Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q8NEX9 (reductase)
 26,410 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A serum-free chemically defined medium (CDM) has been developed which sustains the growth in culture of the highly differentiated human hepatoma cell line Hep G2. Unlike rodent hepatoma lines, Hep G2 cells in serum-free medium have an absolute requirement for lipoprotein lipids (either low density lipoprotein (LDL) or high density lipoprotein (HDL)) for growth. In the presence of LDL (or HDL) growth was further enhanced by insulin, triiodo-L-thyronine, 17 alpha-ethinylestradiol but not by epidermal growth factor (EGF). On type I collagen gels cells cultured in CDM were contact inhibited and formed monolayers. This contrasted with the pattern of growth of cells cultured in the presence of serum on type I collagen gels and cells cultured on tissue-culture plastic in either CDM or medium containing serum which formed foci of multilayered cells. Expression of the LDL receptor and HMG-CoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase genes was comparable in Hep G2 cells cultured in CDM and serum-containing medium. Furthermore, the binding and internalisation of 125I-LDL at 37 degrees C was modulated by hormones that have previously been shown to affect LDL receptor levels in liver in vivo or in hepatocytes cultured in serum-containing medium in vitro. The culture system described provides a basis for studying the regulation of hepatocyte-specific functions by soluble factors (either plasma- or cell-derived) and cell-substratum interactions in a human liver cell line.
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PMID:Growth requirements and expression of LDL receptor and HMG-CoA reductase in Hep G2 hepatoblastoma cells cultured in a chemically defined medium. 133 14

NADH oxidase activity (electron transfer from NADH to molecular oxygen) of plasma membranes purified from rat liver was characterized by a cyanide-insensitive rate of 1 to 5 nmol/min per mg protein. The activity was stimulated by growth factors (diferric transferrin and epidermal growth factor) and hormones (insulin and pituitary extract) 2- to 3-fold. In contrast, NADH oxidase was inhibited up to 80% by several agents known to inhibit growth or induce differentiation (retinoic acid, calcitriol, and the monosialoganglioside, GM3). The growth factor-responsive NADH oxidase of isolated plasma membranes was not inhibited by common inhibitors of oxidoreductases of endoplasmic reticulum or mitochondria. As well, NADH oxidase of the plasma membrane was stimulated by concentrations of detergents which strongly inhibited mitochondrial NADH oxidases and by lysolipids or fatty acids. Growth factor-responsive NADH oxidase, however, was inhibited greater than 90% by chloroquine and quinone analogues. Addition of coenzyme Q10 stimulated the activity and partially reversed the analogue inhibition. The pH optimum for NADH oxidase was 7.0 both in the absence and presence of growth factors. The Km for NADH was 5 microM and was increased in the presence of growth factors. The stoichiometry of the electron transfer reaction from NADH to oxygen was 2 to 1, indicating a 2 electron transfer. NADH oxidase was separated from NADH-ferricyanide reductase, also present at the plasma membrane, by ion exchange chromatography. Taken together, the evidence suggests that NADH oxidase of the plasma membrane is a unique oxidoreductase and may be important to the regulation of cell growth.
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PMID:A growth factor- and hormone-stimulated NADH oxidase from rat liver plasma membrane. 156 90

Male mouse urogenital ridges (URs) at 15.5 days of gestation (vaginal plug = day 0) containing Wolffian (WDs) and Mullerian ducts were cultured for 4 days with or without gonads in serum-free medium (1:1 mixture of Dulbecco's modified Eagle's medium and Ham's F-12 supplemented with insulin, transferrin, cholera toxin, epidermal growth factor, and BSA). URs without gonads were grown in serum-free medium with testosterone (T, 10(-7) M), 5 alpha-dihydrotestosterone (DHT, 10(-8) M), T (10(-7) M) plus cyproterone acetate (antiandrogen, 10(-5) M), or T (10(-8) M) plus 390 MSD (17 beta-N, N-diisopropylcarbamoyl-4-aza-5 alpha- androstan-3-one, an inhibitor of 5 alpha-reductase, 10(-5) M). After 4 days of culture the number of epididymal curvatures that appeared in the upper portion of WDs were quantified. DNA content of URs grown in serum-free medium was also measured. Both T and DHT increased DNA contents in a dose- (T = 10(-8) to 10(-10) M, DHT = 10(-9) to 10(-11) M) and time-dependent manner. DHT was approximately 10-fold more effective than T in eliciting epididymal coiling and increasing DNA content of URs. The effects of T or DHT were mimicked by coculture with fetal testes. Epididymal coiling and an increase in DNA content occurred in URs grown in the presence of T plus 390 MSD. By contrast, URs cultured without androgens or with T plus cyproterone acetate failed to undergo epididymal coiling and to increase DNA content. The conversion rate per mg protein of [1 beta, 2 beta-3H]T into [3H]DHT was 0.30-fold lower in 15.5 day URs cultured over a 4-day period in comparison to urogenital sinuses whose development is known to be dependent upon DHT. These data suggest that T is an important hormone in the development of the upper portion of WDs, although it is not possible to exclude a role for DHT in the development of the epididymis.
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PMID:In vitro androgen-induced growth and morphogenesis of the Wolffian duct within urogenital ridge. 182 79

In a serum-free medium we have established two new human breast carcinoma cell lines from a single primary tumor. Cultures were maintained on chemically defined medium CDM3 or on minor modifications of this medium, Dulbecco's modified Eagle medium-Ham's F12 supplemented with epidermal growth factor, insulin, transferrin, estradiol, hydrocortisone, triiodothyronine, cyclic AMP, phosphoethanolamine, ethanolamine, fibronectin, fetuin, ascorbic acid, bovine serum albumin, and trace element salts including selenite (Petersen and van Deurs, Cancer Res., 47: 856-866, 1987). Primary cultures comprised both NADPH-neotetrazolium reductase-positive carcinoma cells and NADPH-neotetrazolium reductase-negative cells of stromal appearance, as well as normal epithelial cells (Petersen and van Deurs, Cancer Res., 46: 2013-2020, 1986). In subsequent passages the cells were monitored exclusively using the tumorigenicity assay on nude mice. Two cell lines, one nontumorigenic, HMT-3909S1, and one tumorigenic, HMT-3909S8, were selected from the primary cultures. Selection of S8 through subline S4 required transient supplementation of CDM3 with fetal calf serum. Permanent lines S1 and S8 were maintained on serum-free medium. Further characterization of the two cell lines in terms of normal breast gland differentiation (Petersen and van Deurs, Differentiation, 39: 197-215, 1988) was carried out using immunocytochemistry, immunochemistry, electron microscopy, and cytogenetics. S8 appeared to be identical with the NADPH-neotetrazolium reductase-positive carcinoma cells of the primary cultures, with a particular subpopulation of carcinoma cells in the tumor of origin, and with the tumorigenic cells of the nude mice. This subline was aneuploid, typically epithelial in morphology, and expressed keratins K8 and K18 and the glycoprotein MAM-6, typical of luminal epithelial cells in the normal breast gland. Subline S1 appeared more like the elongated cells in the primary cultures and like a second subpopulation of cells in the carcinoma of origin. However, S1 cells were in fact epithelial, since they expressed keratins. Also, S1 cells seemed to be a triploidation of a cell with close resemblance to S4, while only few cytogenetic differences were found between S4 and S8, suggesting an origin of S1 and S8 via S4 from a single hypothetical stem cell.
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PMID:Differential tumorigenicity of two autologous human breast carcinoma cell lines, HMT-3909S1 and HMT-3909S8, established in serum-free medium. 215 55

The seminal vesicles (SV) develop from the lower portion of the Wolffian ducts (WD) in response to androgens, which prevent their degeneration and subsequently stimulate organogenesis of the epididymis, vas deferens, seminal vesicles, and ejaculatory ducts. Earlier studies suggest that testosterone (T) is the active androgen for WD development. By contrast, development of urogenital sinus and external genitalia is dependent upon 5 alpha-dihydrotestosterone (DHT), produced by 5 alpha-reductase within the target tissue itself. To reevaluate the possible role of DHT during SV morphogenesis, SVs from 0-day-old (day of birth) mice were grown for 3, 6, or 9 days in either serum-free or serum-containing medium in the presence or absence of T (10(-7) M) or DHT (10(-8) M). The serum-free medium consisted of Ham's F-12-Dulbecco's Modified Eagle's Medium (1:1) containing insulin, transferrin, cholera toxin, BSA, and epidermal growth factor. The serum-containing medium was Ham's F-12-Dulbecco's Modified Eagle's Medium containing 10% fetal calf serum. Epithelial branching morphogenesis of SVs occurred in serum-free or serum-containing medium supplemented with either T or DHT and was comparable to that of SVs of similar ages in vivo. In serum-containing medium the DNA content of the cultures was about 2-fold higher in T-containing vs. T-deficient medium. However, in serum-free medium the DNA content was the same in cultures grown with or without T. SVs cultured under serum-free conditions in the presence of T plus 390 MSD (17 beta-N,N-diisopropylcarbamoyl-4-aza-5 alpha-androstan-3-one, an inhibitor of 5 alpha-reductase) were completely inhibited in their development, while in the presence of DHT plus 390 MSD, branching morphogenesis was comparable to that in SVs cultured in the presence of T or DHT alone. In medium lacking either T or DHT, SV development was inhibited. In addition, it was confirmed by TLC that [1 beta,2 beta-3H]T was converted into [3H]DHT at the ratio of 15.4% for the first 2 days and at 35.3% for the subsequent 2 days of the culture of SVs in serum-free medium. These data demonstrate that T is important as a precursor of DHT and DHT is the major androgen in the postnatal development of mouse SVs from the lower WD.
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PMID:Postnatal growth of mouse seminal vesicle is dependent on 5 alpha-dihydrotestosterone. 224 47

The present studies examined the hormonal regulation of 5 alpha-reductase activity in cultured immature rat Leydig cells. Within the testis 5 alpha-reductase was concentrated in the interstitial cell compartment, and among interstitial cells, the enzyme was localized primarily in Band 3 of Percoll density gradients, which contains the majority of Leydig cells. Among various factors reported previously to stimulate testicular 5 alpha-reductase activity when administered in vivo to immature rats (LH/hCG, FSH, luteinizing hormone releasing hormone or prolactin), only LH/hCG directly stimulated 5 alpha-reductase activity of cultured immature Band 3 cells. Neither growth hormone which was reported previously to stimulate hepatic 5 alpha-reductase activity, nor insulin, insulin-like growth factor-I, or epidermal growth factor, which have been reported to modulate Leydig cell function, had any effect on 5 alpha-reductase activity of Band 3 cells. These studies suggest that the major factor directly stimulating 5 alpha-reductase activity in Leydig cells during early maturation is LH. However, it is possible that other factors acting indirectly may modulate the maturational rise in 5 alpha-reductase activity.
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PMID:Regulation of 5 alpha-reductase activity in cultured immature leydig cells by human chorionic gonadotropin. 236 32

Using human adipose stromal cells in monolayer culture as a model system for study of the regulation of aromatase activity, as well as polyclonal antibodies raised in this laboratory against aromatase cytochrome P-450 (cytochrome P-450AROM), it was found that the rate of synthesis of cytochrome P-450AROM was stimulated by dibutyryl cyclic AMP. This stimulation was attenuated by epidermal growth factor and was potentiated by phorbol esters. These changes in cytochrome P-450AROM synthesis were associated with comparable changes in the levels of translatable cytochrome P-450AROM mRNA, as well as with changes in the activity of aromatase of these cells. By contrast, there was little change in the synthesis of the reductase component of the aromatase enzyme complex in response to these factors. The increase in mRNA was blocked by cycloheximide, indicative of a requirement for protein synthesis in mediating this inductive response. It is concluded that aromatase activity is regulated primarily by changes in the level of mRNA encoding cytochrome P-450AROM, and that such changes are likely a reflection of changes in the rate of transcription of the gene encoding this enzyme. Increases in the levels of cytochrome P-450AROM mRNA are apparently mediated by a regulatory protein(s), similar to that found for other steroidogenic forms of cytochrome P-450.
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PMID:Regulation of estrogen biosynthesis in human adipose stromal cells. Effects of dibutyryl cyclic AMP, epidermal growth factor, and phorbol esters on the synthesis of aromatase cytochrome P-450. 303 80

Androgen controls the expression of beta-glucuronidase and several other proteins in the kidney of the standard laboratory mouse, Mus musculus. Other species within the genus Mus exhibit a variety of response patterns for kidney beta-glucuronidase and other markers of androgen action. We have investigated the mechanism of androgen action in M. caroli, a Mus species that does not produce beta-glucuronidase in response to testosterone. The failure of testosterone to induce beta-glucuronidase in M. caroli females cannot be overcome by treatment with dihydrotestosterone, with pharmacological doses of testosterone propionate or dihydrotestosterone propionate, or with a variety of potent androgen analogues. All of these compounds induce kidney beta-glucuronidase in M. musculus females and kidney ornithine decarboxylase, submandibular gland renin, and submandibular gland epidermal growth factor in both M. caroli and M. musculus females. Furthermore, kidney androgen receptor proteins from M. caroli and M. musculus animals have the same sedimentation characteristics on sucrose density gradients. These data indicate that androgen resistance in M. caroli is not due to deficient 5 alpha-reductase or aberrant hormone metabolism producing suboptimal levels of functional androgen and is not caused by a defective androgen receptor. They suggest that the resistance of beta-glucuronidase in M. caroli kidney to induction by androgen occurs at the level of the beta-glucuronidase gene.
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PMID:Specificity of androgen resistance in Mus caroli kidney. 307 98

The proliferation of 3T6 cells was substantially decreased when the monolayer cultures were allowed to reach confluency. This growth inhibition (so-called density-dependent inhibition) was of the same magnitude as that following serum depletion in non-confluent cultures. Each type of growth inhibition was correlated to a depression of the activity of 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG CoA) reductase, an enzyme that regulates the biosynthesis of cholesterol and isoprenoid derivatives (e.g. dolichol) by catalysing the reduction of HMG CoA (which is derived from acetyl-CoA) into mevalonate. However, the depression of enzyme activity was more substantial in cells exposed to cell crowding than that in serum-depleted cells (87 and 48%, respectively). On the other hand, there was a 60-65% inhibition of the incorporation of mevalonate into dolichol due to serum deprivation, while it remained at normal level in confluent cultures, which implies that the inhibitory effects on dolichol synthesis due to these two experimental conditions were approximately equipotent. Addition of epidermal growth factor (EGF) to the cell cultures, whose proliferation was inhibited due to serum depletion, restored DNA synthesis completely, and these effects were related to a normalization of the activity of HMG CoA reductase and of the incorporation of mevalonate into dolichol. In contrast, in confluent cells addition of EGF only caused a slight increase in DNA synthesis and activity of HMG CoA reductase, and there was no significant increase in the incorporation of mevalonate into dolichol either.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The role of HMG CoA reductase and dolichol synthesis in the control of 3T6 cell proliferation: effects of cell crowding, serum depletion and addition of epidermal growth factor. 326 15

Recently improved culture conditions for human adult arterial endothelial and smooth muscle cells from a wide variety of donors have been used to study the effects of lipoproteins on proliferation of both cell types in low serum culture medium. Optimal growth of endothelial and smooth muscle cells in an optimal nutrient medium (MCDB 107) containing epidermal growth factor, a partially purified fraction from bovine brain, and 1% (v/v) lipoprotein-deficient serum was dependent on either high- or low-density lipoprotein. High- and low-density lipoprotein stimulated cell growth by three- and five-fold, respectively, over a 6-day period. Optimal stimulation of both endothelial and smooth muscle cell growth occurred between 20 and 60 micrograms/ml of high- and low-density lipoproteins, respectively. No correlation between the activation of 3-hydroxyl-3-methylglutaryl coenzyme. A reductase activity and lipoprotein-stimulated cell proliferation was observed. Lipid-free total apolipoproteins or apolipoprotein C peptides from high-density lipoprotein were partially effective and together with oleic acid effectively replaced native high-density lipoprotein for the support of endothelial cell growth. In contrast, apolipoproteins or apolipoprotein C peptides from high-density lipoprotein alone or with oleic acid had no effect on smooth muscle cell proliferation. The results suggest a functional role of high- and low-density lipoproteins and apolipoproteins in the proliferation of human adult endothelial and smooth muscle cells.
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PMID:Role of lipoproteins in growth of human adult arterial endothelial and smooth muscle cells in low lipoprotein-deficient serum. 353 60


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