The eye lens crystallins : a playground for evolution

Abstract

From the dawn of evolution where primitive one-cellular organisms oriented themselves to the light of our sun by simple photoreceptors in search of energy to sustain their existence, to the current day where light from the environment is captured by our eyes, focused on the retina by the eye lens and then processed by our brain to useful visual information, light has been one of the strongest driving forces ever to have determined the course of evolution. Although eyes have been invented multiple times during evolution, and the great diversity of eyes found in species today represents the various solutions to a similar problem, very ancient underlying molecular mechanisms have been maintained in all species and still guide the development of eyes at various levels. The vertebrate eye is one of the more advanced types of eyes that can be found in animals today. It is characteristically called a 'camera-type' eye. The central position in the vertebrate eye is taken by the eye lens. This remarkable tissue has two properties crucial to vision. First, it is transparent, allowing light to pass through. Second, it is able to refract light, allowing the correct focusing of light on the retina. Responsible for both of these properties are the eye lens crystallins, structural proteins that are present in high concentrations in the lens fiber cells. In this thesis, some of the underlying molecular mechanisms for recruitment of these eye lens crystallins -- in particular of ßA3/A1-crystallin and iota-crystallin -- and the implications for their physiochemical properties are discussed