In this week's Science, a team led by investigators at the Salk Institute for Biological Studies in La Jolla, Calif., shows that the JumonjiC and ARID domain-containing histone lysine demethylase 1a, or JARID1a, forms a complex with the transcription factors CLOCK and BMAL1 in a demethylase-independent manner. The researchers report that "depletion of JARID1a in mammalian cells reduced Per promoter histone acetylation, dampened expression of canonical circadian genes, and shortened the period of circadian rhythms."
Elsewhere, researchers at University Medical Center Utrecht and at the Leiden University Medical Center show that "chromosome segregation errors can … result in structural chromosome aberrations." The UMC Utrecht-led team says "chromosomes that missegregate are frequently damaged during cytokinesis, triggering a DNA double-strand break response in the respective daughter cells involving ATM, Chk2, and p53." Overall, the team shows that segregation errors can cause translocations, and says its study provides "insights into the role of whole-chromosome instability in tumorigenesis."
Brooke Gardner and Peter Walter at the University of California, San Francisco, discuss in this week's Science how the endoplasmic reticulum adjusts the protein-folding capacity to the needs of the cell when under stress. Gardner and Walter show that "the core ER-lumenal domain of yeast Ire1 binds to unfolded proteins in yeast cells and to peptides primarily composed of basic and hydrophobic residues in vitro," and that "mutation of amino acid side chains exposed in a putative peptide-binding groove of Ire1 cLD [core ER-lumenal domain] [impairs] peptide binding."