Nidogen and nidogen-associated basement membrane proteins and neuronal plasticity

Extracellular matrix (ECM) proteins are thought to subserve structural functions as, for example, tissue barriers as well as guidance structures during cell growth, differentiation and tissue repair. Deletion of basement membrane (BM) components results in malformations of different organs, including the brain. Recent data, however, suggest that interference with cellular membrane-associated proteins interacting with ECM can alter neuronal excitability and synaptic plasticity without obvious underlying structural damage. This does not only apply to classical ECM proteins such as laminin, reelin and tenascin, but also to molecules of a rather specialized ECM, the BM. Here, nidogen (also termed entactin) appears to subserve a function in neuronal plasticity. Nidogen ablation leads to epileptic activity in vivo and the appearance of spontaneous epileptiform activity in vitro. This raises the intriguing question whether the BM protein nidogen may directly influence neuronal function in the CNS, opening the possibility of modulatory mechanisms of synaptic plasticity and excitability reaching beyond classical processes confined to cellular interactions.