Androgens regulate expression of the gene coding for a mouse vas deferens protein related to the aldo-keto reductase superfamily in epithelial cell subcultures

The Effects of Anabolic Androgenic Steroid Abuse on Gingival Tissues

BACKGROUND

Anabolic androgenic steroid (AAS) is the familiar name for synthetic derivatives of the male sex hormone, testosterone. A large number of young adults abuse AAS to enhance performance and physical appearance. The aim of this study was to evaluate the effects of AAS abuse on the gingival tissues in a group of bodybuilders and weight lifters.

METHODS

The test group was composed of 24 athletes aged between 17 and 29 years who had been using AAS for >1 year. All subjects were clinically examined for plaque levels (plaque index), gingival inflammation (gingival index), and gingival enlargement. The results were compared to a control group of 20 bodybuilders who had never used AAS drugs and who matched for age, educational level, and oral habits according to the data obtained from the test group.

RESULTS

Although there were no statistical differences between the plaque index (P>0.05) and gingival index (P>0.05) scores of the study group and the control group, the AAS abusers had statistically higher scores of gingival thickness, extent of gingival encroachment, and total gingival enlargement scores (P<0.001 each) compared to non-users.

CONCLUSIONS

The results of this study have revealed that the prolonged use of AAS is closely associated with significant levels of gingival enlargement. Because recreational abuse and abuse in non-competitive sports seem to increase despite legislation, dentists and periodontists should be familiar with the adverse effects of these synthetic derivatives of testosterone on the gingival tissues.

Androgen metabolic response to indomethacin and the alkaline phosphatase inhibitor levamisole in fibroblasts

OBJECTIVES

The aim of this investigation is to study the effects of indomethacin (I) and the alkaline phosphatase (ALP) inhibitor levamisole (L) on androgen 5alpha-reductase expression in gingival and periosteal fibroblasts, in the context of repair in the periodontium. Chronically inflamed human gingival fibroblasts (HGF) were used to demonstrate the comparative effects of L on HGF and human oral periosteal fibroblasts (HPF).

MATERIAL AND METHODS

Monolayer cultures of six cell lines of HPF of the fifth to ninth passage were incubated in duplicate with 14C-testosterone/14C-4-androstenedione as substrates in Eagle's MEM; I was added at concentrations of 1 and 3 microg/ml in the presence or absence of the established inhibitory concentration of 30 microg/ml L and incubated for 24 h. The medium was solvent extracted for radioactive metabolites, separated by thin layer chromatography and quantified.

RESULTS

L caused 50% inhibition of 5alpha-reductase and 17beta-hydroxysteroid dehydrogenase activity in HGF. In HPF, 5alpha-reductase expression was enhanced by I with both substrates, by 65-76% (n = 6; p<0.01), inhibited by 30-50% (n = 6; p<0.01) with L and restored to control values in combination.

CONCLUSION

Yields of androgen metabolites may be linked to ALP activity, with implications on healing, during adjunctive treatment of inflammatory periodontal disease with I.

Immortalization by large T-antigen of the adult epididymal duct epithelium

The SV40 large T-antigen has been widely used to convert various cell types to a transformed phenotype, and also to induce progressive tumours in transgenic animals. The objectives of this review are to compare and discuss three different approaches to generate epididymal epithelial cell lines using the large T-antigen. In the first approach, retroviral transfection of primary cultures was used to immortalize canine epididymal cells in vitro; the other two approaches used transgenic mice expressing the large T-antigen. In one of these in vivo approaches, a construct consisting of the coding sequence of a temperature sensitive (ts) SV40 large T-antigen was inserted in a mouse genome. When the cells are exposed to the permissive temperature of 33 degrees C, functional expression of the large T-antigen occurs and cells start to proliferate. In the second in vivo approach a tissue-specific promoter, the 5kb GPX5 promoter, was used to direct expression of the large T-antigen to the epididymal duct epithelium.

Proteomic analysis of androgen-regulated protein expression in a mouse fetal vas deferens cell line

During sex differentiation, androgens are essential for development of the male genital tract. The Wolffian duct is an androgen-sensitive target tissue that develops into the epididymis, vas deferens, and seminal vesicle. The present study aimed to identify androgen-regulated proteins that are involved in development of Wolffian duct-derived structures. We have used male mouse embryos transgenic for temperature-sensitive simian virus 40 large tumor antigen at 18 d of gestation, to generate immortalized mouse fetal vas deferens (MFVD) parental and clonal cell lines. The MFVD parental and clonal cell lines express androgen receptor protein and show features of Wolffian duct mesenchymal cells. Clonal cell line MFVD A6 was selected for proteomic analysis and cultured in the absence or presence of androgens. Subsequently, two-dimensional gel electrophoresis was performed on total cell lysates. Differentially expressed proteins were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and two androgen-regulated proteins were identified as mElfin and CArG-binding factor-A (CBF-A). CBF-A and mElfin are known to bind to cytoskeletal F-actin. Both proteins appeared to be regulated by androgens at the posttranslational level, possibly involving phosphorylation. Posttranslational modification of mElfin and CBF-A by androgens may be associated with a cytoskeletal change that is involved in androgen-regulated gene expression.

Phenytoin-mediated androgen metabolism in gingival fibroblasts. Effects of the antiandrogen finasteride and the alkaline phosphatase inhibitor levamisole

OBJECTIVES

This investigation attempts to identify the role of the alkaline phosphatase inhibitor levamisole (L) and the antiandrogen finasteride (F) on 5alpha-reductase activity in gingival fibroblasts, to elucidate mechanisms for phenytoin-induced gingival overgrowth.

MATERIAL AND METHODS

Human gingival fibroblasts were incubated with Eagle's MEM and 14C-testosterone/14C-4-androstenedione as substrates; effective concentrations of phenytoin (Ph), levamisole (L) and finasteride (F), alone and in combinations of (Ph + F) (Ph + L) were added to the incubate. After 24 h, the medium was analysed for steroid metabolites and quantified using a radioisotope scanner.

RESULTS

The metabolites isolated were 5alpha-dihydrotestosterone (DHT), 4-androstenedione (4-A) or testosterone (T) from each substrate. With 14C-T as substrate, Ph stimulated DHT synthesis by 1.7-fold, while F and L inhibited this activity by 1.8-fold and 34%, respectively (n = 6; P < 0.001). The combination of Ph + F reduced yields by 2.7-fold compared with Ph alone and Ph + L reduced DHT synthesis by 2.4-fold compared with Ph alone (n = 6; P < 0.001). When 14C-4-androstenedione was used as substrate, similar trends were identified.

CONCLUSION

These results suggest that the alkaline phosphatase inhibitor levamisole and the 5alpha-reductase inhibitor finasteride can substantially decrease the yields of DHT in fibroblasts, stimulated by phenytoin. This could be a potential target for reducing the gingival overgrowth caused by phenytoin.

The modulation of androgen metabolism by estradiol, minocycline, and indomethacin in a cell culture model

BACKGROUND

This investigation attempts to clarify the proanabolic effects of minocycline and indomethacin by studying their effects on androgen metabolism and mediation by estradiol. A cell culture model was used with androgen substrates because of the proanabolic effects of androgen metabolites.

METHODS

Monolayer cultures of human gingival fibroblasts (HGF) derived from 6 patients were incubated in duplicate with 14C- testosterone or 14C-4-androstenedione as substrates and optimal concentrations of estradiol (E1,3 microgram/ml) and minocycline (M25 microgram/ml) or indomethacin (I, 1 microgram/ml) alone and in combination (E1,3+11 or E1,3+M25 microgram/ml); similar experiments were carried out with human oral periosteal fibroblasts (HPF), M, I, E, and the combinations. At the end of a 24-hour incubation period in Eagle's MEM, the medium was solvent extracted with ethyl acetate and the metabolites were separated by TLC in a benzene:acetone solvent system (4:1 v/v). The separated metabolites were quantified using a radioisotope scanner.

RESULTS

Both androgens were metabolized to 5alpha-dihydrotestosterone (DHT) and 4-androstenedione (4-A) or testosterone (T) at baseline and in response to the agents tested, by HGF and HPF. With HGF, there were significant increases in the yields of DHT and 4-A or T in response to M, E, and M+E, resulting in 50% to 2.4-fold increases in these metabolites over control incubations (n = 6; P<0.01). The responses to I and combinations of I+E were similar. HPF also demonstrated significant increases of 29% to 4-fold in the yields of androgen metabolites in response to M, E, and M+E (n = 6; P<0.01). I and E similarly increased the yields of androgen metabolites, alone and in combination.

CONCLUSIONS

Adjunctive periodontal treatment with minocycline or indomethacin can contribute to hormone-modulated anabolic responses in males and females in gingival and periosteal fibroblasts derived from a chronically inflamed source.

Dexamethasone-mediated androgen metabolism in human gingival and oral periosteal fibroblasts

Dexamethasone modulates the effects of other hormones and mediates cell function; the periodontium is a target tissue for androgens. It was therefore relevant to investigate the modulation of androgen metabolism by dexamethasone in cultured human gingival (HGF) and oral periosteal fibroblasts (HPF). Each cell line was incubated in Eagle minimum essential medium with [(14)C]testosterone/[(14)C]4-androstenedione as substrates and serial concentrations of dexamethasone (0.5-50 microg/ml), for 24h; the medium was solvent-extracted, analyzed and quantified for steroid metabolites. In response to dexamethasone, both HGF (n=6) and HPF (n=4) showed up to two-fold increases in the formation of 5alpha-dihydrotestosterone and 4-androstenedione (P<0.01, one-way ANOVA), and 3.6- to 5-fold increases in the formation of testosterone (P<0.001), from [(14)C]4-androstenedione, with some inhibition at higher concentrations. Dexamethasone stimulated the formation of physiologically active androgen metabolites in a dose-dependent manner. These metabolites might therefore contribute to dichotomous effects in connective tissues of the periodontium, dependent on effective concentrations of dexamethasone.

Modulatory effects of indomethacin on androgen metabolism in human gingival and oral periosteal fibroblasts

The non-steroidal anti-inflammatory agent indomethacin (I) suppresses gingival inflammation and alveolar bone resorption. Androgens particularly 5 alpha-dihydrotestosterone (DHT) have anabolic effects on connective tissue and bone matrices. Human oral periosteal fibroblasts (HPF) and gingival fibroblasts (HGF) instigate healing in inflammatory periodontal lesions. The aim of this investigation was to compare the modulatory effects of I on the metabolism of two androgen substrates in human oral periosteal and gingival fibroblasts in culture. Monolayer cultures of both cell types (5(th)-9(th) passage) were established in Eagle's MEM and incubated with 14C-testosterone/14C-4-androstenedione and serial concentrations of I (0.5-50 microg/ml) for 24 h. The steroid metabolites were solvent extracted from the medium, separated by TLC and quantified using a radioisotope scanner. Both androgen substrates were metabolized mainly to DHT and 4-androstenedione/testosterone respectively, expressing 5 alpha-reductase and 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) activity in both HPF and HGF. There were 51% and 73% increases in the levels of DHT over controls, with HGF and HPF respectively (n = 6; n = 4, P < 0.01) in response to I at 1-5 microg/ml, often reaching control values at 50 microg/ml. The expression of 17 beta-HSD activity showed less stimulation than the levels of DHT. Both androgen substrates were effective in this metabolic conversion, which is applicable to healing responses in both males and females in vivo. There were 57% increases (n = 4; P < 0.01) over controls, in the formation of androstanediol from 14C-4-androstenedione at 10 microg of I, in HPF. This transformation may regulate androgen action in androgen-dependent tissue. In addition to its anti-inflammatory properties, indomethacin can contribute to anabolic reparatory responses, by increasing the expression of steroid metabolizing enzymes in gingival and periosteal fibroblasts, in the inflammatory periodontal lesion.

The effects of human mast-cell products and of phenytoin on androgen 5alpha-reductase expression in human gingival fibroblasts

The aim was to elucidate mechanisms for phenytoin-induced gingival overgrowth, using effects of type 1 human mast cell (HMC-1) supernatant and histamine on the expression of 5alpha-reductase in human gingival fibroblasts (HGF), and the effects of phenytoin on this activity. Duplicate incubations of HGF in Eagle's minimum essential medium (MEM) were performed with [14C] testosterone and serial concentrations of mast-cell histamine (1-100 microgram/ml)/HMC-1 culture supernatant at serial dilutions of 1-100 microl/ml for 24 h. Other experiments employed optimal concentrations of HMC-1 supernatant (10 microl/ml) or histamine (8 microgram/ml) and phenytoin (1 and 5 microgram/ml), alone and in combination, using two androgen substrates, [14C] testosterone and [14C] 4-androstenedione. At the end of a 24-h incubation the medium was solvent-extracted for steroid metabolites, analysed and quantified in a radioisotope scanner. HMC-1, histamine (n=3) and phenytoin (n=6) significantly increased the synthesis of dihydrotestosterone and 4-androstenedione by up to 80% (P<0.01); the combination of HMC-1 and phenytoin caused two-fold increases (n=6; P<0.01). The incubations with histamine alone and in combination with phenytoin showed significant stimulation of dihydroxytestosterone and the diols alone and in combination, which was less pronounced in combination. This investigation demonstrates significant stimulation of 5alpha-reductase activity in human gingival fibroblasts by mast-cell supernatant and a specific product histamine, alone and in combination with phenytoin. Androgen 5alpha-reductase-mediated anabolic actions in connective tissue are well documented. The findings suggest a novel hypothesis that mast-cell mediated androgen action in the gingiva in response to phenytoin could contribute to gingival overgrowth.

Effects of the anti-androgen finasteride on the modulatory actions of oestradiol on androgen metabolism by human gingival fibroblasts

5 alpha-Reduction of androgen substrates results in the formation of the biologically active androgen 5 alpha-dihydrotestosterone (DHT), while 17 beta-hydroxysteroid dehydrogenase metabolises androgen substrates to 4-androstenedione or testosterone. The aim here was to study the effect of the anti-androgen finasteride on 5 alpha-reduction of androgens by human gingival fibroblasts (HGF) and its modulation by oestradiol-17 beta. Duplicate cultures of HGF were incubated with [14C]testosterone/[14C]4-androstenedione in Eagle minimum essential medium (n=6) in the presence or absence of oestradiol-17 beta (O) or finasteride (F; 0.1-3 microg/ml) for 24 h. The steroid metabolites were analysed and quantified using a radioisotope scanner. With [14C]testosterone as substrate, oestradiol stimulated the formation of DHT by 63% (n=6; P<0.01). In contrast, finasteride inhibited this activity by 61% (n=6; P<0.01). The combination of O+F produced 43% less inhibition than finasteride alone (n=6; P<0.01). There were 200-300% increases in the formation of 4-androstenedione in response to O and F, being less pronounced in combination. Oestradiol stimulated the formation of DHT from [14C]4-androstenedione by 300-600% and finasteride reduced the yield of DHT by 40-64%; there was less inhibition in combination with O. There were 300-700% increases in the formation of testosterone in response to F and O alone and in combination (n=6; P<0.01). Oestradiol-induced stimulation of 5 alpha-reductase activity on androgen substrates by HGF is suggestive of hormone modulatory mechanisms in the healing periodontium of both sexes. Its inhibition by finasteride is suggestive of type 2 isoenzyme activity, confirming target-tissue functions in the gingiva.

Physiological functions and hormonal regulation of mouse vas deferens protein (AKR1B7) in steroidogenic tissues

The MVDP (mouse vas deferens protein) gene encodes an aldose reductase-like protein (AKR1B7) highly expressed in vas deferens epithelium and zona fasciculata of the adrenal cortex. Recombinant MVDP showed kinetic properties distinct from those of aldose reductase, including its spectrum of substrates, cofactor preference and sensitivity to inhibitors. We demonstrate that in adrenocortical cells, MVDP, rather than aldose reductase, is the principal reductase for isocaproaldehyde (a product of side-chain cleavage of cholesterol) and 4-hydroxynonenal (a lipid peroxidation product). In steroidogenic tissues MVDP expression is regulated by pituitary trophic hormones, namely ACTH in adrenals, FSH in ovaries, and LH in testicular Leydig cells.

The effect of minocycline on the metabolism of androgens by human oral periosteal fibroblasts and its inhibition by finasteride

The antimicrobial minocycline has matrix-stimulatory effects on connective tissue and bone. The aim here was to study the effect of minocycline on 5alpha reduction of androgen substrates to 5alpha-dihydrotestosterone (DHT) in periosteal fibroblasts and the influence of the antiandrogen finasteride on this conversion. Confluent cultures of periosteal fibroblasts established from oral periosteum isolated from the bone surface were incubated in duplicate in multiwell dishes with two androgen substrates, [(14)C]-testosterone/[(14)C]-4-androstenedione, in the presence or absence of serial concentrations of minocycline or the antiandrogen finasteride or the two in combination for 24 h. The metabolites formed were solvent-extracted with ethyl acetate, separated by thin-layer chromatography and quantified using a radioisotope scanner. Both androgen substrates were metabolized to DHT and 4-androstenedione or testosterone. Minocycline stimulated the synthesis of DHT from these substrates by 75-83% at 20-30 microg/ml (n=4; p<0.01). Finasteride inhibited the 5alpha-reductase activity of these substrates by 3-5-fold at 1 microg/ml and 40-80% at 0.01 and 0.1 microg/ml (n=4; p<0.01), with little change in 17beta-hydroxysteroid dehydrogenase activity. Minocycline and finasteride in combination showed an intermediate response with one substrate. As finasteride inhibits the type 2, 5alpha-reductase isoenzyme associated with anabolic functions, these findings demonstrate target-tissue androgen metabolic activity in periosteal fibroblasts at baseline and in response to minocycline. This has implications for the reparatory potential of the diseased periodontium during adjunctive treatment with minocycline.

Down-regulation of AP1 activities after polarization of vas deferens epithelial cells correlates with androgen-induced gene expression

Vas deferens epithelial cell subcultures were used to study the sequential regulation of jun/fos proto-oncogene expression and AP1 activities during cell proliferation, polarization and androgen-induced expression of a terminal differentiation marker, i. e. the mvdp gene. Proliferation of epithelial cells is associated with a high expression in the nucleus of most Jun and Fos oncoproteins. After cell seeding on an extracellular matrix which allows polarization and expression of the mvdp gene in response to androgens, AP1 protein accumulation is greatly altered and consists in a loss of JunB, Fra1, FosB and a decrease in c-Fos, c-Jun and Fra2, while JunD remained at the same level. This was correlated with a drop in AP1 binding activity as evaluated by gel shift assay using either AP1 consensus sequence or AP1 binding sites of the mvdp gene promoter region, and in AP1 transactivating activity, as estimated by stable transfection experiments using an AP1 responsive promoter (TRE-TK-luc). Androgens did not significantly influence AP1 activities. On the contrary, stimulation of AP1 proteins by the tumor-promoting phorbol ester caused a decrease in androgen-induced mvdp mRNA accumulation, and this effect was reversed by staurosporine, a potent inhibitor of PKC. Our data suggest that a down-regulation of AP1 activities induced by epithelial cell differentiation is a prerequisite to androgen-induced mvdp gene expression. The high AP1 activities observed during proliferative state or induced in TPA-treated polarized cells, exert a repressive effect on androgen action.

Implications of minocycline, platelet-derived growth factor, and transforming growth factor-beta on inflammatory repair potential in the periodontium

BACKGROUND

Semisynthetic tetracyclines used in the adjunctive treatment of inflammatory periodontal disease enhance collagen expression in induced periodontal lesions of rats. Polypeptide growth factors regulate key cellular events in tissue repair. The physiologically active androgen 5 alpha-dihydrotestosterone (DHT) stimulates bone and connective tissue turnover. It was relevant to study the effects of transforming growth factor beta (TGF-beta)/platelet-derived growth factor (PDGF) and minocycline alone and in combination on the formation of biologically effective androgens which can influence repair.

METHODS

Confluent monolayer cultures of human gingival fibroblasts of the fifth through the ninth passage were incubated in Eagle's minimum essential medium, with 14C-testosterone/14C-4-androstenedione in the presence or absence of optimal concentrations of TGF-beta/PDGF/minocycline (M), alone and in combination. At the end of a 24-hour incubation period, the medium was analyzed for steroid metabolites and quantified using a radioisotope scanner.

RESULTS

The androgen substrates 14C-testosterone (14C-T) and 14C-4-androstenedione (14C-4-A) were metabolized to DHT and 4-androstenedione/testosterone respectively. There were significant increases in the formation of DHT from 14C-T in response to M, TGF-beta, and PDGF, alone and in combination (13 to 48%), compared with controls (n = 4; P<0.01). The yields of 4-androstenedione were also greater in response to these agents (31%; 3-fold). When 14C-4-A was used as substrate, there were 21 to 80% increases in the formation of DHT in response to these agents alone and in combination (n = 4; P<0.01).

CONCLUSIONS

The biologically effective androgen metabolites formed in response to minocycline, TGF-beta, and PDGF can contribute to reparatory events in the inflamed periodontium. Judicious, adjunctive usage of the chemically-modified tetracyclines in the treatment of periodontal diseases can obviate the risk of microbial resistance, with potential applications of their anti-inflammatory and proanabolic effects in regenerative technology.

Modulation of androgen metabolism by estradiol-17beta and progesterone, alone and in combination, in human gingival fibroblasts in culture

BACKGROUND

Androgens, particularly 5alpha-dihydrotestosterone (DHT), have anabolic effects on connective tissues and bone with implications on periodontal healing. This can be enhanced by estradiol-17beta (E-17beta), in synergy with androgen action. The effects of progesterone (P) contribute to plaque-induced inflammatory changes. The aim of this investigation was to study the modulation of androgen metabolism by E-17beta and P, alone and in combination.

METHODS

Human gingival fibroblasts were established in monolayer culture and duplicate incubations were performed in Eagle's MEM for 24 hours with either 14C-testosterone (14C-T) or 14C-4-androstenedione (14C-4-A) as substrate and serial concentrations of E-17beta, P and E-17beta + P. The medium was solvent extracted for steroid metabolites, analyzed, and quantified using a radioisotope scanner. The androgen substrates were converted mainly to DHT and 4-androstenedione/testosterone from 14C-T and 14C-4-A respectively.

RESULTS

At concentrations of 0.1 and 0.5 microg/ml, E-17beta stimulated DHT synthesis from 14C-T by 18% and 12%, respectively, decreasing to control values at 0.1 microg/ml. While the effect of similar concentrations of P on the same substrates was inhibitory by 18, 70, and 82% (n = 4; P <0.01). E-17beta + P showed a 12% increase in DHT synthesis over controls at 0.1 microg/ml, similar to that of E-17beta alone, despite the inhibitory effects of P (n = 4; P <0.01) with 12% and 77% decreases at 0.5 and 1 microg/ml (n = 4; P <0.01). The inhibitory effect of P on DHT synthesis was less apparent when E-17beta was present in combination. The formation of 4-androstenedione from 14C-T was stimulated by E-17beta (12.5%), inhibited by P (50%) and showed an intermediate response with E + P (33% stimulation). At the concentrations used, E-17beta stimulated DHT synthesis from 14C-4-A by 3.6-, 3- and 2.6-fold. P also stimulated this conversion from the same substrate by 16%, 2-fold, and 1.6-fold increases, partly due to the low yields at baseline. The combination of E + P stimulated the synthesis of DHT from 14C-4-A by 4-fold at 0.1 and 0.5 microg/ml and a 2.3-fold increase at 1 microg/ml. The formation of T from 14C-4-A was stimulated by E-17beta (50%) and inhibited by P (40%), with 93% stimulation by E + P at 0.1 microg/ml.

CONCLUSIONS

The modulatory effects of estradiol-17beta and progesterone on androgen metabolism may influence disease presentation and the progress of healing responses in the inflamed periodontium.

The combined effects of TGF-β, IGF and PDGF on 5α-reductase activity on androgen substrates in human gingival tissue

The combined effects of the growth factors, PDGF, TGF-beta and IGF, on the metabolism of two androgen substrates by human gingival tissue were investigated. Having established their wet weight, duplicate incubations were performed in Eagle's MEM using [(14)C]testosterone/[(14)C]4-androstenedione as substrates and growth factors, PDGF, TGF-beta and IGF, alone and in combination. Steroid metabolites were then isolated, separated and quantified, using a radioisotope scanner. With [(14)C]testosterone as substrate, there were 3-5-fold decreases in 5alpha-reductase activity in response to individual growth factors, while the combinations, PDGF+TGF-beta, PDGF+IGF and TGF-beta-IGF, resulted in approximately half the stimulation, or similar to that of one of the growth factors, but still about 2-fold greater than control values. When [(14)C]4-androstenedione was used as substrate, there were approximately 2-6-fold increases in DHT synthesis in response to the growth factors alone. When used in combination, and intermediate response was seen. Growth factor combinations can enhance anabolic activity in the chronically inflamed periodontium.

Sequence and expression levels in human tissues of a new member of the aldo-keto reductase family

We have isolated a human cDNA clone from small intestine that represents a new member of the aldo-keto reductase family. This new member showed 70% identity at the protein level to human aldose reductase and around 80% identity to other Chinese hamster and mouse reductases. The expression pattern shows that this message is located primarily in the adrenal gland, thus suggesting an involvement in steroid metabolism. It is also strongly expressed in the intestinal tract and has been called human small intestine reductase.

The effect of PDGF, TGF-beta and IGF in combination on androgen metabolism by fibroblasts

The aim of this investigation is to study growth factor combinations (PDGF/IGF PDGF/TGF-beta and TGF-beta/IGF) on the metabolism of 2 androgen substrates 14C-testosterone/14C-4-androstenedione to the matrix stimulatory androgen 5alpha-dihydrotestosterone (DHT). Human gingival fibroblasts in culture were incubated in Eagle's MEM with the radiolabelled substrates and growth factors for 24 h, when the medium was extracted and analysed for radioactive metabolites. When 14C-testosterone was used as substrate, there was an 80% increase in DHT synthesis over controls with the PDGF/IGF combination (n=7; p<0.01), which was less than the effects of each of the growth factors alone. Similarly, PDGF/TGF-beta resulted in a 2-fold increase in DHT synthesis over controls (n=5; p<0.01) which compared with individual PDGF incubations, and the TGF-beta/IGF combination resulted in a 30% increase in DHT synthesis over controls (n=3; p<0.01); this was less than the 2.8/2.5-fold increases produced individually. Similarly, when 14C-4-androstenedione was used as the substrate, there were 2-fold increases in DHT synthesis in response to combinations of PDGF/IGF and PDGF/TGF-beta (n=5; p<0.01). These results demonstrate feedback inhibition when individually active growth factors function in combination; this may be indicative of mechanisms for physiological homeostasis seen in vivo.

Differential control of murine aldose reductase and fibroblast growth factor (FGF)-regulated-1 gene expression in NIH 3T3 cells by FGF-1 treatment and hyperosmotic stress

Aldose reductase (AR) is an NADPH-dependent aldo-keto reductase implicated in cellular osmoregulation and detoxification. Two distinct murine genes have been identified that are predicted to encode proteins with significant amino acid sequence identity with mouse AR: mouse vas deferens protein and fibroblast growth factor (FGF)-regulated-1 protein (FR-1). Here we report that the AR and FR-1 genes are differentially regulated in NIH 3T3 fibroblasts. FGF-1 stimulation of quiescent cells induces both AR and FR-1 mRNA levels, but the effect on FR-1 mRNA expression is significantly greater. FGF-1 treatment also increases FR-1 protein expression, as determined by Western-blot analysis using FR-1-specific polyclonal antiserum. Calf serum stimulation of quiescent cells increases AR mRNA expression but not FR-1 mRNA expression. Finally, when NIH 3T3 cells are grown in hypertonic medium, AR mRNA levels are significantly increased whereas FR-1 mRNA levels are only slightly up-regulated. These results indicate that the AR and FR-1 genes are differentially regulated in murine fibroblasts by two different growth-promoting agents and by hyperosmotic stress. Therefore these structurally related enzymes may have at least some distinct cellular functions; for example, although both AR and FR-1 activity may be important for the metabolic changes associated with cellular proliferation, AR may be the primary aldo-keto reductase involved in cellular osmoregulation.

Tissue-specific expression of two aldose reductase-like genes in mice: abundant expression of mouse vas deferens protein and fibroblast growth factor-regulated protein in the adrenal gland

Aldose reductase (AR), the first enzyme in the polyol pathway, has been implicated in the pathogenesis of diabetic complications, although its physiological role is unclear. In mice, besides AR, two AR-like proteins, mouse vas deferens protein (MVDP) and fibroblast growth factor-regulated protein (FR-1), have been reported recently. Tissue-specific expression of these two genes was examined using the RNase protection assay method. Contrary to previous reports, MVDP was detected in a variety of tissues besides the vas deferens. High levels of MVDP mRNA were found in the adrenal glands, and low levels of expression were detected in eye, intestine, seminal vesicle, kidney, liver, testis and lung. The major gene expression pattern for FR-1 was slightly different from that of MVDP, with the highest levels of mRNA detected in testis, heart, adrenal gland, and ovary; less was found in the lung and it was barely detectable in eye, intestine, liver and seminal vesicle tissue. Mouse embryos, as early as 10.5 days post coitum, expressed both genes, although the levels of expression were different. Human AR mRNA was found in human vas deferens, although not at the high level found in mice. The localization of both MVDP and FR-1 transcripts in the adrenal cortex by in situ hybridization led to the speculation that these two AR-like proteins could be related to hormone production.