Article

The SIOD disorder protein SMARCAL1 is an RPA-interacting protein involved in replication fork restart.

Howard Hughes Medical Institute and Department of Genetics, Harvard Medical School, Division of Genetics, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
Genes & development (Impact Factor: 12.64). 09/2009; 23(20):2415-25. DOI: 10.1101/gad.1832309
Source: PubMed

ABSTRACT The integrity of genomic DNA is continuously challenged by the presence of DNA base lesions or DNA strand breaks. Here we report the identification of a new DNA damage response protein, SMARCAL1 (SWI/SNF-related, matrix associated, actin-dependent regulator of chromatin, subfamily a-like 1), which is a member of the SNF2 family and is mutated in Schimke immunoosseous dysplasia (SIOD). We demonstrate that SMARCAL1 directly interacts with Replication protein A (RPA) and is recruited to sites of DNA damage in an RPA-dependent manner. SMARCAL1-depleted cells display sensitivity to DNA-damaging agents that induce replication fork collapse, and exhibit slower fork recovery and delayed entry into mitosis following S-phase arrest. Furthermore, SIOD patient fibroblasts reconstituted with SMARCAL1 exhibit faster cell cycle progression after S-phase arrest. Thus, the symptoms of SIOD may be caused, at least in part, by defects in the cellular response to DNA replication stress.

Download full-text

Full-text

Available from: Marie-Emilie Terret, Jan 30, 2015
0 Followers
 · 
119 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: The signal transduction pathway of the DNA damage response (DDR) is activated to maintain genomic integrity following DNA damage. The DDR promotes genomic integrity by regulating a large network of cellular activities that range from DNA replication and repair to transcription, RNA splicing, and metabolism. In this study we define an interaction between the DDR factor NBS1 and TCOF1, a nucleolar protein that regulates ribosomal DNA (rDNA) transcription and is mutated in Treacher Collins syndrome. We show that NBS1 relocalizes to nucleoli after DNA damage in a manner dependent on TCOF1 and on casein kinase II and ATM, which are known to modify TCOF1 by phosphorylation. Moreover, we identify a putative ATM phosphorylation site that is required for NBS1 relocalization to nucleoli in response to DNA damage. Last, we report that TCOF1 promotes cellular resistance to DNA damaging agents. Collectively, our findings identify TCOF1 as a DDR factor that could cooperate with ATM and NBS1 to suppress inappropriate rDNA transcription and maintain genomic integrity after DNA damage.
  • [Show abstract] [Hide abstract]
    ABSTRACT: SMARCAL1 catalyzes replication fork remodeling to maintain genome stability. It is recruited to replication forks via an interaction with Replication Protein A (RPA), the major single-strand DNA (ssDNA) binding protein in eukaryotic cells. In addition to directing its localization, RPA also activates SMARCAL1 on some fork substrates but inhibits it on others, thereby conferring substrate specificity to SMARCAL1 fork remodeling reactions. We investigated the mechanism by which RPA regulates SMARCAL1. Our results indicate that while an interaction between SMARCAL1 and RPA is essential for SMARCAL1 activation, the location of the interacting surface on RPA is not. Counterintuitively, high-affinity DNA binding of the RPA DBD-A and DBD-B domains near the fork junction makes it easier for SMARCAL1 to remodel the fork, which requires removing RPA. We also find that the DBD-C and DBD-D RPA domains are not required for SMARCAL1 regulation. Thus, the orientation of the high-affinity RPA DNA binding domains at forks dictates SMARCAL1 substrate specificity. Copyright © 2014, The American Society for Biochemistry and Molecular Biology.
    Journal of Biological Chemistry 12/2014; 290(7). DOI:10.1074/jbc.M114.627083 · 4.60 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Replication Protein A (RPA) complex is an essential regulator of eukaryotic DNA metabolism. RPA avidly binds to single-stranded DNA (ssDNA) through multiple oligonucleotide/oligosaccharide-binding folds and coordinates the recruitment and exchange of genome maintenance factors to regulate DNA replication, recombination and repair. The RPA-ssDNA platform also constitutes a key physiological signal which activates the master ATR kinase to protect and repair stalled or collapsed replication forks during replication stress. In recent years, the RPA complex has emerged as a key target and an important regulator of post-translational modifications in response to DNA damage, which is critical for its genome guardian functions. Phosphorylation and SUMOylation of the RPA complex, and more recently RPA-regulated ubiquitination, have all been shown to control specific aspects of DNA damage signaling and repair by modulating the interactions between RPA and its partners. Here, we review our current understanding of the critical functions of the RPA-ssDNA platform in the maintenance of genome stability and its regulation through an elaborate network of covalent modifications.Cell Research advance online publication 18 November 2014; doi:10.1038/cr.2014.147.
    Cell Research 11/2014; DOI:10.1038/cr.2014.147 · 11.98 Impact Factor