Proteomic Study on X-irradiation-responsive Proteins and Ageing: Search for Responsible Proteins for Radiation Adaptive Response

Abstract

We investigated high- or low-dose irradiation-responsive proteins using proteomics on two-dimensional (2D) PAGE, and the effects of ageing on cell responses to radiation in variously aged rat astrocytes. After 5 Gy irradiation, the relative abundance of peroxiredoxin 2, an antioxidant enzyme, and latexin, an inhibitor of carboxypeptidase, increased. The induction of these proteins was suppressed by ageing, suggesting that the response to high-dose radiation decreased with ageing. The relative abundance of elongation factor 2 (EF-2) fragment increased 3 h and reduced 24 h after 0.1 Gy irradiation. Temporal enhancement of the EF-2 fragment due to low-dose irradiation was suppressed by ageing. Since radiation adaptive response in cultured astrocytes was observed 3 h but not 24 h after 0.1 Gy irradiation and suppressed by ageing as previously reported, alteration of the EF-2 fragment corresponded to the radiation adaptive response. We also examined phospho-protein profiles, resulting in the relative abundance of phospho-EF-1beta and phospho-beta-actin being altered by 0.1 Gy irradiation; however, ageing did not affect the alteration of phospho-EF-1beta and phospho-beta-actin, unlike the EF-2 fragment. The results suggested that the EF-2 fragment was a possible candidate for the protein responsible for the radiation adaptive response in cultured astrocytes.

Plasma biomarkers of mouse aging

“…In Caenorhabditis elegans, Prx protects against oxidative stress and heat stress, as well as promotes longevity (OlÃhovà et al 2008). In rats, Prx-2 is induced in primary astrocyte cultures from young rats (1 month) but not adult or aged rats (9 and 24 months of age) after exposure to X-ray irradiation (Miura et al 2007). In terms of intracellular signaling, Prx-2 inhibits mouse embryonic fibroblast senescence by inhibiting the Ras-ERK-NFκB pathway (Han et al 2006).…”

“…Proteomic techniques including two-dimensional gel electrophoresis (2-DE) have been used to study aging (Ballesteros et al 2001;Gromov et al 2003;Sato et al 2006;Miura et al 2007) and have led to the identification of many candidate proteins that are altered by aging. For example, older human skin expresses reduced levels of certain proteins, including manganese-superoxide dismutase, tryptophanyl-tRNA synthetase, the p85ß subunit of phosphatidylinositol 3-kinase, and proteasomal proteins PA28-α (Gromov et al 2003).…”

“…For example, older human skin expresses reduced levels of certain proteins, including manganese-superoxide dismutase, tryptophanyl-tRNA synthetase, the p85ß subunit of phosphatidylinositol 3-kinase, and proteasomal proteins PA28-α (Gromov et al 2003). In rats, peroxiredoxin-2, an antioxidant enzyme, is able to be induced by irradiation in cultured astrocytes from young but less so from old rats (Miura et al 2007). Phosphorylation of α-tubulin is increased with age in rat astrocytes (Miura et al 2007) and N-glycosylated proteins including cathepsin D, a lysosomal protease, are found to accumulate in aged rat cerebral cortex (Sato et al 2006).…”

“…In rats, peroxiredoxin-2, an antioxidant enzyme, is able to be induced by irradiation in cultured astrocytes from young but less so from old rats (Miura et al 2007). Phosphorylation of α-tubulin is increased with age in rat astrocytes (Miura et al 2007) and N-glycosylated proteins including cathepsin D, a lysosomal protease, are found to accumulate in aged rat cerebral cortex (Sato et al 2006). Additionally, oxidized proteins have been found to be increased in senescent bacteria cells (Ballesteros et al 2001).…”

Proteomic Approach for Biomarker Discovery in Radioadaptive Responses-Age-Dependent Variations of Cell Response to Low-Dose Radiation-

“…Radiation effects on protein profiles have been generally studied on the high-dose effects to explore clinical biomarkers of radiotherapy (Menard et al, 2006) and the factors responsible for radiation resistance (Wang et al, 2005), and to elucidate radiation injury caused by depleted uranium (Malard et al, 2005). We focused on low-dose effects and analyzed the variation of protein expression and phosphorylation involved in the radioadaptive response using proteomics (Miura et al, 2007).…”