In a paper published in advance online in Science this week, an international research team shows that chromatin remodeling gene ARID1A is frequently mutated in ovarian clear cell carcinoma. The team sequenced the exomes of eight OCCC tumors and then compared them with those of normal cells from the same patients. They identified four genes that were mutated in at least two tumors, including PIK3CA and KRAS — both previously implicated in OCCC — as well as PPP2R1A and ARID1A, two novel mutated genes. "The nature and pattern of the mutations suggest that PPP2R1A functions as an oncogene and ARID1A as a tumor suppressor gene," the authors write.
In this week's issue of Science, an international team of investigators led by Duke University's Miguel Moreno-Risueno report that "oscillating gene expression determines competence for periodic Arabidopsis root branching." Specifically, Moreno-Risueno and colleagues performed genetic screens and found that "some oscillating transcriptional regulators are required for periodicity in … developmental processes," which they say resembles molecular clock-driven activity in animals.
Researchers in Denmark and the UK demonstrate that "SIRT6 facilitates [double-strand break] processing and homologous recombination," therefore promoting genome stability, in Science this week. SIRT6, a protein lysine deacetylase, helps to promote DNA end resection. Loss of SIRT6, the authors write, impairs "the accumulation of replication protein A and single-stranded DNA at DNA damage sites, reduced rates of homologous recombination, and sensitized cells to DSB-inducing agents."
Investigators at the University of California, Berkeley, report that a large family of clustered regularly interspaced short palindromic repeats — or CRISPRs — process RNA in a sequence- and structure-specific manner in bacteria and archaea. The also identify Csy4 as "the endoribonuclease responsible for CRISPR transcript (pre-crRNA) processing in Pseudomonas aeruginosa."