Cells are crisscrossed by microtubules, protein cables that provide infrastructure, which facilitate cellular migration and assist in transport of molecular cargo, among other functions.
Most microtubules radiate out from structures known as centrosomes, but many cells also contain non-centrosomal microtubules of ambiguous function that are anchored to yet-unknown cellular targets.
For example, in epithelia—cell sheets that compose tissues including the skin and digestive tract—evidence has suggested that microtubules may interact with adherens junctions (AJs), protein complexes that connect epithelial cells together. “However, it was not clearly understood whether and how microtubules were involved in AJ formation,” says Masatoshi Takeichi, of the RIKEN Center for Developmental Biology in Kobe.
Fortunately, a new study by Takeichi’s team, including lead author Wenxiang Meng, offers some illumination. The researchers were looking for interacting partners for p120-catenin, a protein that participates in formation of the zonula adherens (ZA)—bands of AJs that encircle epithelial cells, reinforcing their shape and linking them tightly into two-dimensional sheets.
Their search led to the identification of PLEKHA7 and Nezha, two novel proteins that appear to provide the ‘missing link’ between the ZA and the microtubule network1. Nezha binds to PLEKHA7, which interacts directly with p120, and both Nezha and PLEKHA7 localize to the ZA, where they appear to play an important role in maintaining its integrity.
Meng and Takeichi subsequently found that Nezha interacts directly with non-centrosomal microtubules. Every microtubule has a defined ‘minus’ and ‘plus’ end, with fiber growth occurring exclusively taking place at the latter. Nezha binds specifically to microtubule minus ends, enabling further extension at the plus end, and this association seems to play an essential part in enabling PLEKHA7-Nezha stabilization of the ZA.
Although the details of microtubule involvement in the ZA are still unclear, the researchers uncovered a promising lead when they identified a motor protein, KIFC3, which travels along microtubules towards PLEKHA7-Nezha-associated junctions. “Minus-end directed motors like KIFC3 may utilize these microtubules as a ‘rail’ to transport cargo necessary to maintain the ZA,” says Takeichi.
These findings raise many new questions, but also represent major progress in cell biology, confirming the involvement of microtubules in maintenance of cell-cell junctions and revealing factors that help mediate this function. “To my knowledge, Nezha is the first non-centrosomal protein shown to tether the microtubule minus-ends,” says Takeichi. “These findings are thus a breakthrough for our deeper understanding of the dynamics and biological roles of non-centrosomal microtubules.”
1. Meng, W., Mushika, Y., Ichii, T. & Takeichi, M. Anchorage of microtubule minus ends to adherens junctions regulates epithelial cell-cell contacts. Cell 135, 948–959 (2008).
The corresponding author for this highlight is based at the RIKEN Laboratory for Cell Adhesion and Tissue Patterning
A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
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...
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...
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...
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...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
18.08.2017 | Life Sciences
18.08.2017 | Physics and Astronomy
18.08.2017 | Materials Sciences