IIIkollagen

IIIkollagen, commonly known as type III collagen, is a fibrillar collagen that forms a homotrimer of three alpha-1(III) chains encoded by the COL3A1 gene. It is broadly distributed in tissues that require elasticity and a supportive reticular framework, including the skin, lungs, vascular walls, intestines, uterus, and fetal tissues. In mature tissues it often coexists with type I collagen, contributing to a delicate, thin-fibril reticular network.

Biosynthesis and maturation begin in fibroblasts, endothelial cells, and smooth muscle cells, where type III collagen is produced as procollagen with N- and C-terminal propeptides. After secretion, extracellular proteases remove these propeptides to form mature collagen that assembles into thin fibrils and is cross-linked by lysyl oxidase, enhancing tissue strength and resilience.

Functionally, type III collagen provides structural support and elasticity, supporting rapidly changing tissues and wound healing. Its reticular network helps organize cells and forms a scaffold for vessel walls and other soft tissues.

Clinical significance centers on COL3A1 mutations, which are associated with vascular Ehlers-Danlos syndrome (EDS). This condition features fragility of blood vessels and hollow organs, easy bruising, and a heightened risk of arterial rupture. Altered type III collagen is also observed in some fibrotic conditions and during aging. Diagnosis can involve histological assessment of reticular fibers and specific COL3A1 testing.

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