Greater understanding about the role of mucin proteins in the skin

The outermost layer of skin, the epidermis, provides a physical barrier of protection from harmful substances and invasion of pathogens such as viruses and bacteria. Part of this skin barrier consists of types of proteins called mucins. Mucins are also found in other body organs, but less is known about their role in the skin than in other organs. However, we see that mucin can be used as a diagnostic clue in some skin disorders, such as overexpression of mucin in some skin cancers. In this study from Korea, the authors set out to understand more about the role of mucin proteins in the skin. The study found that several mucin proteins are expressed in human skin. Among these, mucin‐like protein 1 (MUCL1) showed high expression and a clear negative association with melanogenesis (the production of melanin pigments, which determine the colour of our skin and protect us against ultraviolet radiation damage) as the mucin layer is mainly composed of the amino acids serine and threonine. The present study investigated the relationship of these amino acids with MUCL1 and found that the amino acid threonine could regulate MUCL1 in melanocytes (the cells producing melanin) and melanoma cells (i.e. cells found in some forms of skin cancers). This study provides a greater understanding of the role of mucins and threonine in skin dysfunction.