Genome-wide association studies have indicated that polymorphisms in a stretch of DNA upstream from the MYC oncogene are also related to increased cancer risk. Further, a regulatory element in that region appears to alter MYC expression levels. And so researchers from the Karolinksa Institute in Sweden and the University of Helsinki in Finland developed mice deficient in that regulatory region, Myc-335, to determine its role in Myc expression and tumor formation. As the researchers report in this week's Science, the Myc-335-deficient mice are resistant to intestinal tumorigenesis. "These results establish that a cancer-associated SNP identified in human genome-wide association studies has a functional effect in vivo," the researchers write.
Also in Science, researchers led by Cancer Research UK London Research Institute's Nick Proudfoot report that "by adopting a gene-loop conformation, actively transcribed mRNA encoding genes restrict divergent transcription of [non-coding] RNAs." Such loops, they add, "maintain the directionality of transcription" and may contribute "to determining which transcription units are fully productive."
Johns Hopkins University researchers say that Drosophila male germline stem cells "preserve preexisting histones through asymmetric cell division." The researchers used a dual-color method to label histones in Drosophila male germline stem cells to determine how histones are segregated into daughter cells. "We show that preexisting canonical H3, but not variant H3.3, histones are selectively segregated to the GSC, whereas newly synthesized histones incorporated during DNA replication are enriched in the differentiating daughter cell," they add.