Featured Research

from universities, journals, and other organizations

Linchpin of skin response to UVA light discovered

Date:
January 21, 2013
Source:
Brown University
Summary:
Researchers have strengthened their understanding of how skin cells called melanocytes sense ultraviolet light and act to protect themselves with melanin. In a new study, they report experiments showing that an ion channel well-known elsewhere in the body for its chemical sensitivity, plays a central role in this process.

In search of a light-sensitive trigger Certain skin cells respond to ultraviolet light by pumping out melanin, the pigment responsible for the tanning response. The hunt for a light-receptor mechanism outside the eye led to an ion channel called TRPA1.
Credit: Mike Cohea/Brown University

Researchers have strengthened their understanding of how skin cells called melanocytes sense ultraviolet light and act to protect themselves with melanin. In a new study, they report experiments showing that an ion channel well-known elsewhere in the body for its chemical sensitivity, plays a central role in this process.

Related Articles


Last year, a team of researchers at Brown University discovered that certain skin cells use a light-sensitive receptor found outside of the eye to sense ultraviolet light and quickly begin pumping out melanin to protect against DNA damage. In a new study, lab members identify a key player in that biomolecular chain of events that could someday become a pharmacological target for improving this protective response.

The new discovery, published the week of Jan. 21 in the Proceedings of the National Academy of Sciences, is that human melaoncyte skin cells rely on an ion channel called TRPA1 to allow a flood of calcium ions into the cells when they are exposed to UVA light. The resulting abundance of calcium ions signals the cell to begin making melanin, the pigment responsible for the tanning response in people.

The discovery "is exciting because it confirms this phototransduction pathway is similar to those found in the eye."Several experiments described in the paper show that TRPA1, which is known from a number of other appearances elsewhere in the body, is an essential step in the skin's response to UVA light, said senior author Elena Oancea, assistant professor of medical science in the Department of Molecular Pharmacology, Physiology, and Biotechnology at Brown.

As a matter of basic science, the finding strengthens the evidence of a striking parallel between the skin's response to UVA light and the way the eye detects light.

"Its exciting because it confirms this phototransduction pathway is similar to those found in the eye. It consists of a light-sensitive receptor, molecular signaling cascade, and an ion channel," Oancea said. "The involvement of an ion channel makes this pathway a lot more like other phototransduction pathways."

In other parts of the body, TRPA1 has been shown to help detect pungent but benign chemicals, such as those in intensely flavorful foods. Oancea and lead author Nicholas Bellono said the chemical sensitivity of TRPA1 offers the intriguing possibility that it could become a target for experiments to boost melanin production.

"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 melanin following exposure to UVA when TRPA1 is blocked.

They did not, however, do experiments to see whether adding TRPA1 stimulating substances could increase melanin production.

In addition to Bellono and Oancea, other authors on the paper are Laura Kammel and Anita Zimmerman.

The National Science Foundation, the National Institutes of Health (grant T32-GM077995), and Brown University funded the research.


Story Source:

The above story is based on materials provided by Brown University. Note: Materials may be edited for content and length.


Cite This Page:

Brown University. "Linchpin of skin response to UVA light discovered." ScienceDaily. ScienceDaily, 21 January 2013. <www.sciencedaily.com/releases/2013/01/130121161928.htm>.
Brown University. (2013, January 21). Linchpin of skin response to UVA light discovered. ScienceDaily. Retrieved October 25, 2014 from www.sciencedaily.com/releases/2013/01/130121161928.htm
Brown University. "Linchpin of skin response to UVA light discovered." ScienceDaily. www.sciencedaily.com/releases/2013/01/130121161928.htm (accessed October 25, 2014).

Share This



More Health & Medicine News

Saturday, October 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

IKEA Desk Converts From Standing to Sitting With One Button

IKEA Desk Converts From Standing to Sitting With One Button

Buzz60 (Oct. 24, 2014) IKEA is out with a new convertible desk that can convert from a sitting desk to a standing one with just the push of a button. Jen Markham explains. Video provided by Buzz60
Powered by NewsLook.com
Ebola Protective Suits Being Made in China

Ebola Protective Suits Being Made in China

AFP (Oct. 24, 2014) A factory in China is busy making Ebola protective suits for healthcare workers and others fighting the spread of the virus. Duration: 00:38 Video provided by AFP
Powered by NewsLook.com
WHO: Millions of Ebola Vaccine Doses by 2015

WHO: Millions of Ebola Vaccine Doses by 2015

AP (Oct. 24, 2014) The World Health Organization said on Friday that millions of doses of two experimental Ebola vaccines could be ready for use in 2015 and five more experimental vaccines would start being tested in March. (Oct. 24) Video provided by AP
Powered by NewsLook.com
Doctor in NYC Quarantined With Ebola

Doctor in NYC Quarantined With Ebola

AP (Oct. 24, 2014) An emergency room doctor who recently returned to the city after treating Ebola patients in West Africa has tested positive for the virus. He's quarantined in a hospital. (Oct. 24) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins