Junctions between the endoplasmic reticulum (ER) and the plasma membrane (PM) are specialized membrane contacts ubiquitous in eukaryotic cells. Concentration of intracellular signaling machinery near ER-PM junctions allows these domains to serve critical roles in lipid and Ca2+ signaling and homeostasis. Subcellular compartmentalization of protein kinase A (PKA) signaling also regulates essential cellular functions, however, no specific association between PKA and ER-PM junctional domains is known. Here, we show that in brain neurons type I PKA is directed to Kv2.1 channel-dependent ER-PM junctional domains via SPHKAP, a type I PKA-specific anchoring protein. SPHKAP association with type I PKA regulatory subunit RI and ER-resident VAP proteins results in the concentration of type I PKA between stacked ER cisternae associated with ER-PM junctions. This ER-associated PKA signalosome enables reciprocal regulation between PKA and Ca2+ signaling machinery to support Ca2+ influx and excitation-transcription coupling. These data reveal that neuronal ER-PM junctions support a receptor-independent form of PKA signaling driven by membrane depolarization and intracellular Ca2+, allowing conversion of information encoded in electrical signals into biochemical changes universally recognized throughout the cell.
We thank Kayla Templeton and Peter Turcanu for technical assistance, Michelle Salemi for assistance with LC-MS data acquisition and analysis, Dr. Belvin Gong for advice on monoclonal antibody generation, Drs. Maria Casas Prat and Eamonn Dickson for assistance with super-resolution TIRF microscopy, Dr. Oscar Cerda for assistance with the design of TAT-FFAT peptides, Dr. Fernando Santana for helpful discussions, and Dr. Jodi Nunnari for a careful reading of our manuscript. We also thank Dr. Alan Howe, Dr. Sohum Mehta, and Dr. Jin Zhang for providing plasmids used in this study. This project was funded by NIH Grants R01NS114210 and R21NS101648 (J.S.T.), and F32NS108519 (N.C.V.).
Vierra NC, Ribeiro-Silva L, Kirmiz M, et al. Neuronal ER-plasma membrane junctions couple excitation to Ca2+-activated PKA signaling. Nature Communications. 2023;14. doi:10.1038/s41467-023-40930-6
Vierra, N. C., Ribeiro-Silva, L., Kirmiz, M., Van Der List, D., Bhandari, P., Mack, O. A., … Trimmer, J. S. (2023). Neuronal ER-plasma membrane junctions couple excitation to Ca2+-activated PKA signaling. Nature Communications. Springer Nature. https://doi.org/10.1038/s41467-023-40930-6
Vierra, Nicholas C., Luisa Ribeiro-Silva, Michael Kirmiz, Deborah Van Der List, Pradeep Bhandari, Olivia A. Mack, James Carroll, et al. “Neuronal ER-Plasma Membrane Junctions Couple Excitation to Ca2+-Activated PKA Signaling.” Nature Communications. Springer Nature, 2023. https://doi.org/10.1038/s41467-023-40930-6.
N. C. Vierra et al., “Neuronal ER-plasma membrane junctions couple excitation to Ca2+-activated PKA signaling,” Nature Communications, vol. 14. Springer Nature, 2023.
Vierra NC, Ribeiro-Silva L, Kirmiz M, Van Der List D, Bhandari P, Mack OA, Carroll J, Le Monnier E, Aicher SA, Shigemoto R, Trimmer JS. 2023. Neuronal ER-plasma membrane junctions couple excitation to Ca2+-activated PKA signaling. Nature Communications. 14, 5231.
Vierra, Nicholas C., et al. “Neuronal ER-Plasma Membrane Junctions Couple Excitation to Ca2+-Activated PKA Signaling.” Nature Communications, vol. 14, 5231, Springer Nature, 2023, doi:10.1038/s41467-023-40930-6.
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