In PNAS this week, researchers at Stanford's School of Medicine elucidate the roles of Gqα signaling in C. elegans' regulation of immunity, oxidative stress, and longevity. A signaling module formed by Gqα and its downstream signal transducer phospholipase C β can affect these processes, the authors say. As a result of losing its Gqα and PLCβ functions, C. elegans becomes increasingly sensitive to pathogens and oxidative stress. "We propose a model whereby Gqα signaling differentially regulates pathogen sensitivity, oxidative stress, and longevity through cell autonomous and noncell autonomous effects on p38 MAPK and insulin/IGF1 signaling, respectively," the researchers write.
Also in PNAS this week, researchers at Northwestern University present a "physically grounded" approach for using microarray data to estimate gene expression. McMullen et al. say the difficulties in interpreting microarray data arise from limitations in the data modeling, and propose a "physically motivated" approach for estimating gene expression levels from microarray data by separately modeling the "noises" specific to sample amplification, hybridization, and fluorescence detection. "We find that our model produces estimates of gene expression that are reproducible and unbiased," the authors suggest. "While the details of our model are specific to gene-expression microarrays, we argue that the physically grounded modeling approach we pursue is broadly applicable to other molecular biology technologies."
Researchers at Vanderbilt University present their insights on eukaryotic DNA priming from the structure and functional interactions of the 4FE-4S cluster domain in PNAS this week. By using X-ray crystallography, the researchers were able to map the structure of the C-terminal regulatory domain of the large subunit (p58C) of DNA primase to 1.7-Å resolution, revealing "a novel arrangement of an evolutionarily conserved 4Fe-4S cluster buried deeply within the protein core and is not similar to any known protein structure." Their results, the authors write, explain function defects in human DNA primase mutants and show insight into the regulation of primase activity.
And finally, researchers in California used single-cell mechanics to probe the interactions between amyloid-β peptide and neuronal cells. Using atomic force microscopy-based single-cell compression, Lulevich et al. measured the rigidity of cultured N2a and HT22 neuronal cells as a function of amyloid-β42 protein treatment, and found that Aβ42 oligomers led to significant cellular stiffening. "These findings and measurements provide a deeper, more characteristic, and quantitative insight into interactions between cells and Aβ42 oligomers, which have been considered the prime suspect for initiating neuronal dysfunction in Alzheimer's disease," the authors write.