For all you genomics and systems-level junkies out there, here are two very juicy genome-scale (in one case, proteome-scale) studies of two very different aging-related phenomena: From Miller et al., we have a systems-level analysis of gene expression in both Alzheimer’s disease (AD) and normal aging. The authors use the transcriptional data in conjunction with genome annotation to identify pathways that are coherently regulated, either by neurodegenerative changes or age-related decline. Since the authors focus on brain tissue rather than the more easily accessible (or biopsy-able) parts of the body, these findings will be more relevant to understanding the pathology of AD than to its diagnosis. Hence, this approach is complementary to recent studies aimed at identifying proteins that are differentially expressed in the blood of AD patients and can therefore be used as diagnostic biomarkers for the disease.
Meanwhile, Krüger et al. have used mass spectrometry to characterize the tyrosine phosphoproteome of the insulin signaling pathway — in other words, they looked for proteins that are differentially tyrosine-phosphorylated as a result of insulin action. In addition to rounding up proteins already known to be involved, they also report the identification of several novel effectors of insulin signaling. The technique appears quite robust, and I look forward to seeing this methodology extended to other aging-related signaling networks (such as the closely related IGF-1 pathway).