Tropoelastina

Tropoelastina is the soluble precursor to elastina, the protein that forms elastic fibers in the extracellular matrix. In humans, the tropoelastina polypeptide is encoded by the ELN gene and is produced by cells such as fibroblasts and vascular smooth muscle cells. It is synthesized as a secreted polypeptide of substantial size, containing regions that are hydrophobic as well as cross-linking domains, and it includes a signal peptide that directs its export from the cell.

After secretion, tropoelastina interacts with a scaffold of microfibrillar proteins, notably fibrillin-1 and fibrillin-2, at the cell surface. The final elastin fiber is formed when tropoelastina molecules are cross-linked extracellularly by enzymes such as lysyl oxidase, creating desmosine and isodesmosine cross-links that stabilize the elastic network.

The elastic fibers assembled from tropoelastina provide resilience and the ability of tissues to stretch and recoil. Elastin-rich tissues include skin, lungs, major arteries, and certain ligaments. Tropoelastina synthesis continues during growth and tissue repair, contributing to the maintenance of tissue elasticity, while elastin itself is long-lived and turnover is relatively limited in mature tissues.

Regulation and clinical relevance: mutations in the ELN gene or defects in elastin assembly can lead to connective tissue disorders such as cutis laxa and, in some cases, vascular anomalies like supravalvular aortic stenosis. Elastin degradation by proteases and age-related changes also reduce tissue elasticity, contributing to conditions such as emphysema, arterial stiffening, and skin aging. Research on tropoelastina focuses on understanding its synthesis, assembly, and potential therapeutic modulation of elastogenesis.