Human ISWI complexes are targeted by SMARCA5 ATPase and SLIDE domains to help resolve lesion-stalled transcription.
Bottom Line: Using live cell imaging, we identify a novel function for two distinct mammalian ISWI adenosine triphosphate (ATP)-dependent chromatin remodeling complexes in resolving lesion-stalled transcription.After initial recruitment to UV damage, SMARCA5 re-localizes away from the center of DNA damage, requiring its HAND domain.Our studies support a model in which SMARCA5 targeting to DNA damage-stalled transcription sites is controlled by an ATP-hydrolysis-dependent scanning and proofreading mechanism, highlighting how SWI2/SNF2 chromatin remodelers identify and bind nucleosomes containing damaged DNA.
Affiliation: Department of Genetics, Medical Genetics Cluster, Cancer Genomics Netherlands, Erasmus MC, Rotterdam, 3015 GE, The Netherlands.Show MeSH
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Mentions: SMARCA5 is the catalytic subunit of several ISWI family ATP-dependent chromatin remodeling complexes including ATP-utilizing Chromatin assembly and remodeling Factor (ACF) (54) and WSTF-ISWI CHromatin remodeling complex (WICH) (55). Both complexes were previously shown to be involved in DSB repair (28,32), while Drosophila ACF complex was also shown to facilitate NER of DNA damage in linker DNA in vitro (56). The human ACF complex consists of SMARCA5 and ACF1 (57), whereas the WICH complex consists of SMARCA5 and WSTF (55) (Supplementary Figure S5A and B). As shown in Figure 6A and B, knock-down of ACF1 and WSTF (Supplementary Figure S5C) rendered cells hypersensitive to UV. In addition, loss of ACF1 and WSTF clearly reduced RRS (Figure 6C and D) but not UDS (Figure 6E). This was achieved using different siRNAs, ruling out off-target effects (Supplementary Figure S5C). These results indicate that ACF1 and WSTF are both involved in TC-NER but not GG-NER, consistent with a function in complex with SMARCA5. Based on these results, we hypothesize that both the ACF and the WICH complex may remodel chromatin during initiation of TC-NER.
Affiliation: Department of Genetics, Medical Genetics Cluster, Cancer Genomics Netherlands, Erasmus MC, Rotterdam, 3015 GE, The Netherlands.