No one knows whether these kinds of changes to nuclear structure trigger aging and disease or result from them, or both. In any case, it is clear “that if you mess around with the [nuclear] architecture, you can get disease,” Misteli says. It might one day be possible to diagnose diseases and age-related problems simply by looking at nuclear snapshots, he adds.

Perhaps the biggest remaining mystery is how the nucleus gets organized in the first place. Do molecular scaffolds tether nuclear constituents in a deterministic way, or does genome activity affect positioning in a probabilistic manner? Evidence supports both theories, and Spector posits that RNA may play an important role. This past March he and his colleagues identified an RNA that helps to structure nuclear compartments called paraspeckles. Undoubtedly, the mechanisms controlling nuclear organization will prove to be varied and complex. As Spector puts it: “Things in biology tend to not be in black and white.”

Note: This article was originally printed with the title, "Nuclear Architecture."

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