The Experts below are selected from a list of 117 Experts worldwide ranked by ideXlab platform

Elena Klenova - One of the best experts on this subject based on the ideXlab platform.

  • generation of poly adp ribosyl ation deficient mutants of the Transcription Factor CTCF
    Methods of Molecular Biology, 2011
    Co-Authors: Dawn Farrar, Igor Chernukhin, Elena Klenova
    Abstract:

    Generation of the mutated versions of proteins deficient for poly(ADP-ribosyl)ation (PARylation) is a major challenge because there is no clearly defined consensus site for PARylation. In this chapter, we describe possible strategies to produce such mutants, demonstrated by the example of CTCF, a Transcription Factor. To achieve this in our study, the protein domain modified by PARylation was mapped and the amino acids, which can be potentially PARylated, selected. Mutations of such individual amino acids as either single or combinatorial mutations were introduced by site-directed mutagenesis, using mutagenic primers and the wild-type sequences as a template. Mutants were validated by DNA sequencing and assessed for the presence of the PARylation mark. The latter was achieved by ectopic expression of mutated proteins in cells, followed by immunoprecipitation with the polyclonal anti-PAR antibody and Western analysis with a protein-specific antibody. The PARylation-deficient CTCF mutant was identified and compared with the wild-type protein. Based on several general characteristics (nuclear distribution/localisation, stability and levels of expression in the cell), the PARylation-deficient mutant was comparable with the wild-type CTCF.

  • mutational analysis of the poly adp ribosyl ation sites of the Transcription Factor CTCF provides an insight into the mechanism of its regulation by poly adp ribosyl ation
    Molecular and Cellular Biology, 2010
    Co-Authors: Dawn Farrar, Igor Chernukhin, Yoko Ito, Sushma Rai, Maja Jagodic, Samer Yammine, Rolf Ohlsson, Adele Murrell, Elena Klenova
    Abstract:

    Poly(ADP-ribosyl)ation of the conserved multifunctional Transcription Factor CTCF was previously identified as important to maintain CTCF insulator and chromatin barrier functions. However, the molecular mechanism of this regulation and also the necessity of this modification for other CTCF functions remain unknown. In this study, we identified potential sites of poly(ADP-ribosyl)ation within the N-terminal domain of CTCF and generated a mutant deficient in poly(ADP-ribosyl)ation. Using this CTCF mutant, we demonstrated the requirement of poly(ADP-ribosyl)ation for optimal CTCF function in Transcriptional activation of the p19ARF promoter and inhibition of cell proliferation. By using a newly generated isogenic insulator reporter cell line, the CTCF insulator function at the mouse Igf2-H19 imprinting control region (ICR) was found to be compromised by the CTCF mutation. The association and simultaneous presence of PARP-1 and CTCF at the ICR, confirmed by single and serial chromatin immunoprecipitation assays, were found to be independent of CTCF poly(ADP-ribosyl)ation. These results suggest a model of CTCF regulation by poly(ADP-ribosyl)ation whereby CTCF and PARP-1 form functional complexes at sites along the DNA, producing a dynamic reversible modification of CTCF. By using bioinformatics tools, numerous sites of CTCF and PARP-1 colocalization were demonstrated, suggesting that such regulation of CTCF may take place at the genome level.

  • decreased poly adp ribosyl ation of CTCF a Transcription Factor is associated with breast cancer phenotype and cell proliferation
    Clinical Cancer Research, 2009
    Co-Authors: Georgiaxanthi Kita, Igor Chernukhin, Dawn Farrar, Parmjit S Jat, Michael J Ohare, Svetlana Gretton, Adhip Mandal, Louise Caroline Alldridge, Elena Klenova
    Abstract:

    Purpose: There is compelling evidence of a relationship between poly(ADP-ribosyl)ation and tumorigenesis; however, much less is known about the role of specific targets of poly(ADP-ribosyl)ation in tumor development. Two forms of the multifunctional Transcription Factor, CTCF, were previously identified: a 130-kDa protein (CTCF-130), characteristic for cell lines, and a 180-kDa protein (CTCF-180), modified by poly(ADP-ribosyl)ation. This study was aimed to investigate differential poly(ADP-ribosyl)ation of CTCF in normal and tumor breast tissues. Experimental Design: Western blot analysis, mass spectrometry, and immunohistochemical and immunofluorescent stainings were used to characterize CTCF-130 and CTCF-180 in breast cell lines, primary cultures, and normal and tumor breast tissues. The immunoreactivity score was used for CTCF-130 quantification in tissues. Results: We discovered that only CTCF-180 is detected in the normal breast tissues, whereas both CTCF-130 and CTCF-180 are present in breast tumors. Using an antibody specific for CTCF-130, we observed that 87.7% of breast tumors were positive for CTCF-130. A negative correlation existed between the levels of CTCF-130, tumor stage, and tumor size. Significantly, a transition from CTCF-180 to CTCF-130 was discovered in primary cultures generated from normal breast tissues, indicating a link between CTCF-130 and proliferation. Conversely, the appearance of CTCF-180 was observed following growth arrest in breast cell lines. Conclusions: Collectively, our data suggest that the loss of CTCF poly(ADP-ribosyl)ation is associated with cell proliferation and breast tumor development. We propose the use of CTCF-130 as a marker for tumor breast cells and lower levels of CTCF-130 as an indicator of unfavorable prognosis. (Clin Cancer Res 2009;15(18):5762–71)

  • Regulation of the Transcription Factor, CTCF, by phosphorylation with protein kinase CK2.
    FEBS Letters, 2005
    Co-Authors: Ayman El-kady, Elena Klenova
    Abstract:

    CTCF is a Transcription Factor involved in various aspects of gene regulation. We previously reported that CTCF function is modulated by protein kinase CK2. In this report we investigate further the role of CK2 in regulating the Transcriptional properties of CTCF. We demonstrate that coexpression of CTCF with CK2 switches function of CTCF from repressor to activator. The non-phosphorylatable mutant increases repression by CTCF and potentiates the growth-suppressive ability of the protein, whereas the phospho-mimetic mutant behaves in the opposite fashion. Mutation of the individual serines reveals that Serine 612 is a critical residue in regulation of CTCF by CK2.

  • Molecular weight abnormalities of the CTCF Transcription Factor: CTCF migrates aberrantly in SDS-PAGE and the size of the expressed protein is affected by the UTRs and sequences within the coding region of the CTCF gene.
    Nucleic Acids Research, 1997
    Co-Authors: Elena Klenova, Victor V Lobanenkov, Robert H. Nicolas, Sally U, Alexander F. Carne, Robin E. Lee, Graham H. Goodwin
    Abstract:

    CTCF belongs to the Zn finger Transcription Factors family and binds to the promoter region of c-myc. CTCF is highly conserved between species, ubiquitous and localised in nuclei. The endogenous CTCF migrates as a 130 kDa (CTCF-130) protein on SDS-PAGE, however, the open reading frame (ORF) of the CTCF cDNA encodes only a 82 kDa protein (CTCF-82). In the present study we investigate this phenomenon and show with mass-spectra analysis that this occurs due to aberrant mobility of the CTCF protein. Another paradox is that our original cDNA, composed of the ORF and 3'-untranslated region (3'-UTR), produces a protein with the apparent molecular weight of 70 kDa (CTCF-70). This paradox has been found to be an effect of the UTRs and sequences within the coding region of the CTCF gene resulting in C-terminal truncation of CTCF-130. The potential attenuator has been identified and point-mutated. This restored the electrophoretic mobility of the CTCF protein to 130 kDa. CTCF-70, the aberrantly migrating CTCF N-terminus per se, is also detected in some cell types and therefore may have some biological implications. In particular, CTCF-70 interferes with CTCF-130 normal function, enhancing transactivation induced by CTCF-130 in COS6 cells. The mechanism of CTCF-70 action and other possible functions of CTCF-70 are discussed.

Dawn Farrar - One of the best experts on this subject based on the ideXlab platform.

  • generation of poly adp ribosyl ation deficient mutants of the Transcription Factor CTCF
    Methods of Molecular Biology, 2011
    Co-Authors: Dawn Farrar, Igor Chernukhin, Elena Klenova
    Abstract:

    Generation of the mutated versions of proteins deficient for poly(ADP-ribosyl)ation (PARylation) is a major challenge because there is no clearly defined consensus site for PARylation. In this chapter, we describe possible strategies to produce such mutants, demonstrated by the example of CTCF, a Transcription Factor. To achieve this in our study, the protein domain modified by PARylation was mapped and the amino acids, which can be potentially PARylated, selected. Mutations of such individual amino acids as either single or combinatorial mutations were introduced by site-directed mutagenesis, using mutagenic primers and the wild-type sequences as a template. Mutants were validated by DNA sequencing and assessed for the presence of the PARylation mark. The latter was achieved by ectopic expression of mutated proteins in cells, followed by immunoprecipitation with the polyclonal anti-PAR antibody and Western analysis with a protein-specific antibody. The PARylation-deficient CTCF mutant was identified and compared with the wild-type protein. Based on several general characteristics (nuclear distribution/localisation, stability and levels of expression in the cell), the PARylation-deficient mutant was comparable with the wild-type CTCF.

  • Regulation of the apoptotic genes in breast cancer cells by the Transcription Factor CTCF
    Breast Cancer Research, 2010
    Co-Authors: Claudia Fabiola Méndez-catalá, Elena M Pugacheva, Igor Chernukhin, Dawn Farrar, Alexander A. Vostrov, Yoko Ito, F Docquier, G-x Kita, A Murrell, V Lobanankov
    Abstract:

    CTCF is a highly conserved and ubiquitous Transcription Factor with versatile functions. We previously demonstrated that elevated protein levels of CTCF in breast cancer cells were associated with the specific anti-apoptotic function of CTCF. We used proteomics and microarray approaches to identify regulatory targets of CTCF specific for breast cancer cells. Among the CTCF identified targets were proteins involved in the control of apoptosis. A proapoptotic protein, Bax, negatively regulated by CTCF, was chosen for further investigation. Repression of the human Bax gene at the Transcriptional level by CTCF in breast cancer cells was confirmed by real-time PCR. Two CTCF binding sites within the Bax promoter were identified by electrophoretic mobility shift assay and footprinting. In reporter assays, the Bax-luciferase reporter construct, containing CTCF-binding sites, was negatively regulated by CTCF. In vivo, CTCF occupied its binding sites in breast cancer cells and tissues, as confirmed by chromatin immunoprecipitation assay. Our findings suggest a possible mechanism of the specific CTCF anti-apoptotic function in breast cancer cells whereby CTCF is bound to the Bax promoter, resulting in repression of Bax and inhibition of apoptosis; depletion of CTCF leads to activation of Bax and apoptotic death. CTCF binding sites in the Bax promoter are unmethylated in all cells and tissues inspected. Therefore, specific CTCF interaction with the Bax promoter in breast cancer cells, and the functional outcome, may depend on a combination of epigenetic Factors characteristic for these cells. Interestingly, CTCF appears to be a negative regulator of other proapoptotic genes (for example, Fas, Apaf-1, TP531NP1). Conversely, stimulating effects of CTCF on the anti-apoptotic genes (Bcl-2, Bag-3) have been observed. Taken together, these findings suggest that specific mechanisms have evolved in breast cancer cells to protect them from apoptosis; regulation of apoptotic genes by CTCF appears to be one of the resistance strategies.

  • mutational analysis of the poly adp ribosyl ation sites of the Transcription Factor CTCF provides an insight into the mechanism of its regulation by poly adp ribosyl ation
    Molecular and Cellular Biology, 2010
    Co-Authors: Dawn Farrar, Igor Chernukhin, Yoko Ito, Sushma Rai, Maja Jagodic, Samer Yammine, Rolf Ohlsson, Adele Murrell, Elena Klenova
    Abstract:

    Poly(ADP-ribosyl)ation of the conserved multifunctional Transcription Factor CTCF was previously identified as important to maintain CTCF insulator and chromatin barrier functions. However, the molecular mechanism of this regulation and also the necessity of this modification for other CTCF functions remain unknown. In this study, we identified potential sites of poly(ADP-ribosyl)ation within the N-terminal domain of CTCF and generated a mutant deficient in poly(ADP-ribosyl)ation. Using this CTCF mutant, we demonstrated the requirement of poly(ADP-ribosyl)ation for optimal CTCF function in Transcriptional activation of the p19ARF promoter and inhibition of cell proliferation. By using a newly generated isogenic insulator reporter cell line, the CTCF insulator function at the mouse Igf2-H19 imprinting control region (ICR) was found to be compromised by the CTCF mutation. The association and simultaneous presence of PARP-1 and CTCF at the ICR, confirmed by single and serial chromatin immunoprecipitation assays, were found to be independent of CTCF poly(ADP-ribosyl)ation. These results suggest a model of CTCF regulation by poly(ADP-ribosyl)ation whereby CTCF and PARP-1 form functional complexes at sites along the DNA, producing a dynamic reversible modification of CTCF. By using bioinformatics tools, numerous sites of CTCF and PARP-1 colocalization were demonstrated, suggesting that such regulation of CTCF may take place at the genome level.

  • decreased poly adp ribosyl ation of CTCF a Transcription Factor is associated with breast cancer phenotype and cell proliferation
    Clinical Cancer Research, 2009
    Co-Authors: Georgiaxanthi Kita, Igor Chernukhin, Dawn Farrar, Parmjit S Jat, Michael J Ohare, Svetlana Gretton, Adhip Mandal, Louise Caroline Alldridge, Elena Klenova
    Abstract:

    Purpose: There is compelling evidence of a relationship between poly(ADP-ribosyl)ation and tumorigenesis; however, much less is known about the role of specific targets of poly(ADP-ribosyl)ation in tumor development. Two forms of the multifunctional Transcription Factor, CTCF, were previously identified: a 130-kDa protein (CTCF-130), characteristic for cell lines, and a 180-kDa protein (CTCF-180), modified by poly(ADP-ribosyl)ation. This study was aimed to investigate differential poly(ADP-ribosyl)ation of CTCF in normal and tumor breast tissues. Experimental Design: Western blot analysis, mass spectrometry, and immunohistochemical and immunofluorescent stainings were used to characterize CTCF-130 and CTCF-180 in breast cell lines, primary cultures, and normal and tumor breast tissues. The immunoreactivity score was used for CTCF-130 quantification in tissues. Results: We discovered that only CTCF-180 is detected in the normal breast tissues, whereas both CTCF-130 and CTCF-180 are present in breast tumors. Using an antibody specific for CTCF-130, we observed that 87.7% of breast tumors were positive for CTCF-130. A negative correlation existed between the levels of CTCF-130, tumor stage, and tumor size. Significantly, a transition from CTCF-180 to CTCF-130 was discovered in primary cultures generated from normal breast tissues, indicating a link between CTCF-130 and proliferation. Conversely, the appearance of CTCF-180 was observed following growth arrest in breast cell lines. Conclusions: Collectively, our data suggest that the loss of CTCF poly(ADP-ribosyl)ation is associated with cell proliferation and breast tumor development. We propose the use of CTCF-130 as a marker for tumor breast cells and lower levels of CTCF-130 as an indicator of unfavorable prognosis. (Clin Cancer Res 2009;15(18):5762–71)

  • boris a paralogue of the Transcription Factor CTCF is aberrantly expressed in breast tumours
    British Journal of Cancer, 2008
    Co-Authors: Igor Chernukhin, F Docquier, Vivien Darcy, N Pore, Ziedulla Abdullaev, Georgiaxanthi Kita, Sauharda Rai, Melissa C Smart, Dawn Farrar
    Abstract:

    BORIS (for brother of the regulator of imprinted sites), a paralogue of the Transcription Factor, CTCF, is a novel member of the cancer-testis antigen family. The aims of the present study were as follows: (1) to investigate BORIS expression in breast cells and tumours using immunohistochemical staining, western and real-time RT–PCR analyses and (2) assess potential correlation between BORIS levels in tumours with clinical/pathological parameters. BORIS was detected in all 18 inspected breast cell lines, but not in a primary normal breast cell culture. In 70.7% (41 of 58 cases) BORIS was observed in breast tumours. High levels of BORIS correlated with high levels of progesterone receptor (PR) and oestrogen receptor (ER). The link between BORIS and PR/ER was further confirmed by the ability of BORIS to activate the promoters of the PR and ER genes in the reporter assays. Detection of BORIS in a high proportion of breast cancer patients implies potential practical applications of BORIS as a molecular biomarker of breast cancer. This may be important for diagnosis of the condition and for the therapeutic use of BORIS. The ability of BORIS to activate promoters of the RP and ER genes points towards possible involvement of BORIS in the establishment, progression and maintenance of breast tumours.

Igor Chernukhin - One of the best experts on this subject based on the ideXlab platform.

  • generation of poly adp ribosyl ation deficient mutants of the Transcription Factor CTCF
    Methods of Molecular Biology, 2011
    Co-Authors: Dawn Farrar, Igor Chernukhin, Elena Klenova
    Abstract:

    Generation of the mutated versions of proteins deficient for poly(ADP-ribosyl)ation (PARylation) is a major challenge because there is no clearly defined consensus site for PARylation. In this chapter, we describe possible strategies to produce such mutants, demonstrated by the example of CTCF, a Transcription Factor. To achieve this in our study, the protein domain modified by PARylation was mapped and the amino acids, which can be potentially PARylated, selected. Mutations of such individual amino acids as either single or combinatorial mutations were introduced by site-directed mutagenesis, using mutagenic primers and the wild-type sequences as a template. Mutants were validated by DNA sequencing and assessed for the presence of the PARylation mark. The latter was achieved by ectopic expression of mutated proteins in cells, followed by immunoprecipitation with the polyclonal anti-PAR antibody and Western analysis with a protein-specific antibody. The PARylation-deficient CTCF mutant was identified and compared with the wild-type protein. Based on several general characteristics (nuclear distribution/localisation, stability and levels of expression in the cell), the PARylation-deficient mutant was comparable with the wild-type CTCF.

  • Regulation of the apoptotic genes in breast cancer cells by the Transcription Factor CTCF
    Breast Cancer Research, 2010
    Co-Authors: Claudia Fabiola Méndez-catalá, Elena M Pugacheva, Igor Chernukhin, Dawn Farrar, Alexander A. Vostrov, Yoko Ito, F Docquier, G-x Kita, A Murrell, V Lobanankov
    Abstract:

    CTCF is a highly conserved and ubiquitous Transcription Factor with versatile functions. We previously demonstrated that elevated protein levels of CTCF in breast cancer cells were associated with the specific anti-apoptotic function of CTCF. We used proteomics and microarray approaches to identify regulatory targets of CTCF specific for breast cancer cells. Among the CTCF identified targets were proteins involved in the control of apoptosis. A proapoptotic protein, Bax, negatively regulated by CTCF, was chosen for further investigation. Repression of the human Bax gene at the Transcriptional level by CTCF in breast cancer cells was confirmed by real-time PCR. Two CTCF binding sites within the Bax promoter were identified by electrophoretic mobility shift assay and footprinting. In reporter assays, the Bax-luciferase reporter construct, containing CTCF-binding sites, was negatively regulated by CTCF. In vivo, CTCF occupied its binding sites in breast cancer cells and tissues, as confirmed by chromatin immunoprecipitation assay. Our findings suggest a possible mechanism of the specific CTCF anti-apoptotic function in breast cancer cells whereby CTCF is bound to the Bax promoter, resulting in repression of Bax and inhibition of apoptosis; depletion of CTCF leads to activation of Bax and apoptotic death. CTCF binding sites in the Bax promoter are unmethylated in all cells and tissues inspected. Therefore, specific CTCF interaction with the Bax promoter in breast cancer cells, and the functional outcome, may depend on a combination of epigenetic Factors characteristic for these cells. Interestingly, CTCF appears to be a negative regulator of other proapoptotic genes (for example, Fas, Apaf-1, TP531NP1). Conversely, stimulating effects of CTCF on the anti-apoptotic genes (Bcl-2, Bag-3) have been observed. Taken together, these findings suggest that specific mechanisms have evolved in breast cancer cells to protect them from apoptosis; regulation of apoptotic genes by CTCF appears to be one of the resistance strategies.

  • mutational analysis of the poly adp ribosyl ation sites of the Transcription Factor CTCF provides an insight into the mechanism of its regulation by poly adp ribosyl ation
    Molecular and Cellular Biology, 2010
    Co-Authors: Dawn Farrar, Igor Chernukhin, Yoko Ito, Sushma Rai, Maja Jagodic, Samer Yammine, Rolf Ohlsson, Adele Murrell, Elena Klenova
    Abstract:

    Poly(ADP-ribosyl)ation of the conserved multifunctional Transcription Factor CTCF was previously identified as important to maintain CTCF insulator and chromatin barrier functions. However, the molecular mechanism of this regulation and also the necessity of this modification for other CTCF functions remain unknown. In this study, we identified potential sites of poly(ADP-ribosyl)ation within the N-terminal domain of CTCF and generated a mutant deficient in poly(ADP-ribosyl)ation. Using this CTCF mutant, we demonstrated the requirement of poly(ADP-ribosyl)ation for optimal CTCF function in Transcriptional activation of the p19ARF promoter and inhibition of cell proliferation. By using a newly generated isogenic insulator reporter cell line, the CTCF insulator function at the mouse Igf2-H19 imprinting control region (ICR) was found to be compromised by the CTCF mutation. The association and simultaneous presence of PARP-1 and CTCF at the ICR, confirmed by single and serial chromatin immunoprecipitation assays, were found to be independent of CTCF poly(ADP-ribosyl)ation. These results suggest a model of CTCF regulation by poly(ADP-ribosyl)ation whereby CTCF and PARP-1 form functional complexes at sites along the DNA, producing a dynamic reversible modification of CTCF. By using bioinformatics tools, numerous sites of CTCF and PARP-1 colocalization were demonstrated, suggesting that such regulation of CTCF may take place at the genome level.

  • decreased poly adp ribosyl ation of CTCF a Transcription Factor is associated with breast cancer phenotype and cell proliferation
    Clinical Cancer Research, 2009
    Co-Authors: Georgiaxanthi Kita, Igor Chernukhin, Dawn Farrar, Parmjit S Jat, Michael J Ohare, Svetlana Gretton, Adhip Mandal, Louise Caroline Alldridge, Elena Klenova
    Abstract:

    Purpose: There is compelling evidence of a relationship between poly(ADP-ribosyl)ation and tumorigenesis; however, much less is known about the role of specific targets of poly(ADP-ribosyl)ation in tumor development. Two forms of the multifunctional Transcription Factor, CTCF, were previously identified: a 130-kDa protein (CTCF-130), characteristic for cell lines, and a 180-kDa protein (CTCF-180), modified by poly(ADP-ribosyl)ation. This study was aimed to investigate differential poly(ADP-ribosyl)ation of CTCF in normal and tumor breast tissues. Experimental Design: Western blot analysis, mass spectrometry, and immunohistochemical and immunofluorescent stainings were used to characterize CTCF-130 and CTCF-180 in breast cell lines, primary cultures, and normal and tumor breast tissues. The immunoreactivity score was used for CTCF-130 quantification in tissues. Results: We discovered that only CTCF-180 is detected in the normal breast tissues, whereas both CTCF-130 and CTCF-180 are present in breast tumors. Using an antibody specific for CTCF-130, we observed that 87.7% of breast tumors were positive for CTCF-130. A negative correlation existed between the levels of CTCF-130, tumor stage, and tumor size. Significantly, a transition from CTCF-180 to CTCF-130 was discovered in primary cultures generated from normal breast tissues, indicating a link between CTCF-130 and proliferation. Conversely, the appearance of CTCF-180 was observed following growth arrest in breast cell lines. Conclusions: Collectively, our data suggest that the loss of CTCF poly(ADP-ribosyl)ation is associated with cell proliferation and breast tumor development. We propose the use of CTCF-130 as a marker for tumor breast cells and lower levels of CTCF-130 as an indicator of unfavorable prognosis. (Clin Cancer Res 2009;15(18):5762–71)

  • boris a paralogue of the Transcription Factor CTCF is aberrantly expressed in breast tumours
    British Journal of Cancer, 2008
    Co-Authors: Igor Chernukhin, F Docquier, Vivien Darcy, N Pore, Ziedulla Abdullaev, Georgiaxanthi Kita, Sauharda Rai, Melissa C Smart, Dawn Farrar
    Abstract:

    BORIS (for brother of the regulator of imprinted sites), a paralogue of the Transcription Factor, CTCF, is a novel member of the cancer-testis antigen family. The aims of the present study were as follows: (1) to investigate BORIS expression in breast cells and tumours using immunohistochemical staining, western and real-time RT–PCR analyses and (2) assess potential correlation between BORIS levels in tumours with clinical/pathological parameters. BORIS was detected in all 18 inspected breast cell lines, but not in a primary normal breast cell culture. In 70.7% (41 of 58 cases) BORIS was observed in breast tumours. High levels of BORIS correlated with high levels of progesterone receptor (PR) and oestrogen receptor (ER). The link between BORIS and PR/ER was further confirmed by the ability of BORIS to activate the promoters of the PR and ER genes in the reporter assays. Detection of BORIS in a high proportion of breast cancer patients implies potential practical applications of BORIS as a molecular biomarker of breast cancer. This may be important for diagnosis of the condition and for the therapeutic use of BORIS. The ability of BORIS to activate promoters of the RP and ER genes points towards possible involvement of BORIS in the establishment, progression and maintenance of breast tumours.

Gary Felsenfeld - One of the best experts on this subject based on the ideXlab platform.

  • sodium valproate rescues expression of trank1 in ipsc derived neural cells that carry a genetic variant associated with serious mental illness
    Molecular Psychiatry, 2019
    Co-Authors: Xueying Jiang, Sevilla D Deterawadleigh, Nirmala Akula, Barbara S Mallon, Liping Hou, Tiaojiang Xiao, Gary Felsenfeld, Francis J Mcmahon
    Abstract:

    Biological characterization of genetic variants identified in genome-wide association studies (GWAS) remains a substantial challenge. Here we used human-induced pluripotent stem cells (iPSC) and their neural derivatives to characterize common variants on chromosome 3p22 that have been associated by GWAS with major mental illnesses. IPSC-derived neural progenitor cells carrying the risk allele of the single nucleotide polymorphism (SNP), rs9834970, displayed lower baseline TRANK1 expression that was rescued by chronic treatment with therapeutic dosages of valproic acid (VPA). VPA had the greatest effects on TRANK1 expression in iPSC, NPC, and astrocytes. Although rs9834970 has no known function, we demonstrated that a nearby SNP, rs906482, strongly affects binding by the Transcription Factor, CTCF, and that the high-affinity allele usually occurs on haplotypes carrying the rs9834970 risk allele. Decreased expression of TRANK1 perturbed expression of many genes involved in neural development and differentiation. These findings have important implications for the pathophysiology of major mental illnesses and the development of novel therapeutics.

  • sodium valproate rescues expression of trank1 in ipsc derived neural cells that carry a genetic variant associated with serious mental illness
    bioRxiv, 2017
    Co-Authors: Xueying Jiang, Sevilla D Deterawadleigh, Nirmala Akula, Barbara S Mallon, Liping Hou, Tiaojiang Xiao, Gary Felsenfeld, Francis J Mcmahon
    Abstract:

    Biological characterization of genetic variants identified in genome-wide association studies (GWAS) remains a substantial challenge. Here we used human induced pluripotent stem cells (hiPSC) and their neural derivatives to characterize common variants on chromosome 3p22 that have been associated by GWAS with major mental illnesses. HiPSC-derived neural progenitor cells carrying the risk allele of the single nucleotide polymorphism (SNP), rs9834970, displayed lower baseline TRANK1 expression that was rescued by chronic treatment with therapeutic dosages of valproic acid (VPA). Although rs9834970 has no known function, we demonstrated that a nearby SNP, rs90832, strongly affects binding by the Transcription Factor, CTCF, and that the high-affinity allele usually occurs on haplotypes carrying the rs9834970 risk allele. Decreased expression of TRANK1 perturbed expression of many genes involved in neural development and differentiation. These findings have important implications for the pathophysiology of major mental illnesses and the development of novel therapeutics.

  • sodium valproate rescues expression of trank1 in ipsc derived neural cells that carry a genetic variant associated with serious mental illness
    bioRxiv, 2017
    Co-Authors: Xueying Jiang, Sevilla D Deterawadleigh, Nirmala Akula, Barbara S Mallon, Liping Hou, Tiaojiang Xiao, Gary Felsenfeld, Francis J Mcmahon
    Abstract:

    SUMMARY Biological characterization of genetic variants identified in genome-wide association studies (GWAS) remains a substantial challenge. Here we used human induced pluripotent stem cells (hiPSC) and their neural derivatives to characterize common variants on chromosome 3p22 that have been associated by GWAS with major mental illnesses. HiPSC-derived neural progenitor cells carrying the risk allele of the single nucleotide polymorphism (SNP), rs9834970, displayed lower baseline TRANK1 expression that was rescued by chronic treatment with therapeutic dosages of valproic acid (VPA). Although rs9834970 has no known function, we demonstrated that a nearby SNP, rs90832, strongly affects binding by the Transcription Factor, CTCF, and that the high-affinity allele usually occurs on haplotypes carrying the rs9834970 risk allele. Decreased expression of TRANK1 perturbed expression of many genes involved in neural development and differentiation. These findings have important implications for the pathophysiology of major mental illnesses and the development of novel therapeutics. Highlights hiPSC-derived neural cells carrying a mental illness risk allele showed lower expression of TRANK1 Valproic acid rescued TRANK1expression in cells carrying the risk allele Risk haplotypes usually carry an allele that increased CTCF binding Reduced expression of TRANK1 perturbed genes involved in neural development and differentiation In Brief Using neural derivatives of human induced pluripotent stem cells, Jiang et al. demonstrate that genetic variants associated with mental illness alter Transcription Factor binding and decrease expression of a nearby gene, an effect which is rescued by valproic acid.

  • conserved CTCF insulator elements flank the mouse and human β globin loci
    Molecular and Cellular Biology, 2002
    Co-Authors: Catherine M Farrell, Adam G West, Gary Felsenfeld
    Abstract:

    A binding site for the Transcription Factor CTCF is responsible for enhancer-blocking activity in a variety of vertebrate insulators, including the insulators at the 5' and 3' chromatin boundaries of the chicken beta-globin locus. To date, no functional domain boundaries have been defined at mammalian beta-globin loci, which are embedded within arrays of functional olFactory receptor genes. In an attempt to define boundary elements that could separate these gene clusters, CTCF-binding sites were searched for at the most distal DNase I-hypersensitive sites (HSs) of the mouse and human beta-globin loci. Conserved CTCF sites were found at 5'HS5 and 3'HS1 of both loci. All of these sites could bind to CTCF in vitro. The sites also functioned as insulators in enhancer-blocking assays at levels correlating with CTCF-binding affinity, although enhancer-blocking activity was weak with the mouse 5'HS5 site. These results show that with respect to enhancer-blocking elements, the architecture of the mouse and human beta-globin loci is similar to that found previously for the chicken beta-globin locus. Unlike the chicken locus, the mouse and human beta-globin loci do not have nearby transitions in chromatin structure but the data suggest that 3'HS1 and 5'HS5 may function as insulators that prevent inappropriate interactions between beta-globin regulatory elements and those of neighboring domains or subdomains, many of which possess strong enhancers.

  • structural and functional conservation at the boundaries of the chicken β globin domain
    The EMBO Journal, 2000
    Co-Authors: Noriko Saitoh, Adam C Bell, Felix Recillastarga, Adam G West, Melanie A Simpson, Michael J Pikaart, Gary Felsenfeld
    Abstract:

    We show that the 3′ boundary of the chicken β-globin locus bears striking structural similarities to the 5′ boundary. In erythroid cells a clear transition in DNase I sensitivity of chromatin at the 3′ end of the locus is observed, the location of this transition is marked by a constitutive DNase I hypersensitive site (HS), and DNA spanning this site has the enhancer-blocking capacity of an insulator. This HS contains a binding site for the Transcription Factor CTCF. As in the case of the 5′ insulator, the CTCF site is both necessary and sufficient for the enhancer-blocking activity of the 3′ boundary. The position of this insulator is consistent with our proposal that it may function to maintain the distinct regulatory programs of the globin genes and their closely appended 3′ neighbor, an odorant receptor gene. We conclude that both boundaries of the chicken β-globin domain are capable of playing functionally similar roles and that the same protein is a necessary component of the molecular mechanism through which these boundaries are defined.

Francis J Mcmahon - One of the best experts on this subject based on the ideXlab platform.

  • sodium valproate rescues expression of trank1 in ipsc derived neural cells that carry a genetic variant associated with serious mental illness
    Molecular Psychiatry, 2019
    Co-Authors: Xueying Jiang, Sevilla D Deterawadleigh, Nirmala Akula, Barbara S Mallon, Liping Hou, Tiaojiang Xiao, Gary Felsenfeld, Francis J Mcmahon
    Abstract:

    Biological characterization of genetic variants identified in genome-wide association studies (GWAS) remains a substantial challenge. Here we used human-induced pluripotent stem cells (iPSC) and their neural derivatives to characterize common variants on chromosome 3p22 that have been associated by GWAS with major mental illnesses. IPSC-derived neural progenitor cells carrying the risk allele of the single nucleotide polymorphism (SNP), rs9834970, displayed lower baseline TRANK1 expression that was rescued by chronic treatment with therapeutic dosages of valproic acid (VPA). VPA had the greatest effects on TRANK1 expression in iPSC, NPC, and astrocytes. Although rs9834970 has no known function, we demonstrated that a nearby SNP, rs906482, strongly affects binding by the Transcription Factor, CTCF, and that the high-affinity allele usually occurs on haplotypes carrying the rs9834970 risk allele. Decreased expression of TRANK1 perturbed expression of many genes involved in neural development and differentiation. These findings have important implications for the pathophysiology of major mental illnesses and the development of novel therapeutics.

  • sodium valproate rescues expression of trank1 in ipsc derived neural cells that carry a genetic variant associated with serious mental illness
    bioRxiv, 2017
    Co-Authors: Xueying Jiang, Sevilla D Deterawadleigh, Nirmala Akula, Barbara S Mallon, Liping Hou, Tiaojiang Xiao, Gary Felsenfeld, Francis J Mcmahon
    Abstract:

    Biological characterization of genetic variants identified in genome-wide association studies (GWAS) remains a substantial challenge. Here we used human induced pluripotent stem cells (hiPSC) and their neural derivatives to characterize common variants on chromosome 3p22 that have been associated by GWAS with major mental illnesses. HiPSC-derived neural progenitor cells carrying the risk allele of the single nucleotide polymorphism (SNP), rs9834970, displayed lower baseline TRANK1 expression that was rescued by chronic treatment with therapeutic dosages of valproic acid (VPA). Although rs9834970 has no known function, we demonstrated that a nearby SNP, rs90832, strongly affects binding by the Transcription Factor, CTCF, and that the high-affinity allele usually occurs on haplotypes carrying the rs9834970 risk allele. Decreased expression of TRANK1 perturbed expression of many genes involved in neural development and differentiation. These findings have important implications for the pathophysiology of major mental illnesses and the development of novel therapeutics.

  • sodium valproate rescues expression of trank1 in ipsc derived neural cells that carry a genetic variant associated with serious mental illness
    bioRxiv, 2017
    Co-Authors: Xueying Jiang, Sevilla D Deterawadleigh, Nirmala Akula, Barbara S Mallon, Liping Hou, Tiaojiang Xiao, Gary Felsenfeld, Francis J Mcmahon
    Abstract:

    SUMMARY Biological characterization of genetic variants identified in genome-wide association studies (GWAS) remains a substantial challenge. Here we used human induced pluripotent stem cells (hiPSC) and their neural derivatives to characterize common variants on chromosome 3p22 that have been associated by GWAS with major mental illnesses. HiPSC-derived neural progenitor cells carrying the risk allele of the single nucleotide polymorphism (SNP), rs9834970, displayed lower baseline TRANK1 expression that was rescued by chronic treatment with therapeutic dosages of valproic acid (VPA). Although rs9834970 has no known function, we demonstrated that a nearby SNP, rs90832, strongly affects binding by the Transcription Factor, CTCF, and that the high-affinity allele usually occurs on haplotypes carrying the rs9834970 risk allele. Decreased expression of TRANK1 perturbed expression of many genes involved in neural development and differentiation. These findings have important implications for the pathophysiology of major mental illnesses and the development of novel therapeutics. Highlights hiPSC-derived neural cells carrying a mental illness risk allele showed lower expression of TRANK1 Valproic acid rescued TRANK1expression in cells carrying the risk allele Risk haplotypes usually carry an allele that increased CTCF binding Reduced expression of TRANK1 perturbed genes involved in neural development and differentiation In Brief Using neural derivatives of human induced pluripotent stem cells, Jiang et al. demonstrate that genetic variants associated with mental illness alter Transcription Factor binding and decrease expression of a nearby gene, an effect which is rescued by valproic acid.