Mechanisms for Generating the Autonomous cAMP-Dependent Protein Kinase Required for Long-Term Facilitation in Aplysia

• Published in: Neuron (Cambridge, Mass.) Vol. 22; no. 1; pp. 147 - 156
• Main Authors: Chain, Daniel G, Casadio, Andrea, Schacher, Samuel, Hegde, Ashok N, Valbrun, Mireille, Yamamoto, Naoki, Goldberg, Alfred L, Bartsch, Dusan, Kandel, Eric R, Schwartz, James H
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 1999
• Subjects: Animals; Aplysia; Aplysia - metabolism; Aplysia - physiology; Cattle; Cyclic AMP - physiology; Cyclic AMP-Dependent Protein Kinases - biosynthesis; Cyclic AMP-Dependent Protein Kinases - metabolism; Cyclic AMP-Dependent Protein Kinases - pharmacology; Cysteine Endopeptidases - physiology; Injections; Long-Term Potentiation - physiology; Multienzyme Complexes - physiology; Neurons, Afferent - drug effects; Neurons, Afferent - physiology; Peptide Fragments - metabolism; Peptide Fragments - pharmacology; Proteasome Endopeptidase Complex; Serotonin - pharmacology; Ubiquitins - metabolism
• ISSN: 0896-6273; 1097-4199
• DOI: 10.1016/S0896-6273(00)80686-8

The formation of a persistently active cAMP-dependent protein kinase (PKA) is critical for establishing long-term synaptic facilitation (LTF) in Aplysia. The injection of bovine catalytic (C) subunits into sensory neurons is sufficient to produce protein synthesis–dependent LTF. Early in the LTF induced by serotonin (5-HT), an autonomous PKA is generated through the ubiquitin–proteasome-mediated proteolysis of regulatory (R) subunits. The degradation of R occurs during an early time window and appears to be a key function of proteasomes in LTF. Lactacystin, a specific proteasome inhibitor, blocks the facilitation induced by 5-HT, and this block is rescued by injecting C subunits. R is degraded through an allosteric mechanism requiring an elevation of cAMP coincident with the induction of a ubiquitin carboxy-terminal hydrolase.