Research Summary
Skin undergoes dramatic age-related changes in its mechanical properties, including changes in tissue hydration and resiliency. Proteoglycans, which are macromolecular conjugates of protein and carbohydrate (glycosaminoglycan), play a role in these tissue properties. To investigate whether age-related changes in skin proteoglycans contribute to the mechanical changes in aging skin, proteoglycans from human skin of various ages were extracted and analyzed. Samples were taken from two different fetal stages, as well as from mature and senescent skin.
As skin ages, there is a decrease in the proportion of large chondroitin sulfate proteoglycans (versican) and a corresponding increase in the proportion of small dermatan sulfate proteoglycans (decorin). Fetal versican differs from the versican found in older skin, particularly in its chondroitin sulfate chains, as revealed by reactivity with antibodies to various chondroitin sulfate epitopes. Additionally, fetal skin decorin is slightly larger, whereas decorin from older skin shows greater polydispersity in both size and charge-to-mass ratio. Age-related differences were also observed in the size and polydispersity of the core proteins of decorin.
The most significant change in skin proteoglycans is the emergence in mature skin of a proteoglycan smaller than decorin, which has the same amino terminal sequence as decorin. This small proteoglycan, abundant in mature skin, may be either a catabolic fragment or an alternatively spliced form of decorin. Given decorin's known influence on collagen fibrillogenesis and fibril diameter, the appearance of this small decorin-related proteoglycan could have a notable effect on skin elasticity.
These findings suggest that the age-related differences in skin proteoglycans may play a role in the mechanical changes that occur with skin aging.
Key Words: proteoglycan, chondroitin sulfate, dermatan sulfate, glycosaminoglycan, skin.
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