STUDIES ON THE FUNCTION OF INTRACELLULAR RIBONUCLEASES

The RNase activity and properties of ribosome and polysome preparations from normal rat liver and some hepatomas have been examined. Polysome and ribosome preparations from the Novikoff, McCoy MDAB, and Dunning hepatomas had considerably higher specific RNase activity than corresponding preparations from normal rat liver, Novikoff ascites, or Morris 5123 hepatomas. The optimum pH of the RNase was approximately 8.5 for all samples tested, and the samples showed no evidence of latent RNase activity when treated with 3 M sodium chloride, EDTA, urea, or p-chloromercuribenzenesulfonic acid. The RNase activity appeared to be associated principally with breakdown products and/or subunits smaller than 80S. In the presence of Mg++ ions, subunits could reaggregate to form monomer ribosomes indistinguishable from the natural products, but some of the reassociated ribosomes could contain RNase activity which had been bound to the smaller particles. Similar results were obtained with spermine. In the hepatomas, evidence was obtained for the preexistence of considerable amounts of the smaller, RNase-containing subunits in the cell. When a small amount of crystalline bovine pancreatic RNase was added to partly dissociated ribosomes, the RNase was found only in association with the smaller subunits, and little or no enzyme was taken up by ribosomes or polysomes. The results have led to the conclusion that RNase is not a normal constituent of the ribosome or polysome, but that RNase may become associated with these particulates if dissociation and reassociation take place. Some implications of these findings for the stability of messenger RNA and for the mechanism of its breakdown are discussed.

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Mechanism of 67Ga Accumulation in Normal Rat Liver Lysosomes

Nuklearmedizin ◽

10.1055/s-0038-1624962 ◽

1976 ◽

Vol 15 (04) ◽

pp. 185-194 ◽

Cited By ~ 7

Author(s):

A. Gebhardt ◽

E. Schulz ◽

U. Haubold ◽

M. Hristowa ◽

B. Zeggel ◽

...

Keyword(s):

Rat Liver ◽

Malignant Tumors ◽

Gel Filtration ◽

Normal Liver ◽

Protein Band ◽

Lysosomal Fraction ◽

Coomassie Blue ◽

Normal Rat ◽

The Stability ◽

Rat Liver Lysosomes

Summary 67Ga accumulates in various malignant tumors and parenchymatous tissues. It was found to be associated with the soluble fraction of lysosomes (11). The present work investigates the mechanism of 67Ga accumulation in normal liver cells.Lysosomes were isolated from rat liver after intravenous injection of carrier free 67Ga. The soluble lysosomal fraction was obtained by sonication followed by centrifugation at 105,000 xg for 2 hrs. Gel filtration on Sephadex G 25 superfine was carried out on the soluble lysosomal fraction in order to investigate the stability of the 67Ga-protein complex within the lysosomes under EDTA treatment. After treatment with 1 mM/1 EDTA a considerable amount of the protein bound radioactivity was found to be liberated. In further experiments the 67Ga binding lysosomal proteins were fractionated by electrophoresis on 7% Polyacrylamide gels (0.5 cm x 5.5 cm). After staining with Coomassie blue 18 separated protein bands were apparent. 67Ga distribution within the gels was assessed by direct counting of radioactivity in gel slices. A considerable amount of the intralysosomal protein bound radioactivity migrated with a relative mobility of 0.36 corresponding to a protein band of molecular weight 85,000 — 90,000. This peak corresponded to the peak of 67Ga labeled purified transferrin in control gels. These data were confirmed by Immunoelectrophoresis combined with autoradiography: within the soluble lysosomal fraction a slight transferrin line could be identified.We conclude that 67Ga which is transported in the blood by transferrin (23) and taken up by the hepatic cell through endocytosis (32) is accumulated in the lysosomes associated with transferrin and its degraded fragments.

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STUDIES ON THE FUNCTION OF INTRACELLULAR RIBONUCLEASES

The Journal of Cell Biology ◽

10.1083/jcb.8.3.665 ◽

1960 ◽

Vol 8 (3) ◽

pp. 665-673 ◽

Cited By ~ 26

Author(s):

Jay S. Roth

Keyword(s):

Enzyme Activity ◽

Biological Activity ◽

Rat Liver ◽

Liver Microsomes ◽

Rnase Activity ◽

Rat Liver Microsomes ◽

Rnase Inhibitor ◽

Normal Constituent ◽

Liver Ribosomes

Attempts have been made to prepare rat liver microsomes and ribosomes free of RNase activity. Washing of microsomes with a large number of reagents, as well as preparation of microsomes by homogenizing the liver in the presence of a variety of reagents chosen to remove or inhibit RNase activity, failed to abolish completely the enzyme activity. However, when rat liver was homogenized in the presence of optimal concentrations of ATP the microsomes subsequently obtained showed no RNase activity. The composition of such microsomes was compared to controls prepared without the use of ATP. Preparation of microsomes with the use of ATP apparently repressed but did not remove the RNase activity for, when such microsomes were treated with 1 per cent deoxycholate to obtain ribosomes, the latter exhibited normal RNase activity. A possible explanation for these results based on several experiments is given. The incorporation of C14 of L-leucine-C14 into control and ATP-treated microsomes was measured. Repression of RNase activity by use of ATP or with RNase inhibitor, significantly reduced the incorporation. As a result of these and other experiments it is tentatively concluded that an alkaline RNase is a normal constituent of rat liver ribosomes and plays a role in the biological activity of these particles.

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InsP7is a small-molecule regulator of NUDT3-mediated mRNA decapping and processing-body dynamics

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1922284117 ◽

2020 ◽

Vol 117 (32) ◽

pp. 19245-19253 ◽

Cited By ~ 1

Author(s):

Soumyadip Sahu ◽

Zhenzhen Wang ◽

Xinfu Jiao ◽

Chunfang Gu ◽

Nikolaus Jork ◽

...

Keyword(s):

Stress Responses ◽

Messenger Rna ◽

Control Process ◽

Stem Cell Differentiation ◽

Wild Type ◽

Inositol Pyrophosphate ◽

Body Dynamics ◽

Processing Body ◽

The Stability

Regulation of enzymatic 5′ decapping of messenger RNA (mRNA), which normally commits transcripts to their destruction, has the capacity to dynamically reshape the transcriptome. For example, protection from 5′ decapping promotes accumulation of mRNAs into processing (P) bodies—membraneless, biomolecular condensates. Such compartmentalization of mRNAs temporarily removes them from the translatable pool; these repressed transcripts are stabilized and stored until P-body dissolution permits transcript reentry into the cytosol. Here, we describe regulation of mRNA stability and P-body dynamics by the inositol pyrophosphate signaling molecule 5-InsP7(5-diphosphoinositol pentakisphosphate). First, we demonstrate 5-InsP7inhibits decapping by recombinant NUDT3 (Nudix [nucleoside diphosphate linked moiety X]-type hydrolase 3) in vitro. Next, in intact HEK293 and HCT116 cells, we monitored the stability of a cadre of NUDT3 mRNA substrates following CRISPR-Cas9 knockout ofPPIP5Ks(diphosphoinositol pentakisphosphate 5-kinases type 1 and 2, i.e.,PPIP5KKO), which elevates cellular 5-InsP7levels by two- to threefold (i.e., within the physiological rheostatic range). ThePPIP5KKO cells exhibited elevated levels of NUDT3 mRNA substrates and increased P-body abundance. Pharmacological and genetic attenuation of 5-InsP7synthesis in the KO background reverted both NUDT3 mRNA substrate levels and P-body counts to those of wild-type cells. Furthermore, liposomal delivery of a metabolically resistant 5-InsP7analog into wild-type cells elevated levels of NUDT3 mRNA substrates and raised P-body abundance. In the context that cellular 5-InsP7levels normally fluctuate in response to changes in the bioenergetic environment, regulation of mRNA structure by this inositol pyrophosphate represents an epitranscriptomic control process. The associated impact on P-body dynamics has relevance to regulation of stem cell differentiation, stress responses, and, potentially, amelioration of neurodegenerative diseases and aging.

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THE d-AMINO ACID OXIDASE, URICASE, AND CHOLINE OXIDASE IN NORMAL RAT LIVER AND IN NUCLEI OF NORMAL RAT LIVER CELLS

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)72125-x ◽

1943 ◽

Vol 151 (1) ◽

pp. 171-175

Author(s):

Tien Ho Lan

Keyword(s):

Amino Acid ◽

Rat Liver ◽

Liver Cells ◽

Choline Oxidase ◽

Acid Oxidase ◽

Amino Acid Oxidase ◽

Rat Liver Cells ◽

Normal Rat

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Alterations in translatable messenger RNA coding for phosphoenolpyruvate carboxykinase (GTP) in rat liver cytosol during deinduction.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(17)34723-3 ◽

1978 ◽

Vol 253 (12) ◽

pp. 4327-4332

Author(s):

D. Kioussis ◽

L. Reshef ◽

H. Cohen ◽

S.M. Tilghman ◽

P.B. Iynedjian ◽

...

Keyword(s):

Rat Liver ◽

Messenger Rna ◽

Phosphoenolpyruvate Carboxykinase ◽

Liver Cytosol ◽

Rat Liver Cytosol

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Intracellular re-localisation by photochemical internalisation enhances the cytotoxic effect of gelonin — Quantitative studies in normal rat liver

Journal of Controlled Release ◽

10.1016/j.jconrel.2009.11.017 ◽

2010 ◽

Vol 142 (3) ◽

pp. 347-353 ◽

Cited By ~ 17

Author(s):

Josephine Woodhams ◽

Pei-Jen Lou ◽

Pål K. Selbo ◽

Alexander Mosse ◽

Dahmane Oukrif ◽

...

Keyword(s):

Rat Liver ◽

Cytotoxic Effect ◽

Quantitative Studies ◽

Normal Rat

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Synthesis of Biobased Phloretin Analogues: An Access to Antioxidant and Anti-Tyrosinase Compounds for Cosmetic Applications

Antioxidants ◽

10.3390/antiox10040512 ◽

2021 ◽

Vol 10 (4) ◽

pp. 512

Author(s):

Laurène Minsat ◽

Cédric Peyrot ◽

Fanny Brunissen ◽

Jean-Hugues Renault ◽

Florent Allais

Keyword(s):

Natural Products ◽

Consumer Demand ◽

Radical Scavenging ◽

Green Process ◽

Direct Extraction ◽

Low Concentration ◽

Cosmetic Formulations ◽

Valuable Compounds ◽

The Stability

The current cosmetic and nutraceutical markets are characterized by a strong consumer demand for a return to natural products that are less harmful to both the consumers and the environment than current petrosourced products. Phloretin, a natural dihydrochalcone (DHC) found in apple, has been widely studied for many years and identified as a strong antioxidant and anti-tyrosinase ingredient for cosmetic formulations. Its low concentration in apples does not allow it to be obtained by direct extraction from biomass in large quantities to meet market volumes and prices. Moreover, its remarkable structure prevents its synthesis through a green process. To overcome these issues, the synthesis of phloretin analogs appears as an alternative to access valuable compounds that are potentially more active than phloretin itself. Under such considerations, 12 chalcones (CHs) and 12 dihydrochalcones (DHCs) were synthesized through a green Claisen–Schmidt condensation using bio-based reagents. In order to evaluate the potential of these molecules, radical scavenging DPPH and anti-tyrosinase tests have been conducted. Moreover, the UV filtering properties and the stability of these analogs towards UV-radiations have been evaluated. Some molecules showed competitive antioxidant and anti-tyrosinase activities regarding phloretin. Two compounds in particular showed EC50 lower than phloretin, one chalcone and one dihydrochalcone.

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