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This Week in PNAS: Dec 17, 2013

A team from the US and South Africa has found evidence suggesting glitches in a DNA repair enzyme-coding gene called FAN1 can contribute to the risk of both schizophrenia and autism spectrum disorder. As they report in the early, online edition of the Proceedings of the National Academy of Sciences, the researchers scoured exome sequence data for members of two families affected by schizophrenia, focusing on 49 loci that were previously shown to be prone to de novo copy number change in individuals with the condition. In those families and a third affected by ASD, investigators saw an over-representation of rare, non-synonymous FAN1 variants in individuals affected by schizophrenia or ASD.

In another PNAS study, researchers from Harvard University and the Baylor College of Medicine use mathematical modeling to explore epigenetic regulation of olfactory receptor genes in mouse sensory neurons, which each express just one of the animal's 1,400 or so olfactory receptor genes. The theoretical study suggests that this so-called singularity stems from slow activation of a given expressed olfactory receptor gene, which involves progressive demethylation of a repressive histone mark, coupled with a more rapid drop in expression by a gene that normally removes that repressive mark from olfactory receptor genes.

Using genetic selection in mouse cells, a Yale School of Medicine team demonstrated that it is possible to produce proteins that lack amino acid sequences present in known cell or viral peptides. When they screened focused in on four of these proteins, which were 29 amino acids long apiece, the researchers saw that the proteins prompted tumor-like behavior in mouse and human cell lines and tumor formation in mice. From findings so far, study authors say that this de novo selection strategy "can be used to generate structures not observed in nature, create prototypes for research and possibly clinical uses, and provide insight into cell biology, protein-protein interactions, and evolution."