Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Cellular waste management: how animal cells protect themselves against dangerous goods

20.03.2017

In two recent papers, scientists Ahmad Fazeli and Ann Wehman from the University of Würzburg have published new insights into waste disposal in animal cells. These findings may help to better understand the molecular mechanisms underlying autoimmune diseases like lupus.

Animal cells have developed different strategies to degrade unwanted particles. In this way they eliminate invading pathogens, as well as dead cells or cell fragments. Malfunctions in the cell's waste removal systems can lead to overreactions in the immune system or even to autoimmune diseases like lupus.


Microscope image of a dividing embryo of the nematode C. elegans. The midbody remnants (yellow) are released as extracellular vesicles, phagocytosed by neighboring cells, and eventually degraded.

Photo: Wehman

Scientists from the Rudolf Virchow Center for Experimental Biomedicine at the University of Würzburg investigated a specific type of cell fragment: the midbody remnant. The midbody is a transient structure occurring at the end of each cell division that represents the last linkage between daughter cells. This structure was first discovered in 1891 by the German anatomist Walther Flemming and is therefore also called the Flemming body.

After cell division, the midbody is either inherited by one of the daughter cells or released into the cellular environment. However, in either case, the midbody needs to be rapidly degraded to avoid further impacts on the cell. "Remnants of the midbody can influence the polarity and fate of a cell after cell division”, explains Ahmad Fazeli, first author of the two publications. For example, stem cells and cancer cells accumulate midbodies, which could allow them to give rise to more daughter cells.

"However, it was unresolved so far, how cells normally control the removal or degradation of midbodies", continues Fazeli. Previous studies considered two possible scenarios: either the midbody remains inside one of the daughter cells, where it would later be degraded by autophagy (a self-eating mechanism used to remove internal particles), or the midbody is released from both cells to the environment and then taken up again by any cell through a process called phagocytosis (a process used to eat and digest external particles).

In two recent papers, the team of Ann Wehman revealed a model that unifies both possible scenarios, as they describe in the Journal of Cell Science and in Communicative & Integrative Biology. They investigated the midbody in the fast dividing cells of the nematode Caenorhabditis elegans, as many proteins and their cellular functions are similar between worms and humans. They systematically analyzed the roles of different proteins from the phagocytosis and autophagy pathways and discovered unexpectedly that these two pathways can work together in the degradation of the midbody.

As the scientists report, the midbodies in embryonic cells of the nematode are released by daughter cells out to the environment and then eaten by neighboring cells. There, autophagy proteins surround the phagocytosed midbody and help its digestion. This means that proteins responsible for removing internal particles also help to degrade external particles. These recent studies revealed that the midbody is degraded by a process called LC3-associated phagocytosis (LAP). LAP was already known as a sort of cellular waste management process used to remove invading bacteria or the corpses of dead cells. The novel finding is LAP's involvement in midbody degradation.

"At first glance it seems surprising that cells carry out this complex series of events to release the midbody only to take it up again,” explains Ann Wehman, senior author of the study. “However, since this transient structure possesses signaling properties, its regulation is of great importance for the cell." The release of the midbody happens immediately after cell division. Otherwise, a midbody that stays in one of the daughter cells could continue to tell the cell to divide, which could lead to changes in the shape or size of cells or even result in cell fragmentation. Since a midbody could also influence the polarity and fate of the cell that eats it, rapid digestion of this structure is essential. Once the midbody has been broken down into its components, it is rendered harmless and provides the cell with bonus raw materials for further growth.

The new model of midbody degradation reconciles findings of previous studies in nematodes, flies and mammalian cells. Therefore, the authors propose that their findings are likely to be transferable to humans and might help in understanding the mechanisms behind human diseases like cancer or the autoimmune disease lupus.

Currently, the Wehman group is investigating other roles of LAP in developing worm embryos. In this way they want to understand how cells use this process to clean up the cellular environment and protect the embryo from accumulating litter.

Publications:
Fazeli G, Trinkwalder M, Irmisch L, Wehman AM. (2016) C. elegans midbodies are released, phagocytosed and undergo LC3-dependent degradation independent of macroautophagy. J Cell Science. 129(20):3721-3731.
http://jcs.biologists.org/content/129/20/3721

Fazeli G and Wehman AM. (2017) Rab GTPases mature the LC3-associated midbody phagosome. Communicative & Integrative Biology, DOI 10.1080/19420889.2017.1297349
http://www.tandfonline.com/doi/full/10.1080/19420889.2017.1297349

Website:
http://www.rudolf-virchow-zentrum.de/en/news/news/article/zellulaere-muellabfuhr...

Contact:
Dr. Ann Wehman (Research group leader, Rudolf-Virchow-Zentrum)
Tel. 0931 31 81906, ann.wehman@uni-wuerzburg.de

Dr. Ahmad Fazeli (Postdoctoral researcher, Rudolf-Virchow-Zentrum)
Tel. 0931 31 86130, gholamreza.fazeli@uni-wuerzburg.de

Dr. Frank Sommerlandt (Public Science Center, Rudolf-Virchow-Zentrum)
Tel. 0931 31 88449, frank.sommerlandt@uni-wuerzburg.de

Dr. Frank Sommerlandt | idw - Informationsdienst Wissenschaft
Further information:
http://www.rudolf-virchow-zentrum.de

More articles from Life Sciences:

nachricht Modern genetic sequencing tools give clearer picture of how corals are related
17.08.2017 | University of Washington

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

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

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,...

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...

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

Gold shines through properties of nano biosensors

17.08.2017 | Physics and Astronomy

Greenland ice flow likely to speed up: New data assert glaciers move over sediment, which gets more slippery as it gets wetter

17.08.2017 | Earth Sciences

Mars 2020 mission to use smart methods to seek signs of past life

17.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>