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ERK Activation Globally Downregulates miRNAs through Phosphorylating Exportin-5
Hui-Lung Sun1, Ri Cui2, JianKang Zhou3
1Department of Cancer Biology and Genetics, Ohio State University, Columbus, OH 43210, USA; Pharmacological Institute, College of Medicine, National Taiwan University, Taipei 10051, Taiwan.
ERK signaling suppresses microRNA export by phosphorylating exportin-5 (XPO5), impacting liver cancer progression and drug resistance. This mechanism reveals a new role for ERK in microRNA biogenesis and offers potential therapeutic targets.
Area of Science:
- Molecular Biology
- Cancer Research
- Biochemistry
Background:
- MicroRNAs (miRNAs) are frequently downregulated in cancer, but the underlying mechanisms and consequences are not fully understood.
- Understanding miRNA regulation is crucial for developing effective cancer therapies.
Purpose of the Study:
- To elucidate the mechanism by which ERK signaling affects miRNA biogenesis.
- To investigate the role of ERK-mediated suppression of miRNA export in liver tumorigenesis and drug resistance.
Main Methods:
- Investigated the interaction between ERK, exportin-5 (XPO5), and pre-miRNA using biochemical assays.
- Utilized cell culture models of liver cancer and analyzed clinical specimens.
Main Results:
- ERK phosphorylates XPO5 at specific sites (T345/S416/S497), leading to conformational changes mediated by Pin1.
- This phosphorylation reduces pre-miRNA loading into XPO5, thereby suppressing miRNA export.
- In liver cancer, reduced miR-122 levels due to ERK-mediated XPO5 suppression promote tumor development and drug resistance.
- XPO5 phosphorylation correlates with poor prognosis in liver cancer patients.
Conclusions:
- ERK signaling plays a novel role in regulating miRNA biogenesis by inhibiting pre-miRNA nuclear export.
- The ERK-XPO5 pathway is implicated in liver cancer progression, offering potential therapeutic strategies targeting miRNA export.
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