Abstract
Purpose::
To evaluate the potential protective role against oxidative stress of overexpression of the proteasome catalytic subunit beta 5 in lens epithelial cells.
Methods::
Cells from the human lens epithelial cell line SRA01/04 (LECs) were stably transfected either with a plasmid expressing the proteasome catalytic subunit beta5 or with an empty plasmid. Beta5-expressing LECs and controls were analyzed for the expression of beta1, beta2, beta5 and alpha1, alpha2, alpha6 proteasome subunits; chymotrypsin-like (CT-L) and peptidylglutamyl-peptide hydrolase (PGPH) catalytic activities; as well as for the accumulation of carbonylated proteins, rates of cell viability, and apoptosis after oxidative stress.
Results::
Stable expression of the beta5 proteasome subunit resulted in increased expression of the other beta catalytic subunits, increased CT-L and PGPH proteasome activities, and increased resistance to accumulation of carbonylated proteins and cell death after oxidative stress.
Conclusions::
The proteasome can be genetically "up-regulated" in lens epithelial cells by overexpression of the beta1 and beta5 catalytic subunit. The resulting increase in proteasome activity leads to a decrease in the accumulation of oxidized proteins and enhanced cell survival following oxidative stress.
Keywords: antioxidants • oxidation/oxidative or free radical damage • cataract