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 inhibit 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.

Protein Kinase A in cellular migration—Niche signaling of a ubiquitous kinase

“…Finally, leading edge PKA activity can be induced in relatively non-motile HeLa cells by simply asymmetrically recruiting RII regulatory subunit to the plasma membrane. This study used a rapamycin inducible recruitment system to recruit R subunit to the plasma membrane and found that at moderate levels of recruitment, PKA activity was increased, and the cell would move toward the rapamycin gradient ( LaCroix et al, 2022 ). At high levels of R subunit recruitment, PKA activity was ultimately inhibited.…”

“…Recalling the study using rapamycin-inducible recruitment of RII subunit, this manipulation had differing effects on PKA activity and directional cell migration depending on the level of induction ( LaCroix et al, 2022 ). Moderate amounts of recruitment of R subunit to the membrane led to increased and sustained PKA activity there whereas high levels ultimately inhibited PKA activity ( LaCroix et al, 2022 ).…”

“…Recalling the study using rapamycin-inducible recruitment of RII subunit, this manipulation had differing effects on PKA activity and directional cell migration depending on the level of induction ( LaCroix et al, 2022 ). Moderate amounts of recruitment of R subunit to the membrane led to increased and sustained PKA activity there whereas high levels ultimately inhibited PKA activity ( LaCroix et al, 2022 ). Though not completely unexpected, this result highlights the complexity of PKA regulation—location, relative abundance of subunits, and availability of upstream activators, binding partners, and targets coalesce to create higher order signaling complexes that bring PKA specifically to bear on a variety of processes involved in 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 – 16 , PKA 38 , and AMPK nuclear signaling 39 , 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.…”