title: Rho GTPase independent regulation of ATM activation and cell survival by the RhoGEF Net1A.
abstract: ATM activation following DNA damage is a critical event which is required for efficient DNA repair and cell survival, yet signaling mechanisms controlling its activation are incompletely understood. The RhoGEF Net1 has previously been reported to control Rho GTPase activation and downstream cell survival outcomes following double strand DNA damage. However the role of Net1 isoforms in controlling ATM-dependent cell signaling has not been assessed. In the present work we show that expression of the Net1A isoform is specifically required for efficient activation of ATM but not the related kinase DNA-PK after ionizing radiation. Surprisingly Net1A overexpression also potently suppresses ATM activation and phosphorylation of its substrate H2AX. This effect does not require catalytic activity towards RhoA or RhoB, and neither Rho GTPase affects ATM activation, on its own. Consistent with a role in controlling ATM activation, Net1A knockdown also impairs DNA repair and cell survival. Taken together these data indicate that Net1A plays a plays a previously unrecognized, Rho GTPase-independent role in controlling ATM activity and downstream signaling after DNA damage to impact cell survival.
authors.affiliation: a Department of Integrative Biology and Pharmacology ; University of Texas Health Science Center at Houston ; Houston , TX USA.
authors.forename: Wonkyung
authors.initials: W
authors.lastname: Oh
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Frost
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism*; D002470:Cell Survival / Q000528:radiation effects; D053903:DNA Breaks, Double-Stranded; D004249:DNA Damage; D006657:Histones / Q000378:metabolism; D006801:Humans; D061986:MCF-7 Cells; D015513:Oncogene Proteins / Q000378:metabolism*; D020033:Protein Isoforms / Q000378:metabolism; D011839:Radiation, Ionizing; D064067:Rho Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D015398:Signal Transduction / Q000528:radiation effects; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*; D020743:rhoB GTP-Binding Protein / Q000378:metabolism*
chemical_list: C468783:H2AX protein, human; D006657:Histones; C099763:NET1 protein, human; D015513:Oncogene Proteins; D020033:Protein Isoforms; D064067:Rho Guanine Nucleotide Exchange Factors; D064007:Ataxia Telangiectasia Mutated Proteins; D020742:rhoA GTP-Binding Protein; D020743:rhoB GTP-Binding Protein
keywords: ATM; ATM, ataxia-telangiectasia mutated; DNA damage; DNA-PK, DNA dependent protein kinase; DSB, double strand break; IR, ionizing radiation; Net1; Net1, neuroepithelial transforming gene 1; RhoGEF, Rho guanine nucleotide exchange factor; breast cancer; ionizing radiation