Cytoprotective effects of proteasome beta5 subunit overexpression in lens epithelial cells.
OBJECTIVE
To determine whether the overexpression of the proteasome catalytic beta5 subunit (PSMB5) can induce the expression of the catalytic subunits beta1 and beta2, enhance proteasome activity, and exert a cytoprotective effect 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. beta-5-expressing LECs and controls were analyzed for the expression of beta1, beta2, beta5, and 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 catalytic subunits beta1 and beta2, increased CT-L and PGPH proteasome activities, and increased resistance to accumulation of carbonylated proteins and cell death after oxidative stress.


CONCLUSIONS
The proteasome activity can be genetically "upregulated" in lens cells by overexpression of the 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.
Liu
Yizhi
Y
Zhongshan Ophthalmic Center of Sun Yat-Sen University, State Key Laboratory of Ophthalmology, Guangzhou, China. yizhiliu_0001@yahoo.com
Liu
Xialin
X
Zhang
Tieying
T
Luna
Coralia
C
Liton
Paloma B
PB
Gonzalez
Pedro
P
D002460:Cell Line; D002470:Cell Survival; D002918:Chymotrypsin / Q000378:metabolism; D019610:Cytoprotection / Q000502:physiology*; D010450:Endopeptidases / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism / Q000502:physiology; D005136:Eye Proteins / Q000378:metabolism; D006801:Humans; D007908:Lens, Crystalline / Q000378:metabolism* / Q000502:physiology; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000502:physiology; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D050050:Protein Carbonylation / Q000502:physiology
D005136:Eye Proteins; D010450:Endopeptidases; D002918:Chymotrypsin; C088874:PSMB5 protein, human; D046988:Proteasome Endopeptidase Complex; C114177:peptidylglutamylpeptide hydrolase