A cataract-free 13-lined ground squirrel. Credit: Jared

Researchers in the US and China have identified a protein that reversed cataracts in rodents.

Writing in the Journal of Clinical Investigation researchers at the US National Eye Institute (NEI) studied a mammalian hibernator, the 13-lined ground squirrel. During hibernation, the ground squirrel’s lenses become cloudy at around 4°C but quickly clarify again after rewarming, said researchers, while non-hibernators (rats, in this study) develop cataracts in the cold, which do not resolve with rewarming. Humans do not develop cataracts when exposed to low temperatures, they noted.

Researchers discovered a CRYAA (crystallin alpha A) enzyme, RNF114, was significantly elevated during rewarming in the ground squirrel, compared with the rat. RNF114 had previously been shown to mediate and maintain protein turnover and homeostasis of CRYAA in the lens. After pre-treating the cold-incubated rat cataract model with RNF114, there was a rapid clearing of the cataract upon rewarming, said researchers.

“The screening and design of drugs that stimulate specific protein degradation pathways can contribute to the precise regulation of protein stability and turnover, potentially leading to advances in proteostasis maintenance and the treatment of protein aggregation diseases,” they concluded.