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 Helping to Transport Proteins Inside the Cell
21.11.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht UNH researchers create a more effective hydrogel for healing wounds
21.11.2018 | University of New Hampshire

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: First diode for magnetic fields

Innsbruck quantum physicists have constructed a diode for magnetic fields and then tested it in the laboratory. The device, developed by the research groups led by the theorist Oriol Romero-Isart and the experimental physicist Gerhard Kirchmair, could open up a number of new applications.

Electric diodes are essential electronic components that conduct electricity in one direction but prevent conduction in the opposite one. They are found at the...

Im Focus: Nonstop Tranport of Cargo in Nanomachines

Max Planck researchers revel the nano-structure of molecular trains and the reason for smooth transport in cellular antennas.

Moving around, sensing the extracellular environment, and signaling to other cells are important for a cell to function properly. Responsible for those tasks...

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Optical Coherence Tomography: German-Japanese Research Alliance hosted Medical Imaging Conference

19.11.2018 | Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

 
Latest News

Helping to Transport Proteins Inside the Cell

21.11.2018 | Life Sciences

Meta-surface corrects for chromatic aberrations across all kinds of lenses

21.11.2018 | Power and Electrical Engineering

Removing toxic mercury from contaminated water

21.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>