Aging is associated with quantitative and qualitative changes in circulating cell-free DNA: the Vitality 90+ study.

As a marker of cellular death, cell-free DNA (cf-DNA) has a utility in diagnosis and prognosis of various disorders. Since aging accompanies increased cellular senescence and death, we aimed to characterize potential age-related alterations in cf-DNA. The study population consisted of 12 nonagenarian women (participants in the Vitality 90+ Study) and 11 healthy control women (aged 22-37 years). Some of the nonagenarians (n=8) were also recruited for follow-up after one year. cf-DNA was extracted using two different methods. Total cf-DNA was quantified directly in plasma and the amplifiable cf-DNA was assessed using quantitative PCR. Quality of cf-DNA was analysed with a DNA Chip assay. For all the quantification methods, the concentration of cf-DNA was significantly higher (p<0.05) in nonagenarians as compared to controls. The quality of the cf-DNA also displayed a marked difference between nonagenarians and controls; a fragmented pattern or appearance of low molecular weight cf-DNA was observed in the majority of the nonagenarians, whereas in controls, cf-DNA was intact and had a quasi-genomic, high molecular weight appearance. In nonagenarians, the quality of cf-DNA appeared similar in the original and follow-up samples. We propose that some, as yet uncharacterized, aspects of aging are reflected in the appearance of cf-DNA.

Genome-wide RNA interference in Drosophila cells identifies G protein-coupled receptor kinase 2 as a conserved regulator of NF-kappaB signaling.

Because NF-kappaB signaling pathways are highly conserved in evolution, the fruit fly Drosophila melanogaster provides a good model to study these cascades. We carried out an RNA interference (RNAi)-based genome-wide in vitro reporter assay screen in Drosophila for components of NF-kappaB pathways. We analyzed 16,025 dsRNA-treatments and identified 10 novel NF-kappaB regulators. Of these, nine dsRNA-treatments affect primarily the Toll pathway. G protein-coupled receptor kinase (Gprk)2, CG15737/Toll pathway activation mediating protein, and u-shaped were required for normal Drosomycin response in vivo. Interaction studies revealed that Gprk2 interacts with the Drosophila IkappaB homolog Cactus, but is not required in Cactus degradation, indicating a novel mechanism for NF-kappaB regulation. Morpholino silencing of the zebrafish ortholog of Gprk2 in fish embryos caused impaired cytokine expression after Escherichia coli infection, indicating a conserved role in NF-kappaB signaling. Moreover, small interfering RNA silencing of the human ortholog GRK5 in HeLa cells impaired NF-kappaB reporter activity. Gprk2 RNAi flies are susceptible to infection with Enterococcus faecalis and Gprk2 RNAi rescues Toll(10b)-induced blood cell activation in Drosophila larvae in vivo. We conclude that Gprk2/GRK5 has an evolutionarily conserved role in regulating NF-kappaB signaling.