Protein Kinase A Catalytic and Regulatory Subunits Interact Differently in Various Areas of Mouse Brain

Abstract

Protein kinase A (PKA) are tetramers of two catalytic and two regulatory subunits, docked at precise intracellular sites to provide localized phosphorylating activity, triggered by cAMP binding to regulatory subunits and subsequent dissociation of catalytic subunits. It is unclear whether in the brain PKA dissociated subunits may also be found. PKA catalytic subunit was examined in various mouse brain areas using immunofluorescence, equilibrium binding and western blot, to reveal its location in comparison to regulatory subunits type RI and RII. In the cerebral cortex, catalytic subunits colocalized with clusters of RI, yet not all RI clusters were bound to catalytic subunits. In stria terminalis, catalytic subunits were in proximity to RI but separated from them. Catalytic subunits clusters were also present in the corpus striatum, where RII clusters were detected, whereas RI clusters were absent. Upon cAMP addition, the distribution of regulatory subunits did not change, while catalytic subunits were completely released from regulatory subunits. Unpredictably, catalytic subunits were not solubilized; instead, they re-targeted to other binding sites within the tissue, suggesting local macromolecular reorganization. Hence, the interactions between catalytic and regulatory subunits of protein kinase A consistently vary in different brain areas, supporting the idea of multiple interaction patterns.

The stereospecific interaction sites and target specificity of cGMP analogs in mouse cortex

“…However, this was not the case with Rp-and Sp-cGMP-analogs, because these enriched both types of subunits. When cAMP binds PKA the catalytic subunit dissociates from the holoenzyme (Mucignat-Caretta & Caretta, 2020), and this might be prevented by an inhibiting Rp-cAMP-analog, resulting in pull-down of both types of subunits. In general, cGMP does not activate PKA and cAMP (Poppe et al, 2008).…”

GLP1R inhibits the progression of endometrial carcinoma through activation of cAMP/PKA pathway

“…This pathway has also been confirmed to be involved in cell proliferation, differentiation and apoptosis, ion transport, regulation of metabolism and gene transcription 25 . As the downstream molecule of cAMP, PKA is composed of catalytic subunit and regulatory subunit 26,27 . The catalytic subunit can mediate the phosphorylation of various substrate proteins, while the two subtypes of regulatory subunit, RI and RII, are mainly implicated in cell proliferation and differentiation 28 .…”

“…25 As the downstream molecule of cAMP, PKA is composed of catalytic subunit and regulatory subunit. 26,27 The catalytic subunit can mediate the phosphorylation of various substrate proteins, while the two subtypes of regulatory subunit, RI and RII, are mainly implicated in cell proliferation and differentiation. 28 Once external factors lead to the dominant F I G U R E 3 The effects of GLP1R and PKA on EC cell migration.…”

Estimation of cAMP binding in hippocampus CA1 field by a fluorescent probe

“…Contrary to R1A widespread distribution all over the brain when in soluble form, R1A aggregates are found in the neuronal detergent-insoluble fraction at particular ages and at specific sites only, where they are bound to cytoskeleton (Mucignat-Caretta et al, 1999). In CA1 it partially co-localizes with PKA catalytic subunit (Mucignat-Caretta and Caretta, 2020). Notably, three laboratories using two different technologies reported higher R1A and R1B expression, when compared to R2A and R2B in the whole hippocampus (see Mucignat-Caretta and Caretta, 2020).…”