Replication-Mediated Disassociation of Replication Protein A-XPA Complex Upon Dna Damage: Implications for RPA Handing Off

RPA (replication protein A), the eukaryotic ssDNA (single-stranded DNA)-binding protein, participates in most cellular processes in response to genotoxic insults, such as NER (nucleotide excision repair), DNA, DSB (double-strand break) repair and activation of cell cycle checkpoint signalling. RPA interacts with XPA (xeroderma pigmentosum A) and functions in early stage of NER. We have shown that in cells the RPA-XPA complex disassociated upon exposure of cells to high dose of UV irradiation. The dissociation required replication stress and was partially attributed to tRPA hyperphosphorylation. Treatment of cells with CPT (camptothecin) and HU (hydroxyurea), which cause DSB DNA damage and replication fork collapse respectively and also leads to the disruption of RPA-XPA complex. Purified RPA and XPA were unable to form complex in vitro in the presence of ssDNA. We propose that the competition-based RPA switch among different DNA metabolic pathways regulates the dissociation of RPA with XPA in cells after DNA damage. The biological significances of RPA-XPA complex disruption in relation with checkpoint activation, DSB repair and RPA hyperphosphorylation are discussed

Asymmetric Effect of Media Tone on IPO Underpricing and Volatility

©, Copyright © Taylor & Francis Group, LLC. Because of asymmetric information between issuing companies and investors, media coverage plays an important role in conveying information to investors during an initial public offering (IPO). The stock price is affected by a large amount of information released to the public through media coverage. Using a comprehensive sample of 1,075 IPOs on China’s stock market from 2009 to 2016, this paper conducts a textual analysis to determine the tone of media coverage and examines the relationship between media tone and IPO underpricing as well as post-IPO volatility. The empirical results show that media coverage during an IPO is significantly negatively associated with IPO underpricing, which confirms our hypothesis that the tone of media coverage reduces the degree of information asymmetry between investors and issuers, regardless of whether the tone is positive or negative. Consistent with prospect theory, investors are more sensitive to media coverage with a negative tone

What causes the IPO underpricing? New evidence from China’s SME market

© 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group. We study 10-year IPO initial returns in China’s small and medium-sized enterprise (SME) board between 2006 and 2016, including 755 IPO samples. At the same time, we test how policy changes of IPO pricing and trading mechanism affect first-day initial returns. Our article adopts the stochastic frontier approach to estimate the fair value of IPOs and decompose the components of deliberate underpricing and mis-valuation factors, then using linear regressions investigate correlation between first-day initial returns and deliberate underpricing or mis-valuation factors. We find it is mis-valuation factors, especially, the irrational behaviour of individual investors that mainly cause the IPO underpricing in China’s SME market rather than deliberate underpricing. Besides, influenced by IPO pricing policies, the characteristic of IPO pricing varies from period to period

Uncertainty and IPO initial returns: Evidence from the Tone Analysis of China\u27s IPO Prospectuses

© 2018 Elsevier B.V. IPO prospectuses play an irreplaceable role in the IPO process. The tone of IPO prospectuses, in terms of its definitiveness in characterizing the prospects and assessing the risks of different firms, could affect investors\u27 capability to estimate the firms that are about to go public. In a large sample of 1320 IPO prospectuses of China\u27s A-share market from 2007 to 2016, we find that uncertain or negative tone of IPO prospectuses is significantly associated with IPO initial returns and the post-IPO return volatility. Besides, empirical evidence shows that the negative or uncertain tone in the prospectuses lowers the stocks\u27 long-term returns. Our findings contribute to the literature by investigating the impact of connotative information transmission on stock returns during IPO process, based on which investors can do a better job in risk management

Replication-mediated disassociation of replication protein A–XPA complex upon DNA damage: implications for RPA handing off

RPA (replication protein A), the eukaryotic ssDNA (single-stranded DNA)-binding protein, participates in most cellular processes in response to genotoxic insults, such as NER (nucleotide excision repair), DNA, DSB (double-strand break) repair and activation of cell cycle checkpoint signalling. RPA interacts with XPA (xeroderma pigmentosum A) and functions in early stage of NER. We have shown that in cells the RPA–XPA complex disassociated upon exposure of cells to high dose of UV irradiation. The dissociation required replication stress and was partially attributed to tRPA hyperphosphorylation. Treatment of cells with CPT (camptothecin) and HU (hydroxyurea), which cause DSB DNA damage and replication fork collapse respectively and also leads to the disruption of RPA–XPA complex. Purified RPA and XPA were unable to form complex in vitro in the presence of ssDNA. We propose that the competition-based RPA switch among different DNA metabolic pathways regulates the dissociation of RPA with XPA in cells after DNA damage. The biological significances of RPA–XPA complex disruption in relation with checkpoint activation, DSB repair and RPA hyperphosphorylation are discussed

Synergistic action of the transcription factors Krüppel homolog 1 and Hairy in juvenile hormone/Methoprene-tolerant-mediated gene-repression in the mosquito Aedes aegypti.

Arthropod-specific juvenile hormones control numerous essential functions in development and reproduction. In the dengue-fever mosquito Aedes aegypti, in addition to its role in immature stages, juvenile hormone III (JH) governs post-eclosion (PE) development in adult females, a phase required for competence acquisition for blood feeding and subsequent egg maturation. During PE, JH through its receptor Methoprene-tolerant (Met) regulate the expression of many genes, causing either activation or repression. Met-mediated gene repression is indirect, requiring involvement of intermediate repressors. Hairy, which functions downstream of Met in the JH gene-repression hierarchy, is one such factor. Krüppel-homolog 1, a zinc-finger transcriptional factor, is directly regulated by Met and has been implicated in both activation and repression of JH-regulated genes. However, the interaction between Hairy and Kr-h1 in the JH-repression hierarchy is not well understood. Our RNAseq-based transcriptomic analysis of the Kr-h1-depleted mosquito fat body revealed that 92% of Kr-h1 repressed genes are also repressed by Met, supporting the existence of a hierarchy between Met and Kr-h1 as previously demonstrated in various insects. Notably, 130 genes are co-repressed by both Kr-h1 and Hairy, indicating regulatory complexity of the JH-mediated PE gene repression. A mosquito Kr-h1 binding site in genes co-regulated by this factor and Hairy was identified computationally. Moreover, this was validated using electrophoretic mobility shift assays. A complete phenocopy of the effect of Met RNAi depletion on target genes could only be observed after Kr-h1 and Hairy double RNAi knockdown, suggesting a synergistic action between these two factors in target gene repression. This was confirmed using a cell-culture-based luciferase reporter assay. Taken together, our results indicate that Hairy and Kr-h1 not only function as intermediate downstream factors, but also act together in a synergistic fashion in the JH/Met gene repression hierarchy

Secrecy outage performance of transmit antenna selection for MIMO underlay cognitive radio systems over Nakagami-m channels

This paper considers a multiple-input-multiple-output (MIMO) cognitive wiretap system over Nakagami-m channels with generalized selection combining (GSC), where confidential messages transmitted from a multiple-antenna transmitter to a multiple-antenna legitimate receiver are overheard by a multiple-antenna eavesdropper. Depending on whether the source node has the global channel state information (CSI) of both the main and wiretap channels, we investigate the secrecy outage performances of optimal antenna selection (OAS) and suboptimal antenna selection (SAS) schemes for MIMO underlay cognitive radio systems over Nakagami-m channels, and we compare them with the space-time transmission (STT) scheme. The closed-form expressions for the exact and asymptotic secrecy outage probability (SOP) for various schemes are derived. Simulations are conducted to validate the accuracy of our derived analytical results