ÿþ<html><head><title> 53C;OF8O ?@><>B>@0 35=0 MMTV </title></head> <META NAME="author" CONTENT="Sergei Grokhovsky" content="text/html;charset=windows-1251"> <body><body bgcolor="#ffffdf"> <dir><dir><P><hr size=4 width=30%> <H2><p align=center>-:A?@5AA8O ?@><>B>@0 35=0 MMTV - abstracts</h2> <P><hr size=4 width=30%> <p align="justify"> <p align="justify"> <p align="justify"> <P><hr size=4 width=30%> <H2><p align=center>2004 3>4</h2> <p align="justify"><b> The origin and functions of multiple human glucocorticoid receptor isoforms.</b><p> Ann N Y Acad Sci. 2004 Jun;1024:102-23. <p align="justify">Lu NZ, Cidlowski JA. The Laboratory of Signal Transduction, Molecular Endocrinology Group, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 Alexander Drive, Research Triangle Park, <p align="justify">Glucocorticoid hormones are necessary for life and are essential in all aspects of human health and disease. The actions of glucocorticoids are mediated by the glucocorticoid receptor (GR), which binds glucocorticoid hormones and regulates gene expression, cell signaling, and homeostasis. Decades of research have focused on the mechanisms of action of one isoform of GR, GRa. However, in recent years, increasing numbers of human GR (hGR) isoforms have been reported. Evidence obtained from this and other laboratories indicates that multiple hGR isoforms are generated from one single hGR gene via mutations and/or polymorphisms, transcript alternative splicing, and alternative translation initiation. Each hGR protein, in turn, is subject to a variety of posttranslational modifications, and the nature and degree of posttranslational modification affect receptor function. We summarize here the processes that generate and modify various hGR isoforms with a focus on those that impact the ability of hGR to regulate target genes. We speculate that unique receptor compositions and relative receptor proportions within a cell determine the specific response to glucocorticoids. Unchecked expression of some isoforms, for example hGRbeta, has been implicated in various diseases. <P><hr size=4 width=30%> <p align="justify"><b> Physiological and Pathological Consequences of the Interactions of the p53 Tumor Suppressor with the Glucocorticoid, Androgen, and Estrogen Receptors </b><p> Ann. N.Y. Acad. Sci. 1024: 54 71 (2004). <p align="justify">SAGAR SENGUPTAa and BOHDAN WASYLYKb aLaboratory of Human Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA bInstitut de G?n?tique et de Biologie Mol?culaire et Cellulaire, CNRS/INSERM/ULP, 1 Rue Laurent Fries, 67404 Illkirch cedex, France <p align="justify">The p53 tumor suppressor plays a key role in protection from the effects of different physiological stresses (DNA damage, hypoxia, transcriptional defects, etc.), and loss of its activity has dire consequences, such as cancer. Its activity is finely tuned through interactions with other important regulatory circuits in the cell. Recently, striking evidence has emerged for crosstalk with another class of important regulators, the steroid hormone receptors, and in particular the glucocorticoid (GR), androgen (AR), and estrogen (ER) receptors. These receptors are important in maintaining homeostasis in response to internal and external stresses (GR) and in the development, growth, and maintenance of the male and female reproductive systems (AR and ER, respectively). We review how p53 interacts closely with these receptors, to the extent that they share the same E3 ubiquitin ligase, the MDM2 oncoprotein. We discuss the different physiological contexts in which such interactions occur, and also how these interactions have been undermined in various pathological situations. We will describe future areas for research, with special emphasis on GR, and how certain common features, such as cytoplasmic anchoring of p53 by the receptors, may become targets for the development of therapeutic interventions. Given the importance of GR in inflammation, erythropoiesis, and autoimmune diseases, and the importance of AR and ER in prostate and breast cancer (respectively), the studies on p53 interactions with the steroid receptors will be an important domain in the near future. <P><hr size=4 width=30%> <p align="justify"><b> Modulation of Glucocorticoid Receptor Function via Phosphorylation</b><p> Ann. N.Y. Acad. Sci. 1024: 86-101 (2004). <p align="justify">NAIMA ISMAILIa and MICHAEL J. GARABEDIANa,b Departments of Microbiologya and Urology,b New York University School of Medicine, 550 First Avenue, New York, New York 10016, USA <p align="justify">The glucocorticoid receptor (GR) is phosphorylated at multiple serine residues in a hormone-dependent manner. It has been suggested that GR phosphorylation affects turnover, subcellular trafficking, or the transcriptional regulatory functions of the receptor, yet the contribution of individual GR phosphorylation sites to the modulation of GR activity remains enigmatic. This review critically evaluates the literature on GR phosphorylation and presents more recent work on the mechanism of GR phosphorylation from studies using antibodies that recognize GR only when it is phosphorylated. In addition, we present support for the notion that GR phosphorylation modifies protein-protein interactions, which can stabilize the hypophosphorylated form of the receptor in the absence of ligand, as well as facilitate transcriptional activation by the hyperphosphorylation of GR via cofactor recruitment upon ligand binding. Finally, we propose that GR phosphorylation also participates in the nongenomic activation of cytoplasmic signaling pathways evoked by GR. Thus, GR phosphorylation is a versatile mechanism for modulating and integrating multiple receptor functions. <P><hr size=4 width=30%> <p align="justify"><b> </b><p> <p align="justify"> <p align="justify"> <P><hr size=4 width=30%> <p align="justify"><b> </b><p> <p align="justify"> <p align="justify"> <P><hr size=4 width=30%> <H2><p align=center>2003 3>4</h2> <P><hr size=4 width=30%> <p align="justify"><b> Expression and structural analysis of glucocorticoid receptor isoform gamma in human leukaemia cells using an isoform-specific real-time polymerase chain reaction approach.</b><p> Br J Haematol. 2003 Jul;122(2):245-52. <p align="justify">Beger C, Gerdes K, Lauten M, Tissing WJ, Fernandez-Munoz I, Schrappe M, Welte K. Department of Paediatric Haematology and Oncology, Hannover Medical School, Hannover, Germany. Berger. <p align="justify">Glucocorticoids are broadly used for chemotherapy in childhood acute lymphoblastic leukaemia (ALL). The intracellular effects of glucocorticoids are mediated through the glucocorticoid receptor. The human glucocorticoid receptor gamma isoform (hGR-gamma) differs from the main isoform (hGR-alpha) by an additional amino acid within the DNA binding domain of the receptor protein. This may decrease hGR-alpha-mediated transcriptional activation. The importance of hGR-gamma expression in childhood ALL is unknown. To evaluate hGR-gamma mRNA expression levels, a real-time polymerase chain reaction (PCR)-based approach, allowing the selective amplification of hGR-gamma, was developed and optimized. We were able to demonstrate target selectivity of hGR-gamma amplification using sequence-specific primers. Studying the structure of the 3' end of hGR-gamma, a combination of this isoform with other hGR isoforms could be demonstrated. Using analysis of hGR-gamma-specific amplification in comparison with the expression of hGR-total (all isoforms) in leukaemic blasts from patients with either a good response to prednisone (PGR) or poor-prednisone response (PPR) in vivo, relative hGR-gamma expression was observed to be lower in cells from patients with PGR compared with PPR, in particular after 10 h of dexamethasone stimulation. These data were correlated with cell survival, demonstrating a more pronounced induction of apoptosis in cells from patients with PGR as compared with PPR. <P><hr size=4 width=30%> <p align="justify"><b> Interaction of the Glucocorticoid Receptor and the Chicken Ovalbumin Upstream Promoter-Transcription Factor II (COUP-TFII): Implications for the Actions of Glucocorticoids on Glucose, Lipoprotein, and Xenobiotic Metabolism</b><p> Ann. N.Y. Acad. Sci. 1024: 72-85 (2004). <p align="justify">MASSIMO U. DE MARTINO, SALVATORE ALESCI, GEORGE P. CHROUSOS and TOMOSHIGE KINO Pediatric and Reproductive Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-1583, USA <p align="justify">Glucocorticoids exert their extremely diverse effects on numerous biologic activities of humans via only one protein module, the glucocorticoid receptor (GR). The GR binds to the glucocorticoid response elements located in the promoter region of target genes and regulates their transcriptional activity. In addition, GR associates with other transcription factors through direct protein-protein interactions and mutually represses or stimulates each other's transcriptional activities. The latter activity of GR may be more important than the former one, granted that mice harboring a mutant GR, which is active in terms of protein-protein interactions but inactive in terms of transactivation via DNA, survive and procreate, in contrast to mice with a deletion of the entire GR gene that die immediately after birth. We recently found that GR physically interacts with the chicken ovalbumin upstream promoter-transcription factor II (COUP-TFII), which plays a critical role in the metabolism of glucose, cholesterol, and xenobiotics, as well as in the development of the central nervous system in fetus. GR stimulates COUP-TFII-induced transactivation by attracting cofactors via its activation function-1, while COUP-TFII represses the GR-governed transcriptional activity by tethering corepressors, such as the silencing mediator for retinoid and thyroid hormone receptors (SMRT) and the nuclear receptor corepressors (NCoRs) via its C-terminal domain. Their mutual interaction may play an important role in gluconeogenesis, lipoprotein metabolism, and enzymatic clearance of clinically important compounds and bioactive chemicals, by regulating their rate-limiting enzymes and molecules, including the phosphoenolpyruvate carboxykinase (PEPCK), the cytochrome P450 CYP3A and CYP7A, and several apolipoproteins. It appears that glucocorticoids exert their intermediary effects partly via physical interaction with COUP-TFII. <P><hr size=4 width=30%> <p align="justify"><b> </b><p> <p align="justify"> <p align="justify"> <P><hr size=4 width=30%> <p align="justify"><b> </b><p> <p align="justify"> <p align="justify"> <P><hr size=4 width=30%><H2><p align=center>2002 3>4</h2> <P><hr size=4 width=30%> <p align="justify"><b> Molecular mechanisms of glucocorticoid action and resistance. </b><p> J Steroid Biochem Mol Biol. 2002 Dec;83(1-5):37-48. <p align="justify">Schaaf MJ, Cidlowski JA. Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, 111 Alexander Drive, P.O. Box 12233, Research Triangle Park, NC 27709, USA. <p align="justify">The actions of glucocorticoid hormones are mediated by an intracellular receptor, the glucocorticoid receptor (GR). The mechanism of action of this ligand-inducible transcription factor is discussed, focusing on mechanisms of glucocorticoid resistance. Three mechanisms are highlighted: ligand-induced down-regulation of the receptor, the dominant-negative inhibition by the beta-isoform of the receptor, and repression by the transcription factor NF-kappa B. It has been shown that these mechanisms can significantly inhibit glucocorticoid signaling, and could therefore seriously decrease the efficacy of glucocorticoids used clinically. <P><hr size=4 width=30%> <p align="justify"><b> AUUUA motifs in the 3'UTR of human glucocorticoid receptor alpha and beta mRNA destabilize mRNA and decrease receptor protein expression.</b><p> Steroids. 2002 Jun;67(7):627-36. <p align="justify">Schaaf MJ, Cidlowski JA. Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, 111 Alexander Drive, P.O. Box 12233, Research Triangle Park, NC 27709, USA. schaaf@niehs.nih.gov <p align="justify">An association between a gene polymorphism of the human glucocorticoid receptor (hGR) gene and rheumatoid arthritis has recently been suggested. This polymorphism contains an A to G mutation in the 3'UTR of exon 9beta, which encodes the 3'UTR of the mRNA of the hGRbeta isoform. The hGRbeta isoform can act as a dominant negative inhibitor of hGRalpha, and therefore may contribute to glucocorticoid resistance. The A to G mutation is located in an AUUUA motif, which is known to destabilize mRNA. In the present study, the importance of the mutation in this AUUUA motif was further characterized and mutations in other AUUUA motifs in the 3'UTR of hGRbeta and hGRalpha mRNA were studied. hGRbeta and hGRalpha expression vectors, carrying mutations in one AUUUA motif or all AUUUA motifs were transiently transfected into COS-1 cells. Each transfected vector was analyzed for the mRNA expression level, the mRNA turnover rate and the protein expression level. The naturally occurring mutation in the 3'UTR of hGRbeta mRNA increased mRNA stability and protein expression. Mutation of two other AUUUA motifs in the 3'UTR of hGRbeta, or mutation of all four AUUUA motifs resulted in a similar effect. Mutation of the most 5' AUUUA motif did not alter hGRbeta mRNA expression or mRNA stability. Mutation of all 10 AUUUA motifs in the 3'UTR of hGRalpha mRNA increased hGRalpha mRNA expression and mRNA stability as well as expression of the receptor protein level. Thus, the naturally occurring mutation in an AUUUA motif in the 3'UTR of hGRbeta mRNA results not only in increased mRNA stability, but also in increased receptor protein expression, which may contribute to glucocorticoid resistance. A similar role is suggested for two other AUUUA motifs in the 3'UTR of hGRbeta mRNA and for the 10 AUUUA motifs that are present in the 3'UTR of hGRalpha. <P><hr size=4 width=30%> <p align="justify"><b> The glucocorticoid receptor: coding a diversity of proteins and responses through a single gene. </b>Mol Endocrinol. 2002 Aug;16(8):1719-26. [MEDLINE] <p align="justify">Yudt MR, Cidlowski JA. Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709-2233, USA. <p align="justify">The ability of natural and synthetic glucocorticoids to elicit numerous and diverse physiological responses is remarkable. How the product of a single gene can participate in such a myriad of cell- and tissue-specific pathways has remained largely unknown. The last several years have seen increased description of glucocorticoid receptor (GR) protein isoforms. Here we review the current state of knowledge regarding naturally occurring GR isoforms and discuss how this array of receptor species generates the diversity associated with the glucocorticoid response. We propose that the multiplicity of receptor forms have unique tissue- specific actions on the downstream biology providing a mechanism to create GR signaling networks. <P><hr size=4 width=30%> <p align="justify"><b> </b><p> <p align="justify"> <p align="justify"> <H2><p align=center>2001 3>4</h2> <P><hr size=4 width=30%> <H2><p align=center>2000 3>4</h2> <P><hr size=4 width=30%> <p align="justify"><b> </b><p> <p align="justify"> <p align="justify"> <P><hr size=4 width=30%> <H2><p align=center>1999 3>4</h2> <P><hr size=4 width=30%> <p align="justify"><b> Interaction of glucocorticoid receptor isoforms with transcription factors AP-1 and NF-kappaB: lack of effect of glucocorticoid receptor beta. </b>Mol Cell Endocrinol. 1999 Nov 25;157(1-2):95-104. <p align="justify">Brogan IJ, Murray IA, Cerillo G, Needham M, White A, Davis JR. School of Biological Sciences, University of Manchester, UK. <p align="justify">Glucocorticoids act through the glucocorticoid receptor (GR) to enhance or repress transcription of glucocorticoid responsive genes depending on the promoter context and cellular background. The human GR primary transcript is alternatively spliced resulting in hGR alpha and hGR beta isoforms. Transactivation and transrepression are mediated by hGR alpha and while it has been demonstrated that hGR beta, can act as a dominant negative inhibitor of hGR alpha mediated transactivation, its effects on transrepression are not known. To investigate hGR beta actions, we used GR-deficient COS-7 and HEK-293 cells. When hGR alpha (0.5 microg 10(6) cells(-1)) was transfected into COS-7 cells dexamethasone (150 nM) inhibited TNF alpha (80 U ml(-1)) effects on a NF-kappaB responsive reporter gene by 40%. There was no evidence of a dominant negative effect when hGR beta (1-10 microg) was co-transfected with hGR alpha up to ratios of 10:1. Similarly hGR beta had no effect on hGR alpha inhibition of a phorbol ester stimulated Ap-1-responsive reporter gene in COS-7 or HEK-293 cells. In comparison, an apparent dominant negative effect of hGR beta on hGR alpha-mediated transactivation was found to be attributable to non-specific transcriptional squelching in COS-7 cells. In summary, the potential for hGR beta, to act as a dominant negative inhibitor of hGR alpha-mediated transactivation remains controversial, but our data suggest that hGR beta, was unable to act as a dominant negative inhibitor of either hGR alpha-mediated transrepression or transactivation in these promoter and cell contexts. <P><hr size=4 width=30%> <p align="justify"><b> </b><p> <p align="justify"> <p align="justify"> <P><hr size=4 width=30%> <H2><p align=center>1996 3>4</h2> <P><hr size=4 width=30%> <P><hr size=4 width=30%> <p align="justify"><b> </b><p> <p align="justify"> <p align="justify"> <P><hr size=4 width=30%> <H2><p align=center>1995 3>4</h2> <P><hr size=4 width=30%> <p align="justify"><b>Activation of a MMTV/mdr3 fusion transcript from a cryptic viral promoter is stimulated by mdr-derived sequences located in intron I.</b><p> Virology. 1995 Jul 10;210(2):244-53. <p align="justify">Lepage P, Underhill DA, Gros P. Department of Biochemistry, McGill University, Montreal, Quebec, Canada. <p align="justify">In P388/VCR-10 cells, resistance to cytotoxic drugs is caused by the overexpression of the mdr3 gene, in absence of gene amplification. The gene is transcriptionally activated following integration of a full-length mouse mammary tumor virus (MMTV) within intron I, upstream of the coding region of the gene. This integration results in the production of MMTV/mdr3 fusion transcripts that originate from the antisense 5'LTR of the provirus. The mechanism of mdr3 activation in these cells remains unclear since it cannot be accounted for either by activation from the normal MMTV promoter or by activation of the mdr3 promoter by MMTV enhancer sequences. Subcloning and sequence analysis of the genomic region encompassing the 5' LTR of the provirus with adjacent mdr3 sequences up to exon 2 showed that the LTR had not undergone small rearrangements or deletions. Transfections of fusion plasmids containing this genomic fragment and the reporter gene luciferase showed the presence of transcriptionally active sequences in that region. Deletions of 5' and 3' sequences from this fragment have shown that the antisense LTR itself has little contribution to the activation of the luciferase gene, whereas the mdr3 derived sequences that include part of intron I and the beginning of exon 2 strongly activated luciferase expression when inserted in either orientations upstream of the reporter gene. These results suggest the presence of an activator element within intron I of mdr3 capable of activating transcription from a cryptic start site present in the antisense MMTV LTR. Derepression of this activator sequence within intron I by a mechanism involving integration of a transposable element may be a prerequisite to transcriptional activation of the gene which is silent in the parental P388 cells. Further support for a derepression mechanism of activation in P388 cells is provided by the identification of independent genomic rearrangements in the 5' region of mdr3 in additional MDR P388 derivatives analyzed in this study. PMID: 7618265 [PubMed - indexed for MEDLINE] <P><hr size=4 width=30%> <H2><p align=center>1994 3>4</h2> <P><hr size=4 width=30%> <P><hr size=4 width=30%> <p align="justify"><b> </b><p> <p align="justify"> <p align="justify"> <P><hr size=4 width=30%> <p align="justify"><b> </b><p> <p align="justify"> <p align="justify"> <P><hr size=4 width=30%> <CENTER><P><!--TopList COUNTER--><a target=_top href="http://top.list.ru/jump?from=56983"><img src="http://top.list.ru/counter?id=56983;t=52" border=0 height=31 width=88 alt="TopList"></a><!--TopList COUNTER--> </CENTER> <P><hr size=4 width=30%> <p align="center"> <a href="../index.html"> >3;02;5=8N</a> </body></html>