Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Retinoic acid (RA) receptors (RARs) are ligand-inducible transcription factors that bind to specific DNA sequences associated with the regulatory regions of RA-regulatable genes. Since RA has been implicated as an important factor both in normal development and in teratological studies, one would like to have a model system that detects the presence of activated receptors during development. We have constructed a recombinant reporter gene that has three copies of the RA response element (RARE) from the RAR beta-2 promoter 5' to the herpes simplex virus thymidine kinase promoter; this regulatory region is coupled to the bacterial beta-galactosidase reporter gene. This construct was RA inducible in transient transfection assays in F9 embryonal carcinoma cells. Transgenic embryos with this reporter gene construct exhibited restricted and reproducible patterns of beta-galactosidase activity during embryogenesis, beginning between gestational ages day 7.5 and 8.5. At day 8.5, beta-galactosidase activity was detected in the closed neurotube and somites. Day 8.5 embryos, from pregnant females fed RA 14 hr earlier, exhibited a greater intensity and distribution of beta-galactosidase activity. Similarly, at later stages of gestation, maternal RA exposure resulted in enhanced embryonic beta-galactosidase expression. This type of transgenic indicator mouse should be useful in detailing the role of activated RARs during embryonic development.
 ...
PMID:Transgenic indicator mice for studying activated retinoic acid receptors during development. 131 86

Expression vectors have been constructed for a region of the human retinoic acid receptor-alpha (hRAR-alpha) and transferred into F9 embryonal carcinoma (EC) cells. When the vectors are overexpressed in F9 cells, clones can be selected for resistance to retinoic acid-induced differentiation. This effect is obtained even when the hRAR-alpha region is expressed as a beta-galactosidase fusion protein. Using the beta-galactosidase component of the fusion protein as a marker, overexpression of the fusion protein has been correlated with the retinoic acid-resistance effect. The clones resistant to retinoic acid no longer exhibit the normal retinoic acid induction of endo B cytokeratin, laminin B-1, and tissue plasminogen activator mRNAs observed with normal F9 cells. Retinoic acid induction of type IV alpha-1 collagen and Hox-1.3 RNAs is observed with these clones. When transfected with a thyroid receptor DNA-binding sequence (TRE)/thymidine kinase promoter/luciferase construct, the retinoic acid-resistant clones do not yield the same retinoic acid-induced level of luciferase obtained with F9 cells. It is hypothesized that the RAR vectors are interfering with endogenous RAR(s) in a dominant-negative manner to inhibit retinoic acid-induced differentiation of F9 EC cells.
 ...
PMID:Retinoic acid receptor expression vector inhibits differentiation of F9 embryonal carcinoma cells. 255 44

A reporter cell line was established from F9 mouse teratocarcinoma cells containing the RAR beta 2 promoter coupled to the lacZ (beta-galactosidase) reporter gene. All-trans-, 9-cis-, and all-trans-4-oxoretinoic acid were equipotent in inducing cell differentiation at 1 microM, determined by induction of collagen IV mRNA expression, of morphological changes, as well as of beta-galactosidase enzyme activity. By the same criteria, beta-carotene at 10 microM also induced differentiation, but less strongly and more slowly than the retinoic acids. In contrast, the oxocarotenoid (or xanthophyll) canthaxanthin, at 10 microM, had little effect on differentiation, unless preincubated in culture medium, from which 4-oxoretinoic acid was recovered and identified as a decomposition product. This indicates that canthaxanthin can act as an effective inducer of differentiation only after breakdown to active metabolites. Likewise, beta-carotene probably also acts subsequent to breakdown to retinoic acid. Throughout these experiments the response of the RAR beta promoter-lacZ reporter gene correlated well with other parameters of differentiation, making this cell line a useful system for examination of inducers of embryonal carcinoma cell differentiation.
 ...
PMID:Efficacy of all-trans-beta-carotene, canthaxanthin, and all-trans-, 9-cis-, and 4-oxoretinoic acids in inducing differentiation of an F9 embryonal carcinoma RAR beta-lacZ reporter cell line. 786 21

Retinoic acid and its derivatives (retinoids) exert profound influences on epithelial growth differentiation in a variety of tissues, including the skin. How retinoic acid mediates these effects is not fully understood. The recent cloning of a series of nuclear receptors for retinoic acid (RARs) has demonstrated that these proteins can function as ligand-inducible transcriptional enhancing factors. Moreover, all receptors are members of the steroid/thyroid hormone multigene family. In vitro studies have demonstrated the expression of RAR alpha, RAR beta, and RAR gamma in various cell types found in the skin. While multiple isoforms exist for each of the three RARs, it is unclear where each of these receptors functions in vivo to mediate the tissue-specific effects of retinoic acid. As a first step in determining sites of retinoic acid-mediated transcriptional activation in the skin and its appendages, we developed a transgenic model in which the retinoic acid response element (RARE) of the RAR beta 2 isoform is linked to a beta-galactosidase reporter gene. Our observations consistently demonstrate that retinoic acid transcriptionally activates the beta 2RARE in distinct areas of the skin. Of interest, certain of these areas are known to contain stem cells. These data clearly demonstrate that this type of transgenic "reporter" model can be used to further define retinoic acid-regulated signal transduction pathways in the skin, as well as other complex tissues. Furthermore, these observations raise the possibility that transcriptional activation of RAR beta 2 may regulate the growth and differentiation programs of selected populations of stem cells in the skin and its appendages.
 ...
PMID:A beta 2RARE-LacZ transgene identifies retinoic acid-mediated transcriptional activation in distinct cutaneous sites. 808 29

1,25-Dihydroxyvitamin D3 (calcitriol) at 100 nmol/l elicited morphological differentiation and expression of collagen IV in mouse F9 embryonal carcinoma cells, and its effect was enhanced and accelerated by dibutyryl-cAMP (db-cAMP). The RAR beta 2 promoter was also activated, as evidenced by an increase in beta-galactosidase activity in an F9 reporter cell line with a stably integrated RAR beta 2-lacZ construct. All three effects were slower and less extensive with calcitriol than with retinoic acid, even in the presence of db-cAMP. Activation of the RAR beta 2 promoter by calcitriol required its TRE sequence, whereas db-cAMP required the CRE. TPA also activated the RAR beta 2 promoter, requiring a functional TRE. Thus, in the RAR beta 2 promoter the TRE sequence, whose function has so far been unidentified, mediates the effects of calcitriol and TPA. RAR beta 2 promoter activation by calcitriol was blocked by inhibitors of protein kinase C indicating that calcitriol elicits its effect via protein kinase C. Therefore, calcitriol induces differentiation of F9 mouse embryonal carcinoma cells at least in part by a pathway different from the classical one operative with retinoic acids.
 ...
PMID:Induction of mouse embryonal carcinoma cell differentiation and activation of the retinoic acid receptor beta 2 promoter by 1,25-dihydroxyvitamin D3. 896 Mar 71

The regulation of mouse cellular retinoic acid-binding protein-I (CRABP-I) gene expression by the retinoids and thyroid hormones was examined, by using a beta-galactosidase (lacZ) reporter gene and a CRABP-I specific antibody, in transgenic mouse embryos and a mouse embryonal carcinoma cell line P19. The CRABP-lacZ reporter gene expression recapitulated the expression pattern of endogenous CRABP-I in the developing central nervous system. In mid-gestation mouse embryos the expression of both the transgene and the endogenous protein was elevated under the condition of hypovitaminosis A, suggesting that depletion of retinoic acid (RA) induced CRABP-I expression in embryos. Consistently, this reporter was suppressed by RA in P19 cells. In co-transfection experiments it was demonstrated that the expression of RAR beta, RAR gamma or RXR alpha suppressed this reporter expression. In experiments designed to alter the thyroid hormone status in animals it was demonstrated that both the reporter gene and the endogenous CRABP-I expression were reduced by triiodothyronine injection and were elevated in a hypothyroidic condition induced by feeding with iodine-deficient diet supplemented with 6-propyl-2-thiouracil. In co-transfection experiments it was also demonstrated that the expression of T3R beta suppressed the reporter expression in P19 cells. It was concluded that RA had a suppressive effect on CRABP-I gene expression in embryos and P19 cells and the effect could be mediated through RAR beta, RAR gamma or RXR alpha. A role of thyroid hormones in CRABP-I gene expression and vitamin A metabolism in animals is discussed.
 ...
PMID:Regulation of the mouse cellular retinoic acid-binding protein-I gene by thyroid hormone and retinoids in transgenic mouse embryos and P19 cells. 939 4

Human salivary gland adenocarcinoma cells (HSG) express nuclear receptors, all-trans-retinoic acid (at-RA) receptors (RARs), and retinoid X/9-cis-retinoic acid (9-c-RA) receptors (RXRs). In order to investigate whether the endogenous RARs or RXRs of HSG cells can induce transcription activation, the thymidine kinase promoter (TK)-driven luciferase reporter gene containing the retinoic acid response element (RARE), of RARbeta, betaRARE2-TK-Luc, was transfected into HSG cells and ligand-dependent transcription activation was examined. Luciferase activity of cell lysate increased by the treatment with either at-RA or 9-c-RA. Co-transfection of RARalpha and (or) RXRalpha-expression plasmids with the reporter gene enhanced the luciferase activity, suggesting that endogenous RARs and RXRs work as ligand-dependent transfactors in HSG cells. Reverse transcriptase - polymerase chain reaction analysis revealed that HSG cells express chicken ovalbumin upstream promoter - transcription factor I (COUP-TFI). Co-transfection of COUP-TFI-expression plasmid suppressed the at-RA-induced transcription activation of the reporter gene. Similar results were shown using a chromatin-integrated reporter gene system, using a stably transfected beta-RARE2-TK-beta-galactosidase (beta-Gal) reporter gene. The at-RA-dependent increase in the beta-Gal expression was completely inhibited by COUP-TFI. The transfection of antisense oligonucleotide of COUP-TFI squelched the RA-dependent growth inhibition induced by RAR-RXR heterodimers. Conclusively, RARs and RXRs of HSG cells are functional and play roles as transactivators in at-RA-sensitive processes such as the proliferation or differentiation of cells. COUP-TFI very likely regulates these processes by repressing the functions of these transactivators.
 ...
PMID:Inhibition of retinoic acid-inducible transcription by COUP-TFI in human salivary gland adenocarcinoma cell line HSG. 1066 29