Cellular Expression of Zonula Occludens-1 Protein in Benign Neurofibroma and Normal Peripheral Nerves

Cell-cell attachment in the epithelial and endothelial cell sheets are held in place by tight junctions, adherens junctions and desmosomes. Tight junctions are made up of three integral membrane proteins, namely; claudins, occludin and junctional adhesion molecules. There is a wealth of evidence in the literature suggesting that tight junctions are primarily involved in the sealing of cellular sheets thereby regulating paracellular ion movements between sheets of epithelial cells. Thus, tight junction proteins constitute an essential part of this barrier in perineurial and endothelial cells particularly in peripheral nerves. Schwann cells in the peripheral nerves are isolated from the adjacent tissues by the perineurium which creates a diffusion barrier responsible for the maintenance of endoneurial stability. Some researchers have suggested that oncogenic Ras down regulates tight junction barrier functions thereby leading to the disruption of these barriers. Therefore, the loss of tight junction barriers function may enable growth factors to penetrate from the surrounding tissues to quiescent Schwann cells of the peripheral nerves that are capable of proliferation thus, ensuing neurofibroma formation. Here the researchers demonstrate the cellular expression of Zonula Occludens-1 (ZO-1) to the perineurial fibroblasts of the normal peripheral nerve and benign neurofibroma.