ATF3 and p15PAF are novel gatekeepers of genomic integrity upon UV stress

Abstract

After genotoxic stress, normal cells trigger DNA repair or, if unable to repair, undergo apoptosis to eradicate the cells that bear the risk of becoming tumorigenic. Here we show that repression of the transcription factor, activating transcription factor 3 (ATF3), after ultraviolet (UV)-mediated genotoxic stress impairs the DNA repair process. We provide evidence that ATF3 directly regulates the proliferating cell nuclear antigen (PCNA)-associated factor KIAA0101/p15 PAF . We further show that the expressions of ATF3 and p15 PAF is sufficient to trigger the DNA repair machinery, and that attenuation of their expression alters DNA repair mechanisms. We show that the expression of p15 PAF compensates for a lack of ATF3 expression, thereby constituting a major effector of ATF3 in the DNA repair process. In addition, we provide evidence that p15 PAF expression is required for the correct function of PCNA during DNA repair, as prevention of their interaction significantly alters DNA repair mechanisms. Finally, defective DNA repair, because of the downregulation of p15 PAF expression, rendered the cells more sensitive to UV-induced cell death. Therefore, our results suggest ATF3 and p15 PAF as novel gatekeepers of genomic integrity after UV exposure. Environmental genotoxic stress is one of the major causes of genomic instability. During such a stress, the maintenance of genomic integrity is of crucial importance to allow correct cellular function. The nucleotide excision repair (NER) machinery is responsible for recognition and incision of DNA lesions caused by ultraviolet (UV) irradiation and chemical agents. 1 Proliferating cell nuclear antigen (PCNA) is responsible for recruitment of Pold and, therefore, mediates DNA resynthesis within the site of the lesion. 1 The importance of such machinery is underscored by the numerous human syndromes, such as xeroderma pigmentosum (XP) and trichothiodystrophy (TTD), caused by the mutation of genes involved in DNA repair. Such mutations compromise genomic integrity, and XP and TTD patients are highly photosensitive and prone to develop skin tumors of keratinocyte origin, such as basal and squamous cell carcinoma. Severe defects in the DNA repair mechanism thus impair the apoptotic pathway responsible for destruction of cells that bear the risk of becoming tumorigenic. The correct DNA damage response is therefore of great importance in the maintenance of a UV-inducible anticancer barrier that elicits growth arrest, repair or cell death.Activating transcription factor 3 (ATF3) is a member of the ATF/CREB subfamily of the basic region leucine zipper (bZIP) family and may be strongly induced in a variety of tissues by different stress signals. 2 Several pathways are responsible for ATF3 induction, such as ATM and Nibrin 1, JNK and NF-kB, in a p53-dependent or -independent manner. 3-5 Induction of ATF3 often correlates with cellular damage, suggesting an important role during the cellular stress response. 6 We have recently reported that the alteration of Egr-1 expression during ...

Proliferating cell nuclear antigen (PCNA)-associated KIAA0101/PAF15 protein is a cell cycle-regulated anaphase-promoting complex/cyclosome substrate

“…Tandem mass spectroscopy (MS/MS) identified copurifying proteins. Accordingly, we identified PCNA as having a strong interaction with PAF15, as has been reported by others (11)(12)(13)(14). Silver staining of the immunoprecipitates together with MS/MS data suggested that PAF15 is stoichiometrically associated with PCNA in a 1:1 complex (Fig.…”

“…The decrease in S-phase cells in both cell lines, together with PAF15's tight association with PCNA, suggests that PAF15 plays a role in DNA replication. Discussion PAF15 depletion has been reported to sensitize cells to DNA crosslinking agents (13). We were unable to recapitulate these results using U2OS, HeLa, HCT116, DLD1, and 293T cells with UV, IR, hydroxyurea, and mitomycin c-mediated DNA damage, even though we can deplete PAF15 below detectable levels.…”

Role of activating transcription factor 3 (ATF3) in sublytic C5b‐9‐induced glomerular mesangial cell apoptosis

“…34 Our experiments have revealed that sublytic C5b-9 can trigger activation of the PI3-k/Akt signal pathway in GMCs, causing activation of some transcription factors, i.e., early growth response-1 (data not shown), and release of inflammatory mediators (i.e., nitric oxide) or cytokines (i.e., tumor-necrosis factor-a. 10,21 Because ATF3 is a nuclear transcription factor induced by stress signals, 28,35,36 upregulation of ATF3 express- The data analysis showed that the percentage of GMC apoptosis increased significantly at 3 h after sublytic C5b-9 attack compared with other control groups (**P,0.01 vs MEM, gg P,0.01 vs Thy-1 Ab, %% P,0.01 vs Thy-1 Ab1HIS, ## P,0.01 vs Thy-1 Ab1C6DS). All data represent averages and mean6SD from three independent experiments.…”

Kiaa0101 (Kiaa0101)

“…KIAA0101 was also reported to be down-regulated in colon cancer cells (Simpson et al, 2006) and human hepatocellular carcinoma (Guo et al, 2006). Nuclear protein NF-kappaB (p50) , the Hepatitis C virus protein non-structural protein 5A (NS5A) and ATF3 (Turchi et al, 2009) bind to the promoter region upstream of the KIAA0101 transcription initiation site promoting transcription in response to DNA damage.…”

“…KIAA0101 also competes with p21WAF for binding to PCNA (Yu et al, 2001). KIAA0101 most recently been shown to act in concert with ATF3 to control genomic integrity after UV stress (Turchi et al, 2009). KIAA0101 expression levels are also regulated by NF-kappaB, this protein family having significant roles in apoptosis, cell cycle regulation and onocgenesis (Hosokawa et al, 2007;Li et al, 2008).…”