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
Could this protein protect people against coronary artery disease?
17.11.2017 | University of North Carolina Health Care
Microbial resident enables beetles to feed on a leafy diet
17.11.2017 | Max-Planck-Institut für chemische Ökologie
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
17.11.2017 | Physics and Astronomy
17.11.2017 | Health and Medicine
17.11.2017 | Studies and Analyses