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Author : Amy M. Fowler
Publisher :
ISBN 13 :
Total Pages : 226 pages
Book Rating : 4.:/5 (89 download)
Download or read book Concentration-dependent Estrogen Receptor-alpha Transcriptional Function in Breast Cancer written by Amy M. Fowler and published by . This book was released on 2005 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 460 pages
Book Rating : 4.:/5 (98 download)
Download or read book Phosphorylation-dependent Prolyl Cis/trans Isomerase Pin1 Regulation of Estrogen Receptor-alpha Functions in Breast Cancer written by and published by . This book was released on 2013 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt: Estrogen receptor-alpha (ER[alpha]) is a member of nuclear receptor superfamily of transcription factors. It is known to regulate carcinogenic gene expression programs that are involved in the development and progression of breast cancer. The transcriptional function of ER[alpha] is mediated by a C-terminal AF2 and an N-terminal AF1 activation domains. Ligand-dependent AF2 activity is well-characterized and serves as a basis for hormonal therapy for breast cancer. In contrast, structural and functional mechanisms governing AF1 functions remain poorly understood. AF1 activity of ER[alpha] is regulated by phosphorylation stemming from hormone, peptide growth factors, and second messenger pathways. Paradoxically, phosphorylation results in contrasting responses (differentiation and growth, protein stability and degradation, agonist and antagonist activities). How phosphorylation translates into diverse outcome is not clearly understood. The work presented in this thesis has uncovered a post-translation modification beyond phosphorylation that regulates the function and fate of ER[alpha]. I found that phosphorylation-dependent prolyl cis/trans isomerase, Pin1, causes structural changes at the AF1 region of ER[alpha]. These local changes allosterically regulate DNA binding and dimerization activities, enhancing overall ER[alpha] transcriptional function. Pin1 also stabilizes ER[alpha] protein by blocking its ubiquitination and degradation by the proteasome. Further studies in understanding the role of Pin1 in breast cancer led us to uncover the importance of Pin1 in proliferation of ER[alpha]-positive breast cancer cells and mammary tumors in rodent models. Pin1 overexpression was sufficient to overcome the antagonistic effects of tamoxifen and also contributed to tamoxifen resistance in breast cancer cells. Finally, the clinical relevance of Pin1 activity was confirmed by our findings in human breast tumors, where Pin1 levels were correlated with ER[alpha] protein levels, and ER[alpha]-positive tumor patients with high Pin1 levels had poor overall survival. Overall, the findings in this thesis have identified a new regulatory mechanism governing ER[alpha] AF1 function in breast cancer and discovered Pin1 as an important component modulating ER[alpha] protein levels and transactivation functions.
Author : Kyuri Kim
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (774 download)
Download or read book Regulation of Estrogen Receptor-alpha Mediated Gene Expression and Endocrine Resistance Through Estrogen Receptor-alpha Phosphorylation and Micro-RNA in Breast Cancer written by Kyuri Kim and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Estrogens are associated with the development and progression of breast cancer in addition to their role in normal reproductive physiology, and estrogen receptors (ER) mediate the actions of estrogen in target tissues by regulating the expression of numerous biologically important target genes. The progression of human breast cancer and the development of resistance to endocrine therapies are thought to be associated with ER phosphorylation. We generated multiple combinations of ER phospho-mutants, at residues serine 104, 106, 118, 167, 236, and 305, and examined their impact on receptor half-life, the agonist and antagonist balance of selective estrogen receptor modulators (SERMs) and selective estrogen receptor downregulators (SERDs), the regulation of ER transcriptional activity, and stimulation of cell proliferation in response to estradiol and SERMs/SERD. We showed that changes in ER affecting the phosphorylation status of the receptor greatly impact receptor function and differential SERM and SERD modulated cellular responses that could contribute to resistance to endocrine therapies in breast cancer. We also studied the regulation of microRNAs (miRNAs) by estradiol and growth factors through ER and extracellular signal-regulated kinase 2 (ERK2) in order to understand their physiological impact on breast cancer. We identified nine miRNA- encoding genes harboring overlapping ER and ERK2 binding sites close to their transcription start sites, which require ER and ERK2 for transcriptional induction as well as estradiol- mediated miRNA regulation. We then identified TP63, a target of miR-101, miR-190 and miR- 196a2, and showed that TP63 plays an important role in estradiol- or growth factor-mediated cellular response in breast cancer cells (MCF-7 and MDA-MB-231) by increasing tumor cell growth and in vitro invasion mainly controlled by miR-196a2 action. These results suggest a tumor-suppressive role of miR-196a2 in regulating TP63 expression and the aggressive behavior of breast cancers.
Author : Joseph Sin
Publisher :
ISBN 13 :
Total Pages : 42 pages
Book Rating : 4.:/5 (54 download)
Download or read book Mechanisms of Estrogen Receptor Alpha Mediated Transcriptional Repression written by Joseph Sin and published by . This book was released on 2009 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: Prolonged exposure to increased levels of estrogen has been shown to increase the risk of breast cancer. In addition, estrogen has been shown to cause breast cancer cell proliferation. A common form of breast cancer treatment involved selective estrogen receptor modulation. A molecular explanation of how this works is that estrogen regulates and binds to estrogen receptor (ER), a ligand-dependent transcription factor. ER associated with estrogen induces gene transcription by translocating into the nucleus and binding to estrogen response element. ER also recruits cofactor proteins, which results in chromatin remodeling and gene expression regulation through interacting with histone acetylases or transcriptional machinery. Most studies have focused on the study of how ER can activate gene transcription. Recently, ER has been shown to also repress gene transcription. my research has two parts. The first part was to find genes that were down regulated by estrogen in order to increase the data pool of genes down-regulated by estrogen. Four target genes, ARGN, MGC16169, CALML5, and NFIB are suspected to be involved in down-regulation by ER. However, after conducting validation tests, these genes were determined to not be repressed. The second part includes characterizing the specific effects of co-repressors NCoR, NRIP1, and SMRT. Removal of these co-repressors and subsequent effect of their removal on following four ER target sites, HES1, PSCA, SLC35A1, and MME were studied. A knock down of a single co-repressor did not affect the majority of transcriptional activity in ER repressed target genes. A triple knock down was also conducted in hope that removal of multiple co-repressors might affect repression. However, the triple knock down was a failure and future experiments need to be done. Understanding the mechanisms of ER transcriptional repression would significantly aid the creation of effective treatments for breast cancer.
Author : Edmund Chi-Ru Chang
Publisher : ProQuest
ISBN 13 : 9780549339304
Total Pages : 105 pages
Book Rating : 4.3/5 (393 download)
Download or read book Cross-modulatory Actions of Estrogen Receptor Beta on Estrogen Receptor Alpha Transcriptional Activity in Breast Cancer Cells written by Edmund Chi-Ru Chang and published by ProQuest. This book was released on 2007 with total page 105 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our observations indicate that the ability of ERalpha and ERbeta to serve as determinants of gene expression is greatly influenced by the nature of the ligand, ligand dose, and the ability of ligand-ER complexes to recruit coregulators at ER binding sites of hormone-regulated genes.
Author :
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (914 download)
Download or read book Dissecting the Role of Estrogen Receptor Palmitoylation in Breast Cancer Cells written by and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Estrogen signaling is primarily mediated by two estrogen receptors (ERs), ER[alpha] and ER[beta]. ER[alpha] is expressed in ~70% of breast cancers and is an important diagnostic and therapeutic target. Developing better treatment options and overcoming limitations of endocrine therapy depend on a detailed understanding of ER[alpha]-signaling pathways. ER[alpha], a member of the class I nuclear receptor superfamily of transcription factors, localizes mainly to the nucleus and interacts with DNA regulatory sequences either directly or through interaction with other transcription factors to regulate gene transcription. ER[alpha] is also rapidly activates signaling cascades. S-palmitoylation, a reversible lipid modification is catalyzed by palmitoyl acyl-transferases (PAT), which increase affinity of proteins to the membrane. Based on the results of previous studies, it is hypothesized that palmitoylation of ER[alpha] regulates extranuclear and nuclear signaling of ER[alpha]. We utilized palmitoylation-defective mutant ER[alpha]C447A-expressing MDA-MB-468 breast cancer cells to dissect the role of palmitoylation in a breast cancer cell line model. The substitution of ER[alpha] palmitoylation site abrogated ER[alpha] palmitoylation, membrane localization and estrogen-dependent phosphorylation of ERK1/2 in MDA-MB-468 cell line. Besides loss of E2-dependent extranuclear signaling, the substitution of palmitoylation sites led to the loss of other ER[alpha]-dependent events in ER[alpha]C447A-expressing MDA-MB-468 cells, such as decreased E2-dependent S118 phosphorylation, impaired regulation of certain target genes, and loss of estrogen-dependent cell cycle inhibition. This study thus highlights the importance of ER[alpha] palmitoylation in both nuclear and extranuclear ER signaling pathways in breast cancer cells. A better understanding of the mechanisms of estrogen action will help us to design more effective drugs affecting signal pathways depending on both membrane and nuclear receptors.
Author : Fritz F. Parl
Publisher : IOS Press
ISBN 13 : 9780967335544
Total Pages : 280 pages
Book Rating : 4.3/5 (355 download)
Download or read book Estrogens, Estrogen Receptor and Breast Cancer written by Fritz F. Parl and published by IOS Press. This book was released on 2000 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: Estrogens have been implicated to play a role in the development of breast cancer. The purpose of this book is to provide a comprehensive analysis of experimental, clinical and epidemiological evidence in support of the carcinogenicity of estrogens.
Author : Kenneth Wing Merrell
Publisher :
ISBN 13 :
Total Pages : 80 pages
Book Rating : 4.:/5 (367 download)
Download or read book Mechanisms of Estrogen Receptor Alpha Mediated Transcriptional Suppression written by Kenneth Wing Merrell and published by . This book was released on 2007 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: A better understanding of the molecular mechanisms of ER function will likely provide insight into the role of estrogens and ERs in breast cancer biology. Identification of differential mechanisms of transcriptional repression may suggest potential targets in the treatment of hormone-dependent breast cancers.
Author :
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (946 download)
Download or read book Dynamics of Estrogen Receptor Transcription Complex Assembly in Breast Cancer written by and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Estrogen plays a critical role in the development and progression of breast cancer. While endocrine therapies play an important part in breast cancer treatment, the failure of these therapies reflects a lack of knowledge concerning the molecular mechanisms involved in estrogen signaling. The biological activities of estrogen are mediated by estrogen receptors (ER) . In addition, a large number of proteins termed cofactors are involved in ER signaling. Until recently, our knowledge regarding these cofactors was based on their ability to bind receptors in vitro and affect transcriptional activation in transfection experiments. The in vivo role of these cofactors and the specific target genes involved in breast cancer are not well known. Therapeutic agents, such as tamoxifen, also bind ER, but block proliferation in breast cells. However, tamoxifen increases the risk of endometrial cancer. We have used chromatin immunoprecipitation (ChIP) to investigate cofactor involvement in ER signaling in vivo and to understand the mechanisms underlying the different actions of tamoxifen in breast and endometrial cells. We are in the process of using ChIP to identify the set of genes regulated by ER and its cofactors in these tissues. The detailed understanding of tissue- and ligand-dependent changes in gene expression gained through these studies will lead to more effective therapies for ER-dependent breast cancer.
Author : Ajay K. Singh
Publisher : Academic Press
ISBN 13 : 0080920462
Total Pages : 534 pages
Book Rating : 4.0/5 (89 download)
Download or read book Textbook of Nephro-Endocrinology written by Ajay K. Singh and published by Academic Press. This book was released on 2009-01-12 with total page 534 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Textbook of Nephro-Endocrinology is the definitive translational reference in the field of nephro-endocrinology, investigating both the endocrine functions of the kidneys and how the kidney acts as a target for hormones from other organ systems. It offers researchers and clinicians expert, gold-standard analyses of nephro-endocrine research and translation into the treatment of diseases such as anemia, chronic kidney disease (CKD), rickets, osteoporosis, and, hypoparathyroidism. - Investigates both the endocrine functions of the kidneys and how the kidney acts as a target for hormones from other organ systems - Presents a uniquely comprehensive and cross-disciplinary look at all aspects of nephro-endocrine disorders in one reference work - Clear translational presentations by the top endocrinologists and nephrologists in each specific hormone or functional/systems field
Author :
Publisher :
ISBN 13 :
Total Pages : 13 pages
Book Rating : 4.:/5 (742 download)
Download or read book The Role of Estrogen Related Receptor in Modulating Estrogen Receptor Mediated Transcription in Breast Cancer Cells written by and published by . This book was released on 2004 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unlike most nuclear receptors, the Estrogen Receptor-Related Receptors (ERRs) activate transcription constitutively, interacting with coactivators and target gene promoters in the absence of ligand. Structurally, this subfamily of receptors is related to the classical estrogen receptors and has been shown to positively regulate the transcription of several estrogen responsive genes. Interestingly, the transcriptional activity of ERRalpha is not inhibited by classical anti-estrogens suggesting that its ability to regulate ER- responsive genes may contribute to the development of tamoxifen resistant breast cancer. Without pharmacological agents to regulate ERRalpha activity it has been difficult to define the specific roles of this orphan receptor in the pathogenesis of breast cancer and thus its potential as a therapeutic target is unknown. To address this issue we have developed approaches to both positively and negatively regulate ERRalpha activity in target cells. Specifically, we have developed peptide antagonists to inhibit ERRalpha activity by blocking cofactor binding and have developed activating "protein ligands" by creating modified coactivators that selectively regulate ERRalpha transcriptional activity. With these tools, we have characterized the critical regions of the receptor important for coactivator binding and defined differential binding requirements between coactivator families. In addition, we are identifying the target genes and processes regulated by ERRalpha.
Author : Crystal Eileen Berger
Publisher :
ISBN 13 : 9781267967527
Total Pages : pages
Book Rating : 4.9/5 (675 download)
Download or read book The Reciprocal Regulatory Effects of Estrogen Receptor Alpha and P53 in Estrogen-dependent Breast Cancer written by Crystal Eileen Berger and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In response to genotoxic stress, the p53 tumor suppressor induces target genes for cell cycle arrest, apoptosis and DNA repair. Although p53 is the most commonly mutated gene in all human cancers, it is only mutated in about 20% of breast cancers. 70% of all breast cancer cases are estrogen receptor positive (ER-positive) and express estrogen receptor alpha (ER alpha). ER-positive breast cancer generally indicates good patient prognosis and treatment responsiveness with anti-estrogens such as tamoxifen. However, ER-positive breast cancer patients can experience loss or a reduction in ER alpha, which is associated with aggressive tumor growth, increased invasiveness, poor prognosis, and loss of p53 function. Consistent with this, we found that p53 is a target gene of ER alpha. Specifically, we found that knockdown of ER alpha decreases expression of p53 and its downstream target genes, MDM2 and p21. In addition, we found that ER alpha activates p53 transcription via binding to ERE half-sites within the p53 promoter. Moreover, we found that loss of ER alpha desensitizes, whereas ectopic expression of ER alpha sensitizes, breast cancer cells to DNA damage-induced growth suppression in a p53-dependent manner. Together, this study provides an insight into a feedback loop between ER alpha and p53 and a biological role of p53 in the DNA damage response in ER-positive breast cancers.
Author : Chun Gong
Publisher :
ISBN 13 : 9781361320174
Total Pages : pages
Book Rating : 4.3/5 (21 download)
Download or read book Regulation of Estrogen Receptor Alpha Expression by Translation Or Degradation and the Relevance to Tamoxifen Resistance in Breast Cancer written by Chun Gong and published by . This book was released on 2017-01-26 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Regulation of Estrogen Receptor Alpha Expression by Translation or Degradation and the Relevance to Tamoxifen Resistance in Breast Cancer" by Chun, Gong, 龚纯, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Breast cancer is one of the most prevalent cancers affecting women worldwide. In the breast, estrogen receptor alpha (ERα), upon binding with ligands, activates gene transcription and promotes cell growth and proliferation. Tamoxifen, a selective antagonist of ERα in breast, has been proved to be effective therapeutically. In spite of this, resistance remains a prominent issue and underlying mechanisms are not yet fully understood. Aberrant regulation of ER expression at genetic and transcriptional levels has been implicated as the mechanisms accounting for tamoxifen resistance. However, regulation of ERα expression at translational level including protein synthesis and degradation has not yet been characterized and its relevance to tamoxifen resistance has not been described. At level of protein synthesis, eukaryotic translation initiation factor 4E (eIF4E) selectively enhances the translation of 4E-sensitive mRNAs which contain long and complex 5''-untraslated regions (5''-UTR). eIF4E is often over-expressed in cancers. In silico analysis revealed that ERα contained a highly structured 5''-UTR similar to reported eIF4E-sensitive mRNAs, suggesting that ERα mRNA might be eIF4Esensitive. We showed by polysome fractionation and subsequent Q-PCR quantification that the ERα mRNAs were more actively translated in the cell line expressing higher levels of eIF4E. Consistently, transient transfection of eIF4E into an ERα-positive cell line resulted in enhanced protein expression of ERα. Moreover, subcelluar fractionation showed that eIF4E was bound with ERα mRNAs in the nucleus thus participating in transportation of mRNAs from the nucleus into the cytoplasm. Therefore, eIF4E could positively modulate protein synthesis of ERα by enhancing mRNA export in the nucleus as well as translation in the cytoplasm. Their positive correlation was validated in vivo using 106 Chinese breast cancer samples (Chi-square test, p=0.004). It was also found that elevated expression of eIF4E could mediate resistance to tamoxifen treatment and enhance cell survival. This could be due to enhanced expression of ERα or activation of PI3K/Akt pathway upon eIF4E over-expression. At the level of degradation, ERα is conjugated to poly-ubiquitin chains catalyzed by multiple enzymes and degraded by 26S polysomes. Carboxyl-terminus of Hsc70- interacting protein (CHIP) is an E3 enzyme specific for ERα degradation through interaction with ERα''s ligand-binding domain (LBD). Various splicing variants of ERα have been reported and implicated in tamoxifen resistance by interfering with functions of ERα wild type. Variants ERαΔ4, ERαΔ5, ERαΔ6/7 and ERαΔ7 with different degrees of truncation in their LBDs and differential expression were detected or reported in human breast cancers. Their interactions with CHIP may be different, resulting in variations in degradation. We found that the degradation of ERαΔ6/7 through ubiquitin-proteasome pathway was impaired whilst the degradation of other variants were less affected. This finding suggests that the binding site of CHIP to ERαmight be located within the peptide sequences encoded by exon6. Furthermore, as ERαΔ6/7 plays a dominant negative role in regulating functions of ERα wild type, aborted degradation of this variant may result in accumulation of this variant in the cell, inhibiting and in
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Author : Genevieve Deblois
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (922 download)
Download or read book Molecular and Functional Genomics Analyses of Estrogen- Related Receptor Alpha (ERR[alpha]) Function in Breast Cancer written by Genevieve Deblois and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "The estrogen-related receptor [alpha] (ERR[alpha]) is an orphan nuclear receptor whose expression in breast tumors is inversely correlated to that of the ER[alpha] but positively correlates with the poor prognosis receptor tyrosine kinase (RTK) HER2. Using binding sites location analyses in breast cancer cells we show that ERR[alpha] displays strict binding site specificity and ER[alpha]-independent transcriptional programs. Ablation of ERR[alpha] in a mouse model of Neu-initiated mammary tumorigenesis significantly delays HER2-induced tumor development. ERR[alpha] regulates the expression of ERBB2 and co-amplified transcripts in a process confering resistance to tamoxifen treatment in breast cancer cells. We further use genome-wide profiling of ERR[alpha] by ChIP-Sequencing, to show that [beta]-1-heregulin (HRG) and epidermal growth factor (EGF) lead to AP1-dependant reprogramming of ERR[alpha] recruitment to chromatin in breast cancer cells. We next show that the dual EGFR/HER2 tyrosine kinase inhibitor (TKI) lapatinib induces the degradation of ERR[alpha] protein. The expression of ERR[alpha] is recovered in lapatinib-resistant breast cancer cells in an mTOR-dependant manner despite sustained inhibition of EGFR/HER2. Finally, we show that ERR[alpha] signalling in lapatinib-resistant breast cancer cells provides a suitable metabolic context to sustain growth under therapeutic pressure. Together this work has uncovered important aspects of ERR[alpha] transcriptional profiles in breast cancer cells and has established ERR[alpha] as a significant player in the development, progression and therapeutic susceptibility of breast cancer cells." --
Author : Shweta Bhatt
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (776 download)
Download or read book Cross-modulatory Actions of Cell Cycle Machinery on Estrogen Receptor-alpha Level and Transcriptional Activity in Breast Cancer Cells written by Shweta Bhatt and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Chien-Cheng Chen
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (69 download)
Download or read book Mechanisms of Transcriptional Activation of Estrogen Responsive Genes in Breast Cancer Cells written by Chien-Cheng Chen and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Estrogen receptor (ER) acts as a ligand-activated transcription factor that regulates the expression of genes. The genomic mechanisms of ER action include ligand-induced dimerization of ER which binds estrogen responsive elements (EREs) in the promoters of target genes. There are also nongenomic mechanisms of ER action which are associated with membrane bound or cytosol ER-dependent activation of various protein-kinase cascades which also influence expression of target genes. Egr-1 is an immediate-early gene induced by 17B-estradiol (E2) in the rodent uterus and breast cancer cells. Deletion analysis of the Egr-1 promoter identified a minimal E2-responsive region that contained serum response element (SRE3) which bound Elk-1 and serum response factor (SRF) in gel mobility shift assays. Hormone-responsiveness of Egr-1 in MCF-7 cells was specifically inhibited by PD98059, a MAPKK inhibitor, but not by LY294002, an inhibitor of PI3-K. These results contrasted with the hormone-dependent activation of the SRE in the c-fos promoter, which was inhibited by both PD98059 and LY294002, suggesting that Egr-1, like c-fos, is activated through non-genomic pathways of estrogen action but through activation of different kinases. COUP-TFs are orphan nuclear receptors expressed in a variety of tissues where they regulate biological functions and organogenesis. In this study, we investigated coactivation of ERa by COUP-TF1 in cell lines transiently cotransfected with the pERE3 construct. COUP-TFI coactivated ERał-mediated transactivation, but unlike many other coactivators, COUP-TFI also enhanced transactivation of ERa when cells were cotransfected with the TAF1-ERa mutant or the 19c-ERa mutant. These data indicate that helix 12 of ERa is not required for coactivation by COUP-TFI when AF-1 of ERa is intact. However, when the AF-1 of ERa is deleted, the intact AF-2 function is required for coactivation by COUP-TFI. Analysis of multiple COUP-TFI deletion mutants showed that the DNA-binding domain and C-terminal region of COUP-TFI were important for coactivation of ERa. Point mutations of the DNA-binding domain of COUP-TFI resulted in loss of interactions with ERa, suggesting that the DNA-binding domain of COUP-TFI is important for its coactivation activity facilitating interactions with ERa. These results demonstrate that COUP-TFI coactivated ERa through a non-classical LXXLL-independent pathway.
Author : Ahmed Edan Dhamad
Publisher :
ISBN 13 :
Total Pages : 402 pages
Book Rating : 4.:/5 (16 download)
Download or read book Molecular and Biochemical Studies of Several Novel Estrogen Receptor Alpha-interacting Proteins in Breast Cancer Cells written by Ahmed Edan Dhamad and published by . This book was released on 2017 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt: Breast cancer is the second leading cause of cancer-related death in women, and approximately 70% of incidences are estrogen receptor (ER)-positive breast cancer. ERÜ and its interacting proteins play a key role in the development and progression of breast cancer. However, how ERÜ regulates its target gene expression and hence cell proliferation is not fully understood. To enhance our understanding of the molecular mechanism by which ERÜ regulates gene expression, we used a quantitative proteomic method to identify cellular proteins that interact with ERÜ. The first group of proteins that were identified to associate with ERÜ are heat shock proteins (Hsps). We identified 21 Hsps and 3 Hsp cochaperones that were associated with ERÜ. Co-immunoprecipitation assay demonstrated that Hsp70-1 and Hsc70, the two most abundant ERÜ-associated proteins, interacted with ERÜ in both transcriptionally active and inactive chromatin of MCF7 cells. A novel of protein that was identified to interact with ERÜ is histone acetyltransferase 1 (HAT1). We showed that HAT1 physically binds ERÜ through the E domain of ERÜ, and silencing HAT1 by shRNA significantly increased the ERÜ-mediated transcription in MCF7 cells. Importantly, our data suggest that HAT1 regulates ERÜ transcriptional activity through affecting the interactions of ERÜ with histone proteins around the promoter region of ERÜ target genes in breast cancer cells. We also identified and confirmed that protein arginine methyltransferase 5 (PRMT5) is a new ERÜ interacting partner, and PRMT5 interacts with ERÜ preferentially in the cytoplasm of MCF7 cells. Functionally, we found that overexpression of PRMT5 in MCF7 cells significantly decreased ERÜ transcriptional activity. Finally, we demonstrated that chromatin target of PRMT1 (CHTOP) directly binds to ERÜ through the E domain of ERÜ. We found that knockout of CHTOP by CRISPR-Cas9 significantly decreased ERÜ transcriptional activity, and the effect is potentially through decreasing protein levels of MEP50, an ERÜ coactivator. In summary, we identified and characterized several novel ERÜ-interacting proteins that play significant roles in regulating ERÜ transcriptional activities. Our results provide new insight into the molecular mechanisms by which ERÜ controls its target gene expression and regulates cell proliferation in ERÜ-positive cells.
