Fibrillin

Fibrillin-1 was isolated by Engvall in 1986; fibrillin-2 was first isolated by Zhang in 1994.

Fibrillin is the main component of microfibrils. Fibrillin is an unusually cysteine-rich glycoprotein. Phylogenetically, fibrillin appeared about 800 to 1,000 million years ago and thus about 500 million years earlier than elastin, which is only found in vertebrates.

Fibrillin (fibrillin -1 and -2) is a 350 kDa, ubiquitously expressed, extracellular, unusually cysteine-rich glycoprotein. It is secreted by fibroblasts into the extracellular matrix where it organizes itself into microfibrils (fibrin microfibrils, FMF). These enter into a close structural and functional bond with the amorphous elastin, which, as in the case of elastic fibres, envelops them like a sheath.

Microfibrils also occur as elastin-free fibers, e.g. in the skin as so-called oxytalan fibers in the dermo-epidermal junction zone of the papillary dermis. This fine-structured fibre system can be well represented by elastic staining. Furthermore, elastin-free fibres are found in the hyaline cartilage and in the zonula fibres of the eye lens.

During the regeneration process of the skin, microfibrils are first formed which are then coated with elastin.

Beyond their importance for the structural integrity of tissues, these proteins also control the growth and differentiation processes of the connected tissues. This is done by controlling the activities of growth factors. It has been shown that fibrillin microfibrils can bind growth factors such as the "transforming growth factor-β" (TGF- β).

FBN1 mutations lead to hereditary diseases with overlapping and opposing characteristics, which are called "fibrillinopathies". The clinical manifestations of these "fibrillinopathies" range from thin to thick and hyperelastic or fragile to hard skin. Mutations in the FBN1 gene are responsible for Marfan syndrome.

Fibrillin-2 plays an essential role in the early phase of elastogenesis (formation of elastic fibres). Mutations in the fibrillin-2 gene have been linked to Beals pike syndrome.