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Marie Ménard, Clélia Costechareyre, Gabriel Ichim, Jonathan Blachier, David Neves, Loraine Jarrosson-Wuilleme, Reinhard Depping, Jan Koster, Pierre Saintigny, Patrick Mehlen, Servane Tauszig-Delamasure
The neurotrophin-3 (NT-3) receptor tropomyosin receptor kinase C (TrkC/NTRK3) has been described as a dependence receptor and, as such, triggers apoptosis in the absence of its ligand NT-3. This proapoptotic activity has been proposed to confer a tumor suppressor activity to this classic tyrosine kinase receptor (RTK). By investigating interacting partners that might facilitate TrkC-induced cell death, we have identified the basic helix-loop-helix (bHLH) transcription factor Hey1 and importin-α3 (karyopherin alpha 4 [KPNA4]) as direct interactors of TrkC intracellular domain, and we show that Hey1 is required for TrkC-induced apoptosis...
May 11, 2018: PLoS Biology
Huai-Chin Chiang, Xiaowen Zhang, Xiayan Zhao, Chi Zhang, Jerry Chen, Paula Garza, Sabrina Smith, Thomas Ludwig, Richard J Baer, Rong Li, Yanfen Hu
Germ-line mutations in breast cancer susceptibility gene, BRCA1, result in familial predisposition to breast and ovarian cancers. The BRCA1 protein has multiple functional domains that interact with a variety of proteins in multiple cellular processes. Understanding the biological consequences of BRCA1 interactions with its binding partners is important for elucidating its tissue-specific tumor suppression function. The Cofactor of BRCA1 (COBRA1) is a BRCA1-binding protein that, as a component of negative elongation factor (NELF), regulates RNA polymerase II pausing during transcription elongation...
February 9, 2018: Scientific Reports
Xiaowen Zhang, Huai-Chin Chiang, Yao Wang, Chi Zhang, Sabrina Smith, Xiayan Zhao, Sreejith J Nair, Joel Michalek, Ismail Jatoi, Meeghan Lautner, Boyce Oliver, Howard Wang, Anna Petit, Teresa Soler, Joan Brunet, Francesca Mateo, Miguel Angel Pujana, Elizabeth Poggi, Krysta Chaldekas, Claudine Isaacs, Beth N Peshkin, Oscar Ochoa, Frederic Chedin, Constantine Theoharis, Lu-Zhe Sun, Tyler J Curiel, Richard Elledge, Victor X Jin, Yanfen Hu, Rong Li
Most BRCA1-associated breast tumours are basal-like yet originate from luminal progenitors. BRCA1 is best known for its functions in double-strand break repair and resolution of DNA replication stress. However, it is unclear whether loss of these ubiquitously important functions fully explains the cell lineage-specific tumorigenesis. In vitro studies implicate BRCA1 in elimination of R-loops, DNA-RNA hybrid structures involved in transcription and genetic instability. Here we show that R-loops accumulate preferentially in breast luminal epithelial cells, not in basal epithelial or stromal cells, of BRCA1 mutation carriers...
June 26, 2017: Nature Communications
Eman El Zeneini, Sarah Kamel, Mahmoud El-Meteini, Asma Amleh
Cofactor of BRCA1 (COBRA1) is one of the four subunits that make up the negative elongation factor (NELF) complex that is involved in the stalling of RNA polymerase II early during transcription elongation. As such, it regulates the expression of a substantial number of genes involved in cell cycle control, cellular metabolism and DNA repair. With no DNA binding domain, its capacity to modulate gene expression occurs via its ability to interact with different transcription factors. In the field of cancer, its role is not yet fully understood...
March 2017: Oncology Reports
Sreejith J Nair, Xiaowen Zhang, Huai-Chin Chiang, Md Jamiul Jahid, Yao Wang, Paula Garza, Craig April, Neeraj Salathia, Tapahsama Banerjee, Fahad S Alenazi, Jianhua Ruan, Jian-Bing Fan, Jeffrey D Parvin, Victor X Jin, Yanfen Hu, Rong Li
The breast cancer susceptibility gene BRCA1 is well known for its function in double-strand break (DSB) DNA repair. While BRCA1 is also implicated in transcriptional regulation, the physiological significance remains unclear. COBRA1 (also known as NELF-B) is a BRCA1-binding protein that regulates RNA polymerase II (RNAPII) pausing and transcription elongation. Here we interrogate functional interaction between BRCA1 and COBRA1 during mouse mammary gland development. Tissue-specific deletion of Cobra1 reduces mammary epithelial compartments and blocks ductal morphogenesis, alveologenesis and lactogenesis, demonstrating a pivotal role of COBRA1 in adult tissue development...
March 4, 2016: Nature Communications
Gabriel Ichim, Anne-Laure Genevois, Marie Ménard, Li-Ying Yu, Juliana M Coelho-Aguiar, Fabien Llambi, Loraine Jarrosson-Wuilleme, Jonathan Lefebvre, David Tulasne, Elisabeth Dupin, Nicole Le Douarin, Urmas Arumäe, Servane Tauszig-Delamasure, Patrick Mehlen
The neurotrophin receptor TrkC was recently identified as a dependence receptor, and, as such, it triggers apoptosis in the absence of its ligand, NT-3. The molecular mechanism for apoptotic engagement involves the double cleavage of the receptor's intracellular domain, leading to the formation of a proapoptotic "killer" fragment (TrkC KF). Here, we show that TrkC KF interacts with Cobra1, a putative cofactor of BRCA1, and that Cobra1 is required for TrkC-induced apoptosis. We also show that, in the developing chick neural tube, NT-3 silencing is associated with neuroepithelial cell death that is rescued by Cobra1 silencing...
September 12, 2013: Molecular Cell
Manisha Mishra, Noriko Inoue, Klaus Heese
The novel protein p33MONOX (p33Monooxygenase) was over-expressed in neuroblastoma cells demonstrating its inhibitory effect on the phosphorylation of the App (amyloid precursor protein) and Bcl2 (B-cell lymphoma 2) proteins but mediating higher activation of Mapk1/3 (mitogen-activated protein kinase 1/3). We employed a variety of cell biology techniques to show the localization of p33MONOX to the cytoplasm of pyramidal neurons in the mouse brain hippocampus. We also carried out a yeast-two-hybrid screening plus co-immunoprecipitation and bio-informatics to determine COBRA1 (cofactor of BRCA1 (breast cancer type 1)), NOL12 (nucleolar protein 12), and PRNP (prion protein) as p33MONOX-interacting proteins...
April 2011: Molecular and Cellular Biochemistry
Asma Amleh, Sreejith J Nair, Jianlong Sun, Ann Sutherland, Paul Hasty, Rong Li
BACKGROUND: Negative elongation factor (NELF) is a four-subunit protein complex conserved from Drosophila to humans. In vitro biochemical and tissue culture-based studies have demonstrated an important role of NELF in controlling RNA polymerase II (Pol II) pausing in transcription. However, the physiological significance of NELF function is not clear due to the lack of any genetic systems for studying NELF. PRINCIPAL FINDINGS: Here we show that disruption of the mouse B subunit of NELF (NELF-B), also known as cofactor of BRCA1 (Cobra1), causes inner cell mass (ICM) deficiency and embryonic lethality at the time of implantation...
2009: PloS One
Sarah E Aiyar, HyungJun Cho, Jae Lee, Rong Li
Cofactor of BRCA1 (COBRA1) was first identified as a protein that binds to the breast cancer susceptibility gene product BRCA1. COBRA1 modulates estrogen-dependent and independent transcription and suppresses the growth of breast cancer cells. Its expression is significantly reduced in metastatic and recurrent breast cancer, pointing to a tumor suppressor function in breast cancer development. In light of these initial implications of COBRA1 in human breast cancer, the current investigation sought to obtain more direct functional evidence that links COBRA1 with BRCA1 in transcriptional regulation in breast cancer cells...
November 26, 2007: International Journal of Biological Sciences
Jianlong Sun, Gareth Watkins, Ashley L Blair, Christopher Moskaluk, Sagar Ghosh, Wen G Jiang, Rong Li
Cofactor of BRCA1 (COBRA1) is an integral component of the human negative elongation factor (NELF), a four-subunit protein complex that inhibits transcription elongation. Previous in vivo work indicates that COBRA1 and the rest of the NELF complex repress estrogen-dependent transcription and the growth of breast cancer cells. In light of the COBRA1 function in breast cancer-related gene expression, we sought to examine regulation of COBRA1 expression in both established breast cancer cell lines and breast carcinoma tissues...
April 15, 2008: Journal of Cellular Biochemistry
Jianlong Sun, Ashley L Blair, Sarah E Aiyar, Rong Li
Transcriptional activity of nuclear receptors (NRs) is influenced by a large number of coregulators that exert their actions predominantly at the transcription initiation step. Unlike most well-characterized NR coregulators, cofactor of BRCA1 (COBRA1), a subunit of the negative elongation factor (NELF), binds to estrogen receptor alpha (ERalpha) and modulates estrogen-dependent transcription by impeding the movement of RNA polymerase II (RNAPII) during the transcription elongation stage. Here we show that, in addition to ERalpha, COBRA1 also displays various degrees of affinity for several other NRs...
November 2007: Journal of Steroid Biochemistry and Molecular Biology
Francisco Castaneda, Sigrid Rosin-Steiner, Klaus Jung
We previously found that ethanol at millimolar level (1 mM) activates the expression of transcription factors with subsequent regulation of apoptotic genes in human hepatocellular carcinoma (HCC) HepG2 cells. However, the role of ethanol on the expression of genes implicated in transcriptional and translational processes remains unknown. Therefore, the aim of this study was to characterize the effect of low concentration of ethanol on gene expression profiling in HepG2 cells using cDNA microarrays with especial interest in genes with transcriptional and translational function...
2007: International Journal of Medical Sciences
S E Aiyar, A L Blair, D A Hopkinson, S Bekiranov, R Li
Eucaryotic genes that are coordinately expressed tend to be clustered. Furthermore, gene clusters across chromosomal regions are often upregulated in various tumors. However, relatively little is known about how gene clusters are coordinately expressed in physiological or pathological conditions. Cofactor of BRCA1 (COBRA1), a subunit of the human negative elongation factor, has been shown to repress estrogen-stimulated transcription of trefoil factor 1 (TFF1 or pS2) by stalling RNA polymerase II. Here, we carried out a genome-wide study to identify additional physiological target genes of COBRA1 in breast cancer cells...
April 19, 2007: Oncogene
Patricia A McChesney, Sarah E Aiyar, Ok-Jae Lee, Alexander Zaika, Christopher Moskaluk, Rong Li, Wa'el El-Rifai
Cofactor of BRCA1 (COBRA1) is a newly characterized member of the negative elongation factor (NELF) complex. In this work, we show that COBRA1 is overexpressed in the majority of primary upper gastrointestinal adenocarcinomas (UGC), and its overexpression correlates with down-regulation of TFF1. We have detected overexpression of COBRA1 mRNA using quantitative real-time reverse transcription-PCR in 28 (79%) primary UGCs. Immunohistochemical analysis of UGC tissue arrays that contained 70 tumor samples showed moderate-strong staining for COBRA1 in 60 (84%) tumors...
February 1, 2006: Cancer Research
Gudrun Pohl, Chung-Liang Ho, Robert J Kurman, Robert Bristow, Tian-Li Wang, Ie-Ming Shih
Activation of mitogen-activated protein kinase (MAPK) occurs in response to various growth stimulating signals and as a result of activating mutations of the upstream regulators, KRAS and BRAF, which can be found in many types of human cancer. To investigate the roles of MAPK activation in tumors harboring KRAS or BRAF mutations, we inactivated MAPK in ovarian tumor cells using CI-1040, a compound that selectively inhibits MAPK kinase, an upstream regulator of MAPK and thus prevents MAPK activation. Profound growth inhibition and apoptosis were observed in CI-1040-treated tumor cells with mutations in either KRAS or BRAF in comparison with the ovarian cancer cells containing wild-type sequences...
March 1, 2005: Cancer Research
Hongjun Zhong, Jianhua Zhu, Hao Zhang, Lihua Ding, Yan Sun, Cuifen Huang, Qinong Ye
Mutations in the breast cancer susceptibility gene (BRCA1) account for a significant proportion of hereditary breast and ovarian cancers. Cofactor of BRCA1 (COBRA1) was isolated as a BRCA1-interacting protein and exhibited a similar chromatin reorganizing activity to that of BRCA1. However, the biological role of COBRA1 remains largely unexplored. Here, we report that ectopic expression of COBRA1 inhibited activator protein 1 (AP-1) transcriptional activity in transfected cells in a dose-dependent manner, whereas reduction of endogenous COBRA1 with a small interfering RNA significantly enhanced AP-1-mediated transcriptional activation...
December 10, 2004: Biochemical and Biophysical Research Communications
Sarah E Aiyar, Jian-long Sun, Ashley L Blair, Christopher A Moskaluk, Yun-zhe Lu, Qi-Nong Ye, Yuki Yamaguchi, Amitava Mukherjee, Da-ming Ren, Hiroshi Handa, Rong Li
Estrogen receptor alpha (ERalpha) signaling is paramount for normal mammary gland development and function and the repression of breast cancer. ERalpha function in gene regulation is mediated by a number of coactivators and corepressors, most of which are known to modify chromatin structure and/or influence the assembly of the regulatory complexes at the level of transcription initiation. Here we describe a novel mechanism of attenuating the ERalpha activity. We show that cofactor of BRCA1 (COBRA1), an integral subunit of the human negative elongation factor (NELF), directly binds to ERalpha and represses ERalpha-mediated transcription...
September 1, 2004: Genes & Development
Jianhua Zhu, Santai Song, Zefei Jiang, Jinghua Yan, Qiujun Lu, Cuifen Huang, Qinong Ye
Mutations in the breast cancer susceptibility gene BRCA1 predispose individuals to breast and ovarian cancers. Cofactor of BRCA1 (COBRA1), a novel protein, was isolated as a BRCA1-interacting protein. However, the role of COBRA1 in breast cancer is poorly understood. In this study, we demonstrate that COBRA1 mRNA was differentially expressed in breast cancer cell lines by semi-quantitative reverse transcription-polymerase chain PCR (RT-PCR). We developed a highly specific rabbit polyclonal anti-COBRA1 antibody using GST-COBRA1 fusion protein...
March 2004: IUBMB Life
Takashi Narita, Yuki Yamaguchi, Keiichi Yano, Seiji Sugimoto, Sittinan Chanarat, Tadashi Wada, Dong-ki Kim, Jun Hasegawa, Masashi Omori, Naoto Inukai, Masaki Endoh, Tomoko Yamada, Hiroshi Handa
The multisubunit transcription elongation factor NELF (for negative elongation factor) acts together with DRB (5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole) sensitivity-inducing factor (DSIF)/human Spt4-Spt5 to cause transcriptional pausing of RNA polymerase II (RNAPII). NELF activity is associated with five polypeptides, A to E. NELF-A has sequence similarity to hepatitis delta antigen (HDAg), the viral protein that binds to and activates RNAPII, whereas NELF-E is an RNA-binding protein whose RNA-binding activity is critical for NELF function...
March 2003: Molecular and Cellular Biology
Q Ye, Y F Hu, H Zhong, A C Nye, A S Belmont, R Li
The breast cancer susceptibility gene BRCA1 encodes a protein that has been implicated in multiple nuclear functions, including transcription and DNA repair. The multifunctional nature of BRCA1 has raised the possibility that the polypeptide may regulate various nuclear processes via a common underlying mechanism such as chromatin remodeling. However, to date, no direct evidence exists in mammalian cells for BRCA1-mediated changes in either local or large-scale chromatin structure. Here we show that targeting BRCA1 to an amplified, lac operator-containing chromosome region in the mammalian genome results in large-scale chromatin decondensation...
December 10, 2001: Journal of Cell Biology
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