Oxidative stress reprograms the transcriptional coactivator Yki to suppress cell proliferation.

The transcriptional coactivator Yorkie (Yki) regulates organ size by promoting cell proliferation. It is unclear how cells control Yki activity when exposed to harmful stimuli such as oxidative stress. In this study, we show that oxidative stress inhibits the binding of Yki to Scalloped (Sd) but promotes the interaction of Yki with another transcription factor, forkhead box O (Foxo), ultimately leading to a halt in cell proliferation. Mechanistically, Foxo normally exhibits a low binding affinity for Yki, allowing Yki to form a complex with Sd and activate proliferative genes. Under oxidative stress, Usp7 deubiquitinates Foxo to promote its interaction with Yki, thereby activating the expression of proliferation suppressors. Finally, we show that Yki is essential for Drosophila survival under oxidative stress. In summary, these findings suggest that oxidative stress reprograms Yki from a proliferation-promoting factor to a proliferation suppressor, forming a self-protective mechanism.

Phosphorylation of LZTS2 by PLK1 activates the Wnt pathway.

Lung adenocarcinoma (LUAD), responsible for nearly half of lung cancer cases, is one of the most prevalent and lethal malignant tumors globally. There is increasing evidence suggesting that the oncoprotein PLK1 plays a role in the onset and advancement of different types of cancer, including LUAD. Nonetheless, the precise mechanism by which PLK1 promotes tumorigenesis remains unclear. In this study, we demonstrate the upregulation of PLK1 in LUAD samples, which leads to a poor prognosis for LUAD patients. Intriguingly, PLK1 enables to bind to LZTS2 and promote its phosphorylation without affecting LZTS2 degradation. Furthermore, we identify that Ser451 is a key phosphorylation site in LZTS2 protein. LZTS2 exerts an anti-tumor effect by restricting the translocation of the transcription factor ß-Catenin into the nucleus, thereby suppressing the Wnt pathway. PLK1 disrupts the interaction between LZTS2 and ß-Catenin, resulting in the nuclear accumulation of ß-Catenin and the activation of the Wnt pathway. Additionally, we reveal that LZTS2 inhibits the proliferation and migration of LUAD cells, which is rescued by PLK1. Finally, PLK1 inhibitors exhibit a dose-dependent suppression of LUAD cell proliferation and migration. Collectively, this study uncovers the pro-tumorigenic mechanism of PLK1, positioning it as a promising therapeutic target for Wnt-related LUAD.