PP1A-mediated dephosphorylation positively regulates YAP2 activity

Area of Science:

• Molecular Biology
• Cell Signaling
• Cancer Research

Background:

• The Hippo/MST1 pathway regulates cell proliferation and apoptosis.
• Yes-associated protein 2 (YAP2) is a key downstream target involved in organ size and cancer.
• MST1/Lats kinase inhibits YAP2 activity via phosphorylation and 14-3-3 binding, but YAP2 dephosphorylation is less understood.

Purpose of the Study:

• To investigate the role of protein phosphatase 1 alpha (PP1A) in YAP2 dephosphorylation.
• To elucidate the functional consequences of PP1A-mediated YAP2 dephosphorylation on YAP2 activity and cell survival.
• To explore the therapeutic implications of this pathway in ovarian cancer.

Main Methods:

• In vitro and in vivo interaction and dephosphorylation assays of PP1A and YAP2.
• Treatment with okadaic acid (OA) to inhibit PP1 activity.
• Assessment of YAP2 nuclear accumulation, transcriptional activity, and cell survival.
• YAP2 knockdown experiments in ovarian cancer cells treated with cisplatin.

Main Results:

• PP1A directly interacts with and dephosphorylates YAP2.
• PP1A-mediated YAP2 dephosphorylation promotes nuclear accumulation and transcriptional activation.
• PP1 inhibition (OA) increases YAP2 phosphorylation, cytoplasmic localization, and reduces transcriptional activity.
• PP1A enhances YAP2's pro-survival role; YAP2 knockdown sensitizes cells to cisplatin.

Conclusions:

• PP1A positively regulates YAP2 activity through dephosphorylation.
• This PP1-mediated dephosphorylation mechanism is crucial for cell survival.
• Targeting this pathway may offer new strategies for ovarian cancer therapy.