'Electronic switch' opens doors in rheumatoid joints

January 3, 2008

A breakthrough in understanding the way atoms move across cell membranes in

the human body could pave the way for the development of new treatments for

inflammatory diseases such as rheumatoid arthritis.

Scientists at the University of Leeds have identified a previously unknown

natural mechanism that opens ion channels - proteins at the cell surface

that act as doorways into and out of cells - through the naturally occurring

protein thioredoxin.

Ion channels allow movement of ions - electrically charged atoms - across

the cell membrane to carry out various functions such as pain transmission,

timing of the heart beat, and regulation of blood glucose. Often, they need

to be stimulated to open and, until now, two main groups of activating

mechanisms have been acknowledged: changes in cell voltage and binding of

chemical factors.

In a paper published today (03 January) in Nature, Professor Beech and

colleagues from the University's Faculty of Biological Sciences reveal that

thioredoxin works in a different manner: it activates an ion channel by

donating electrons to it, in a process Professor Beech likens to " an

electronic on-switch " .

" Thioredoxin is naturally present in cells and is secreted to help the body

counter stressful chemical reactions that occur in inflammation, which can

damage cells, " he explains. " We already knew that inflammatory diseases

cause the production of high levels of thioredoxin - in fact with rheumatoid

arthritis, it's striking how much is present in affected joints. But we

didn't

know until now that thioredoxin can also activate ion channels, conferring

additional protective potential and offering opportunities for mimicking the

effect with drugs. "

" It would seem that the body's own natural defences have provided us with

new understanding that could be significant in the development of future

treatments for arthritis and related diseases, " he says.

###

The research has been funded by the Wellcome Trust, which has recently

provided the group with further funding to expand its research into ion

channels.

Contact: Jo

jokelly@...

44-011-325-89880

University of Leeds

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