Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Improving pore 'vision'

18.10.2010
The formation of nuclear pores in dividing human cells is being illuminated by new visualization techniques

A team led by Naoko Imamoto of the RIKEN Advanced Science Institute in Wako has uncovered processes governing the formation of functionally important structures called nuclear pore complexes (NPCs) in dividing human cells1.

Mitosis, the process of mammalian cell division, is followed by a period called ‘interphase’ during which the volume of the cell nucleus almost doubles; as does the number of NPCs on the nuclear envelope separating the ‘nucleoplasm’ from the cytoplasm—the rest of the cell’s contents.

Innumerable molecules shuttle between the nucleus and cytoplasm through pores formed by NPCs, which are large octagonal structures composed of multiple copies of around 30 different proteins called ‘nucleoporins’ (Nups). NPCs form at the end of mitosis, when previously disassembled NPCs are reassembled, and during interphase when their number increases in preparation for another round of cell division.

“We wished to understand how NPCs form on the nuclear envelope of interphase cells, which is much less understood than post-mitotic NPC formation initiating on mitotic chromosomes,” says Imamoto.

The researchers began by developing fluorescence-based NPC visualization methods. Their first approach involved using a laser to photobleach certain nuclear surface areas of early human interphase cells expressing fluorescently tagged ‘scaffold’ Nups. This allowed them to monitor the formation of new NPCs, which appeared as bright dots in the bleached areas.

A second method involved monitoring NPC formation in fused cells called ‘heterokaryons’. “Our heterokaryon method allows quantitative analysis of many nuclei without risking laser damage,” explains Imamoto.

By combining these visualization techniques with cell engineering experiments they found that the formation of NPCs in human interphase cells is promoted by known cell-cycle regulators called cyclin-dependent protein kinases (Cdks).

Cdk inhibition experiments further revealed that CdK1 and CdK2, in particular, govern NPC formation during interphase, but not in post-mitotic NPC assembly, suggesting that different regulatory mechanisms are at play. Interestingly, Cdks also govern the behavior of nuclear envelope proteins, suggesting an as yet unknown mechanistic connection between NPC formation and membrane dynamics.

Cdks appear to act early in NPC formation because their inhibition suppressed the generation of small ‘nascent’ pores observed on early interphase nuclear envelopes using scanning electron microscopy.

“We believe that these ‘nascent pores’ are probably immature nuclear pores, although this needs to be confirmed,” says Imamoto.

Cdk inhibition did not greatly affect nuclear growth, suggesting that its mechanism of regulation is distinct from that of NPC formation, which is something that future research must also address.

The corresponding author for this highlight is based at the Cellular Dynamics Laboratory, RIKEN Advanced Science Institute

Journal information

1. Maeshima, K., Iino, H., Hihara, S., Funakoshi, T., Watanabe, A., Nishimura, M., Nakatomi, R., Yahata, K., Imamoto, F., Hashikawa, T., Yokota, H. & Imamoto, N. Nuclear pore formation but not nuclear growth is governed by cyclin-dependent kinases (Cdks) during interphase. Nature Structural & Molecular Biology 17, 1065–1071 (2010).

gro-pr | Research asia research news
Further information:
http://www.riken.jp
http://www.researchsea.com
http://www.rikenresearch.riken.jp/eng/research/6420

More articles from Life Sciences:

nachricht The irresistible fragrance of dying vinegar flies
16.08.2017 | Max-Planck-Institut für chemische Ökologie

nachricht How protein islands form
15.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

Im Focus: Scientists improve forecast of increasing hazard on Ecuadorian volcano

Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, the Italian Space Agency (ASI), and the Instituto Geofisico--Escuela Politecnica Nacional (IGEPN) of Ecuador, showed an increasing volcanic danger on Cotopaxi in Ecuador using a powerful technique known as Interferometric Synthetic Aperture Radar (InSAR).

The Andes region in which Cotopaxi volcano is located is known to contain some of the world's most serious volcanic hazard. A mid- to large-size eruption has...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

New thruster design increases efficiency for future spaceflight

16.08.2017 | Physics and Astronomy

Transporting spin: A graphene and boron nitride heterostructure creates large spin signals

16.08.2017 | Materials Sciences

A new method for the 3-D printing of living tissues

16.08.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>