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 How brains surrender to sleep
23.06.2017 | IMP - Forschungsinstitut für Molekulare Pathologie GmbH

nachricht A new technique isolates neuronal activity during memory consolidation
22.06.2017 | Spanish National Research Council (CSIC)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>