{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,9]],"date-time":"2026-08-09T10:55:25Z","timestamp":1786272925323,"version":"build-2736575974"},"reference-count":44,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2021,5,22]],"date-time":"2021-05-22T00:00:00Z","timestamp":1621641600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Grant Agency of the Slovak Republic (VEGA)","award":["2\/0147\/17"],"award-info":[{"award-number":["2\/0147\/17"]}]},{"name":"Slovak Research and Development Agency (APVV)","award":["APVV-15-0250"],"award-info":[{"award-number":["APVV-15-0250"]}]},{"name":"Structural Funds of European Union","award":["Protonbeam - ITMS26220220200"],"award-info":[{"award-number":["Protonbeam - ITMS26220220200"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Dephosphorylation inhibitor calyculin A (cal A) has been reported to inhibit the disappearance of radiation-induced \u03b3H2AX DNA repair foci in human lymphocytes. However, other studies reported no change in the kinetics of \u03b3H2AX focus induction and loss in irradiated cells. While apoptosis might interplay with the kinetics of focus formation, it was not followed in irradiated cells along with DNA repair foci. Thus, to validate plausible explanations for significant variability in outputs of these studies, we evaluated the effect of cal A (1 and 10 nM) on \u03b3H2AX\/53BP1 DNA repair foci and apoptosis in irradiated (1, 5, 10, and 100 cGy) human umbilical cord blood lymphocytes (UCBL) using automated fluorescence microscopy and annexin V-FITC\/propidium iodide assay\/\u03b3H2AX pan-staining, respectively. No effect of cal A on \u03b3H2AX and colocalized \u03b3H2AX\/53BP1 foci induced by low doses (\u226410 cGy) of \u03b3-rays was observed. Moreover, 10 nM cal A treatment decreased the number of all types of DNA repair foci induced by 100 cGy irradiation. 10 nM cal A treatment induced apoptosis already at 2 h of treatment, independently from the delivered dose. Apoptosis was also detected in UCBL treated with lower cal A concentration, 1 nM, at longer cell incubation, 20 and 44 h. Our data suggest that apoptosis triggered by cal A in UCBL may underlie the failure of cal A to maintain radiation-induced \u03b3H2AX foci. All DSB molecular markers used in this study responded linearly to low-dose irradiation. Therefore, their combination may represent a strong biodosimetry tool for estimation of radiation response to low doses. Assessment of colocalized \u03b3H2AX\/53BP1 improved the threshold of low dose detection.<\/jats:p>","DOI":"10.3390\/ijms22115470","type":"journal-article","created":{"date-parts":[[2021,5,23]],"date-time":"2021-05-23T23:58:05Z","timestamp":1621814285000},"page":"5470","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Evaluation of Calyculin A Effect on \u03b3H2AX\/53BP1 Focus Formation and Apoptosis in Human Umbilical Cord Blood Lymphocytes"],"prefix":"10.3390","volume":"22","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5059-9750","authenticated-orcid":false,"given":"Luci\u00e1n","family":"Zastko","sequence":"first","affiliation":[{"name":"Department of Radiobiology, Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, University Science Park for Biomedicine, D\u00fabravsk\u00e1 Cesta 9, 845 05 Bratislava, Slovakia"},{"name":"Department of Medical Biophysics, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Mal\u00e1 Hora 4, 036 01 Martin, Slovakia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anna","family":"Ra\u010dkov\u00e1","sequence":"additional","affiliation":[{"name":"Department of Radiobiology, Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, University Science Park for Biomedicine, D\u00fabravsk\u00e1 Cesta 9, 845 05 Bratislava, Slovakia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Petra","family":"Petrovi\u010dov\u00e1","sequence":"additional","affiliation":[{"name":"Department of Radiobiology, Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, University Science Park for Biomedicine, D\u00fabravsk\u00e1 Cesta 9, 845 05 Bratislava, Slovakia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mat\u00fa\u0161","family":"Durd\u00edk","sequence":"additional","affiliation":[{"name":"Department of Radiobiology, Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, University Science Park for Biomedicine, D\u00fabravsk\u00e1 Cesta 9, 845 05 Bratislava, Slovakia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jakub","family":"M\u00ed\u0161ek","sequence":"additional","affiliation":[{"name":"Department of Medical Biophysics, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Mal\u00e1 Hora 4, 036 01 Martin, Slovakia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eva","family":"Markov\u00e1","sequence":"additional","affiliation":[{"name":"Department of Radiobiology, Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, University Science Park for Biomedicine, D\u00fabravsk\u00e1 Cesta 9, 845 05 Bratislava, Slovakia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Igor","family":"Belyaev","sequence":"additional","affiliation":[{"name":"Department of Radiobiology, Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, University Science Park for Biomedicine, D\u00fabravsk\u00e1 Cesta 9, 845 05 Bratislava, Slovakia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,5,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"45","DOI":"10.1038\/nrg1746","article-title":"The role of double-strand break repair\u2014Insights from human genetics","volume":"7","author":"Jeggo","year":"2006","journal-title":"Nat. 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