Complex contributions of fibronectin to initiation and maturation of microfibrils

Fibrillins constitute the backbone of extracellular multi-functional assemblies present in elastic and non-elastic matrices, termed microfibrils. Assembly of fibrillins into microfibrils and their homeostasis is poorly understood and is often compromised in connective tissue disorders such as Marfan syndrome and other fibrillinopathies. Using interaction mapping studies, we demonstrate that fibrillins require the complete gelatin-binding region of fibronectin for interaction, which is comprised of domains FNI6-FNI9. However, the interaction of fibrillin-1 with the gelatin-binding domain of fibronectin is not involved in fibrillin-1 network assembly mediated by human skin fibroblasts. We further show that the fibronectin network is essential for microfibril homeostasis in early stages. Fibronectin is present in extracted mature microfibrils from tissue and cells as well as in some in situ microfibrils observed at the ultra-structural level, indicating an extended mechanism for the involvement of fibronectin in microfibril assembly and maturation.
Source: BJ Cell - Category: Biochemistry Authors: Tags: BJ Cell Source Type: research