Protein kinase A is a functional component of focal adhesions

Mingu Kang; Amanda J Senatore; Hannah Naughton; Madeline McTigue; Rachel J Beltman; Andrew A Herppich; Mary Kay H Pflum; Alan K Howe

doi:10.1016/j.jbc.2024.107234

Protein kinase A is a functional component of focal adhesions

J Biol Chem. 2024 Mar 27;300(5):107234. doi: 10.1016/j.jbc.2024.107234. Online ahead of print.

Authors

Mingu Kang¹, Amanda J Senatore¹, Hannah Naughton¹, Madeline McTigue¹, Rachel J Beltman², Andrew A Herppich², Mary Kay H Pflum², Alan K Howe³

Affiliations

¹ Department of Pharmacology, Larner College of Medicine, University of Vermont Cancer Center, Burlington, Vermont, USA; Department of Molecular Physiology & Biophysics, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA.
² Department of Chemistry, Wayne State University, Detroit, Michigan, USA.
³ Department of Pharmacology, Larner College of Medicine, University of Vermont Cancer Center, Burlington, Vermont, USA; Department of Molecular Physiology & Biophysics, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA. Electronic address: alan.howe@med.uvm.edu.

Abstract

Focal adhesions (FAs) form the junction between extracellular matrix (ECM)-bound integrins and the actin cytoskeleton and also transmit signals that regulate cell adhesion, cytoskeletal dynamics, and cell migration. While many of these signals are rooted in reversible tyrosine phosphorylation, phosphorylation of FA proteins on Ser/Thr residues is far more abundant yet its mechanisms and consequences are far less understood. The cAMP-dependent protein kinase (protein kinase A; PKA) has important roles in cell adhesion and cell migration and is both an effector and regulator of integrin-mediated adhesion to the ECM. Importantly, subcellular localization plays a critically important role in specifying PKA function. Here, we show that PKA is present in isolated FA-cytoskeleton complexes and active within FAs in live cells. Furthermore, using kinase-catalyzed biotinylation of isolated FA-cytoskeleton complexes, we identify 53 high-stringency candidate PKA substrates within FAs. From this list, we validate tensin-3 (Tns3)-a well-established molecular scaffold, regulator of cell migration, and a component of focal and fibrillar adhesions-as a novel direct substrate for PKA. These observations identify a new pathway for phospho-regulation of Tns3 and, importantly, establish a new and important niche for localized PKA signaling and thus provide a foundation for further investigation of the role of PKA in the regulation of FA dynamics and signaling.

Keywords: biosensor; focal adhesions; phosphorylation; protein kinase A (PKA); signal transduction.