Truly Remarkable Proteins
SCRUB YOUR TEETH with mentholated toothpaste and the cooling sensation is palpably there. Your teeth and gums feel cold. Eat chili peppers and the resulting heat in your mouth and right down your throat is unmistakable. Right? Not so fast‚ says Tibor Rohacs‚ MD‚ PhD‚ associate professor‚ pharmacology and physiology. These sensations are much more complicated than you might think. That menthol action is not really physically cold. And the actual temperature inside your mouth doesn't go up as a result of eating extra hot chilis. What you are experiencing is from activation of transient receptor potential (TRP) channels‚ the cold sensor TRPM8 (also activated by the menthol) or by heat sensor TRPV1 (also turned on by things like capsaicin‚ the active component of chili peppers‚ and a number of other pain–producing stimuli).
"TRP channels are indeed fascinating and even though the abbreviation stands for transient receptor potential‚ some people prefer to think that the letters stand for ‘truly remarkable proteins' instead." Rohacs is obviously one of those people. He has been awarded more than $2 million in funding from the National Institutes of Health (NIH) and other sources for his TRP research‚ which began when he was a post–doctoral fellow at Mount Sinai School of Medicine in New York City back in 1998. Since 2005‚ his lab at UMDNJ-New Jersey Medical School has been studying temperature and pain sensation‚ with a long–term translational goal of finding new ways to design a better pain medication. "We are going to stay at the more basic science or molecular level for now but the main treatments currently available for pain fall short‚" he says. "Sometimes‚ anti–inflammatories are not strong enough while the opiates‚ which can be quite strong‚ are addictive. This is why there has been quite a lot of interest in TRP channels."
TRPs are involved in a variety of important biological processes. "Their function is remarkably diverse‚" explains Rohacs‚ who was born in Hungary and earned both his MD and his PhD at Semmelweiss University of Medicine in Budapest. TRPs are involved in temperature sensing‚ mechanosensation (the body's response to mechanical stimuli as well as the physiological foundation for the senses of touch‚ hearing and balance)‚ vision‚ taste‚ calcium and magnesium transport across epithelial cells‚ apoptosis (cell death) and calcium signaling by hormones and neurotransmitters.
They are part of a much larger group of proteins‚ ion channels‚ that are basically responsible for all the electrical activities of the cell and they sit right in the plasma membrane. "Our laboratory mainly focuses on TRPV1‚ activated by heat and capsaicin and TRPM8‚ the cold and menthol sensitive channel." And his team is studying the mechanism behind desensitization or why these reactions are transitory. Capsaicin has been used as a topical analgesic for a long time. Apply it to the skin and after an initial burning sensation‚ it provides relief from pain. And the same sort of action exists for reactions to cold. "It is well known that we adapt to moderately cold temperatures with the same temperature feeling less cold over time‚" he says. The Rohacs team wants to know why desensitization occurs. "We are using various electrophysiological and molecular techniques to study the regulation of the TRP channels by a biologically important component of the plasma membrane known as PIP2."
Puzzles like this one keep
Rohacs coming back into the lab.
"I went to medical school but
decided to go into research
because you are always facing
new problems and solving
puzzles. I like putting the pieces
together." Married to a medical
researcher at the University of
Pennsylvania in Philadelphia‚ this
father of two has found America
"the most welcoming place for
foreigners." His wife is also from
Hungary but they both "like the
opportunities here in the U.S. and
the openness of the society. If
you work hard‚ you can succeed."
— Maryann Brinley