RESUMO
The classical small Rho GTPase (Rho, Rac, and Cdc42) protein family is mainly responsible for regulating cell motility and polarity, membrane trafficking, cell cycle control, and gene transcription. Cumulative recent evidence supports important roles for these proteins in the maintenance of genomic stability. Indeed, DNA damage response (DDR) and repair mechanisms are some of the prime biological processes that underlie several disease phenotypes, including genetic disorders, cancer, senescence, and premature aging. Many reports guided by different experimental approaches and molecular hypotheses have demonstrated that, to some extent, direct modulation of Rho GTPase activity, their downstream effectors, or actin cytoskeleton regulation contribute to these cellular events. Although much attention has been paid to this family in the context of canonical actin cytoskeleton remodeling, here we provide a contextualized review of the interplay between Rho GTPase signaling pathways and the DDR and DNA repair signaling components. Interesting questions yet to be addressed relate to the spatiotemporal dynamics of this collective response and whether it correlates with different subcellular pools of Rho GTPases. We highlight the direct and indirect targets, some of which still lack experimental validation data, likely associated with Rho GTPase activation that provides compelling evidence for further investigation in DNA damage-associated events and with potential therapeutic applications in translational medicine.
Assuntos
Citoesqueleto de Actina/metabolismo , Dano ao DNA , Reparo do DNA , Instabilidade Genômica , Transdução de Sinais , Proteínas rho de Ligação ao GTP/metabolismo , Animais , HumanosRESUMO
Actin polymerization, actomyosin ring contraction, and stress fiber formation are examples of relevant actions of the RhoA/B/C pathway as GTPases that regulate the cytoskeleton. However, open questions that remain to be addressed are whether this pathway and/or downstream components protect against or facilitate the formation of DNA double-strand breaks, the most lethal form of DNA damage in cells. Genotoxic drugs are radiomimetic and/or chemotherapeutic agents that are currently used for cancer treatments and are associated with specific methodologies; thus, these compounds should represent good tools to answer these questions. In this chapter, we describe two methods, the alkaline comet assay and homologous/nonhomologous recombination assays, to investigate the mechanism by which the Rho pathway modulates the repair of DNA breaks in tumor epithelial cell lines.