Biosensor For Measuring Stress In Cells

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Biosensor For Measuring Stress In Cells

http://www.medicalnewstoday.com/articles/107889.php

Cancer, nervous system disorders such as Parkinson's disease,

cardiovascular disorders and old age have one thing in common: Both

in afflicted tissue and in aging cells, scientists have observed

oxidative changes in important biomolecules. These are caused by

reactive oxygen molecules, including the notorious " free radicals "

that are formed as a by-product of cellular respiration and attack

cellular proteins, nucleic and fatty acids.

Today, reactive oxygen molecules are no longer regarded by and large

as culprits, since it has turned out that they are also involved in

regulating major life processes such as growth and cell death. The

right balance between oxidation and the reverse reaction, reduction,

makes the difference between health and disease. " Oxidative stress "

arises when this balance shifts towards oxidation-promoting

processes.

So far, it has hardly been possible for scientists to measure the

level of oxidation and, thus, the stress status of living cells. This

will now be feasible thanks to a highly sensitive biomarker presented

in the journal Nature Methods by Dr. Tobias Dick and co-workers of

the German Cancer Research Center, jointly with colleagues from the

University of Heidelberg.

The biosensor specifically measures the oxidation state of

glutathione. This is an important protection molecule that captures a

large portion of reactive oxygen molecules within a cell by

oxidation. If much of a cell's glutathione is present in an oxidized

state, this is an important indicator of the cell's overall oxidation

level. The investigators equipped test cells with a fluorescent

protein that reacts to changes in oxidation level by releasing light

signals. Since the fluorescent protein on its own is not sensitive

enough, it was coupled with an enzyme called glutaredoxin. This

enzyme " measures " the oxidation state of glutathione and transmits

the value to the fluorescent protein.

The stress biosensor developed by Dick and colleagues measures the

slightest changes in the oxidation state of glutathione without

destroying the cell. Even more relevant, however, is its precise time

resolution, as Tobias Dick explains: " In order to measure short-term

variations of oxidation state, the systems needs to react instantly

and dynamically. This is guaranteed with our biosensor, which works

down to the scale of seconds. " The measuring system allows

researchers to determine those short-term variations that occur when

reactive oxygen compounds are released as signaling molecules.

However, the biosensor is equally suitable for use in pharmaceutical

research, for example, to determine the effect of new substances or

plant food constituents on oxidative processes and, thus, on the

stress status of cells.