Over-expression of human clusterin increases stress resistance and extends lifespan in Drosophila melanogaster

► We established transgenic Drosophila alleles to induce the expression of clusterin. ► Clusterin overexpression prolongs mean lifespan in Drosophila. ► Clusterin overexpression increases stress resistance and reduces ROS in Drosophila. ► Clusterin reduces ROS via its cysteine sulfhydryl groups and delays aging in flies. Clusterin is a disulfide-linked heterodimeric glycoprotein that has been implicated in a variety of biological processes. Its expression has been shown to be elevated during cellular senescence and normal aging, but it is uncertain whether clusterin protects against aging or whether its expression is a consequence of aging. To investigate the functions of clusterin during organismal aging, we established transgenic Drosophila alleles to induce the expression of the secretory form of human clusterin (hCluS) using the Gal4/UAS system. hCluS protein (∼60kDa) was detected in both adult homogenates and larval hemolymphs of flies ubiquitously overexpressing hCluS (da-Gal4>UAS-hCluS) and in motoneurons (D42-Gal4>UAS-hCluS). Interestingly, the mean lifespans of these hCluS-overexpressing flies were significantly greater than those of control flies that exhibited no hCluS induction. hCluS-overexpressing flies also showed significantly greater tolerance to heat shock, wet starvation, and oxidative stress. Furthermore, amounts of reactive oxygen species (ROS) in whole bodies were significantly lower in hCluS-overexpressing flies. In addition, clusterin was found to prevent the inactivation of glutamine synthetase (GS) by metal-catalyzed oxidation (MCO) in vitro, and this protection was only supported by thiol-reducing equivalents, such as, DTT or GSH, and not by ascorbate (a non-thiol MCO system). Furthermore, this protection against GS inactivation by clusterin was abolished by reacting clusterin with N-ethylmaleimide, a sulfhydryl group-modifying agent. Taken together, these results suggest that a disulfide-linked form of clusterin functions as an antioxidant protein via its cysteine sulfhydryl groups to reduce ROS levels and delay the organismal aging in fruit flies.