Long interspersed nuclear element-1 (LINE-1) retrotransposons are mobile elements that insert into new genomic locations via reverse transcription of an RNA intermediate. The mechanism of retrotransposition is not entirely understood. The integration of these elements occurs by target-primed reverse transcription (TPRT), which initiates double-strand breaks (DSBs) during the LINE-1 integration. Also, X-ray is known to induce DNA damage. The aim of this study was to evaluate the potential effects of LINE-1 de novo retrotransposition on the expression of different genes after X-ray irradiation in human endothelial cells. After stable transfection of the human hybrid endothelial cell line EA.hy926 with the human LINE-1 element, we analyzed the expression of different genes after irradiation with 5 Gy X-rays by reverse transcription–polymerase chain reaction (RT-PCR). We determine the expression level of phosphorylated p53 and γ-histone H2AX protein levels upon X-ray irradiation with 5 Gy for 24 h. Our results showed that EA.hy926 LINE-1 cell clones react with a strong upregulation of phosphorylated p53 protein, already 15 min after irradiation compared to the wild type (WT) cells. Also, the expression of γ-histone H2AX protein was elevated in the cell clones with retrotransposition events 15 min after irradiation, whereas the WT cells have a delayed expression of phosphorylated histone H2AX protein. Taken together, our findings provide that LINE-1 retrotransposition events regulate different gene expression after irradiation in the EA.hy926 cell line.
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References
1.
AsakawaJ., KuickR., KodairaM., NakamuraN., KatayamaH., PierceD., FunamotoS., PrestonD., SatohC., NeelJ.V., HanashS.2004. A genome scanning approach to assess the genetic effects of radiation in mice and humans. Radiat Res, 161:380–390.
2.
Banaz-YasarF., LennartzK., WinterhagerE., GellhausA.2008. Radiation-induced bystander effects in malignant trophoblast cells are independent from gap junctional communication. J Cell Biochem, 103:149–161.
BelancioV.P., DeiningerP.L., Roy-EngelA.M.2009. LINE dancing in the human genome: transposable elements and disease. Genome Med, 1:97.
5.
BelancioV.P., HedgesD.J., DeiningerP.2006. LINE-1 RNA splicing and influences on mammalian gene expression. Nucleic Acids Res, 34:1512–1521.
6.
BelgnaouiS.M., GosdenR.G., SemmesO.J., HaoudiA.2006. Human LINE-1 retrotransposon induces DNA damage and apoptosis in cancer cells. Cancer Cell Int, 6:13.
7.
BurmaS., ChenB.P., MurphyM., KurimasaA., ChenD.J.2001. ATM phosphorylates histone H2AX in response to DNA double-strand breaks. J Biol Chem, 276:42462–42467.
8.
CallahanK.E., HickmanA.B., JonesC.E., GhirlandoR., FuranoA.V.2012. Polymerization and nucleic acid-binding properties of human L1 ORF1 protein. Nucleic Acids Res, 40:813–827.
9.
CordauxR., BatzerM.A.2009. The impact of retrotransposons on human genome evolution. Nat Rev Genet, 10:691–703.
10.
DaleR., Carabe-FernandezA.2005. The radiobiology of conventional radiotherapy and its application to radionuclide therapy. Cancer Biother Radiopharm, 20:47–51.
11.
EdgellC.J., McDonaldC.C., GrahamJ.B.1983. Permanent cell line expressing human factor VIII-related antigen established by hybridization. Proc Natl Acad Sci U S A, 80:3734–3737.
12.
El-SawyM., KaleS.P., DuganC., NguyenT.Q., BelancioV., BruchH., Roy-EngelA.M., DeiningerP.L.2005. Nickel stimulates L1 retrotransposition by a post-transcriptional mechanism. J Mol Biol, 354:246–257.
13.
ErgunS., BuschmannC., HeukeshovenJ., DammannK., SchniedersF., LaukeH., ChalajourF., KilicN., StratlingW.H., SchumannG.G.2004. Cell type-specific expression of LINE-1 open reading frames 1 and 2 in fetal and adult human tissues. J Biol Chem, 279:27753–27763.
14.
FarkashE.A., KaoG.D., HormanS.R., PrakE.T.2006. Gamma radiation increases endonuclease-dependent L1 retrotransposition in a cultured cell assay. Nucleic Acids Res, 34:1196–1204.
GasiorS.L., WakemanT.P., XuB., DeiningerP.L.2006. The human LINE-1 retrotransposon creates DNA double-strand breaks. J Mol Biol, 357:1383–1393.
19.
HaoudiA., SemmesO.J., MasonJ.M., CannonR.E.2004. Retrotransposition-competent human line-1 induces apoptosis in cancer cells with intact p53. J Biomed Biotechnol, 2004:185–194.
20.
HarrisC.R., DewanA., ZupnickA., NormartR., GabrielA., PrivesC., LevineA.J., HohJ.2009. p53 responsive elements in human retrotransposons. Oncogene, 28:3857–3865.
21.
KaleS.P., MooreL., DeiningerP.L., Roy-EngelA.M.2005. Heavy metals stimulate human LINE-1 retrotransposition. Int J Environ Res Public Health, 2:14–23.
22.
KazazianH.H.Jr.2004. Mobile elements: drivers of genome evolution. Science, 303:1626–1632.
23.
KirilyukA., TolstonogG.V., DamertA., HeldU., HahnS., LowerR., BuschmannC., HornA.V., TraubP., SchumannG.G.2008. Functional endogenous LINE-1 retrotransposons are expressed and mobilized in rat chloroleukemia cells. Nucleic Acids Res, 36:648–665.
LaneD.P.1992. Cancer. p53, guardian of the genome. Nature, 358:15–16.
26.
LuanD.D., EickbushT.H.1996. Downstream 28S gene sequences on the RNA template affect the choice of primer and the accuracy of initiation by the R2 reverse transcriptase. Mol Cell Biol, 16:4726–4734.
27.
McClintockB.1956. Controlling elements and the gene. Cold Spring Harb Symp Quant Biol, 21:197–216.
MoranJ.V., HolmesS.E., NaasT.P., DeBerardinisR.J., BoekeJ.D., KazazianH.H.Jr.1996. High frequency retrotransposition in cultured mammalian cells. Cell, 87:917–927.
30.
OricchioE., SciamannaI., BeraldiR., TolstonogG.V., SchumannG.G., SpadaforaC.2007. Distinct roles for LINE-1 and HERV-K retroelements in cell proliferation, differentiation and tumor progression. Oncogene, 26:4226–4233.
31.
RangwalaS.H., KazazianH.H.Jr.2009. The L1 retrotransposition assay: a retrospective and toolkit. Methods, 49:219–226.
32.
RogakouE.P., BoonC., RedonC., BonnerW.M.1999. Megabase chromatin domains involved in DNA double-strand breaks in vivo. J Cell Biol, 146:905–916.
33.
RogakouE.P., PilchD.R., OrrA.H., IvanovaV.S., BonnerW.M.1998. DNA double-stranded breaks induce histone H2AX phosphorylation on serine 139. J Biol Chem, 273:5858–5868.
34.
RogakouE.P., Sekeri-PataryasK.E.1999. Histone variants of H2A and H3 families are regulated during in vitro aging in the same manner as during differentiation. Exp Gerontol, 34:741–754.
35.
SassamanD.M., DombroskiB.A., MoranJ.V., KimberlandM.L., NaasT.P., DeBerardinisR.J., GabrielA., SwergoldG.D., KazazianH.H.Jr.1997. Many human L1 elements are capable of retrotransposition. Nat Genet, 16:37–43.
36.
SchulzW.A.2006. L1 retrotransposons in human cancers. J Biomed Biotechnol, 2006:83672.
ServomaaK., RytomaaT.1990. UV light and ionizing radiations cause programmed death of rat chloroleukaemia cells by inducing retropositions of a mobile DNA element (L1Rn)Int J Radiat Biol, 57:331–343.
