Age-dependent alterations of decorin glycosaminoglycans in human skin

Abstract

Proteoglycans, a family of glycosaminoglycan (GAG) conjugated proteins, are important constituents of human skin connective tissue (dermis) and are essential for maintaining mechanical strength of the skin. Age-related alterations of dermal proteoglycans have not been fully elucidated. We quantified transcripts of 20 known interstitial proteoglycans in human skin and found that decorin was the most highly expressed. Decorin was predominantly produced by dermal fibroblasts. Decorin was localized in dermal extracellular matrix with GAG bound to type I collagen fibrils. Analysis of decorin extracted from young (21–30 years) and aged (>80 years) sun-protected human buttock skin revealed that decorin molecular size in aged skin is significantly smaller than in young skin. The average size of decorin protein did not alter, indicating size of GAG chain is reduced in aged, compared to young skin. This age-dependent alteration of decorin GAG may contribute to skin fragility of elderly people.

Aging Versus Postmenopausal Osteoporosis: Bone Composition and Maturation Kinetics at Actively-Forming Trabecular Surfaces of Female Subjects Aged 1 to 84 Years

“…(51) The subsequent significant decline in the PreM and PostM groups would be in agreement with data on skin decorin showing that in advanced aging, the size of the GAG chains is greatly reduced whereas the average size of the decorin protein remains unaltered. (46) Inclusion of the PostM-OP individual data in the regression analyses considerations improved the calculated r 2 values (Table 5), but there were no statistical differences between the two regression models, suggesting that this metric may not be used to discriminate between healthy aging and PostM-OP.…”

“…(46) Thus, changes in the spectroscopically determined GAG content may be due to either changes in proteoglycan content, or altered posttranslational modifications, or altered microporosity and nanoporosity (proteoglycans are abundant in the canalicular network (34) ), or any combination of the three. In disease (PostM-OP), the GAG content was significantly lower than in health (PostM) at TA3.…”

Ring-Mesh Model of Proteoglycan Glycosaminoglycan Chains in Tendon based on Three-dimensional Reconstruction by Focused Ion Beam Scanning Electron Microscopy

“…5a). In the "binding model" (18,25) where GAG chains adhere to the surface of collagen fibrils, GAG chains will appear on both sides or on the center of a collagen fibril (Fig. 5b).…”

“…The general thickness of ultrathin sections for TEM observation is ϳ70 nm. The diameter of collagen fibrils in the dermis is approximately 60 nm (25), whereas the tendon contains a large number of collagen fibrils Ͼ 100 nm in diameter, which form regular waves called crimps (23,26,27). Thus, it is possible that decorin GAG chains in the tendon were not always observed to be straight but were assumed to be helical and wavy, making it difficult to observe GAG chains surrounding collagen fibrils.…”

“…In the dermis of the skin, decorin GAG chains were suggested to surround collagen fibrils (18,25), though the ring mesh-like structure has not been explicitly proposed. In contrast, in the tendon, decorin GAG chains are assumed to have a radial arrangement between collagen fibrils (11,14), as illustrated in Fig.…”