抄録
In Caenorhabditis elegans (C. elegans), it is confirmed a radiation hormesis which extends life span by exposing to short term oxygen radicals. We have clarified that daf-16 gene which is a homolog of human fork head transcription factor is associated with hormesis. That is, daf-16(m26) animal has short lifespan and its lifespan extension by holmesis was not observed. The purpose of this presentation is to demonstrate an activated mechanism of the downstream genes which is directly related to the lifespan extension by hormesis.
Comparison of mRNA level using cDNA microarray between daf-16(m26) and age-1(hx546) animals showed decreased expression of metallothionein, protease and anti-oxidative genes in daf-16 animal. A mutation of age-1 gene functioned in the upstream within the signal transduction pathway of the DAF-16 leads to a remarkable lifespan extension by hormesis. In these genes, we measured the expression levels of genes with eight bases of the DAF-16 consensus binding element (DBE) in the 5'-UTR, and demonstrated that the expression of daf-16 mutant was less compared to age-1 mutant. Therefore, to express the life span extension effect by radiation hormesis, it is necessary for anti-oxidative and proteolysis systems to be activated. The possible action of daf-16 gene in the upstream for the activation is also suggested.
