MFAP-4, Important for Elastin Formation, Related to Elasticity in Human Skin, and Association of Reduced Level with Aging and UV Exposure - First Findings

Kao researchers were among the first to notice the importance of dermal elastin as a causal factor of wrinkles and have been continuously performing related investigations for more than 30 years. Elastin is a protein complex consisting mainly of elastin molecules in a stacked formation. It has a highly elastic rubber-like construction and plays an important role in maintaining cutaneous elasticity.

In 2001, Kao researchers made a unique discovery regarding the expression of elastase (elastin degrading enzyme) inherent in skin by identifying an inhibitory substance. Later in 2011, Kao was the first to report that MFAP-4 is essential for formation of elastin. Those findings clarified that elastin formation is enhanced when the amount of MFAP-4 is high in cutaneous fibroblasts by which elastin is produced, whereas that formation is inhibited when the amount is reduced (Figure 1).^*2

Normal elastin formation is significant for maintaining skin elasticity. However, elastin is known to decrease and degenerate due to aging and UV exposure. In view of findings showing that the amount of MFAP-4 is involved in elastin formation, Kao researchers considered that its level might be related to human skin elasticity.

In the present study, the relationship between MFAP-4 expression and elasticity, as well as the effects of aging and UV radiation on MFAP-4 were quantitatively examined in human skin.

To confirm changes in MFAP-4 level associated with aging, amounts^*3 in skin in UV-unexposed (inner part of upper arm) and UV-exposed (external part of forearm) areas were compared between women in their 20s and 30s with those in their 60s. Those results confirmed that the amount of MFAP-4 was markedly lower in UV-unexposed areas of women in their 60s as compared to those in their 20s and 30s. These findings are the first to show that MFAP-4 level in human skin is decreased in association with aging (Figure 3).

Furthermore, a comparison of MFAP-4 amounts between UV-exposed and -unexposed areas of the women in their 60s revealed lower levels in exposed areas, confirming that MFAP-4 in human skin is reduced by chronic UV exposure (Figure 4).

The present quantitative results are the first to show that elasticity is low in human skin with reduced expression of MFAP-4, essential for elastin formation, and that its amount is decreased in association with aging and UV exposure. These findings confirm that MFAP-4 is closely linked with skin elasticity.

By making use of the findings obtained in the present study, Kao will continue to pursue research of elastin, with the aim to propose technology for realizing beautiful and healthy skin.

Elastin is formed by the following process:
(1) Proteins such as elastin molecules, MFAP-4, and fibrillin are produced by fibroblasts.
(2) Fibrillin is assembled to form microfibrils as a foundation for elastin.
(3) Elastin molecules bind to microfibrils to form mature elastin.
In step (2), the role of MFAP-4 is to assist with fibrillin assembly and form microfibrils at a relatively early stage of elastin formation.

Kao creates high-value-added products that enrich the lives of consumers around the world. Through its portfolio of over 20 leading brands such as Attack, Bioré, Goldwell, Jergens, John Frieda, Kanebo, Laurier, Merries and Molton Brown, Kao is part of the everyday lives of people in Asia, Oceania, North America and Europe. Combined with its chemical division, which contributes to a wide range of industries, Kao generates about 1,500 billion yen in annual sales. Kao employs about 33,000 people worldwide and has 130 years of history in innovation. Please visit the Kao Group website for updated information.