Cell Activity In Animals Research Articles

Identification of a third autonomous activation domain within the human estrogen receptor.

Using a genetic selection system established in the yeast Saccharomyces cerevisiae, we have isolated, by random mutagenesis of the human estrogen receptor (ER), six mutants that display constitutive transcriptional activity. All of the mutants identified contained single base insertions or deletions leading to frameshift mutations, resulting in receptor truncations within the hormone-binding domain between amino acids (aa) 324-351. Interestingly, an ER mutant (aa 1-282) was transcriptionally inactive in yeast, suggesting that a domain important for transcriptional activity lies between aa 282 and 351 within human ER. Deletions representative of the mutants isolated in the yeast system were created in mammalian expression vectors and examined for transcriptional activity in animal cells to determine the physiological relevance of this domain. Receptors truncated at aa 282 were either weakly active or inactive; however, an ER deletion at aa 351 was approximately 50% as active as wild type ER (induced with estrogen). Furthermore, a chimeric receptor consisting of the DNA binding domain of GAL4 fused to aa 282-351 of the human ER was transcriptionally active on a GAL4 reporter. We conclude, therefore, that an autonomous activation domain (referred to as AF2a), functional in both yeast and mammalian cells, lies between aa 282-351 of the human ER.

Pavlovian conditioning of morphine-induced alterations of immune status

The present study provides the first demonstration that alterations of immune status can be conditioned to environmental stimuli paired with morphine administration. In the first manipulation, male Lewis rats received 0, 2, 4, 8 or 16 conditioning sessions during which a subcutaneous injection of morphine (15 mg/kg) was paired with a distinctive environment. The results showed that subsequent re-exposure to the distinctive environment induced a decrease in the mitogenic responsiveness of splenic lymphocytes and a decrease in natural killer cell activity in animals which had received 2, 4, 8 and 16 conditioning sessions. In the second manipulation, using two conditioning sessions, a wider range of immune measures was assessed and control groups were included to ascertain whether the observed immune alterations were due to Pavlovian conditioning processes. The results showed that the environment which had been paired with morphine altered the mitogenic responsiveness of blood and splenic lymphocytes, decreased natural killer cell activity and decreased interleukin-2 production. In contrast, the conditioned environment did not have any effect on mitogenic responsiveness of lymphocytes derived from the mesenteric lymph nodes. Data from the control groups revealed that the compartment-specific immune alterations were the result of a Pavlovian conditioning process.

Stimulation of the type III olfactory adenylyl cyclase by calcium and calmodulin.

Characterization of adenylyl cyclases has been facilitated by the isolation of cDNA clones for distinct adenylyl cyclases including the type I and type III enzymes. Expression of type I adenylyl cyclase activity in animal cells has established that this enzyme is stimulated by calmodulin and Ca2+. Type III adenylyl cyclase is enriched in olfactory neurons and is regulated by stimulatory G proteins. The sensitivity of the type III adenylyl cyclase to Ca2+ and calmodulin has not been reported. In this study, type III adenylyl cyclase was expressed in human kidney 293 cells to determine if the enzyme is stimulated by Ca2+ and calmodulin. The type III enzyme was not stimulated by Ca2+ and calmodulin in the absence of other effectors. It was, however, stimulated by Ca2+ through calmodulin when the enzyme was concomitantly activated by either GppNHp or forskolin. The concentrations of free Ca2+ for half-maximal stimulation of type I and type III adenylyl cyclases were 0.05 and 5.0 microM Ca2+, respectively. These data suggest that the type III adenylyl cyclase is stimulated by Ca2+ when the enzyme is activated by G-protein-coupled receptors and that increases in free Ca2+ accompanying receptor activation may amplify the primary cyclic AMP signal.

On the regulation of DNA methylation by higher-order structure in the cell nucleus

Several years ago it was postulated that DNA methylation may play a role in the regulation of gene activity in animal cells. Progress has been made in establishing the mechanisms by which methylation influences gene expression, but little is known about the mechanisms that control methylation itself. Here is proposed a modek, susceptible of experimental confirmation, which suggests that chromatin higher-order structure is a determinant factor for the regulation of DNA methylation. The background for such a model as well as current evidence in support of it are discussed.

6-Nitrocholesterol inhibits 3-hydroxy-3-methylglutaryl coenzyme a reductase and tumor cell growth

6-Nitrocholesterol has been shown to cause a 50% reduction in the level of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity in animal cells in culture at 1.9 microM and it has relative binding affinity for the cytosolic oxysterol binding protein of 357 nM in cell-free extracts from the same cell line. In addition, significant cytotoxicity was observed when this sterol was incubated with hepatoma and lymphoma cells in culture.

Multiplication of tobacco mosaic virus in tobacco leaf disks is inhibited by (2'-5) oligoadenylate.

The oligonucleotide (2'-5') oligoadenylate that is induced in interferon-treated animal cells protects plant tissue from infection by the tobacco mosaic virus. This inhibition of virus multiplication was obtained at concentrations comparable to those affecting protein synthesis and antiviral activities in animal cells. After treatment with (2'-5') oligoadenylate, the multiplicability of tobacco mosaic virus was reduced by 80 to 90 percent as measured by enzyme-linked immunosorbent assay. These results, along with the observation that human interferon protects tobacco tissue from infection by tobacco mosaic virus, indicate that plants and animals may have a common pathway for virus resistance.

Activation of an NAD:arginine ADP-ribosyltransferase by histone.

An ADP-ribosyltransferase from turkey erythrocytes which utilizes proteins and low molecular weight guanidino compounds such as arginine and agmatine as ADP-ribose acceptors was stimulated by histones. The effect was specific in that choleragen, a bacterial mono(ADP-ribosyl)transferase that increased adenylate cyclase activity in animal cells, was not activated by histones. With the erythrocyte enzyme, histones decreased the apparent Km values for arginine methyl ester and agmatine and increased the stability of the transferase to thermal denaturation. Activation of the transferase by histones was rapid, with a minimal delay observed upon addition of histones to a histone-free assay. Activation by histones was reversed upon dilution of a sample containing histones into an assay mix free of histone. In the absence of histone, the transferase existed as a rapidly sedimenting species; in the presence of histone, the transferase sedimented as a protomer.

Appearance of β-lactamase activity in animal cells upon liposome-mediated gene transfer

A restriction fragment, 875 bp, which encodes for a β-lactamase activity, was isolated from the Escherichia coli plasmid pBR322 DNA and entrapped in liposomes. The incubation of the DNA-liposomes with avian, murine, and human cultured cells results in the uptake of the DNA with the efficiency of around 2000 molecules per cell. Extracts of the recipient cells show a β-lactamase activity as demonstrated by spectroscopic and microbiological methods. These results indicate the expression of a prokaryotic gene in eukaryotic cells.

A comparative study of “soluble” RNA polymerase activity of Zajdela hepatoma ascites cells and calf thymus

FEBS LettersVolume 22, Issue 1 p. 67-72 Full-length articleFree Access A comparative study of “soluble” RNA polymerase activity of Zajdela hepatoma ascites cells and calf thymus François Amalric, François Amalric Laboratoire de Chimie Biologique, Institut de Physiologie, Faculté des Sciences, 84 Grande Rue St-Michel, Toulouse, FranceSearch for more papers by this authorMonique Nicoloso, Monique Nicoloso Laboratoire de Chimie Biologique, Institut de Physiologie, Faculté des Sciences, 84 Grande Rue St-Michel, Toulouse, FranceSearch for more papers by this authorJean-Pierre Zalta, Jean-Pierre Zalta Laboratoire de Chimie Biologique, Institut de Physiologie, Faculté des Sciences, 84 Grande Rue St-Michel, Toulouse, FranceSearch for more papers by this author François Amalric, François Amalric Laboratoire de Chimie Biologique, Institut de Physiologie, Faculté des Sciences, 84 Grande Rue St-Michel, Toulouse, FranceSearch for more papers by this authorMonique Nicoloso, Monique Nicoloso Laboratoire de Chimie Biologique, Institut de Physiologie, Faculté des Sciences, 84 Grande Rue St-Michel, Toulouse, FranceSearch for more papers by this authorJean-Pierre Zalta, Jean-Pierre Zalta Laboratoire de Chimie Biologique, Institut de Physiologie, Faculté des Sciences, 84 Grande Rue St-Michel, Toulouse, FranceSearch for more papers by this author First published: April 15, 1972 https://doi.org/10.1016/0014-5793(72)80221-7Citations: 17AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat References 1 S.B. Weiss, Proc. Natl. Acad. Sci. U.S., 46, (1960), 1020. 2 L.H. Goldberg, Biochim. Biophys. Acta, 51, (1961), 201. 3 M. Ramuz, J. Doly, P. Mandel, P. Chambon, Biochem. Biophys. Res. Commun., 19, (1965), 14. 4 J.J. Furth, P. Loh, Biochem. Biophys. Res. Commun., 13, (1963), 100. 5 J.J. Furth, P. Loh, Science, 145, (1964), 161. 6 P.L. Ballard, H.G. Williams-Ashman, Nature, 203, (1964), 150. 7 P.L. Ballard, H.G. Williams-Ashman, Biol. Chem., 241, (1966), 1602. 8 H. Stein, P. Hausen, European J. Biochem., 14, (1970), 270. 9 R.G. Roeder, W.J. Rutter, Nature, 224, (1969), 234. 10 P. Chambon, F. Gissinger, J.L. Mandel, C. Kedinger Jr., M. Gniazdowski, M. Meihlac, Cold Spring Harbor Symp. Quant. Biol., 35, (1970), 693. 11 C.J. Chesterton, P.H.W. Butterworth, FEBS Letters, 12, (1971), 301. 12 C. Kedinger, P. Nuret, P. Chambon, FEBS Letters, 15, (1971), 169. 13 F. Amalric, J.P. Zalta, R. Simard, Exp. Cell. Res., 55, (1971), 370. 14 S.T. Jacob, E.M. Sajdel, H.N. Munro, Biochem. Biophys. Res. Commun., 32, (1968), 831. 15 O.M. Lowry, N.J. Rosebrough, A.L. Farr, R. Randall, J. Biol. Chem., 193, (1951), 265. 16 J.L. Mandel, P. Chambon, FEBS Letters, 15, (1971), 175. 17 M.E. Haines, A.M. Holmes, I.R. Johnston, FEBS Letters, 17, (1971), 63. 18 R.F. Weaver, S.P. Blatti, W. Rutter, Proc. Natl. Acad. Sci. U.S., 68, (1971), 2994. Citing Literature Volume22, Issue1April 15, 1972Pages 67-72 ReferencesRelatedInformation