USP9X Deubiquitylates DVL2 to Regulate WNT Pathway Specification
Casey P Nielsen1, Kristin K Jernigan1, Nicole L Diggins2
1Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240, USA.
Abstract:
The WNT signaling network is comprised of multiple receptors that relay various input signals via distinct transduction pathways to execute multiple complex and context-specific output processes. Integrity of the WNT signaling network relies on proper specification between canonical and noncanonical pathways, which presents a regulatory challenge given that several signal transducing elements are shared between pathways. Here, we report that USP9X, a deubiquitylase, and WWP1, an E3 ubiquitin ligase, regulate a ubiquitin rheostat on DVL2, a WNT signaling protein. Our findings indicate that USP9X-mediated deubiquitylation of DVL2 is required for canonical WNT activation, while increased DVL2 ubiquitylation is associated with localization to actin-rich projections and activation of the planar cell polarity (PCP) pathway. We propose that a WWP1-USP9X axis regulates a ubiquitin rheostat on DVL2 that specifies its participation in either canonical WNT or WNT-PCP pathways. These findings have important implications for therapeutic targeting of USP9X in human cancer.
Insights
USP9X and WWP1 control DVL2 ubiquitylation, directing WNT signaling. USP9X promotes canonical WNT, while ubiquitylation activates the WNT-planar cell polarity pathway, impacting cancer therapeutics.
Area of Science:
- Cellular biology
- Molecular signaling
- Biochemistry
Background:
- The WNT signaling network regulates complex cellular processes through distinct pathways.
- Distinguishing between canonical and noncanonical WNT pathways is crucial but challenging due to shared signaling components.
Purpose of the Study:
- To investigate the roles of USP9X and WWP1 in regulating DVL2 ubiquitylation.
- To elucidate how DVL2 ubiquitylation status determines its involvement in canonical WNT versus WNT-planar cell polarity (PCP) pathways.
Main Methods:
- Investigated the deubiquitylase USP9X and E3 ligase WWP1 activity on DVL2.
- Analyzed DVL2 ubiquitylation levels and localization under different WNT pathway activations.
Main Results:
- USP9X deubiquitylation of DVL2 is essential for canonical WNT pathway activation.
- Increased ubiquitylation of DVL2 correlates with its localization to actin-rich regions and activation of the WNT-PCP pathway.
- A WWP1-USP9X axis regulates DVL2 ubiquitylation, acting as a switch between WNT pathways.
Conclusions:
- A novel regulatory mechanism involving a ubiquitin rheostat on DVL2 specifies WNT pathway choice.
- Targeting USP9X offers potential therapeutic strategies for WNT-pathway-driven human cancers.
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