Transit of molecules into and out of the cell nucleus is governed by generic physical principles

The mechanism to describe how our cells allow certain molecules to enter and exit their nucleus while blocking others to protect genetic material and normal functions of the cell can be explained using basic physical principles. This is the main conclusion drawn from the work of scientists from CIC biomaGUNE, the Basque Centre for Cooperative Research in Biomaterials.

Essentially, the behaviour pattern resembles the movement of meatballs on a plate of sticky spaghetti, though on a much smaller scale. The research, conducted by an international team of scientists led by Ralf Richter of CIC biomaGUNE and Bart Hoogenboom from the London Centre for Nanotechnology, was recently published in the prestigious online journal eLife.

The article, entitled “A physical model describing the interaction of nuclear transport receptors with FG nucleoporin domain assemblies”, explains that the cells of humans, animals and plants have a nucleus that contains most of their genetic material. As Dr. Ralf Richter points out, “... for the appropriate use of this genetic material, it is essential that proteins and other molecules can only enter and exit the nucleus in a highly selective way through channels in the protective membrane surrounding the nucleus”.

These tiny channels house specialised proteins (FG domains) that arrange similarly to sticky spaghetti to act as a selective barrier. The molecules that cross the barrier can be thought of as meatballs, some of which – those known as nuclear transport receptors – are capable of freely shuttling into and out of the spaghetti-like FG domains and enable other molecules to do likewise.

To study how these meatballs penetrate the channels, the scientists made layers of FG domains of only 100,000th of a millimetre thick and subsequently measured how nuclear transport receptors interacted with those layers. As the results were highly similar for different FG domains and different nuclear transport receptors, the next step was to design a physical model that only included the features that were universal to all; namely, that the FG domains behaved as rather sticky spaghetti interacting with the nuclear transport receptors as if they were sticky meatballs.

About CIC biomaGUNE
The Centre for Cooperative Research in Biomaterials (CIC biomaGUNE), located in the Donostia-San Sebastián Technology Park, conducts cutting-edge research at the interface between Chemistry, Biology and Physics, and particularly on the properties of molecular level biological nanostructures and their biomedical applications.

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