Elastin

Elastin is a highly elastic extracellular matrix protein that provides resilience and elasticity to connective tissues. It is the major component of elastic fibers, which also include fibrillin-containing microfibrils that form a scaffold. Elastin-rich tissues include skin, lungs, arteries, ligaments, and certain tendons. The protein allows tissues to stretch and snap back after deformation, contributing to mechanical properties such as recoil.

Elastin is synthesized as the soluble precursor tropoelastin by fibroblasts and smooth muscle cells. Tropoelastin is secreted into the extracellular space, where it assembles with microfibrils and undergoes cross-linking catalyzed by lysyl oxidase. This cross-linking creates desmosine and isodesmosine residues that stabilize elastin; the mature elastin fiber is highly insoluble and long-lived, with slow turnover.

Elastin is encoded by the ELN gene on chromosome 7q11.23. Mutations or haploinsufficiency of ELN can cause connective tissue disorders, notably supravalvular aortic stenosis and other vascular anomalies associated with Williams syndrome. Elastin deficiency or degradation also contributes to skin aging and to pulmonary diseases such as emphysema when elastin in alveolar walls is destroyed by elastases.

Clinical relevance: the structural integrity of elastic tissues depends on elastin content and cross-linking; changes in elastin affect tissue elasticity and mechanical aging. Therapeutic considerations in some diseases aim to preserve elastin integrity or limit excessive elastolysis.