Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers describe how cells take out the trash to prevent disease

12.11.2008
Garbage collectors are important for removing trash; without them waste accumulates and can quickly become a health hazard. Similarly, individual cells that make up such biological organisms as humans also have sophisticated methods for managing waste.

For example, cells have developed complex systems for recycling, reusing and disposing of damaged, nonfunctional waste proteins. When such systems malfunction and these proteins accumulate, they can become toxic, resulting in many diseases, including Alzheimer's, cystic fibrosis and developmental disorders.

Scott Emr, director of the Weill Institute for Cell and Molecular Biology at Cornell, and colleagues, describe in detail how cells recycle protein waste in two recent papers appearing in the journals Cell and Developmental Cell.

"We are interested in understanding how cells deal with garbage," said Emr. "It's really a very sophisticated recycling system."

Cells use enzymes known as proteases to break down proteins into their component amino acids in the cytoplasm -- the fluid inside the cell's surface membrane. Those amino acids are then reused to make new proteins. But water-insoluble proteins embedded in the cell's membrane require a much more complicated recycling process.

Emr's paper in Cell identifies a family of proteins that controls the removal of unwanted water-insoluble proteins from the membrane. The research advances understanding of how cells recognize which proteins out of hundreds on a cell's surface should be removed. For example, hormone receptors at a cell's surface signal such processes within the cell as growth and proliferation. To inactivate these receptors and terminate the growth signal, receptors are tagged for removal. Failure to inactivate can lead to developmental diseases and cancer.

The researchers, including postdoctoral fellows Jason MacGurn and Chris Stefan, identified nine related proteins in yeast, which they named the "arrestin-related trafficking" adaptors or ARTs. Each of these proteins identifies and binds to a different set of membrane proteins. Once bound, the ART protein links to an enzyme that attaches a chemical tag for that protein's removal. The ARTs are found in both yeast and humans, suggesting the fundamental nature of their function.

Once the protein is tagged, the piece of membrane with the targeted protein forms a packet, called a vesicle, that enters the cell's cytoplasm. There, the vesicle enters a larger membrane body called an endosome, which in turn dumps it into another compartment called the lysosome, where special enzymes break apart big molecules to their core units: proteins to amino acids, membranes to fatty acids, carbohydrates to sugars and nucleic acids to nucleotides, and those basic materials are then reused.

The paper in Developmental Cell, co-authored by Emr with postdoctoral fellows David Teis and Suraj Saksena, describes for the first time how a set of four proteins assemble into a highly ordered complex. This complex encircles membrane proteins that must be disposed of in the lysosome. Emr's lab was the first to identify and characterize these protein complexes (known as ESCRTs). The Developmental Cell paper describes the order of events in which the ESCRT complexes encircle and deliver "waste" proteins into vesicles destined for recycling in the lysosome.

Emr's ESCRT discovery has allowed researchers to better understand how the AIDS virus is released from its host cell. HIV hijacks the cell's ESCRT machinery during virus budding. "So, if you block the function of ESCRTs, you could block HIV release," said Emr.

Blaine Friedlander | EurekAlert!
Further information:
http://www.cornell.edu

More articles from Life Sciences:

nachricht Immune Defense Without Collateral Damage
23.01.2017 | Universität Basel

nachricht The interactome of infected neural cells reveals new therapeutic targets for Zika
23.01.2017 | D'Or Institute for Research and Education

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Quantum optical sensor for the first time tested in space – with a laser system from Berlin

For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.

According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Tracking movement of immune cells identifies key first steps in inflammatory arthritis

23.01.2017 | Health and Medicine

Electrocatalysis can advance green transition

23.01.2017 | Physics and Astronomy

New technology for mass-production of complex molded composite components

23.01.2017 | Process Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>