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Impaired cAMP processivity by phosphodiesterase-protein kinase A complexes in acrodysostosis

Acrodysostosis represents a group of rare genetic disorders characterized by defective skeletal development and is often accompanied by intellectual disabilities. Mutations in the 3′5′cyclic AMP (cAMP)-dependent protein kinase (PKA) type I regulatory subunit isoform α (RIα) and phosphodiesterase (PD...

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Autores principales: Venkatakrishnan, Varun, Ghode, Abhijeet, Tulsian, Nikhil K., Anand, Ganesh S.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10552185/
https://www.ncbi.nlm.nih.gov/pubmed/37808519
http://dx.doi.org/10.3389/fmolb.2023.1202268
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author Venkatakrishnan, Varun
Ghode, Abhijeet
Tulsian, Nikhil K.
Anand, Ganesh S.
author_facet Venkatakrishnan, Varun
Ghode, Abhijeet
Tulsian, Nikhil K.
Anand, Ganesh S.
author_sort Venkatakrishnan, Varun
collection PubMed
description Acrodysostosis represents a group of rare genetic disorders characterized by defective skeletal development and is often accompanied by intellectual disabilities. Mutations in the 3′5′cyclic AMP (cAMP)-dependent protein kinase (PKA) type I regulatory subunit isoform α (RIα) and phosphodiesterase (PDE) PDE4D have both been implicated in impaired PKA regulation in acrodysostosis. How mutations on PDEs and RIα interfere with the regulation of cAMP-PKA signaling is not understood. cAMP-PKA signaling can be described in two phases. In the activation phase, cAMP binding to RIα dissociates the free C-subunit (Catalytic subunit). PDEs hydrolyze cAMP bound to RIα, priming the cAMP-free RIα for reassociation with the C-subunit, thereby completing one PKA activation cycle. Signal termination is thus critical for resetting PKA to its basal state and promoting adaptation to hormonal hyperstimulation. This proceeds through formation of a transient signal termination RIα: PDE complex that facilitates cAMP channeling from the cAMP-binding domain of RIα to the catalytic site of PDE. Signal termination of cAMP-PKA proceeds in three steps: Step 1) Channeling: translocation of cAMP from the CNB of RIα to the PDE catalytic site for hydrolysis. Step 2) Processivity: binding of free cAMP from the cytosol at both CNBs of RIα. Step 3) Product (5′AMP) release from the PDE hydrolysis site through competitive displacement by a new molecule of cAMP that triggers subsequent activation cycles of PKA. We have identified the molecular basis for two acrodysostosis mutants, PDE (PDE8 T690P) and RIα (T207A), that both allosterically impair cAMP-PKA signal termination. A combination of amide hydrogen/deuterium exchange mass spectrometry (HDXMS) and fluorescence polarization (FP) reveals that PDE8 T690P and RIα T207A both blocked processive hydrolysis of cAMP by interfering with competitive displacement of product 5′AMP release from the nucleotide channel at the end of each round of cAMP hydrolysis. While T690P blocked product 5′AMP release from the PDE, T207A greatly slowed the release of the substrate from RIα. These results highlight the role of processivity in cAMP hydrolysis by RIα: PDE termination complexes for adaptation to cAMP from GPCR hyperstimulation. Impairment of the signal termination process provides an alternate molecular basis for acrodysostosis.
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spelling pubmed-105521852023-10-06 Impaired cAMP processivity by phosphodiesterase-protein kinase A complexes in acrodysostosis Venkatakrishnan, Varun Ghode, Abhijeet Tulsian, Nikhil K. Anand, Ganesh S. Front Mol Biosci Molecular Biosciences Acrodysostosis represents a group of rare genetic disorders characterized by defective skeletal development and is often accompanied by intellectual disabilities. Mutations in the 3′5′cyclic AMP (cAMP)-dependent protein kinase (PKA) type I regulatory subunit isoform α (RIα) and phosphodiesterase (PDE) PDE4D have both been implicated in impaired PKA regulation in acrodysostosis. How mutations on PDEs and RIα interfere with the regulation of cAMP-PKA signaling is not understood. cAMP-PKA signaling can be described in two phases. In the activation phase, cAMP binding to RIα dissociates the free C-subunit (Catalytic subunit). PDEs hydrolyze cAMP bound to RIα, priming the cAMP-free RIα for reassociation with the C-subunit, thereby completing one PKA activation cycle. Signal termination is thus critical for resetting PKA to its basal state and promoting adaptation to hormonal hyperstimulation. This proceeds through formation of a transient signal termination RIα: PDE complex that facilitates cAMP channeling from the cAMP-binding domain of RIα to the catalytic site of PDE. Signal termination of cAMP-PKA proceeds in three steps: Step 1) Channeling: translocation of cAMP from the CNB of RIα to the PDE catalytic site for hydrolysis. Step 2) Processivity: binding of free cAMP from the cytosol at both CNBs of RIα. Step 3) Product (5′AMP) release from the PDE hydrolysis site through competitive displacement by a new molecule of cAMP that triggers subsequent activation cycles of PKA. We have identified the molecular basis for two acrodysostosis mutants, PDE (PDE8 T690P) and RIα (T207A), that both allosterically impair cAMP-PKA signal termination. A combination of amide hydrogen/deuterium exchange mass spectrometry (HDXMS) and fluorescence polarization (FP) reveals that PDE8 T690P and RIα T207A both blocked processive hydrolysis of cAMP by interfering with competitive displacement of product 5′AMP release from the nucleotide channel at the end of each round of cAMP hydrolysis. While T690P blocked product 5′AMP release from the PDE, T207A greatly slowed the release of the substrate from RIα. These results highlight the role of processivity in cAMP hydrolysis by RIα: PDE termination complexes for adaptation to cAMP from GPCR hyperstimulation. Impairment of the signal termination process provides an alternate molecular basis for acrodysostosis. Frontiers Media S.A. 2023-09-21 /pmc/articles/PMC10552185/ /pubmed/37808519 http://dx.doi.org/10.3389/fmolb.2023.1202268 Text en Copyright © 2023 Venkatakrishnan, Ghode, Tulsian and Anand. https://creativecommons.org/licenses/by/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Molecular Biosciences
Venkatakrishnan, Varun
Ghode, Abhijeet
Tulsian, Nikhil K.
Anand, Ganesh S.
Impaired cAMP processivity by phosphodiesterase-protein kinase A complexes in acrodysostosis
title Impaired cAMP processivity by phosphodiesterase-protein kinase A complexes in acrodysostosis
title_full Impaired cAMP processivity by phosphodiesterase-protein kinase A complexes in acrodysostosis
title_fullStr Impaired cAMP processivity by phosphodiesterase-protein kinase A complexes in acrodysostosis
title_full_unstemmed Impaired cAMP processivity by phosphodiesterase-protein kinase A complexes in acrodysostosis
title_short Impaired cAMP processivity by phosphodiesterase-protein kinase A complexes in acrodysostosis
title_sort impaired camp processivity by phosphodiesterase-protein kinase a complexes in acrodysostosis
topic Molecular Biosciences
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10552185/
https://www.ncbi.nlm.nih.gov/pubmed/37808519
http://dx.doi.org/10.3389/fmolb.2023.1202268
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