Turnover of Elastin

The turnover rate of mature elastin in healthy persons is relatively low. Insoluble elastin in healthy elastic tissue is usually stable and subjected to minimal proteolytic degradation. In several clinical conditions (e.g., emphysema, advanced atherosclerosis, pancreatitis), increased degradation of fragmentation of elastic fibers may play a significant role. The interaction between insoluble elastin and soluble elastolytic enzymes, and the regulation of these enzymes, may shed light on certain cardiovascular diseases, in view of the role of elastin in arterial dynamics. 

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Elastogenesis occurs primarily during late fetal and early neonatal periods. Elastin is synthesized and secreted from several cell types including smooth muscle cells, fibroblasts, endothelial cells, chondroblasts, and mesothelial cells (Uitto et al, 1991) with tissue-specific induction of elastin expression during development (Swee et al, 1995). After elastin has been deposited, its synthesis ceases and very little turnover of elastin is seen during adult life, unless the elastic fibers are subject to injury. In this case,... 

When the metabolic turnover of elastin in arterial tissue or in lung is examined, it is extremely difficult to demonstrate active turnover. Once an elastin fiber is formed it appears to be fixed. The turnover of rat aorta elastin is best measured in years (8). Data shown in Figure 5 also suggests negliable turnover. The animal used for this study, the Japanese quail, was chosen because it fully matures at 5-6 weeks of age. Similar to the rat its elastin appears to turn over in amounts best estimated in years. 

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