Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Yeast are first cells known to cure themselves of prions

10.12.2014

Yeast cells can sometimes reverse the protein misfolding and clumping associated with diseases such as Alzheimer's, according to new research from the University of Arizona.

The new finding contradicts the idea that once prion proteins have changed into the shape that aggregates, the change is irreversible.


When colonies of baker's yeast cells that contain clumped prion proteins (colonies of white cells on left) are stressed by high temperatures, some can convert the aggregated prion proteins to the non-clumping form of the protein (red cells in the colonies the right).

Credit: Serio laboratory/ University of Arizona molecular and cellular biology

"It's believed that when these aggregates arise that cells cannot get rid of them," said Tricia Serio, UA professor and head of the department of molecular and cellular biology. "We've shown that's not the case. Cells can clear themselves of these aggregates."

Prions are proteins that change into a shape that triggers their neighbors to change, also. In that new form, the proteins cluster. The aggregates, called amyloids, are associated with diseases including Alzheimer's, Huntington's and Parkinson's.

"The prion protein is kind of like Dr. Jekyll and Mr. Hyde," said Serio, senior author of the paper published today in the open-access journal eLife. "When you get Hyde, all the prion protein that gets made after that is folded in that bad way."

For yeast, having clumps of amyloid is not fatal. Serio and her students exposed amyloid-containing cells of baker's yeast to 104 F (40 C), a temperature that would be a high fever in a human. When exposed to that environment, the cells activated a stress response that changed the clumping proteins back to the no-clumping shape.

The finding suggests artificially inducing stress responses may one day help develop treatments for diseases associated with misfolded prion proteins, Serio said.

"People are trying to develop therapeutics that will artificially induce stress responses," she said. "Our work serves as a proof of principal that it's a fruitful path to follow."

First author on the paper "Spatial quality control bypasses cell-based limitations on proteostasis to promote prion curing" is Serio's former graduate student Courtney Klaips, now at the Max Planck Institute for Biochemistry in Munich. The other authors are Serio's students Megan Hochstrasser, now at the University of California, Berkeley, and Christine Langlois of Brown University. The paper is available here: http://dx.doi.org/10.7554/eLife.04288

National Institute of Health grants R01 GM069802001, F31 AG034754 and F31 GM099383 funded the research.

To accomplish their jobs inside cells, proteins must fold into specific shapes. Cells have quality-control mechanisms that usually keep proteins from misfolding. However, under some environmental stresses, those mechanisms break down and proteins do misfold, sometimes forming amyloids.

Cells respond to environmental stress by making specific proteins, known as heat-shock proteins, which are known to help prevent protein misfolding.

Serio and her students wanted to know whether particular heat-shock proteins could make amyloids revert to the normal shape. To that end, the team studied yeast cells that seemed unable to clear themselves of the amyloid form of the prion protein Sup35.

The researchers were testing one heat-shock protein at a time in an attempt to figure out which particular proteins were needed to clear the amyloids. However, the results weren't making sense, she said.

So she and Klaips decided to stress yeast cells by exposing them to a range of elevated temperatures - as much as 104 F (40 C) - and let the cells do what comes naturally.

As a result, the cells made a battery of heat-shock proteins. The researchers found at one specific stage of the cell's reproductive cycle, the yeast could turn aggregates of Sup35 back into the non-clumping form of the protein.

Yeast cells reproduce by budding. The mother cell partitions off a bit of itself into a much smaller daughter cell, which separates and then grows up.

The researchers found in the heat-stressed yeast, just when the daughter was being formed, the mother cell retained most of the heat-shock proteins called chaperones, especially Hsp-104. As a result, the mother had a particularly high concentration of Hsp-104 because little of the protein was shared with the daughter.

The mother cells ended up "curing" themselves of the Sup35 amyloid, although the daughters did not. The degree of curing was correlated with the concentration of Hsp-104 in the cell, and the higher the temperature the more Hsp-104 the cells had.

The Hsp-104 takes the protein in the amyloid and refolds it, Serio said. But she and her colleagues found that just inducing high levels of Hsp-104 in cells by itself does not change the amyloid protein back to the non-clumping form.

"Clearly the heat-shock proteins are collaborating in some way that we don't understand," she said.

Having the amyloid-forming version of the protein is not automatically bad, she said. It may be that shape is good under some environmental conditions, whereas the non-aggregating form is good under others.

Even in humans, amyloid forms of a protein can be helpful, she said. Amyloid proteins are associated with skin pigmentation and with hormone storage.

To clear the amyloid from yeast cells, these experiments triggered cells to make many different heat-shock proteins.

Serio now wants to figure out the minimal system necessary to clear amyloids from a cell. Knowing that may help the development of drug therapies for amyloid-related human diseases, she said.

Researcher Contact

Tricia Serio
tserio@email.arizona.edu
520-621-7563

Tricia Serio's website: http://mcb.arizona.edu/people/tserio

Mari N. Jensen | EurekAlert!
Further information:
http://uanews.org/

Further reports about: Arizona Cells clear daughter diseases heat-shock prion proteins prions proteins responses

More articles from Life Sciences:

nachricht What the world's tiniest 'monster truck' reveals
23.08.2017 | American Chemical Society

nachricht Treating arthritis with algae
23.08.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt

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

What the world's tiniest 'monster truck' reveals

23.08.2017 | Life Sciences

Treating arthritis with algae

23.08.2017 | Life Sciences

Witnessing turbulent motion in the atmosphere of a distant star

23.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>