Researchers have discovered that sunlight breaks down a crucial protective protein, allowing hidden RNA signals to trigger inflammatory processes that can lead to cancer. Understanding this chain of reactions opens new possibilities for preventing sun-induced cellular damage.

The Impact of Sunlight on Health

Sunlight is essential for the synthesis of vital substances, such as vitamin D. However, prolonged exposure to the sun significantly increases the risk of developing skin cancer. In the United States, nearly 5.4 million people are diagnosed with skin cancer each year, and over 90% of these cases are linked to excessive ultraviolet (UV) radiation. UV rays damage DNA and cause oxidative stress in skin cells, leading to inflammation, redness, pain, and blistering from sunburns.

A New Perspective on Molecular Mechanisms

In a recent study published in Nature Communications, scientists from the University of Chicago demonstrated that prolonged UV exposure destroys a key protein called YTHDF2. This protein acts as a "guardian," preventing normal skin cells from turning cancerous. YTHDF2 plays a central role in regulating RNA metabolism, helping to maintain cellular health. Uncovering its functions could pave the way for new strategies in skin cancer prevention and treatment.

The Role of RNA and the YTHDF2 Protein

Ribonucleic acid (RNA) is a vital molecule involved in transmitting genetic information and synthesizing proteins. Of particular interest are non-coding RNAs, which regulate gene activity without producing proteins. These RNAs typically function either in the cell nucleus, where DNA is located, or in the cytoplasm, where most cellular processes occur.

Professor Yu-Ying He's laboratory investigates how environmental factors, including UV radiation and arsenic in drinking water, disrupt molecular pathways and damage cellular systems, contributing to cancer development. During experiments, the team found that UV exposure significantly reduces YTHDF2 levels in cells. This "reader" protein specifically recognizes RNA sequences with a chemical modification called N6-methyladenosine (m6A).

The Mechanism and Consequences of Inflammation

When YTHDF2 was removed from skin cells, UV-induced inflammation became much more severe. This confirms that YTHDF2 plays a crucial role in suppressing inflammatory responses. While inflammation is important for protecting the body against infections, uncontrolled inflammation can lead to serious diseases, including cancer. Until now, the molecular mechanisms that restrain this response after UV damage have been poorly understood.

Interaction Between RNA and Immune Receptors

Using various methods and cell-based assays, researchers showed that YTHDF2 binds to a specific non-coding RNA called U6, which carries the m6A modification and belongs to the small nuclear RNA (snRNA) family. Under UV stress, cancer cells accumulate more U6 snRNA, and these modified RNAs interact with toll-like receptor 3 (TLR3)—an immune sensor that activates inflammation pathways linked to cancer.

Surprisingly, these interactions occurred inside endosomes—cellular compartments that usually process materials rather than contain U6 snRNA. For the first time, researchers demonstrated that the SDT2 protein transports U6 into the endosome, and YTHDF2 moves along with it.

Protective Mechanism and Therapeutic Prospects

When YTHDF2 and m6A-modified U6 RNA reach the endosome, YTHDF2 prevents this RNA from activating TLR3. In the absence of YTHDF2, such as after UV-induced damage, U6 RNA can freely bind to TLR3 and trigger harmful inflammatory reactions.

"Our research reveals a new level of biological regulation—a surveillance system via YTHDF2 that helps protect the body from excessive inflammation and related damage," notes Professor He.

This newly described pathway points to potential strategies for preventing and treating UV-induced skin cancer by targeting the interactions between RNA and proteins that control inflammation.