Overactivated Cdc42 acts through Cdc42EP3/Borg2 and NCK to trigger DNA damage response signaling and sensitize cells to DNA-damaging agents

Author(s)

da Silva, Luiz Eduardo ; Russo, Lilian Cristina ; Forti, Fabio Luis

• Document type: Journal article
• Source: Experimental Cell Research; v. 395, n. 2, p. 12-pg., 2020-10-15.

Abstract

The small GTPase Cdc42, a member of the Rho family, regulates essential biological processes such as cyto-skeleton remodeling, migration, vesicular trafficking and cell cycle. It was demonstrated that Cdc42 over-activation through different molecular strategies increases cell sensitivity to genotoxic stress and affects the phosphorylation status of DNA damage response proteins by unknown mechanisms. By using a combination of approaches including affinity purification/mass spectrometry (AP/MS) and colocalization microscopy analysis we were able to identify Cdc42EP3/Borg2 as a putative molecular effector of these molecular and cellular events that seem to be independent of cell line or DNA damage stimuli. We then investigated the influence of Cdc42EP3/Borg2 and other potential protein partners, such as the NCK and Septin2 proteins, which could mediate cellular responses to genotoxic stress under different backgrounds of Cdc42 activity. Clonogenic assays showed a reduced cell survival when ectopically expressing the Cdc42EP3/Borg2, NCK2 or Septin2 in an overactivated Cdc42-dependent background. Moreover, endogenous NCK appears to relocate into the nucleus upon Cdc42 overactivation, especially under genotoxic stress, and promotes the suppression of Chk1 phosphorylation. In sum, our findings reinforce Cdc42 as an important player involved in the DNA damage response acting through Cdc42EP3/Borg2 and NCK proteins following genomic instability conditions. (AU)

• FAPESP's process: 15/03983-0 - Molecular and functional investigation of the interactions between DUSP3 with nuclear proteins and its implications in DNA repair mechanisms
• Grantee: Fábio Luis Forti
• Support Opportunities: Regular Research Grants
• FAPESP's process: 18/01753-6 - Identification and functional investigation of proteins that interact with Cdc42 and DUSP12 enzymes in human cells under conditions of genomic instability: a proteomic approach
• Grantee: Fábio Luis Forti
• Support Opportunities: Regular Research Grants