USP34 regulates endothelial PAR1 mRNA transcript expression and cellular signaling

Area of Science:

• Cellular signaling
• Molecular biology
• Biochemistry

Background:

• G protein-coupled receptors (GPCRs) mediate cellular responses through complex regulatory mechanisms.
• Posttranslational modifications, particularly phosphorylation, are known to regulate GPCR signaling.
• The role of ubiquitination in GPCR regulation is less understood, prompting investigation into its specific mechanisms.

Purpose of the Study:

• To investigate the role of ubiquitination and deubiquitination in regulating GPCR signaling.
• To determine if the deubiquitinase USP34 influences thrombin-stimulated PAR1 signaling.
• To elucidate the molecular mechanisms by which USP34 affects PAR1-mediated cellular responses.

Main Methods:

• Utilized small interfering RNA (siRNA) to knockdown USP34 expression in cells.
• Assessed PAR1 cell surface abundance, protein expression, and mRNA transcript levels.
• Investigated PAR1 internalization and degradation pathways.
• Examined the ubiquitination status of PAR1 and p38 signaling pathway components.

Main Results:

• USP34 knockdown increased PAR1 cell surface abundance and protein expression.
• PAR1 ubiquitination and p38 pathway component ubiquitination remained unchanged upon USP34 depletion.
• USP34 loss did not affect PAR1 internalization or degradation.
• Loss of USP34 significantly increased F2R mRNA transcript expression.

Conclusions:

• USP34 plays a critical role in regulating GPCR signaling, specifically PAR1.
• USP34 influences PAR1 cell surface levels through the regulation of F2R mRNA expression, not by altering receptor ubiquitination or degradation.
• This study reveals an unexpected function of USP34 in modulating gene expression to control GPCR signaling pathways.