probably mediated by Rim101p through the consensus site 5'-GCCARG-3' at 237 bp preceding the UGA4 coding sequence (201).