RESUMEN
Oxidative DNA damage represents one of the most abundant DNA lesions. It remains unclear how DNA repair and DNA damage response (DDR) pathways are co-ordinated and regulated following oxidative stress. While XRCC1 has been implicated in DNA repair, it remains unknown how exactly oxidative DNA damage is repaired and sensed by XRCC1. In this communication, we have demonstrated evidence that XRCC1 is dispensable for ATR-Chk1 DDR pathway following oxidative stress in Xenopus egg extracts. Whereas APE2 is essential for SSB repair, XRCC1 is not required for the repair of defined SSB and gapped plasmids with a 5'-OH or 5'-P terminus, suggesting that XRCC1 and APE2 may contribute to SSB repair via different mechanisms. Neither Polymerase beta nor Polymerase alpha is important for the repair of defined SSB structure. Nonetheless, XRCC1 is important for the repair of DNA damage following oxidative stress. Our observations suggest distinct roles of XRCC1 for genome integrity in oxidative stress in Xenopus egg extracts.
Asunto(s)
Extractos Celulares/química , Genoma , Óvulo/metabolismo , Proteína 1 de Reparación por Escisión del Grupo de Complementación Cruzada de las Lesiones por Rayos X/metabolismo , Xenopus/metabolismo , Animales , Cromatina , Daño del ADN , Reparación del ADN , Regulación de la Expresión Génica , Masculino , Óvulo/química , Estrés Oxidativo , Plásmidos , Espermatozoides , Proteína 1 de Reparación por Escisión del Grupo de Complementación Cruzada de las Lesiones por Rayos X/química , Proteína 1 de Reparación por Escisión del Grupo de Complementación Cruzada de las Lesiones por Rayos X/genética , Xenopus/genéticaRESUMEN
DNA single-strand breaks (SSBs) are the most common type of DNA lesions as they are generated approximately 10,000 times per mammalian cell each day. Unrepaired SSBs compromise DNA replication and transcription programs, leading to genome instability, and have been implicated in many diseases including cancer. In this chapter, we introduce methods to study the ATR-Chk1 DNA damage response (DDR) pathway and DNA repair pathway in response to a site-specific, defined SSB plasmid in Xenopus laevis egg extracts. This experimental system can be applied in future studies to reveal many aspects of the molecular mechanisms of SSB repair and signaling in eukaryotes.
Asunto(s)
Roturas del ADN de Cadena Simple , Reparación del ADN , ADN/genética , Xenopus laevis/genética , Animales , Proteínas de la Ataxia Telangiectasia Mutada/metabolismo , Quinasa 1 Reguladora del Ciclo Celular (Checkpoint 1)/metabolismo , ADN/metabolismo , Oocitos , Plásmidos/genética , Proteínas de Xenopus/metabolismo , Xenopus laevis/metabolismoRESUMEN
DNA single-strand breaks (SSBs) occur more than 10,000 times per mammalian cell each day, representing the most common type of DNA damage. Unrepaired SSBs compromise DNA replication and transcription programs, leading to genome instability. Unrepaired SSBs are associated with diseases such as cancer and neurodegenerative disorders. Although canonical SSB repair pathway is activated to repair most SSBs, it remains unclear whether and how unrepaired SSBs are sensed and signaled. In this review, we propose a new concept of SSB end resection for genome integrity. We propose a four-step mechanism of SSB end resection: SSB end sensing and processing, as well as initiation, continuation, and termination of SSB end resection. We also compare different mechanisms of SSB end resection and DSB end resection in DNA repair and DNA damage response (DDR) pathways. We further discuss how SSB end resection contributes to SSB signaling and repair. We focus on the mechanism and regulation by APE2 in SSB end resection in genome integrity. Finally, we identify areas of future study that may help us gain further mechanistic insight into the process of SSB end resection. Overall, this review provides the first comprehensive perspective on SSB end resection in genome integrity.
Asunto(s)
Roturas del ADN de Cadena Simple , Reparación del ADN , ADN-(Sitio Apurínico o Apirimidínico) Liasa/metabolismo , Inestabilidad Genómica , Transducción de Señal , Animales , Endonucleasas , Humanos , Enzimas MultifuncionalesRESUMEN
Most chemotherapy regimens contain at least one DNA-damaging agent that preferentially affects the growth of cancer cells. This strategy takes advantage of the differences in cell proliferation between normal and cancer cells. Chemotherapeutic drugs are usually designed to target rapid-dividing cells because sustained proliferation is a common feature of cancer [1,2]. Rapid DNA replication is essential for highly proliferative cells, thus blocking of DNA replication will create numerous mutations and/or chromosome rearrangements-ultimately triggering cell death [3]. Along these lines, DNA topoisomerase inhibitors are of great interest because they help to maintain strand breaks generated by topoisomerases during replication. In this article, we discuss the characteristics of topoisomerase (DNA) I (TOP1) and its inhibitors, as well as the underlying DNA repair pathways and the use of TOP1 inhibitors in cancer therapy.