Human papillomavirus E2 regulates SRSF3 (SRp20) to promote capsid protein expression in infected differentiated keratinocytes

The human papillomavirus (HPV) life cycle is tightly linked to differentiation of the infected epithelial cell suggesting a sophisticated interplay between host cell metabolism and virus replication. Previously we demonstrated in differentiated keratinocytes in vitro and in vivo that HPV16 infection caused increased levels of the cellular SR splicing factors (SRSFs) SRSF1 (ASF/SF2), SRSF2 (SC35) and SRSF3 (SRp20). Moreover, the viral E2 transcription and replication factor that is expressed at high levels in differentiating keratinocytes could bind and control activity of the SRSF1 gene promoter. Here we reveal that E2 proteins of HPV16 and HPV31 control expression of SRSFs 1, 2 and 3 in a differentiation-dependent manner. E2 has the greatest trans-activation effect on expression of SRSF3. siRNA depletion experiments in two different models of the HPV16 life cycle (W12E and NIKS16) and one model of the HPV31 life cycle (CIN612-9E) revealed that only SRSF3 contributed significantly to regulation of late events in the virus life cycle. Increased levels of SRSF3 are required for L1 mRNA and capsid protein expression. Capsid protein expression was regulated specifically by SRSF3 and appeared independent of other SRSFs. Taken together these data suggest a significant role of the HPV E2 protein in regulating late events in the HPV life cycle through transcriptional regulation of SRSF3 expression. IMPORTANCE Human papillomavirus replication is accomplished in concert with differentiation of the infected epithelium. Virus capsid protein expression is confined to the upper epithelial layers so as to avoid immune detection. In this study we demonstrate that the viral E2 transcription factor activates the promoter of the cellular SRSF3 RNA processing factor. SRSF3 is required for expression of the E4̂L1 mRNA and so controls expression of the HPV L1 capsid protein. Thus we reveal a new dimension of virus-host interaction crucial for production of infectious virus. SRSF proteins are known drug targets. Therefore, this study provides an excellent basis for developing strategies to regulate capsid protein production in the infected epithelium and production of new virions

Analysis of the early immune response to infection by infectious bursal disease virus in chickens differing in their resistance to the disease

Chicken whole-genome gene expression arrays were used to analyze the host response to infection by infectious bursal disease virus (IBDV). Spleen and bursal tissue were examined from control and infected birds at 2, 3, and 4 days postinfection from two lines that differ in their resistance to IBDV infection. The host response was evaluated over this period, and differences between susceptible and resistant chicken lines were examined. Antiviral genes, including IFNA, IFNG, MX1, IFITM1, IFITM3, and IFITM5, were upregulated in response to infection. Evaluation of this gene expression data allowed us to predict several genes as candidates for involvement in resistance to IBDV. © 2015, American Society for Microbiology

The Ideology of Rebellion: Philippe de Marnix, Sieur de Sainte Aldegonde, and the Dutch Revolt

By situating the language of Philippe de Marnix in its cultural context, I identify his ideology or rebellion which for him justified the Dutch Revolt. Marnix\u27s problem was to accommodate Calvinist freedom of conscience in a society which traditionally linked heresy and sedition. According to the accepted theory of correspondences, God created the universe, and thus earthly order corresponded to heavenly order. To disturb the peace and order of society was to do the work of the Devil and threaten total destruction--the apocalypse--strict conformity to secular and sacred authority, which were seen as united to preserve order was required. This dissertation reveals a shift in the concept of order. Marnix justified the Calvinist rebellion against Catholicism on the grounds Catholicism did not correspond to God\u27s spiritual order. He then justified the Dutch Revolt against Philip II by claiming that Philip caused a disturbance of earthly order (peace and prosperity) by attempting to suppress Calvinism. Thus, Philip was a tyrant to be removed legitimately by the States of Holland and Zeeland. Marnix separated the link between sacred and secular order. He reserved religious conscience to private order, which was not subject to public interference so long as temporal disorder was not created. This separation of sacred from secular order was institutionalized in the Dutch Republic, which allowed individual freedom of conscience, whereby being a good subject or citizen did not require conforming to a state or provincial church. Traditional historiography of a Calvinist ideological justification of rebellion has focused on France and consequently dates its emergence only after St. Bartholomew\u27s Day massacre in 1572. However, if one studies the Low Countries and the works of Marnix, one finds a Calvinist ideology of rebellion articulating a new separation of sacred and secular order fully in place by 1567

Viral Interactions with Host RNA Decay Pathways

Eukaryotes have evolved a wide variety of RNA decay pathways to maintain cellular homeostasis, carry out programs of gene expression, and respond to changing environmental conditions. Individual RNA turnover mechanisms can operate constitutively or under only particular cellular conditions; similarly, some target many RNAs, while others act with great specificity. It has become increasingly clear that there are extensive interactions between viruses and the host RNA decay machinery. Often, the cellular RNA decay machinery poses a threat to viral gene expression, but viruses can also manipulate RNA decay pathways to promote viral replication. This special issue focuses on how cellular RNA decay factors recognize and degrade viral RNAs and viral strategies to subvert or evade these pathways

Yeast targets for mRNA methylation

N6-Methyladenosine (m6A) is a modified base present in the mRNA of all higher eukaryotes and in Saccharomyces cerevisiae, where there is an increase in m6A levels during sporulation. The methyltransferase, Ime4, is responsible for this modification and has a role in the initiation of meiosis. However, neither the function, nor the extent of distribution of this nucleotide modification is established. We demonstrate that in S. cerevisiae, substantial levels of internal adenosine methylation are present in the GpA context in mRNA from sporulating cells, which is consistent with the preferred methylation consensus of higher eukaryotes. Based upon our quantification data, every second transcript could contain one m6A during meiosis. As methylation is distributed across all mRNA size ranges, it is likely that m6A is not limited to a small population of messages. We developed a new antibody based method for identifying m6A containing messages, and using this method the transcripts of three key, early regulators of meiosis, IME1, IME2 and IME4 itself, were identified as being methylated. The position of m6A in IME2 was narrowed down to a region in the 3′-end. Methylation of these and other targets suggests mechanisms by which IME4 could control developmental choices leading to meiosis

The First Sequenced Carnivore Genome Shows Complex Host-Endogenous Retrovirus Relationships

Host-retrovirus interactions influence the genomic landscape and have contributed substantially to mammalian genome evolution. To gain further insights, we analyzed a female boxer (Canis familiaris) genome for complexity and integration pattern of canine endogenous retroviruses (CfERV). Intriguingly, the first such in-depth analysis of a carnivore species identified 407 CfERV proviruses that represent only 0.15% of the dog genome. In comparison, the same detection criteria identified about six times more HERV proviruses in the human genome that has been estimated to contain a total of 8% retroviral DNA including solitary LTRs. These observed differences in man and dog are likely due to different mechanisms to purge, restrict and protect their genomes against retroviruses. A novel group of gammaretrovirus-like CfERV with high similarity to HERV-Fc1 was found to have potential for active retrotransposition and possibly lateral transmissions between dog and human as a result of close interactions during at least 10.000 years. The CfERV integration landscape showed a non-uniform intra- and inter-chromosomal distribution. Like in other species, different densities of ERVs were observed. Some chromosomal regions were essentially devoid of CfERVs whereas other regions had large numbers of integrations in agreement with distinct selective pressures at different loci. Most CfERVs were integrated in antisense orientation within 100 kb from annotated protein-coding genes. This integration pattern provides evidence for selection against CfERVs in sense orientation relative to chromosomal genes. In conclusion, this ERV analysis of the first carnivorous species supports the notion that different mammals interact distinctively with endogenous retroviruses and suggests that retroviral lateral transmissions between dog and human may have occurred