Lens proteome map and -crystallin profile of the catfish Rita rita.

ABSTRACT

Crystallins are a diverse group of proteins that constitute nearly 90% of the total soluble proteins of the vertebrate eye lens and these tightly packed crystallins are responsible for transparency of the lens. These proteins have been studied in different model and non-model species for understanding the modifications they undergo with ageing that lead to cataract, a disease of protein aggregation. In the present investigation, we studied the lens crystallin profile of the tropical freshwater catfish Rita rita. Profiles of lens crystallins were analyzed and crystallin proteome maps of Rita rita were generated for the first time. A-crystallins, member of the -crystallin family, which are molecular chaperons and play crucial role in maintaining lens transparency were identified by 1-and 2-D immunoblot analysis with anti-A-crystallin antibody. Two protein bands of 19-20 kDa were identified as A-crystallins on 1-D immunoblots and these bands separated into 10 discrete spots on 2-D immunoblot. However, anti-B-crystallin and antiphospho-B-crystallin antibodies were not able to detect any immunoreactive bands on 1- and 2-D immunoblots, indicating B-crystallin was either absent or present in extremely low concentration in Rita rita lens. Thus, Rita rita -crystallins are more like that of the catfish Clarias batrachus and the mammal kangaroo in its A- and B-crystallin content (contain low amount from 5-9% of aB-crystallin) and unlike the dogfish, zebrafish, human, bovine and mouse -crystallins (contain higher amount of B-crystallin from 25% in mouse and bovine to 85% in dogfish). Results of the present study can be the baseline information for stimulating further investigation on Rita rita lens crystallins for comparative lens proteomics. Comparing and contrasting the -crystallins of the dogfish and Rita rita may provide valuable information on the functional attributes of A- and B-isoforms, as they are at the two extremes in terms of A-and B-crystallin content.