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GCN5 and E2F1 stimulate nucleotide excision repair by promoting H3K9 acetylation at sites of damage.

Guo R, Chen J, Mitchell DL, Johnson DG - Nucleic Acids Res. (2010)

Bottom Line: However, the molecular mechanism by which UV radiation induces histone acetylation to allow for efficient NER is not completely understood.UV radiation induces the acetylation of histone H3 lysine 9 (H3K9) and this requires both GCN5 and E2F1.These findings demonstrate a direct role for GCN5 and E2F1 in NER involving H3K9 acetylation and increased accessibility to the NER machinery.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Carcinogenesis, UT MD Anderson Cancer Center, Science Park-Research Division, 1808 Park Road 1C, PO Box 389, Smithville, TX 78957, USA.

ABSTRACT
Chromatin structure is known to be a barrier to DNA repair and a large number of studies have now identified various factors that modify histones and remodel nucleosomes to facilitate repair. In response to ultraviolet (UV) radiation several histones are acetylated and this enhances the repair of DNA photoproducts by the nucleotide excision repair (NER) pathway. However, the molecular mechanism by which UV radiation induces histone acetylation to allow for efficient NER is not completely understood. We recently discovered that the E2F1 transcription factor accumulates at sites of UV-induced DNA damage and directly stimulates NER through a non-transcriptional mechanism. Here we demonstrate that E2F1 associates with the GCN5 acetyltransferase in response to UV radiation and recruits GCN5 to sites of damage. UV radiation induces the acetylation of histone H3 lysine 9 (H3K9) and this requires both GCN5 and E2F1. Moreover, as previously observed for E2F1, knock down of GCN5 results in impaired recruitment of NER factors to sites of damage and inefficient DNA repair. These findings demonstrate a direct role for GCN5 and E2F1 in NER involving H3K9 acetylation and increased accessibility to the NER machinery.

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Related in: MedlinePlus

GCN5 co-localizes with sites of UV-induced DNA damage. NHFs were untreated (upper panels) or irradiated with 50 J/m2 of UVC through a 8 µm pore filter (lower panels) and 30 min later stained for CPD (red) and (A) GCN5 or (B) PCAF (green). Cells were counter-stained with DAPI and images were digitally recorded.
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Figure 1: GCN5 co-localizes with sites of UV-induced DNA damage. NHFs were untreated (upper panels) or irradiated with 50 J/m2 of UVC through a 8 µm pore filter (lower panels) and 30 min later stained for CPD (red) and (A) GCN5 or (B) PCAF (green). Cells were counter-stained with DAPI and images were digitally recorded.

Mentions: The local UV irradiation assay (29–31) was used to examine the recruitment of GCN5 to sites of DNA damage. For these experiments, normal human fibroblasts were covered with polycarbonate filters and exposed to 50 J/m2 of UVC. Cells were fixed 30 min following exposure and UV-induced DNA damage was detected by indirect immunofluorescence (IF) staining using a monoclonal antibody to CPD (Figure 1A). Cells were co-stained with polyclonal antisera to GCN5 followed by a fluorescently labeled secondary antibody. GCN5 staining in the absence of UV treatment, while punctuate, was relatively uniform throughout the nucleus. Following UV irradiation, GCN5 was found to redistribute to discrete areas of the nucleus that overlapped with CPD staining (Figure 1A). In contrast, the staining pattern of the related PCAF acetyltransferase did not change following UV irradiation and no co-localization with UV-damaged sites was observed (Figure 1B).Figure 1.


GCN5 and E2F1 stimulate nucleotide excision repair by promoting H3K9 acetylation at sites of damage.

Guo R, Chen J, Mitchell DL, Johnson DG - Nucleic Acids Res. (2010)

GCN5 co-localizes with sites of UV-induced DNA damage. NHFs were untreated (upper panels) or irradiated with 50 J/m2 of UVC through a 8 µm pore filter (lower panels) and 30 min later stained for CPD (red) and (A) GCN5 or (B) PCAF (green). Cells were counter-stained with DAPI and images were digitally recorded.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3045616&req=5

Figure 1: GCN5 co-localizes with sites of UV-induced DNA damage. NHFs were untreated (upper panels) or irradiated with 50 J/m2 of UVC through a 8 µm pore filter (lower panels) and 30 min later stained for CPD (red) and (A) GCN5 or (B) PCAF (green). Cells were counter-stained with DAPI and images were digitally recorded.
Mentions: The local UV irradiation assay (29–31) was used to examine the recruitment of GCN5 to sites of DNA damage. For these experiments, normal human fibroblasts were covered with polycarbonate filters and exposed to 50 J/m2 of UVC. Cells were fixed 30 min following exposure and UV-induced DNA damage was detected by indirect immunofluorescence (IF) staining using a monoclonal antibody to CPD (Figure 1A). Cells were co-stained with polyclonal antisera to GCN5 followed by a fluorescently labeled secondary antibody. GCN5 staining in the absence of UV treatment, while punctuate, was relatively uniform throughout the nucleus. Following UV irradiation, GCN5 was found to redistribute to discrete areas of the nucleus that overlapped with CPD staining (Figure 1A). In contrast, the staining pattern of the related PCAF acetyltransferase did not change following UV irradiation and no co-localization with UV-damaged sites was observed (Figure 1B).Figure 1.

Bottom Line: However, the molecular mechanism by which UV radiation induces histone acetylation to allow for efficient NER is not completely understood.UV radiation induces the acetylation of histone H3 lysine 9 (H3K9) and this requires both GCN5 and E2F1.These findings demonstrate a direct role for GCN5 and E2F1 in NER involving H3K9 acetylation and increased accessibility to the NER machinery.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Carcinogenesis, UT MD Anderson Cancer Center, Science Park-Research Division, 1808 Park Road 1C, PO Box 389, Smithville, TX 78957, USA.

ABSTRACT
Chromatin structure is known to be a barrier to DNA repair and a large number of studies have now identified various factors that modify histones and remodel nucleosomes to facilitate repair. In response to ultraviolet (UV) radiation several histones are acetylated and this enhances the repair of DNA photoproducts by the nucleotide excision repair (NER) pathway. However, the molecular mechanism by which UV radiation induces histone acetylation to allow for efficient NER is not completely understood. We recently discovered that the E2F1 transcription factor accumulates at sites of UV-induced DNA damage and directly stimulates NER through a non-transcriptional mechanism. Here we demonstrate that E2F1 associates with the GCN5 acetyltransferase in response to UV radiation and recruits GCN5 to sites of damage. UV radiation induces the acetylation of histone H3 lysine 9 (H3K9) and this requires both GCN5 and E2F1. Moreover, as previously observed for E2F1, knock down of GCN5 results in impaired recruitment of NER factors to sites of damage and inefficient DNA repair. These findings demonstrate a direct role for GCN5 and E2F1 in NER involving H3K9 acetylation and increased accessibility to the NER machinery.

Show MeSH
Related in: MedlinePlus