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Hardy JC, Pool EH, Bruystens JGH, Zhou X, Li Q, Zhou DR, Palay M, Tan G, Chen L, Choi JLC, Lee HN, Strack S, Wang D, Taylor SS, Mehta S, Zhang J. Molecular determinants and signaling effects of PKA RIα phase separation. Mol Cell 2024; 84:1570-1584.e7. [PMID: 38537638 PMCID: PMC11031308 DOI: 10.1016/j.molcel.2024.03.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 12/07/2023] [Accepted: 03/01/2024] [Indexed: 04/09/2024]
Abstract
Spatiotemporal regulation of intracellular signaling molecules, such as the 3',5'-cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA), ensures proper cellular function. Liquid-liquid phase separation (LLPS) of the ubiquitous PKA regulatory subunit RIα promotes cAMP compartmentation and signaling specificity. However, the molecular determinants of RIα LLPS remain unclear. Here, we reveal that two separate dimerization interfaces, combined with the cAMP-induced unleashing of the PKA catalytic subunit (PKA-C) from the pseudosubstrate inhibitory sequence, drive RIα condensate formation in the cytosol of mammalian cells, which is antagonized by docking to A-kinase anchoring proteins. Strikingly, we find that the RIα pseudosubstrate region is critically involved in forming a non-canonical R:C complex, which recruits active PKA-C to RIα condensates to maintain low basal PKA activity in the cytosol. Our results suggest that RIα LLPS not only facilitates cAMP compartmentation but also spatially restrains active PKA-C, thus highlighting the functional versatility of biomolecular condensates in driving signaling specificity.
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Affiliation(s)
- Julia C Hardy
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA; Shu Chien-Gene Lay Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Emily H Pool
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA; Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Jessica G H Bruystens
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Xin Zhou
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Qingrong Li
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Daojia R Zhou
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA; Shu Chien-Gene Lay Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Max Palay
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA; Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Gerald Tan
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Lisa Chen
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Jaclyn L C Choi
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Ha Neul Lee
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Stefan Strack
- Department of Pharmacology, University of Iowa, Iowa City, IA 52242, USA
| | - Dong Wang
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA; Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Susan S Taylor
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA; Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Sohum Mehta
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Jin Zhang
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA; Shu Chien-Gene Lay Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA; Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA; Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA.
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