Carbonylated proteins are eliminated during reproduction in C. elegans

Abstract

Oxidatively damaged proteins accumulate with age in many species (Stadtman (1992) Science257, 1220-1224). This means that damage must be reset at the time of reproduction. To visualize this resetting in the roundworm Caenorhabditis elegans, a novel immunofluorescence technique that allows the detection of carbonylated proteins in situ was developed. The application of this technique revealed that carbonylated proteins are eliminated during C.elegans reproduction. This purging occurs abruptly within the germline at the time of oocyte maturation. Surprisingly, the germline was markedly more oxidized than the surrounding somatic tissues. Because distinct mechanisms have been proposed to explain damage elimination in yeast and mice (Aguilaniu etal. (2003) Science299, 1751-1753; Hernebring etal. (2006) Proc Natl Acad Sci USA103, 7700-7705), possible common mechanisms between worms and one of these systems were tested. The results show that, unlike in yeast (Aguilaniu etal. (2003) Science299, 1751-1753; Erjavec etal. (2008) Proc Natl Acad Sci USA105, 18764-18769), the elimination of carbonylated proteins in worms does not require the presence of the longevity-ensuring gene, SIR-2.1. However, similar to findings in mice (Hernebring etal. (2006) Proc Natl Acad Sci USA103, 7700-7705), proteasome activity in the germline is required for the resetting of carbonylated proteins during reproduction in C.elegans. Thus, oxidatively damaged proteins are eliminated during reproduction in worms through the proteasome. This finding suggests that the resetting of damaged proteins during reproduction is conserved, therefore validating the use of C.elegans as a model to study the molecular basis of damage elimination.