Fa P, Qiu Z, Wang QE, Yan C, Zhang J

Cell cycle checkpoints and DNA repair are important for cell survival after exogenous DNA damage. Both rapid blockage of G2 to M phase transition in the cell cycle and the maintenance of relatively slow G2 arrest are critical to protect cells from lethal ionizing radiation (IR). Checkpoint kinase 1 is ...

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pivotal in blocking the transition from G2 to M phases in response to IR. The 14-3-3? protein is important for IR-induced G2 arrest maintenance in which p53-dependent 14-3-3? transcription is involved. It has been demonstrated that Ring finger protein 126 (RNF126), an E3 ligase, is required to upregulate checkpoint kinase 1 expression. Thus, our goal was to study the role of RNF126 in the G2/M phase checkpoint.The transition from G2 to M phases and G2 accumulation in response to IR were determined by flow cytometry through staining with phospho-histone H3 (pS10) antibody and propidium iodide, respectively. The interaction of RNF126 and 14-3-3? was determined by GST-pulldown and coimmunoprecipitation assays. The stability of RNF126 and 14-3-3? was determined by cycloheximide-based stability assay and ubiquitination detection by coimmunoprecipitation. The sequestering of cyclin-dependent kinase 1 and cyclin B1 from the nucleus was determined by immunofluorescence staining.RNF126 knockdown had no impact on the IR-induced transient blockage of G2 to M but impaired IR-induced G2 arrest maintenance in cells with or without wild-type p53. Mechanistically, RNF126 binds 14-3-3? and prevents both proteins from ubiquitination-mediated degradation. Last, RNF126 is required for enforcing the cytoplasmic sequestration of cyclin B1 and cyclin-dependent kinase 1 proteins in response to IR.RNF126 promotes G2 arrest via interaction with 14-3-3? in response to IR. Our study revealed a novel role for RNF126 in promoting G2 arrest, providing a new target for cancer treatment.

Date: Dec. 01, 2021

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