Complex effects of kinase localization revealed by compartment-specific regulation of protein kinase A activity

Abstract

Kinase activity in signaling networks frequently depends on regulatory subunits that can both inhbit activity by interacting with the catalytic subunits and target the kinase to distinct molecular partners and subcellular compartments. Here, using a new synthetic molecular interaction system, we show that translocation of a regulatory subunit of the protein kinase A (PKA-R) to the plasma membrane has a paradoxical effect on the membrane kinase activity. It can both enhance it at lower translocation levels, even in the absence of signaling inputs, and inhibit it at higher translocation levels, suggesting its role as a linker that can both couple and decouple signaling processes in a concentration-dependent manner. We further demonstrate that superposition of gradients of PKA R abundance across single cells can control the directionality of cell migration, reversing it at high enough input levels. Thus complex in vivo patterns of PKA-R localization can drive complex phenotypes, including cell migration.

Fluorescence Resonance Energy Transfer (FRET) Spatiotemporal Mapping of Atypical p38 Reveals an Endosomal and Cytosolic Spatial Bias

“…While these studies are highly suggestive, there are advantages to live-cell imaging, which allows for a comprehensive assessment of the spatially guided signaling dynamics in individual cells. Recent studies have highlighted this potential by exploring intracellular G-protein dynamics, and spatially resolved ERK1/2 signaling (15-18), PKA (35), and AMPK nuclear signaling (36), defining the critical spatial control of kinases, where adaptor and substrate accessibility drives their functional roles. While it is well known that p38 has a central role in the regulation of both cytosolic and nuclear proteins (2,3), direct analysis of the spatiotemporal p38 dynamics has not been carried out.…”