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.
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
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.
David Orenstein | EurekAlert!
The genes are not to blame
20.07.2018 | Technische Universität München
Targeting headaches and tumors with nano-submarines
20.07.2018 | Universitätsmedizin der Johannes Gutenberg-Universität Mainz
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences