Rac1 GTPase-deficient HeLa cells present reduced DNA repair, proliferation, and survival under UV or gamma irradiation

Autor(es)

Espinha, Gisele ^[1] ; Osaki, Juliana H. ^[1] ; Magalhaes, Yuli T. ^[1] ; Forti, Fabio Luis ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Chem, Dept Biochem, Lab Signaling Biomol Syst, BR-05508900 Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Molecular and Cellular Biochemistry; v. 404, n. 1-2, p. 281-297, JUN 2015.
• Citações Web of Science: 15

Resumo

Rac1 GTPase controls essential cellular functions related to the cytoskeleton, such as motility and adhesion. Rac1 is overexpressed in many tumor cells, including breast cancers, where it is also involved in the proliferation and checkpoint control necessary for the cell's recovery after exposure to ionizing radiation. However, its role in DNA damage and repair remains obscure in other tumor cells and under different genotoxic conditions. Here, we compare HeLa cells with mutants exogenously expressing a dominant-negative Rac1 (HeLa-Rac1-N17) by their responses to DNA damage induced by gamma or UV radiation. In HeLa cells, these treatments led to increased levels of active Rac1 (Rac1-GTP) and of stress fibers, with a diminished ability to migrate compared to untreated cells. However, the reduction of Rac1-GTP in Rac1-N17-deficient clones resulted in much higher levels of polymerized stress fibers accompanied by a strong impairment of cell migration, even after both radiation treatments. With regard to proliferation and genomic stability, dominant-negative Rac1 cells were more sensitive to gamma and UV radiation, exhibiting reduced proliferation and survival consistent with increased DNA damage and delayed or reduced DNA repair observed in this Rac1-deficient clone. The DNA damage response, as indicated by pH2AX and pChk1 levels, was increased in HeLa cells but was not effectively triggered in the Rac1-N17 clone after radiation treatment, which is likely the main cause of DNA damage accumulation. These data suggest that Rac1 GTPase plays an important role in signaling and contributes to the sensitivity of cervical cancer cells under UV or gamma radiation treatments. (AU)

• Processo FAPESP: 08/58264-5 - Papel de GTPases da família Rho e de tirosina fosfatases duais no reparo de danos no DNA
• Beneficiário: Fábio Luis Forti
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 11/05822-3 - Investigação da tirosina fosfatase VHR (DUSP3) na resposta a danos do DNA induzidas por radiação ultravioleta em células de melanoma humano
• Beneficiário: Alexsandro dos Santos
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto