AKT and 14-3-3 regulate Notch4 nuclear localization

Ramakrishnan, Gopalakrishnan; Davaakhuu, Gantulga; Chung, Wen Cheng; Zhu, He; Rana, Ajay; Filipovic, Aleksandra; Green, Andrew R.; Atfi, Azeddine; Pannuti, Antonio; Miele, Lucio; Tzivion, Guri

Abstract

Members of the Notch family of transmembrane receptors, Notch1-4 in mammals, are involved in the regulation of cell fate decisions and cell proliferation in various organisms. The Notch4 isoform, which is specific to mammals, was originally identified as a viral oncogene in mice, Int3, able to initiate mammary tumors. In humans, Notch4 expression appears to be associated with breast cancer stem cells and endocrine resistance. Following ligand binding, the Notch4 receptor undergoes cleavage at the membrane and the Notch4-intracellular domain (ICD), translocates to the nucleus and regulates gene transcription. Little is known on the mechanisms regulating Notch4-ICD and its nuclear localization. Here, we describe the identification of four distinct AKT phosphorylation sites in human Notch4-ICD and demonstrate that AKT binds Notch4-ICD and phosphorylates all four sites in vitro and in vivo. The phosphorylation in cells is regulated by growth factors and is sensitive to phosphatidyl inositol-3 kinase (PI3K) inhibitors. This phosphorylation generates binding sites to the 14-3-3 regulatory proteins, which are involved in the regulation of nucleocytoplasmic shuttling of target proteins, restricting phosphorylated Notch4-ICD to the cytoplasm. Our findings provide a novel mechanism for Notch4-ICD regulation, suggesting a negative regulatory role for the PI3K-AKT pathway in Notch4 nuclear signaling.

Citation

Ramakrishnan, G., Davaakhuu, G., Chung, W. C., Zhu, H., Rana, A., Filipovic, A., Green, A. R., Atfi, A., Pannuti, A., Miele, L., & Tzivion, G. (2015). AKT and 14-3-3 regulate Notch4 nuclear localization. Scientific Reports, 5(1), Article 8782. https://doi.org/10.1038/srep08782

• Journal Article Type: Article
• Acceptance Date: Feb 3, 2015
• Online Publication Date: Mar 5, 2015
• Publication Date: 2015-08
• Deposit Date: Oct 17, 2018
• Publicly Available Date: Oct 17, 2018
• Journal: Scientific Reports
• Publisher: Nature Publishing Group
• Peer Reviewed: Peer Reviewed
• Volume: 5
• Issue: 1
• Article Number: 8782
• DOI: https://doi.org/10.1038/srep08782
• Public URL: https://nottingham-repository.worktribe.com/output/1171431
• Publisher URL: https://www.nature.com/articles/srep08782
• Contract Date: Oct 17, 2018