In the current issue of Cell, Roger Greenberg and his colleagues at the University of Pennsylvania School of Medicine report that "ATM-dependent chromatin changes silence transcription in cis to DNA double-strand breaks." Using a "novel reporter that allows for visualization of repair protein recruitment and local transcription in single cells," the team found that ATM prevents RNA pol II elongation-dependent chromatic de-condensation at locations distal to DSBs.
A trio of researchers in the UK provides their review of DNA segregation in prokaryotes. Specifically, Kenn Gerdes et al. discuss the actin homolog ParM, "which forms dynamically unstable filaments that push plasmids apart in a process reminiscent of mitosis." In their paper, the authors illuminate research prospects, and suggest that "it would be highly informative to obtain the crystal structure of ParM in combination with the ParR/parC centromere complex," among other things.
A Max Planck Institute for Molecular Biomedicine-led team reports that component of the BAF complex facilitates somatic cell reprogramming efficiency, in Cell this week. Using a novel assay to screen nuclear fractions from pluripotent murine cells based on Oct4 reactivation, and by using proteomics, "we identified components of the ATP-dependent BAF chromatin-remodeling complex, which significantly increases reprogramming efficiency when used together with the four factors," the authors write.
An international research team reports its collaborative efforts to elucidate that LINE-1 activity supports heterochromatin formation during X-chromosome inactivation. Specifically, the authors show that "LINEs participate in creating a silent nuclear compartment into which genes become recruited," and that they "often lie within escape-prone regions of the X chromosome, but close to genes that are subject to XCI, and are associated with putative endo-siRNAs." The authors say that LINEs may facilitate XCI at varying degrees — silent LINEs participate in the "assembly of a heterochromatic nuclear compartment induced by Xist," while active LINEs are part of the propogation efforts of XCI.