Jacobs Journal of Anatomy and Physiology

Molecular Regulation of Eye Development: Role of the PAX Gene

*Tabinda Hasan
Department Of Medicine, Al Maarefa College Of Medicine, Riyadh, Saudi Arabia

*Corresponding Author:
Tabinda Hasan
Department Of Medicine, Al Maarefa College Of Medicine, Riyadh, Saudi Arabia

Published on: 2018-10-23


The development of eye has long been studied using classical embryological methods in birds, amphibians and primates. Early research has described interactions between different elements that take part in formation of the eye at the tissue level. But molecular regulation of eye development is a field that seems to invite further exploration. A number of ocular mutations and syndromes have been studied to elucidate regulatory molecules in eye development. Positional cloning of genes at mutated loci form the basis of functional and chromosomal location data in responsible molecules. Particular attention has been devoted in recent researches to the molecular biology of the PAX6(paired box) gene because of its high degree of conservation and its ability to regulate development of compound and simple eye structures in both vertebrates and invertebrates through loss and gain of function mechanisms. This paper comprehensively explores the molecular structure of PAX 6 gene, its role in eye development, its analogues and the full potential of its therapeutic and developmental applications.



The eye develops from an out-pouching of the diencephalon. A series of induction and regionalization events in the neuro-ectoderm generate and shape the optic cup, vesicle, lens etc. The origin of Pax(paired box protein) genes predates the origin of eyes and even the nervous system. The ancestral Pax gene (PaxB) was related to Pax2,5 and 8. Interestingly, it was identified in the sponge that has neither eyes nor the nervous system. Cnidaria are the most basal animal models that have simple or complex (lens containing) eyes as well as Pax genes. Cnidarian (Tripedalia) PaxB gene is expressed in lens and retina and activates both lens crystallin and opsin reporter genes. This data indicates that modern the Pax2 and Pax6 genes evolved from a cnidarian PaxB ancestor by the mechanism of duplication and diversification in Bilateria with Pax2 loosing its HD and PAX6 loosing its octapeptide (yellow box) along the way. Aniridia, a human genetic disease manifested by alterations in structure and function of the eye, includes reduced iris size, absence of fovea, and lens deformities. It was documented as a genetic disease more than a hundred years ago. It is an ideal model for demonstrating autosomal dominant genetic disorders because of the high penetrance of its mutant alleles, the ease of diagnosis at birth, and a relatively similar incidence in various populations.