p63, a key regulator of Ago2, links to the microRNA-144 cluster

Area of Science:

• Molecular Biology
• Cancer Research
• RNA Biology

Background:

• Argonaute2 (Ago2) is crucial for RNA-induced silencing complex (RISC) and has a dual role in tumor progression.
• The precise regulatory mechanisms governing Ago2's function in cancer remain unclear.
• p63, a p53 homolog, is implicated in tumorigenesis and metastasis.

Purpose of the Study:

• To elucidate the interaction between p63 isoforms and Ago2.
• To understand how p63 influences Ago2's dual function in cancer.
• To uncover the role of the miR-144/451 cluster in this regulatory network.

Main Methods:

• Co-immunoprecipitation assays to confirm physical interaction between p63 and Ago2.
• Western blotting to assess protein levels of Ago2 and p63.
• shRNA-mediated depletion of p63 to evaluate its effect on Ago2 levels.
• Luciferase reporter assays and qRT-PCR to study the miR-144/451 cluster regulation.
• In vitro and in vivo experiments to assess tumor suppressor functions.

Main Results:

• p63 isoforms physically interact with and stabilize Ago2 protein levels.
• Depletion of p63 reduces Ago2 protein, while its expression increases Ago2.
• TAp63 transactivates the miR-144/451 cluster, forming a positive feedback loop.
• miR-144 targets Itch, increasing p63 levels and enhancing its tumor suppressor activity.
• miR-144 promotes apoptosis and inhibits cell invasion, mediated by TAp63.

Conclusions:

• p63 isoforms are key regulators of Ago2 protein stability and function in cancer.
• A novel positive feedback loop involving TAp63 and the miR-144/451 cluster is identified.
• miR-144 acts as a tumor suppressor by stabilizing p63 and enhancing its anti-tumorigenic functions.
• This study reveals a new molecular mechanism linking p63, Ago2, and the miR-144 cluster in cancer progression.