Production of a Dominant-Negative Fragment Due to G3BP1 Cleavage Contributes to the Disruption of Mitochondria-Associated Protective Stress Granules during CVB3 Infection

Stress granules (SGs) are dynamic cytosolic aggregates containing messenger ribonucleoproteins and target poly-adenylated (A)-mRNA. A key component of SGs is Ras-GAP SH3 domain binding protein-1 (G3BP1), which in part mediates protein-protein and protein-RNA interactions. SGs are modulated during infection by several viruses, however, the function and significance of this process remains poorly understood. In this study, we investigated the interplay between SGs and Coxsackievirus type B3 (CVB3), a member of the Picornaviridae family. Our studies demonstrated that SGs were formed early during CVB3 infection; however, G3BP1-positive SGs were actively disassembled at 5 hrs post-infection, while poly(A)-positive RNA granules persisted. Furthermore, we confirmed G3BP1 cleavage by 3C^pro at Q325. We also demonstrated that overexpression of G3BP1-SGs negatively impacted viral replication at the RNA, protein, and viral progeny levels. Using electron microscopy techniques, we showed that G3BP1-positive SGs localized near mitochondrial surfaces. Finally, we provided evidence that the C-terminal cleavage product of G3BP1 inhibited SG formation and promoted CVB3 replication. Taken together, we conclude that CVB3 infection selectively targets G3BP1-SGs by cleaving G3BP1 to produce a dominant-negative fragment that further inhibits G3BP1-SG formation and facilitates viral replication.     

Effects of Maternal Obstructive Sleep Apnoea on Fetal Growth: A Prospective Cohort Study

Objective

The objective of this study is to determine whether obstructive sleep apnea (OSA) is associated with reduced fetal growth, and whether nocturnal oxygen desaturation precipitates acute fetal heart rate changes.

Study Design

We performed a prospective observational study, screening 371 women in the second trimester for OSA symptoms. 41 subsequently underwent overnight sleep studies to diagnose OSA. Third trimester fetal growth was assessed using ultrasound. Fetal heart rate monitoring accompanied the sleep study. Cord blood was taken at delivery, to measure key regulators of fetal growth.

Results

Of 371 women screened, 108 (29%) were high risk for OSA. 26 high risk and 15 low risk women completed the longitudinal study; 14 had confirmed OSA (cases), and 27 were controls. The median (interquartile range) respiratory disturbance index (number of apnoeas, hypopnoeas or respiratory related arousals/hour of sleep) was 7.9 (6.1–13.8) for cases and 2.2 (1.3–3.5) for controls (p<0.001). Impaired fetal growth was observed in 43% (6/14) of cases, vs 11% (3/27) of controls (RR 2.67; 1.25–5.7; p = 0.04). Using logistic regression, only OSA (OR 6; 1.2–29.7, p = 0.03) and body mass index (OR 2.52; 1.09–5.80, p = 0.03) were significantly associated with impaired fetal growth. After adjusting for body mass index on multivariate analysis, the association between OSA and impaired fetal growth was not appreciably altered (OR 5.3; 0.93–30.34, p = 0.06), although just failed to achieve statistical significance. Prolonged fetal heart rate decelerations accompanied nocturnal oxygen desaturation in one fetus, subsequently found to be severely growth restricted. Fetal growth regulators showed changes in the expected direction- with IGF-1 lower, and IGFBP-1 and IGFBP-2 higher- in the cord blood of infants of cases vs controls, although were not significantly different.

Conclusion

OSA may be associated with reduced fetal growth in late pregnancy. Further evaluation is warranted to establish whether OSA may be an important contributor to adverse perinatal outcome, including stillbirth.     

Targeting Aurora B to the Equatorial Cortex by MKlp2 Is Required for Cytokinesis

Although Aurora B is important in cleavage furrow ingression and completion during cytokinesis, the mechanism by which kinase activity is targeted to the cleavage furrow and the molecule(s) responsible for this process have remained elusive. Here, we demonstrate that an essential mitotic kinesin MKlp2 requires myosin-II for its localization to the equatorial cortex, and this event is required to recruit Aurora B to the equatorial cortex in mammalian cells. This recruitment event is also required to promote the highly focused accumulation of active RhoA at the equatorial cortex and stable ingression of the cleavage furrow in bipolar cytokinesis. Specifically, in drug-induced monopolar cytokinesis, targeting Aurora B to the cell cortex by MKlp2 is essential for cell polarization and furrow formation. Once the furrow has formed, MKlp2 further recruits Aurora B to the growing furrow. This process together with continuous Aurora B kinase activity at the growing furrow is essential for stable furrow propagation and completion. In contrast, a MKlp2 mutant defective in binding myosin-II does not recruit Aurora B to the cell cortex and does not promote furrow formation during monopolar cytokinesis. This mutant is also defective in maintaining the ingressing furrow during bipolar cytokinesis. Together, these findings reveal that targeting Aurora B to the cell cortex (or the equatorial cortex) by MKlp2 is essential for the maintenance of the ingressing furrow for successful cytokinesis.     

Formalin-Inactivated EV71 Vaccine Candidate Induced Cross-Neutralizing Antibody against Subgenotypes B1, B4, B5 and C4A in Adult Volunteers

Background

Enterovirus 71 (EV71) has caused several epidemics of hand, foot and mouth diseases (HFMD) in Asia. No effective EV71 vaccine is available. A randomized and open-label phase I clinical study registered with ClinicalTrials.gov #NCT01268787, aims to evaluate the safety, reactogenicity and immunogenicity of a formalin-inactivated EV71 vaccine candidate (EV71vac) at 5- and 10-µg doses. In this study we report the cross-neutralizing antibody responses from each volunteer against different subgenotypes of EV71 and CVA16.

Methods

Sixty eligible healthy adults were recruited and vaccinated. Blood samples were obtained on day 0, 21 and 42 and tested against B1, B4, B5, C2, C4A, C4B and CVA16 for cross-neutralizing antibody responses.

Results

The immunogenicity of both 5- and 10- µg doses were found to be very similar. Approximately 45% of the participants had <8 pre-vaccination neutralization titers (Nt) against the B4 vaccine strain. After the first EV71vac immunization, 95% of vaccinees have >4-fold increase in Nt, but there was no further increase in Nt after the second dose. EV71vac induced very strong cross-neutralizing antibody responses in >85% of volunteers without pre-existing Nt against subgenotype B1, B5 and C4A. EV71vac elicited weak cross-neutralizing antibody responses (∼20% of participants) against a C4B and Coxsackie virus A16. Over 90% of vaccinated volunteers did not develop cross-neutralizing antibody responses (Nt<8) against a C2 strain. EV71vac can boost and significantly enhance the neutralizing antibody responses in volunteers who already had pre-vaccination antibodies against EV71 and/or CVA16.

Conclusion

EV71vac is efficient in eliciting cross-neutralizing antibody responses against EV71 subgenotypes B1, B4, B5, and C4A, and provides the rationale for its evaluation in phase II clinical trials.

Trial Registration

ClinicalTrials.gov __NCT01268787     

Role of HLA-DP Polymorphisms on Chronicity and Disease Activity of Hepatitis B Infection in Southern Chinese

Background and Aims

The association between HLA-DP single nucleotide polymorphisms (SNPs) and chronic hepatitis B virus (HBV) infection varies between different populations. We aimed to study the association between HLA-DP SNPs and HBV infection and disease activity in the Chinese population of Hong Kong.

Methods

We genotyped SNPs rs3077 (near HLA-DPA1) and rs9277378 and rs3128917 (both near HLA-DPB1) in 500 HBV carriers (hepatitis B surface antigen [HBsAg]-positive), 245 non-HBV infected controls (HBsAg- and antibody to hepatitis B core protein [anti-HBc]-negative), and 259 subjects with natural HBV clearance (HBsAg-negative, anti-HBc-positive). Inactive HBV carriers state was defined by HBV DNA levels <2,000 IU/ml and persistently normal alanine aminotransferase level for least 12 months.

Results

Compared to the non-HBV infected subjects, the HBV carriers had a significantly lower frequency of the rs3077 T allele (p = 0.0040), rs9277378 A allele (p = 0.0068) and a trend for lower frequency of rs3128917 T allele (p = 0.054). These alleles were associated with an increased chance of HBV clearance (rs3077: OR = 1.41, p = 0.0083; rs9277378: OR = 1.61, p = 0.00011; rs3128917: OR = 1.54, p = 0.00017). Significant associations between HLA-DP genotypes and HBV clearance were also found under different genetic models. Haplotype TAT was associated with an increased chance of HBV clearance (OR = 1.64, p = 0.0013). No association was found between these SNPs and HBV disease activity.

Conclusion

HLA-DP SNPs rs3077, rs9277378 and rs3128917 were associated with chronicity of HBV disease in the Chinese. Further studies are required to determine whether these SNPs influence the disease endemicity in different ethnic populations.     

Dhrs3 Protein Attenuates Retinoic Acid Signaling and Is Required for Early Embryonic Patterning

All-trans-retinoic acid (atRA) is an important morphogen involved in many developmental processes, including neural differentiation, body axis formation, and organogenesis. During early embryonic development, atRA is synthesized from all-trans-retinal (atRAL) in an irreversible reaction mainly catalyzed by retinal dehydrogenase 2 (aldh1a2), whereas atRAL is converted from all-trans-retinol via reversible oxidation by retinol dehydrogenases, members of the short-chain dehydrogenase/reductase family. atRA is degraded by cytochrome P450, family 26 (cyp26). We have previously identified a short-chain dehydrogenase/reductase 3 (dhrs3), which showed differential expression patterns in Xenopus embryos. We show here that the expression of dhrs3 was induced by atRA treatment and overexpression of Xenopus nodal related 1 (xnr1) in animal cap assay. Overexpression of dhrs3 enhanced the phenotype of excessive cyp26a1. In embryos overexpressing aldh1a2 or retinol dehydrogenase 10 (rdh10) in the presence of their respective substrates, Dhrs3 counteracted the action of Aldh1a2 or Rdh10, indicating that retinoic acid signaling is attenuated. Knockdown of Dhrs3 by antisense morpholino oligonucleotides resulted in a phenotype of shortened anteroposterior axis, reduced head structure, and perturbed somitogenesis, which were also found in embryos treated with an excess of atRA. Examination of the expression of brachyury, not, goosecoid, and papc indicated that convergent extension movement was defective in Dhrs3 morphants. Taken together, these studies suggest that dhrs3 participates in atRA metabolism by reducing atRAL levels and is required for proper anteroposterior axis formation, neuroectoderm patterning, and somitogenesis.     

A bedr way of genomic interval processing

Background

Next-generation sequencing is making it critical to robustly and rapidly handle genomic ranges within standard pipelines. Standard use-cases include annotating sequence ranges with gene or other genomic annotation, merging multiple experiments together and subsequently quantifying and visualizing the overlap. The most widely-used tools for these tasks work at the command-line (e.g. BEDTools) and the small number of available R packages are either slow or have distinct semantics and features from command-line interfaces.

Results

To provide a robust R-based interface to standard command-line tools for genomic coordinate manipulation, we created bedr. This open-source R package can use either BEDTools or BEDOPS as a back-end and performs data-manipulation extremely quickly, creating R data structures that can be readily interfaced with existing computational pipelines. It includes data-visualization capabilities and a number of data-access functions that interface with standard databases like UCSC and COSMIC.

Conclusions

bedr package provides an open source solution to enable genomic interval data manipulation and restructuring in R programming language which is commonly used in bioinformatics, and therefore would be useful to bioinformaticians and genomic researchers.

     

Intrauterine Growth Restriction Alters Mouse Intestinal Architecture during Development

Infants with intrauterine growth restriction (IUGR) are at increased risk for neonatal and lifelong morbidities affecting multiple organ systems including the intestinal tract. The underlying mechanisms for the risk to the intestine remain poorly understood. In this study, we tested the hypothesis that IUGR affects the development of goblet and Paneth cell lineages, thus compromising the innate immunity and barrier functions of the epithelium. Using a mouse model of maternal thromboxane A₂-analog infusion to elicit maternal hypertension and resultant IUGR, we tested whether IUGR alters ileal maturation and specifically disrupts mucus-producing goblet and antimicrobial-secreting Paneth cell development. We measured body weights, ileal weights and ileal lengths from birth to postnatal day (P) 56. We also determined the abundance of goblet and Paneth cells and their mRNA products, localization of cellular tight junctions, cell proliferation, and apoptosis to interrogate cellular homeostasis. Comparison of the murine findings with human IUGR ileum allowed us to verify observed changes in the mouse were relevant to clinical IUGR. At P14 IUGR mice had decreased ileal lengths, fewer goblet and Paneth cells, reductions in Paneth cell specific mRNAs, and decreased cell proliferation. These findings positively correlated with severity of IUGR. Furthermore, the decrease in murine Paneth cells was also seen in human IUGR ileum. IUGR disrupts the normal trajectory of ileal development, particularly affecting the composition and secretory products of the epithelial surface of the intestine. We speculate that this abnormal intestinal development may constitute an inherent “first hit”, rendering IUGR intestine susceptible to further injury, infection, or inflammation.