Alteration of the Serum N-glycome of Mice Locally Exposed to High Doses of Ionizing Radiation

Abstract

Exposure of the skin to ionizing radiation leads to characteristic reactions that will often turn into a pathophysiological process called the cutaneous radiation syndrome. The study of this disorder is crucial to finding diagnostic and prognostic bioindicators of local radiation exposure or radiation effects. It is known that irradiation alters the serum proteome content and potentially posttranslationally modifies serum proteins. In this study, we investigated whether localized irradiation of the skin alters the serum glycome. Two-dimensional differential ingel electrophoresis of serum proteins from a man and from mice exposed to ionizing radiation showed that potential post-translational modification changes occurred following irradiation. Using a large-scale quantitative mass-spectrometry-based glycomic approach, we performed a global analysis of glycan structures of serum proteins from non-irradiated and locally irradiated mice exposed to high doses of ␥-rays (20, 40, and 80 Gy). Non-supervised descriptive statistical analyses (principal component analysis) using quantitative glycan structure data allowed us to discriminate between uninjured/ slightly injured animals and animals that developed severe lesions. Decisional statistics showed that several glycan families were down-regulated whereas others increased, and that particular structures were statistically significantly changed in the serum of locally irradiated mice. The observed increases in multiantennary N-glycans and in outer branch fucosylation and sialylation were associated with the up-regulation of genes involved in glycosylation in the liver, which is the main producer of serum proteins, and with an increase in the key proinflammatory serum cytokines IL-1␤, IL-6, and TNF␣, which can regulate the expression of glycosylation genes. Our re-

Changes of protein glycosylation in the course of radiotherapy

“…During the glycosylation analysis of irradiated mice serum samples Chaze et al [17] observed the decrease of biantennary structures; and increase of tri-tetra-and pentaantennary Nglycans, outer branch fucosylation and sialylation. No difference was measured in the expression of genes involved in the synthesis of biantennary N-glycans, however genes implicated in the multiantennary N-glycan synthesis were found to be overexpressed.…”

“…Glycans were analyzed after they were removed from the proteins using mass spectrometry. Shifts in the isoelectric point (pI) were observed [17,29] possibly caused by changes in glycosylation, and decrease in biantennary structure, increase in multiantennary N-glycans, outer branch fucosylation and sialylation was found [17].…”

“…Effects of radiation has already been studied in case of phosphorylation [6,[11][12][13], acetylation [12], ubiquitination [14], carbonylation [15,16], nitrosylation [15,16] and glycosylation [17][18][19][20] in different tissues and biofluids and in some cases significant alterations were found.…”

Proteomic overview and perspectives of the radiation-induced bystander effects

“…be limited to the irradiated organ, or to the touching surrounding organs. Also, it appears that in vivo studies of RIBE included a whole body response, where blood vessels were involved in BF dissemination [36], or even an inter-individual communication of BF, when, for example, irradiated fishes communicated with non-irradiated fishes through the water environment [37]. These studies must be considered carefully, because the frontier between bystander and abscopal effects is hard to delimit in vivo, and the observed effects could be indirect without any relation to the irradiation treatment, considering the immune system response, or a potential global stress.…”

“…A list of 15 protein spots was observed as being differentially expressed postirradiation and proposed as a set of protein candidates for triage and prognosis of this kind of irradiation. In a second study, PTM of serum proteins from irradiated mice was analyzed using gel-based and MS-based proteomic strategies [36]. The 2D-DIGE analysis showed a pI-shift of several spots as a function of irradiation, and a MS-based glycomic strategy revealed a modulated glycosylation of proteins in sera of locally irradiated mice.…”