In this week's PNAS Early Edition, researchers at Australia's University of Queensland and Monash University show that the obligate endosymbiont "Wolbachia [pipientis] uses host microRNAs to manipulate host gene expression and facilitate colonization of the dengue vector Aedes aegypti." In particular, the researchers found that an A. aegypti miRNA, miR-2940, is "induced after Wolbachia infection in both mosquitoes and cell lines." Further, the team confirmed an interaction between the A. aegypti miR-2940 and its target sequences using GFP as a reporter. Overall, the authors say that the "manipulation of the mosquito metalloprotease gene via aae-miR-2940 is crucial for efficient maintenance of the endosymbiont."
In another PNAS paper published online in advance this week, investigators at Children's Hospital Boston and elsewhere say that because HIV DNA is heavily uracilated, it is protected from auto-integration. "We find that HIV DNA uracilation, rather than being dangerous, may promote the early phase of the viral life cycle," Nan Yan et al. write.
A trio of investigators at China's Nanjing University proposes a four-module model of the tumor suppressor p53 signaling network and its associated dynamics with cellular outcomes, post-ionizing radiation. The team "found that the cellular response is mediated by both the level and posttranslational modifications of p53 and that p53 is activated in a progressive manner," as it writes in PNAS. More specifically, the trio reports that p53 "undergoes a two-phase response in irreparably damaged cells," and that there may be "a sequential predominance of distinct feedback loops ... [that] elicit multiple-phase dynamical behaviors."
Harvard University's Mariana Mihalusova and her colleagues report this week their use of single-molecule FRET to investigate whether "a region of the RNA downstream of the template may be important for telomerase activity and ... could fold into a pseudoknot." Indeed, the team shows that the isolated pseudoknot sequence stably folds into a pseudoknot, but "in the context of the full-length telomerase RNA, interference by other parts of the RNA prevents the formation of the pseudoknot." Mihalusova et al. say that their study speaks to the "critical role played by telomerase proteins in pseudoknot folding."