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S Masushige

Publications and source records attributed to S Masushige.

At least 37 records · Page 2Linked to original sources
PubMed1996

Vitamin A is involved in estrogen-induced cell proliferation but not in cytodifferentiation of the chicken oviduct.

We examined vitamin A-deficient chicks to determine whether vitamin A affects the estrogen-induced development of the chick oviduct. When oviduct development was stimulated for 5 days with the synthetic estrogen, diethylstilbestrol, the wet weight of the oviduct in vitamin A-deficient chicks was only half that in control chicks. The DNA content in this tissue showed that the decreased oviduct weight in the vitamin A-deficient chicks was caused by the decreased proliferation of oviduct cells. However, the estrogen-induced expression of the ovalbumin gene was not affected by the vitamin A deficiency, suggesting that estrogen-induced cytodifferentiation is not affected by vitamin A. To clarify the vitamin A action on estrogen-induced development in the oviduct, transcripts of nuclear estrogen receptor (ER) and all-trans-retinoic acid (RAR alpha, beta and gamma) receptors, which exert the effects of estrogen and vitamin A, were measured. The ER, RAR alpha and RAR beta genes, but not that of RAR gamma, were expressed during oviduct development, indicating that estrogen and vitamin A may control the expression of target genes through their cognate receptors. Thus, we have shown that vitamin A is involved in estrogen-induced cell proliferation but not in cytodifferentiation of the chicken oviduct.

Animals↗
PubMed1996

Bacterially expressed rat retinol-binding protein is functional for retinol and transthyretin bindings.

Retinol-binding protein (RBP) was expressed in Escherichia coli using the cDNA for rat RBP, and characterized. The expressed RBP was fused to maltose-binding protein (MBP) at the N-terminal end (MBP-RBP), and MBP was enzymatically removed from the MBP-RBP with proteinase factor Xa. The binding of retinol and transthyretin (TTR) to the recombinant RBP was monitored by means of gel filtration. The recombinant RBP specifically bound to retinol with an affinity similar to that of purified RBP from rat serum. Furthermore, the retinol-bound recombinant RBP formed hetero-complexes with TTR similar to RBP. Thus, the results showed that the recombinant RBP expressed in E. coli is as functional as serum RBP in terms of retinol and TTR bindings.

ATP-Binding Cassette Transporters↗
PubMed1995

Activation of the estrogen receptor through phosphorylation by mitogen-activated protein kinase.

The phosphorylation of the human estrogen receptor (ER) serine residue at position 118 is required for full activity of the ER activation function 1 (AF-1). This Ser118 is phosphorylated by mitogen-activated protein kinase (MAPK) in vitro and in cells treated with epidermal growth factor (EGF) and insulin-like growth factor (IGF) in vivo. Overexpression of MAPK kinase (MAPKK) or of the guanine nucleotide binding protein Ras, both of which activate MAPK, enhanced estrogen-induced and antiestrogen (tamoxifen)-induced transcriptional activity of wild-type ER, but not that of a mutant ER with an alanine in place of Ser118. Thus, the activity of the amino-terminal AF-1 of the ER is modulated by the phosphorylation of Ser118 through the Ras-MAPK cascade of the growth factor signaling pathways.

Amino Acid Sequence↗
PubMed1995

Widely spaced, directly repeated PuGGTCA elements act as promiscuous enhancers for different classes of nuclear receptors.

We describe here a novel class of cis-acting response elements for retinoid, vitamin D, and estrogen receptors which are widely spaced (10 to 200 bp) direct repeats (DRs) of the canonical 5'-AGGTCA half-site recognition motif (DR10 to DR200). In contrast to the specificity previously observed with shortly spaced DRs (DR1 to DR5), the different receptors bind promiscuously to these novel elements to activate transcription in the presence of retinoic acid (RA), vitamin D, or estrogen. The greatest RA-dependent transactivation, seen with DR15, was similar to that observed with the canonical DR5. Both RA receptors and retinoid X receptors contribute to transactivation through widely spaced DR elements. With the estrogen receptor, DR15 was one-third as efficient as the classical palindromic response element. A further increase of spacer lengths progressively decreased the efficiency of transactivation. No transactivation was seen with widely spaced DRs when the thyroid and retinoid X receptors were coexpressed in the presence of their ligands. The progesterone receptor was also unable to transactivate through a DR10 element composed of its cognate binding motifs. These results considerably extend the response element repertoire of nuclear receptors and suggest the existence of promiscuous transcriptional regulation through common response elements, as well as the possibility of receptor "cross-talk."

Animals↗
PubMed1995

Gene expression of retinoic acid receptors, retinoid-X receptors, and cellular retinol-binding protein I in bone and its regulation by vitamin A.

We investigated the gene expression of retinoic acid (RA) receptors (RARs) and retinoid-binding proteins, and the effect of vitamin A on gene expression in the rat tibia to understand the actions of vitamin A on bone tissue. The transcripts of all three subtypes of all-trans RAR (alpha, beta, and gamma) and two of three subtypes of retinoid-X receptor (alpha and beta) were detected by Northern blotting. Among cellular retinol-binding protein I (CRBP-I) and CRBP-II and cellular retinoic acid-binding protein I and II, only the CRBP-I gene was expressed. These results indicated that in bone, the actions of vitamin A are exerted through these nuclear receptors by regulating target gene expression, and through CRBP-I by modulating the intracellular transport of vitamin A. Moreover, using rats of various retinoid status, we investigated whether the expression of target genes for vitamin A (RAR beta and CRBP-I) is regulated by retinoic acid (RA) in the adult rat tibia. The messenger RNA levels of these genes in vitamin A-deficient rats decreased to half of those in normal rats and were quickly restored (4 h) by either all-trans-RA or 9-cis-RA. Excess RA given to normal rats doubled the messenger RNA levels of these two genes. These results verified that, like other target tissues, bone is a target for vitamin A in terms of gene expression. In addition, we examined the effect of RAs on the expression of the target genes for vitamin D, because it is possible that 9-cis-RA is involved in the transcriptional control of vitamin D receptor by forming a heterodimer complex with retinoid-X receptor. The vitamin D-regulated osteopontin gene was induced 4 h after the administration of RA regardless of retinoid or vitamin D status. RA also induced osteopontin gene expression in concert with vitamin D in normal rats. Specific inhibitors of transcription showed that gene expression may be regulated by RA at the transcriptional level. Thus, the results presented here clarified at the molecular level that bone is a target organ for vitamin A in terms of gene expression.

Animals↗
PubMed1994

Vitamin A regulates the expression of apolipoprotein AI and CIII genes in the rat.

The effect of vitamin A on the expression of apoAI and CIII genes in intact rats was studied. In vitamin A-deficient rats, the hepatic level of apoAI mRNA was increased and enhanced by an oral administration of excess retinoic acid(RA). A similar administration to normal rats caused an increase in the apoAI mRNA level in the intestine without affecting that of hepatic mRNA. Though the hepatic level of apo CIII mRNA was not affected by the vitamin A status, the intestinal level was positively regulated by vitamin A. These findings show that vitamin A regulates the expression of apolipoprotein AI and CIII genes in a tissue-specific and complex fashion.

Animals↗
PubMed1994

Retinoic acid up-regulates erythropoietin production in hepatoma cells and in vitamin A-depleted rats.

Retinoic acid (RA) stimulated the production of erythropoietin (Epo) in a human hepatoma cell line, HepG2 cells. The stimulation was due to the accumulation of Epo mRNA. The Epo production in HepG2 cells was also dependent on O2 tension for cell culture but the enhancement of Epo production by RA was independent of O2 tension, indicating that RA exerts its effect through a pathway different from O2. Oral administration of RA to the vitamin A-depleted rats elevated the concentration of Epo in serum. These results suggest that RA up-regulates EPO production in vivo as well as in vitro.

Animals↗
PubMed1994

Positive and negative regulation of retinoid X receptor gene expression by thyroid hormone in the rat. Transcriptional and post-transcriptional controls by thyroid hormone.

The 9-cis-retinoic acid receptors (RXRs), belonging to the members of the steroid/thyroid hormone receptor superfamily, act as auxiliary proteins, heterodimerizing with other nuclear receptors such as retinoic acid receptors (RARs), vitamin D receptor, thyroid hormone receptors, and peroxisome-proliferator activated receptor, thereby transactivating target genes in a ligand-dependent manner. We have previously reported that in the rat, thyroid hormone (TH) positively and negatively regulates the hepatic mRNA levels of RXR beta and RXR gamma, respectively. In the present study, we have tried to elucidate the level at which TH regulates the gene expression of RXR beta and RXR gamma in the rat. A RNA synthesis inhibitor (actinomycin D), but not a protein synthesis inhibitor (cycloheximide), blocked the induction of RXR beta mRNA by TH. On the other hand, none of these drugs inhibited the decrease of RXR gamma mRNA levels caused by TH. Nuclear run-on assays showed that the transcription rate of the RXR beta gene was positively regulated by TH, whereas the transcription of RXR gamma gene was not controlled by TH. Taken together, these results indicate that the gene expression of RXR beta is positively regulated by TH at transcriptional level, while the negative regulation of the RXR gamma gene expression by TH may occur at a post-transcriptional level in intact rat. Thus, the RXR-mediated signal transductions may be modulated in part through TH control of the levels of RXR beta and RXR gamma.

Animals↗
PubMed1994

Evidence for other binding component(s) than retinoid receptors specifically interacting with a retinoic acid response element in the rat liver.

A nuclear component interacting with a retinoic acid response element (RARE-beta) derived from the all-trans-retinoic acid receptor beta (RAR beta) gene promoter was detected in the rat liver by gel-shift assay. Competition experiments using the competitors of the other retinoid response elements and non-specific sequences upon the binding of this hepatic component (HBC) to the RARE-beta revealed that the binding of the HBC to the RARE-beta was competed only by the self competitor, but not the other elements, suggesting that the HBC is specific for the RARE-beta. Moreover, although the specific monoclonal antibodies for RAR alpha, RAR beta, and RAR gamma reacted and shifted up the DNA complexes of endogenous as well as recombinant RARs, the DNA complex with HBC was not subjected to the immunoreaction with the antibodies. Thus, newly identified HBC, which is distinct from the characterized retinoid receptors, may modulate retinoid signaling through its direct binding upon the RARE-beta.

Animals↗
PubMed1993

Thyroid hormone affects the gene expression of retinoid X receptors in the adult rat.

Gene expression of three nuclear retinoid X receptors (RXR alpha, beta and gamma) was examined by Northern blot analysis in various rat tissues. The RXR alpha mRNA (5.5 kb) was detected in most tissues and particularly expressed at a high level in the liver. The RXR beta transcripts (2.4 and 3.0 kb) were expressed ubiquitously, and particularly at high levels in the brain and testis. In the liver, heart, kidney and lung, the RXR gamma mRNA (2.0 kb) was specifically detected. Furthermore, we examined the effect of retinoid, vitamin D and thyroid hormone status on the gene expression of RXR alpha, beta and gamma. Though retinoid and vitamin D did not affect the mRNA levels of three RXRs, the mRNA levels of two genes were controlled by thyroid hormone. Namely, positive (RXR beta) and negative (RXR gamma) regulations by thyroid hormone were observed with no effect on the gene expression of RXR alpha. These results suggest that thyroid hormone might affect the signal transduction of retinoid, vitamin D and thyroid hormone by changing RXR levels.

Animals↗
PubMed1993

Intravital and electron microscopic observation of Ito cells in rat hepatic microcirculation.

Intralobular distribution of Ito cells (fat-storing cells) in hepatic microcirculatory units was investigated through intravital fluorescence microscopy. By using a low-level ultraviolet epi-illumination and a sensitive silicon intensified target camera, the intrahepatic autofluorescence was visualized and digitally processed. In rats fed an ordinary diet, the ultraviolet-excited autofluorescence was composed of at least two different origins that could not be spectrophotometrically distinguished, namely, multiple patchy autofluorescence activities along the sinusoids and terminal hepatic venules and diffuse parenchymal autofluorescence. Multiple patchy activities showed a rapid photobleaching phenomenon under the continuous ultraviolet excitation. These fluorescent activities were completely eliminated by depleting the intrahepatic retinoid contents using a vitamin A-deficient diet for 4 weeks. Furthermore repeated administration of vitamin A significantly enhanced the patchy fluorescent activities. Electron microscopy revealed that these vitamin A fluorescent activities are colocalized with the fat droplets in Ito cells, providing evidence that Ito cells exist not only in perisinusoidal spaces but also in the perivascular spaces of the terminal hepatic and portal venules. The current intravital technique thus provides a new method to observe Ito cells in hepatic microcirculatory units in vivo.

Animals↗
PubMed1993

Gene expression of cellular retinol-binding protein I (CRBP I) is affected by dietary proteins in the rat liver.

The effect of dietary proteins and vitamin A status on the gene expression of cellular retinol-binding protein I (CRBP I) was studied in the rat liver. The gene expression was estimated as amounts of transcript (mRNA) by Northern blot analysis using rat CRBP I cDNA. Though vitamin A status is known to positively regulate the gene expression of CRBP I in the extrahepatic tissues, in the present study we observed that the amount of the CRBP I transcript in liver was neither reduced by vitamin A-deficiency, nor affected by replenishment with an excess dose of all-trans retinoic acid. These results indicate that in the liver, different from the extrahepatic tissues, the gene expression of CRBP I may not be controlled by vitamin A. However, when the rats were fed on the diets that differed in dietary proteins, the gene expression of CRBP I in liver was enhanced by higher quality and quantity of dietary proteins, though no effect of dietary proteins was observed upon the hepatic contents of retinol. The concentrations of serum retinol were almost proportional to the mRNA levels of CRBP I. In contrast, the hepatic gene expression of another retinol-binding protein, RBP, and one subtype of retinoic acid receptor, RAR alpha was not influenced in the nutritional condition tested here. Our findings suggest that the gene expression of CRBP I in liver may be under control of the intake of dietary proteins. Thus, it is likely that in the light of the function of CRBP I on cellular transport and metabolism of retinol, dietary proteins may affect the actions of vitamin A in the extrahepatic tissues through changing the amounts of CRBP I in liver.

Animals↗
PubMed1992

Tissue-specific response of estrogen receptor gene expression to estrogen in chick.

We have developed a sensitive assay system by RT (reverse transcription)-PCR(polymerase chain reaction) to detect the low level of chicken estrogen receptor (cER) transcript. Using this system, the differential expression of cER gene in chick tissues was observed. Moreover, we found that the oviduct cER transcript levels in chick was not affected, albeit the remarkable growth of this tissue, by exogenous estrogen. In contrast, estrogen enhanced the hepatic cER transcript level several folds. Thus, the present study clearly showed a novel tissue-specific response of cER gene expression to estrogen in chick.

Animals↗
PubMed1992

Effect of retinoid status on alpha, beta and gamma retinoic acid receptor mRNA levels in various rat tissues.

We have investigated the effects of retinoids, vitamin D and thyroid hormone on the levels of retinoic acid receptor (RAR)alpha, RAR beta and RAR gamma mRNAs in intact animals. Although vitamin A deficiency caused no significant changes in the levels of RAR alpha and RAR gamma mRNAs, the level of RAR beta transcripts was greatly decreased in various tissues of vitamin A-deficient rats, but was restored rapidly to a normal level after administration of retinoic acid. Retinol also restored the RAR beta mRNA level, but the magnitude and kinetics of the induction differed from those by retinoic acid. The use of specific inhibitors demonstrated that this autoregulation of RAR beta gene expression in vivo occurred at the transcriptional level. In addition, from these results it was postulated that the maintenance of the normal RAR beta mRNA levels seemed to require a threshold serum retinol concentration (about 25 micrograms/dl). Moreover, we found that administration of retinol and retinoic acid to normal rats caused the overexpression of RAR beta transcripts (2-15-fold) when compared with the control levels of RAR beta mRNA, although the levels of RAR alpha and RAR gamma mRNAs were not affected. Vitamin D and thyroid hormone did not modulate the levels of RAR transcripts. These findings clearly indicate the specific ligand regulation of RAR beta gene expression in intact animals. The altered levels of RAR beta according to retinoid status may affect retinoid-inducible gene expression.

Animals↗
PubMed1992

A far upstream estrogen response element of the ovalbumin gene contains several half-palindromic 5'-TGACC-3' motifs acting synergistically.

We have identified an estrogen-responsive enhancer element (DH3 ERE) in the estrogen-induced DNAase I-hypersensitive region III of the chicken ovalbumin gene, which is located approximately 3.3 kb upstream from the mRNA start site and does not contain palindromic ERE. Four TGACC half-palindromic motifs, separated from each other by more than 100 bp, are responsible for conferring estrogen inducibility either to the proximal ovalbumin gene promoter or to heterologous promoters. Thus, widely spaced half-palindromic ERE motifs can act synergistically. Each half-palindromic motif was shown to bind the estrogen receptor (ER) with a low efficiency in vitro. However, two widely spaced half-palindromic motifs bound the ER cooperatively, much more efficiently than expected from binding to isolated half-ERE motifs. The ovalbumin promoter half-palindromic ERE motif located close to the TATA box was required for the activity of the distal DH3 ERE, but could be replaced by the binding sites of other transactivators.

Animals↗
PubMed1979

Recent evidence for the participation of vitamin A in glycoprotein synthesis.

Recent evidence supports the concept that vitamin A plays some role in glycoprotein synthesis in a large-variety of tissues examined. Its involvement may be through participation of a retinol-linked sugar, mannosyl retinyl phosphate (MRP). Upon injection of [3H]retinol and [14C]mannose into rats, [14C, 3H]MRP could be isolated from liver and intestinal mucosa, and identified by chromatographic and hydrolytic experiments. The enzyme system that forms MRP from GDP-mannose and retinyl phosphate was located primarily in rough endoplasmic reticulum of fractionated liver cells, with some activity also in smooth membranes and Golgi apparatus. Vitamin A deficiency resulted in depressed synthesis of the rat serum glycoprotein alpha 1-macroglubin (alpha 1-MG), as shown by a decline in labeling. Analysis of the labeled alpha 1-MG from serum of normal and vitamin A-deficient rats showed this to be the result of a defect in glycosylation. The specific activity ratio (deficient:normal) of the alpha 1-MG of serum declined progressively with development of the deficiency, as a result of underglycosylation. Complete carbohydrate analysis of the alpha 1-MG of normal and deficient serum revealed a sugar loss in this glycoprotein as a result of vitamin A deficiency.

Animals↗