PCNA-dependent accumulation of CDKN1A into nuclear foci after ionizing irradiation

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• 作者：Claudia Wiese^b ; ^{CWiese@lbl.gov} ; Jeanette Heede Rudolph^a ; Burkhard Jakob^a ; Daniela Fink^a ; Frank Tobias^a ; Christine Blattner^c ; ¹ ; Gisela Taucher-Scholz^a ; ^{G.Taucher-Scholz@gsi.de}
• 关键词：LET ; linear energy transfer ; DSBs ; DNA double-strand breaks ; SSBs ; DNA single-strand breaks ; CPD ; cumulative population doublings ; NHDF ; neonatal human dermal fibroblasts ; TLC ; thin-layer cellulose ; ICQ ; Intensity Correlation Quotient ; ICA ; Image Correlat
• 刊名：DNA Repair
• 出版年：2012
• 期刊代码：121_15687864
• 类别：ch
• 出版时间：1 May, 2012
• 卷：11
• 期：5
• 页码：511-521
• 文件大小：1837 K

摘要

The cyclin-dependent kinase inhibitor CDKN1A/p21 confers cell-cycle arrest in response to DNA damage and inhibits DNA replication through its direct interaction with the proliferating cell nuclear antigen (PCNA) and cyclin/cyclin-dependent kinase complexes. Previously, we reported that in response to densely ionizing radiation CDKN1A rapidly is recruited to the sites of particle traversal, and that CDKN1A foci formation in response to heavy ions is independent of its transactivation by TP53. Here, we show that exposure of normal human fibroblasts to X-rays or to H₂O₂ also induces nuclear accumulations of CDKN1A. We find that CDKN1A foci formation in response to radiation damage is dependent on its dephosphorylation and on its direct physical interaction with PCNA. Live cell imaging analyses of ectopically expressed EGFP-CDKN1A and dsRed-PCNA show rapid recruitment of both proteins into foci after radiation damage. Detailed dynamic measurements reveal a slightly delayed recruitment of CDKN1A compared to PCNA, which is best described by bi-exponential curve fitting, taking the preceding binding of PCNA to DNA into account. We propose a regulatory role for CDKN1A in mediating PCNA function after radiation damage, and provide evidence that this role is distinct from its involvement in nucleotide excision repair and unrelated to double-strand break repair.