A Novel Missense Mutation in the Gene Encoding Major Intrinsic Protein (MIP) in a Giant Panda with Cataracts

Abstract

Background : Cataracts are defects of the lens that cause progressive visual impairment and ultimately blindness in many vertebrate species. Most cataracts are age-related, but up to one third have an underlying genetic cause. Cataracts are common in captive zoo animals, but it is often unclear whether these are congenital or sporadic (age-related) lesions.Results: Here we used a functional candidate gene-screening approach to identify mutations associated with cataracts in a captive giant panda ( Ailuropoda melanoleuca ). We identified a novel missense mutation ( c.686G>A) in the MIP gene encoding major intrinsic protein, which is expressed in the lens and normally accumulates in the plasma membrane of lens fiber cells, where it plays an important role in fluid transport and cell adhesion. The mutation causes the replacement of serine with asparagine ( p.229S>N ) in the C-terminal tail of the protein, and modeling revealed that mutation-induced conformational changes may interfere with lens permeability and cell–cell interactions.Conclusions: The mutation was not found in healthy pandas, suggesting it could serve as a new informative marker to predict the risk of congenital cataracts in captive giant pandas.