Surface induced assembly of fibronectin into fibrillar networks: a study of the molecular pathway

The cell-mediated assembly of fibronectin (Fn) into fibrillar matrices is a complex, multistep process that is still incompletely understood. This is due to the complexity of the chemical composition of the extracellular matrix combined with a lack of control over molecular interactions and dynamic events. The authors have found that Fn fibril assembly into extended two-dimensional networks can be induced by adsorbing Fn from a physiological buffer solution to a dipalmitoyl-phosphatidylcholine (DPPC) monolayer in the LC phase, followed by gradual monolayer expansion. A sequential model for the assembly pathway is proposed. Striking similarities are found between the properties of these Fn fibrils assembled underneath DPPC monolayers and those found on cellular surfaces as well as between the respective sequential assembly pathways. Spontaneous Fn fibril assembly underneath DPPC monolayers can now serve as a well controlled model system to study how different parameters such as the deletion of key Fn sequences, as well as alterations of solution and surface conditions, and the presence of other proteins, affect the molecular assembly pathway