The Impact of Adherens and Tight Junctions on Physiological Function and Pathological Changes in the Retina

The formation of solid tissues is not a simple aggregation of individual cells but rather an ordered assembly of cells connected by junctions. These junctions provide a diffusion barrier as well as mechanical support and a conduit for signalling changes in the environment to the cells. Cell junctions are functionally categorized as occluding (e.g. tight junctions, TJs), anchoring (e.g. adherens junctions, AJs) and communicating junctions (e.g. gap junctions). Each type of the cell junction is formed by protein complexes with extracellular domains and/or intracellular domains, which bind partners that provide scaffolding and signalling components. Cell junctions are ubiquitously expressed in multiple tissues and organs, including the retina. In the retina, their biological impact is not limited to regulating tissue growth and development. Disruption of the complexes mediates both congenital and postnatal pathogenesis. In this review, we will focus on cell junctions, specifically AJs and TJs in the external limiting membrane, in order to articulate their influence on pathophysiology of the retina.