Navigation Links
Gene discovery sheds light on causes of rare disease, cancer

French scientists have learned how Listeria monocytogenes, which causes a major food-borne illness, commandeers cellular transport machinery to invade cells and hide from the body's immune system. They believe that other infectious organisms may use the same mechanism.

The Listeria bacterium, found in soil and water, can be transmitted to humans via undercooked and unpasteurized food, causing flu-like symptoms or gastrointestinal distress. For individuals with weakened immune systems, listeriosis can be fatal, and infections during pregnancy can lead to miscarriage, stillbirth, premature delivery, or infection of the newborn.

The research was conducted by Pascale Cossart, a Howard Hughes Medical Institute international research scholar, and her colleague Esteban Veiga at the Institut Pasteur in Paris, and will be published in the August 21, 2005, issue of Nature Cell Biology. Cossart and Veiga detailed how Listeria invades cells by activating cellular machinery that transports viruses, small molecules, and proteins. Once it has safely entered a cell, the microbe can replicate and continue the process of infection.

The body usually deals with bacteria and other large, foreign microbes through a process called phagocytosis. Specialized cells engulf the invading microbe and destroy it. Scientists long believed that cells use a second process, called endocytosis, to deal with smaller molecules or viruses. In endocytsosis, a cell's outer membrane pinches inward around the target to form a pocket that's brought inside the cell, creating a structure called a vesicle.

"Phagocytosis and endocytosis may, in fact, be more similar than past research suggests. This is a totally new concept," Cossart says.

Cossart's lab had observed that Listeria ?which is 20 times the size of the largest particle scientists believed a cell could take in by endocytosis ?could invade non-phagocytic cells. Other labs had made similar observations with other bacteria. Cossart and Veiga investigated the underlying machinery behind this uncommon invasion strategy, which they knew depended on an interaction between a protein on the surface of the bacteria, known as InlB, and a protein called Met on the surface of the cell it was invading.

They discovered that when InlB interacts with Met, the cell responds by adding a chemical tag to Met that flags it for protein recycling or degradation. Since Met is on the outside surface of the cell and the recycling and degradation machineries are inside, the cell must bring Met inside through endocytosis in order to dispose of it. As the cell creates the vesicle that will transport tagged Met, Listeria stows away and invades the cell.

By manipulating the gene expression of the cells Listeria was invading, the researchers showed that specific molecules known to be involved in endocytosis were essential for successful invasion by Listeria. Similarly, they found that an enzyme that tags proteins for recycling was also required.

Listeria's use of receptor-mediated endocytosis to infect hosts, according to Cossart, suggests that other bacteria may exploit the same mechanism to gain entry into non-phagocytic cells. "This mechanism of cell entry may be used by several different kinds of bacteria, which is a major deviation from the belief that endocytosis is strictly for importing small molecules into cells," she says.


Source:NIH/National Institute on Aging

Related biology news :

1. Protein discovery could unlock the secret to better TB treatment
2. Purdue proves concept of using nano-materials for drug discovery
3. UCSD discovery may help extend life of natural pesticide
4. Leprosy microbes lead scientists to immune discovery
5. Biochemists report discovery of structure of major piece of telomerase; implications for cancer
6. Researchers make surprise discovery that some neurons can transmit three signals at once
7. Important discovery about second most fatal cancer
8. Harmless virus may hold key to more effective HIV drug discovery
9. Fundamental discovery -- Bone fracture
10. Genetic discovery could lead to drought-resistant plants
11. Biota makes major antiviral discovery
Post Your Comments:

(Date:6/7/2016)... -- Syngrafii Inc. and San Antonio Credit Union (SACU) ... Syngrafii,s patented LongPen™ eSignature "Wet" solution into SACU,s ... in greater convenience for SACU members and operational ... document workflow and compliance requirements. Logo ... Highlights: ...
(Date:6/2/2016)... LONDON , June 2, 2016 ... Systems, Manned Platforms, Unmanned Systems, Physical Infrastructure, Support & ... intelligence provider visiongain offers comprehensive analysis of ... that this market will generate revenues of $17.98 billion ... Systems acquired DVTEL Inc, a leader in software and ...
(Date:5/16/2016)... YORK , May 16, 2016   EyeLock ... solutions, today announced the opening of an IoT Center ... to strengthen and expand the development of embedded iris ... an unprecedented level of convenience and security with unmatched ... authenticate one,s identity aside from DNA. EyeLock,s platform uses ...
Breaking Biology News(10 mins):
(Date:6/27/2016)... ... June 27, 2016 , ... ... findings on what they believe could be a new and helpful biomarker for ... research. Click here to read it now. , Biomarkers are components ...
(Date:6/27/2016)... ... June 27, 2016 , ... Newly created ... services and solutions to the healthcare market. The company's primary focus is on ... sales and marketing strategies that are necessary to help companies efficiently bring their ...
(Date:6/27/2016)... June 27, 2016  Liquid Biotech ... funding of a Sponsored Research Agreement with The ... cells (CTCs) from cancer patients.  The funding will ... levels correlate with clinical outcomes in cancer patients ... will then be employed to support the design ...
(Date:6/24/2016)... 2016  Regular discussions on a range of subjects including ... two entities said Poloz. Speaking at a lecture ... , he pointed to the country,s inflation target, which is ... "In certain areas there ... common economic goals, why not sit down and address strategy ...
Breaking Biology Technology: