ACTN4-dependent regulation of double-strand DNA break repair is independent of NF-Kb activity

Abstract

α-Actinin-4 is an actin-binding protein that is involved in a wide range of cellular processes. Along with actin and other proteins of the actin cytoskeleton, α-actinin-4 was found not only in the cytoplasm, but also in the nucleus of various cells. As a nuclear protein, it is involved in regulation of certain transcription factors. In particular, it can regulate transcriptional activity of NF-kB, which largely determines the resistance of cancer cells to apoptosis and anticancer therapy. During our previous studies, it was found that α-actinin-4 can influence resistance of cancer cells to topoisomerase II inhibitors and determine the efficiency of DNA double-strand break repair. We have demonstrated that α-actinin-4 interferes with the assembly of complexes involved in DNA repair via NHEJ and HRR, which in turn leads to an imbalance between these pathways. In this study, we were answering to the question of how α-actinin-4 is involved in the regulation of the DNA double-strand breaks repair following genotoxic stress. Our results indicate that the effect of α-actinin-4 on repair progression in H1299 non-small cell lung cancer cells does not depend on the transcription factor NF-kB activity. We found that in the nucleus of H1299 cells, α-actinin-4 is localized not only in the nucleoplasm, but also reveals close association with chromatin.