Scientists have identified the reason behind tans appearing only after the sunbather has left the beach. This is something that has puzzled dermatologists – the delayed reaction of tanning. The study comes from Tel Aviv University.
The mechanism behind the delayed tanning phenomenon is because the body first seeks to repair the DNA damage in the skin cells caused by radiation, thereby inhibiting the mechanism responsible for skin pigmentation (tanning).
According to the U.S. FDA “The increase in skin pigment, called melanin, which causes the tan color change in your skin is a sign of damage.” Tanning greatly increases the risk of developing skin cancer.
It is only after the skin cells have repaired the genetic information as far as is possible do the cells begin to produce the increased melanin that darkens the skin. This activity produces a level of physical protection for the genetic material within the cell, protecting against the next occurrence of radiation exposure (the next time the individual is exposed to the sun).
Lead researcher Nadav Elkoshi explains: “In our study, we discovered why the tanning phenomenon does not occur immediately when the body is exposed to the sun, but only following a delay. It turns out that the mechanism that repairs our DNA takes precedence over all other systems in the cell, temporarily inhibiting the pigmentation mechanism. Only after the cells repair the genetic information to the best of their ability do they begin to produce the increased melanin.”
There is a biological imperative with cells to ensure, as far as possible, that genetic information is protected from mutations; hence the repair mechanism takes precedence inside the cell during exposure to ultraviolet radiation from the sun. This DNA repair mechanism suppresses all the other mechanisms in the cell.
A protein called MITF, which is activated during exposure, is responsible for regulating the two mechanisms. Another protein, called ATM activates one mechanism while disabling the other.
It is hoped the research will lead to future treatments that will provide maximum protection of the skin against radiation damage and contribute to the prevention of skin cancer.
The research appears in the Journal of Investigative Dermatology. The research is titled “ATM signaling delays skin pigmentation upon UV exposure by mediating MITF function towards DNA repair mode.”
