Why does it take time for a tan to appear? Scientists have finally figured out what causes it

When it comes to tanning, we often notice that our skin doesn’t darken immediately after being in the sun. Now scientists have discovered the reason for this delay. By conducting experiments on human and mouse skin, a group of researchers from Tel Aviv University (Israel) found that the tan appears only after the skin undergoes emergency DNA repair. The study was published in the Journal of Investigative Dermatology

Skin defense mechanisms

According to molecular biologist Nadav Elkoshi, the skin has two defense mechanisms against dangerous UV radiation. The first mechanism repairs DNA in radiation-damaged skin cells, while the second increases melanin production, which darkens the skin, protecting it from further exposure.

Prioritizing resources and delaying tanning

Researchers have suggested that tanning delay is related to resource prioritization. After exposure to UV radiation, all of the cell’s resources are mobilized to repair radiation damage as quickly as possible. Only after this task is completed can the cell allocate resources to melanin production. To test this hypothesis, experts irradiated human skin samples and cultured them in petri dishes, studying the response of cells to radiation damage.

Activation of ATM protein

The researchers confirmed that the ATM protein kinase kinase, which is activated when DNA damage occurs and plays a key role in cell repair, becomes active shortly after exposure to UV radiation. To learn more, they induced ATM activation in mouse models and observed the results. Even in the absence of harmful radiation, tanning appeared after a certain period of time on both mouse and human skin samples.

DNA repair takes priority

A closer look at cellular processes revealed that ATM activation blocks the activation of the MITF protein, which is responsible for increasing melanin production. This allows DNA repair within the cell during exposure to UV radiation. Carmit Levy, a biochemist and molecular biologist at Tel Aviv University, explains that the DNA repair mechanism essentially commands all other mechanisms in the cell to pause until the repair is complete, which usually occurs a few hours after UV exposure.

Potential consequences of radiation damage to the skin

The researchers believe that DNA repair may even use components of the pigmentation mechanism to enhance cell survival and minimize the risk of mutations. This discovery could pave the way for further research into innovative methods to protect the skin from radiation damage and possibly prevent skin cancer.

Expert opinions and development perspectives

Karmit Levy emphasizes the significance of this scientific discovery, stating that it could serve as a basis for future research and contribute to the development of methods to maximize skin protection. She emphasizes that understanding the molecular mechanisms underlying delayed tanning may lead to innovative approaches to prevent and treat the effects of radiation damage to the skin.

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