Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.5 (RNase)
 17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Retinol (vitamin A alcohol), which plays an important role in the differentiation of epithelia, can be transferred to chromatin in vitro. Rat liver chromatin can accept retinol in a specific and saturable manner only when the retinol is presented as a complex with cellular retinol-binding protein (CRBP). A partial characterization of the nuclear components responsible for accepting retinol is reported here. A preparation of solubilized chromatin isolated from liver nuclei was able to accept retinol from its complex with CRBP as described previously for nuclei and chromatin. The binding of retinol to chromatin was noncovalent. However, chromatin prepared from nuclei which were incubated with DNase I or micrococcal nuclease did not accept retinol specifically. Chromatin in the form of mono and dinucleosomes also did not accept retinol. However, treatment of nuclei with RNase did not affect the specific binding of retinol. Furthermore, it has been found that retinol was not transferred to purified double or single stranded DNA. These results are interpreted to indicate that the transfer of retinol to specific nuclear binding sites requires a higher order of chromatin structure than that occurring in nucleosome preparations.
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PMID:Partial characterization of nuclear binding sites for retinol delivered by cellular retinol binding protein. 298 10

Studies were conducted to explore in rats the role of retinol in the regulation of the synthesis and secretion of retinol-binding protein (RBP) by the visceral yolk sac compared to the liver. Previous studies have shown that in retinol deficiency, hepatic RBP secretion is specifically inhibited, whereas hepatic RBP synthesis rate is unchanged. Retinol-depleted, retinoic acid-supplemented female rats were mated, and maternal liver, fetal liver, and visceral yolk sac were obtained at 14 days of gestation (retinol-depleted group). A group of identically treated, retinol-depleted rats were repleted with retinol on the 14th day of gestation, and the same tissues were collected 6 h later (retinol-repleted group). Normal female rats were used as controls. RBP was assayed by radioimmunoassay and RBP mRNA levels by RNase protection assay using a rat RBP cDNA clone. RBP levels in the visceral yolk sac were elevated 10-fold in the retinol-depleted as compared to the control rats and had declined to near normal values in the retinol-repleted animals. The relative levels of RBP mRNA in the visceral yolk sac were very similar in all three groups of rats. Thus, as in the liver, in the visceral yolk sac retinol deficiency inhibits RBP secretion without altering RBP mRNA levels. In the visceral yolk sac, as in the liver, retinol status appears to regulate RBP secretion specifically, without affecting the rate of RBP biosynthesis.
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PMID:Retinol-binding protein synthesis and secretion by the rat visceral yolk sac. Effect of retinol status. 334 35

The effect of vitamin A supplementation on stearoyl-CoA desaturase gene 1 expression in mouse liver was characterized. Normal BALB/c mice were fed 0.01% and 0.1% retinol palmitate as components of nonpurified diets. This treatment resulted in a 3-fold and a 7-fold induction of SCD1 mRNA levels, respectively, as determined by RNase protection analysis. Vitamin A-deficient animals were also fed diets containing 0.01% and 0.1% retinol palmitate, resulting in a similar pattern of SCD1 mRNA induction. Fatty acid synthase and beta-actin mRNA levels did not respond consistently or significantly to retinoic acid treatment. Dietary and hormonal studies were carried out to investigate the role of the retinoid X receptor in the regulation of SCD1 by type II steroid hormones. A receptor-saturating dose of thyroid hormone, triiodothyronine, repressed vitamin A-elevated SCD1 mRNA levels in vivo. Peroxisome proliferator-elevated SCD1 mRNA levels were unaffected by administration of thyroid hormone. This suggests that the retinoic acid receptor transcriptionally regulates SCD1 through a traditional mechanism of heterodimerization with the retinoid X receptor.
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PMID:Regulation of hepatic stearoyl-CoA desaturase gene 1 by vitamin A. 907 Feb 50

Retinol stimulates the formation of transition vesicles in situ and in all free systems based on rat liver. The stimulation is on vesicle formation from transitional endoplasmic reticulum and not on vesicle fusion with donor membranes. Vesicle budding in the cell free system requires a nucleoside triphosphate and is sensitive to inhibition by thiol reagents. In this report we develop and test a model whereby a retinol-modulated NADH:protein disulfide reductase (NADH oxidase) with protein disulfide-thiol interchange activity is implicated in the vesicle budding mechanism. The protein has the ability to restore activity to scrambled, inactive RNase A and is stimulated or inhibited by retinol depending on the redox environment. Under reducing conditions and in the presence of a chemical reductant such as GSH, the partial reaction stimulated by retinol appears to be the oxidation of membrane thiols. This is the first report of an enzymatic mechanism to explain specific retinol effects both in vivo and in vitro on membrane trafficking not given by retinoic acid.
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PMID:A molecular basis for retinol stimulation of vesicle budding in vivo and in vitro. 978 45