Nuclear pore complexes are tiny channels where the exchange of substances between the cell nucleus and the cytoplasm takes place. Scientists at the University of Basel report on startling new research that might overturn established models of nuclear transport regulation. Their study published in the Journal of Cell Biology reveals how shuttling proteins known as importins control the function of nuclear pores – as opposed to the view that nuclear pores control the shuttling of importins.
Genetic information is protected in the cell nucleus by a membrane that contains numerous nuclear pores. These pores facilitate the traffic of proteins known as importins that deliver molecular cargoes between the nucleus and the surrounding cytoplasm.
In contrast to prevailing views, the team led by Prof. Roderick Lim, Argovia Professor at the Biozentrum and the Swiss Nanoscience Institute of the University of Basel, has now demonstrated that the nuclear pore complex does not work like a simple filter that regulates the nuclear transport process. Rather, different importins cooperate to continuously open and close the pore like a “revolving door”.
Importins regulate nuclear pores
For a long time scientists have reasoned that a molecular filter within the nuclear pore complex prevents or enables the passage of molecules into the nucleus. Lim’s current study now shows that this filter alone is not sufficient for barrier function but provides only the basic infrastructure for establishing one. Instead, cargo-carrying importins function as bona fide components that regulate the nuclear pore complex transport barrier.
Moreover, Lim and colleagues show how the shuttling of importins is coupled to their barrier function. In fact, importins exist in two interacting forms: alpha and beta. Importin beta promotes cargo access into the pore whereas Importin alpha determines the cargo that can enter the nucleus.
Surprisingly, the team has now discovered that importin alpha acts as a molecular switch that helps to release or retain importin beta to open or close the pore. In the absence of importin alpha, importin beta loses its ability to shuttle through the nuclear pore channel.
Importins in health and disease
The insights provided by the study also have implications for the understanding of diseases associated with transport defects at the nuclear pore complex, such as cancer.
“We always thought of the nuclear pore complex as a standalone machine that controls nuclear transport”, says Lim.
“Now, we have a much greater appreciation for how the systematic interplay of importin alpha and beta are able to regulate the nuclear pore complex to sustain continuous transport. Hence, if importin alpha malfunctions the revolving door mechanism might get stuck such that essential proteins cannot get to their nuclear destinations. Or if importin beta is defective, the pore might become leaky against unwanted substances that can enter and poison the nucleus.”
Larisa E. Kapinos, Binlu Huang, Chantal Rencurel and Roderick Y.H. Lim
Karyopherins regulate nuclear pore complex barrier and transport function
Journal of Cell Biology (2017), doi: 10.1083/jcb.201702092
Prof. Dr. Roderick Lim, University of Basel, Biozentrum, and Swiss Nanoscience Institute, Tel. +41 61 207 20 83, E-Mail: firstname.lastname@example.org
Heike Sacher, University of Basel, Biozentrum, Communications, Tel. +41 61 207 14 49, email: email@example.com
Heike Sacher | Universität Basel
Building a brain, cell by cell: Researchers make a mini neuron network (of two)
23.05.2018 | Institute of Industrial Science, The University of Tokyo
Research reveals how order first appears in liquid crystals
23.05.2018 | Brown University
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
23.05.2018 | Life Sciences
23.05.2018 | Life Sciences
23.05.2018 | Physics and Astronomy