141 research outputs found

    Coordinated Regulation of ATF2 by miR-26b in Ξ³-Irradiated Lung Cancer Cells

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    MicroRNA regulates cellular responses to ionizing radiation (IR) through translational control of target genes. We analyzed time-series changes in microRNA expression following Ξ³-irradiation in H1299 lung cancer cells using microarray analysis. Significantly changed IR-responsive microRNAs were selected based on analysis of variance analysis, and predicted target mRNAs were enriched in mitogen-activated protein kinase (MAPK) signaling. Concurrent analysis of time-series mRNA and microRNA profiles uncovered that expression of miR-26b was down regulated, and its target activating transcription factor 2 (ATF2) mRNA was up regulated in Ξ³-irradiated H1299 cells. IR in miR-26b overexpressed H1299 cells could not induce expression of ATF2. When c-Jun N-terminal kinase activity was inhibited using SP600125, expression of miR-26b was induced following Ξ³-irradiation in H1299 cells. From these results, we concluded that IR-induced up-regulation of ATF2 was coordinately enhanced by suppression of miR-26b in lung cancer cells, which may enhance the effect of IR in the MAPK signaling pathway

    Ionizing Radiation-Induced Oxidative Stress Alters miRNA Expression

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    ). treatment, and 45 after etoposide treatment. Substantial overlap between the miRNA expression changes between agents was observed suggesting a signature miRNA response to cell stress. Changes in the expression of selected miRNA species varied in response to radiation dose and time. Finally, production of reactive oxygen species (ROS) increased with increasing doses of radiation and pre-treatment with the thiol antioxidant cysteine decreased both ROS production and the miRNA response to radiation., and etoposide. Additionally, pre-treatment with cysteine prevented radiation-induced alterations in miRNA expression which suggests that miRNAs are responsive to oxidative stress. Taken together, these results imply that miRNAs play a role in cellular defense against exogenous stress and are involved in the generalized cellular response to genotoxic oxidative stress

    'Embrace the masculine; attenuate the feminine': gender, identity work and entrepreneurial legitimation in the nascent context

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    This paper critically analyses how gender bias impacts upon women’s efforts to legitimate nascent ventures. Given the importance of founder identity as a proxy for entrepreneurial legitimacy at nascency, we explore the identity work women undertake when seeking to claim legitimacy for their emerging ventures in a prevailing context of masculinity. In so doing, we challenge taken for granted norms pertaining to legitimacy and question the basis upon which that knowledge is claimed. In effect, debates regarding entrepreneurial legitimacy are presented as gender neutral yet, entrepreneurship is a gender biased activity. Thus, we argue it is essential to recognise how gendered assumptions impinge upon the quest for legitimacy. To illustrate our analysis, we use retrospective and real time empirical evidence evaluating legitimating strategies as they unfold, our findings reveal tensions between feminine identities such as β€˜wife’ and β€˜mother’ and those of the prototypical entrepreneur. This dissonance prompted women to undertake specific forms of identity work to bridge the gap between femininity, legitimacy and entrepreneurship. We conclude by arguing that the pursuit of entrepreneurial legitimacy during nascency is a gendered process which disadvantages women and has the potential to negatively impact upon the future prospects of their fledging ventures

    The atm-1 gene is required for genome stability in Caenorhabditis elegans

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    The Ataxia-telangiectasia-mutated (ATM) gene in humans was identified as the basis of a rare autosomal disorder leading to cancer susceptibility and is now well known as an important signal transducer in response to DNA damage. An approach to understanding the conserved functions of this gene is provided by the model system, Caenorhabditis elegans. In this paper we describe the structure and loss of function phenotype of the ortholog atm-1. Using bioinformatic and molecular analysis we show that the atm-1 gene was previously misannotated. We find that the transcript is in fact a product of three gene predictions, Y48G1BL.2 (atm-1), K10E9.1, and F56C11.4 that together make up the complete coding region of ATM-1. We also characterize animals that are mutant for two available knockout alleles, gk186 and tm5027. As expected, atm-1 mutant animals are sensitive to ionizing radiation. In addition, however, atm-1 mutants also display phenotypes associated with genomic instability, including low brood size, reduced viability and sterility. We document several chromosomal fusions arising from atm-1 mutant animals. This is the first time a mutator phenotype has been described for atm-1 in C. elegans. Finally we demonstrate the use of a balancer system to screen for and capture atm-1-derived mutational events. Our study establishes C. elegans as a model for the study of ATM as a mutator potentially leading to the development of screens to identify therapeutic targets in humans

    Targeting DNA-PKcs and ATM with miR-101 Sensitizes Tumors to Radiation

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    Radiotherapy kills tumor-cells by inducing DNA double strand breaks (DSBs). However, the efficient repair of tumors frequently prevents successful treatment. Therefore, identifying new practical sensitizers is an essential step towards successful radiotherapy. In this study, we tested the new hypothesis: identifying the miRNAs to target DNA DSB repair genes could be a new way for sensitizing tumors to ionizing radiation.HERE, WE CHOSE TWO GENES: DNA-PKcs (an essential factor for non-homologous end-joining repair) and ATM (an important checkpoint regulator for promoting homologous recombination repair) as the targets to search their regulating miRNAs. By combining the database search and the bench work, we picked out miR-101. We identified that miR-101 could efficiently target DNA-PKcs and ATM via binding to the 3'- UTR of DNA-PKcs or ATM mRNA. Up-regulating miR-101 efficiently reduced the protein levels of DNA-PKcs and ATM in these tumor cells and most importantly, sensitized the tumor cells to radiation in vitro and in vivo.These data demonstrate for the first time that miRNAs could be used to target DNA repair genes and thus sensitize tumors to radiation. These results provide a new way for improving tumor radiotherapy
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