Researchers have unravelled the role of a cell signalling protein (cytokine) called IFN-γ in skin tanning1. The protein regulates several skin pigmentation genes and hampers the maturation of a key organelle responsible for tanning of the skin. The finding could have wide implications in the management of ailments such as sunburn and skin cancer.
Skin tanning is a protective response of epidermal cells in which they form more melanin. Overexposure to sun can cause sunburn and even skin cancer, partly due to the accumulation of toxic side products of melanin and its intermediates.
The researchers studied the importance of the key immune cytokine IFN-γ in cultured human melanocyte cells and disease models (both mice and human). They found that IFN-γ signalling regulates enzymes involved in melanin production. IFN-γ signalling hindered the maturation of the key organelle melanosome by regulating several pigmentation genes. Withdrawal of IFN-γ signal was found to restore normal cellular programming. Chronic IFN-γ signalling showed clear hypopigmentation (loss of skin colour) in both mouse and human skin.
The study identifies a new mechanism of skin pigmentation. It proposes that the strength and durability of the skin's immune response may be factors deciding if the anomaly would show up as tanning or cancer.
The finding outlines a "new role of the IFN-γ signalling network in skin pigmentation homeostasis, which could have implications in various cutaneous depigmentary and malignant disorders", the researchers say.
The authors of this work are from: CSIR-Institute of Genomics and Integrative Biology, National Institute of Immunology, Jawaharlal Nehru University & Academy of Scientific and Innovative Research & Post Graduate Institute of Medical Education and Research, Dr. Ram Manohar Lohia Hospital, New Delhi; CSIR-National Chemical Laboratory, Pune, Maharashtra; and Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, Karnataka, India.
