"TRPA1 ion channels are involved in the detection of pungent chemicals such as cinnamaldehyde, wasabi, and mustard oil, and we've now found it's important for this melanin response," Bellono said. "There is a possibility that we can pharmacologically alter pigmentation through regulation of this ion channel."
Oancea and Bellono emphasized, however, that people who go out in the sun should always take widely recommended precautions to protect their skin, such as using high-SPF commercial sunscreens or wearing protective hats and clothing.
Finding the channel
From the prior research in Oancea's lab, Bellono knew he was looking for some kind of molecular pathway that would start with a light sensitive receptor and trigger an elevated level of calcium ions in the melanocytes.
It seemed possible that a TRP ion channel would be involved because TRPs are involved in phototransduction elsewhere in the body that lead to an increase in intracellular calcium. There are, however, many types of TRP channels, and the molecular identity of the UVA-activated channel in melanocytes was not apparent. Oancea confessed that she even suspected another as the culprit. But many experiments later, the team hit on TRPA1 and amassed considerable evidence to confirm its vital role.
In one experiment, for example, they treated melanocytes with "antagonist" chemicals known to block TRPA1 activity. They then exposed the cells to UVA light and measured the resulting electrical response. The cells blocked with the antagonists had 80 to 90 percent reduction in current compared to the unhindered cells.
They used a similar technique of specifically blocking TRPA1 activity to show that the ion channel contributes greatly to the presence of calcium ions after UVA exposure compared to unhindered melanocyte cells. They also found melanocytes produce little or no m
|Contact: David Orenstein|