The role of ceramide in radiation-induced bystander effect on germ cells in Caenorhabditis elegans / 中华放射医学与防护杂志

ABSTRACT

Objective To investigate the role of ceramide in radiation induced bystander effect (RIBE) in vivo by irradiating Caenorhabditis elegans with proton microbeam.Methods The posterior pharynx of wide-type N2 and genetically mutated L4-staged worms was irradiated with 2 000 particles,then germ cell apoptosis and gene expression were analyzed.Results Point-fixed radiation to posterior pharynx of N2 worms significantly increased the number of apoptotic germ cells (t =9.007,P＜0.05),but not in the worms with deletion mutants of ceramide synthase (CerS) genes (hyl-1 and lagr-1) (P＞0.05).Realtime quantitative PCR assay indicated that in both N2 and lagr-1 (gk327);hyl-1 (ok976) worms,the genes of egl-1 and ced-13 in core apoptosis pathway were up-regulated after radiation to posterior pharynx,without statistical significance between these two strains (P＞0.05).The gene expression levels of hyl-1 and lagr-1 were increased in both N2 and hus-1 (op241) worms after radiation with no statistical significant difference between two strains (P＞0.05).Furthermore,radiation-induced germ cell apoptosis was increased in abl-1 (ok171) worms (t=13.241,P＜0.05),rather than in lagr-1(gk327);hyl-1(ok976);abl-1(ok171) worms (t=13.462,P＜0.05).Conclusions Ceramide is required for RIBE on germ cell apoptosis in C.elegans,and it might play function together with egl-1 and ced-13 in core apoptosis pathway and HUS-1 in DNA damage response pathway.But ceramide had antagonistic relationship with anti-apoptotic protein abl-1 in germ cell apoptosis.