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This Week in PNAS: Oct 25, 2016

In the early, online edition of the Proceedings of the National Academy of Sciences, a team from the University of Texas Southwestern Medical Center reports on a family of microRNAs called miR-515 that are found at higher-than-usual levels in placenta samples from women who go on to experience preeclampsia, a form of high blood pressure during pregnancy that lead to maternal or fetal mortality. Following a prior array-based study of differentiating cells related to placenta formation, the team focused on the miR-515 gene cluster, demonstrating that the miR-515-5p that's normally down regulated in differentiating human trophoblast cells in culture was enhanced in term placenta samples from 18 women with preeclampsia compared to samples from as many gestation-matched controls who did not develop the complication.

Japanese researchers explore ties between beta-catenin signaling and long non-coding RNAs (lncRNAs) in colorectal cancer cells. Using RNA sequencing, chromatin immunoprecipitation sequencing, and other approaches, the team searched for genes targeted by beta-catenin. When the beta-catenin protein was knocked down, for example, the group saw more than 1,500 down-regulated genes and almost 2,100 genes with enhanced expression. The latter group included 86 genes coding for lncRNAs, while the combined RNA-seq and ChIP-seq profiles pointed to two lncRNAs — ASBEL and TCF3 — that are up-regulated by beta-catenin and appear to contribute to colorectal cancer cell survival.

Finally, a Penn State-led team takes a look at horizontal gene transfer in parasitic plants from the Orobanchaceae family. Starting with available genome sequence data for 22 plants, along with half a dozen transcriptome sequences, the researchers searched for signs of horizontal gene transfer across a phylogenetic tree of parasitic plants, narrowing in on 192 low-, medium-, or high confidence sets of potential events. From there, they attempted to validate these horizontal gene transfers using additional genome, transcriptome, and RT-PCR data to get to a set of 52 high-confidence events in three parasitic plants. "[Horizontal gene transfer] reflected parasite preference for different host plant and was much more frequent in plants with increasing parasitic dependency," the authors write.