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Saneyoshi T. Reciprocal activation within a kinase effector complex: A mechanism for the persistence of molecular memory. Brain Res Bull 2021; 170:58-64. [PMID: 33556559 DOI: 10.1016/j.brainresbull.2021.01.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 01/10/2021] [Accepted: 01/25/2021] [Indexed: 01/01/2023]
Abstract
Synaptic connections in neuronal circuits change in response to neuronal activity patterns. This can induce a persistent change in the efficacy of synaptic transmission, a phenomenon known as synaptic plasticity. One form of plasticity, long-term potentiation (LTP) has been extensively studied as the cellular basis of memory. In LTP, the potentiated synaptic transmission persists along with structural changes in the synapses. Many studies have sought to identify the "memory molecule" or the "molecular engram". Ca2+/calmodulin-dependent protein kinase II (CaMKII) is probably the most well-studied candidate for the memory molecule. However, consensus has not yet been reached on a very basic aspect: how CaMKII is regulated during LTP. Here, I propose a new model of CaMKII regulation: reciprocal activation within a kinase effector complex (RAKEC) that is made between CaMKII and its effector protein, which is mediated by a persistent interaction between CaMKII and a pseudosubstrate sequence on T-lymphoma invasion and metastasis protein 1 (Tiam1), resulting in reciprocal activation of these two molecules. Through the RAKEC mechanism, CaMKII can maintain memory as biochemical activity in a synapse-specific manner. In this review, the detailed mechanism of the RAKEC and its expansion for the maintenance of LTP is described.
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Affiliation(s)
- Takeo Saneyoshi
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan.
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Saneyoshi T, Matsuno H, Suzuki A, Murakoshi H, Hedrick NG, Agnello E, O'Connell R, Stratton MM, Yasuda R, Hayashi Y. Reciprocal Activation within a Kinase-Effector Complex Underlying Persistence of Structural LTP. Neuron 2019; 102:1199-1210.e6. [PMID: 31078368 DOI: 10.1016/j.neuron.2019.04.012] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 12/07/2018] [Accepted: 04/03/2019] [Indexed: 10/26/2022]
Abstract
Long-term synaptic plasticity requires a mechanism that converts short Ca2+ pulses into persistent biochemical signaling to maintain changes in the synaptic structure and function. Here, we present a novel mechanism of a positive feedback loop, formed by a reciprocally activating kinase-effector complex (RAKEC) in dendritic spines, enabling the persistence and confinement of a molecular memory. We found that stimulation of a single spine causes the rapid formation of a RAKEC consisting of CaMKII and Tiam1, a Rac-GEF. This interaction is mediated by a pseudo-autoinhibitory domain on Tiam1, which is homologous to the CaMKII autoinhibitory domain itself. Therefore, Tiam1 binding results in constitutive CaMKII activation, which in turn persistently phosphorylates Tiam1. Phosphorylated Tiam1 promotes stable actin-polymerization through Rac1, thereby maintaining the structure of the spine during LTP. The RAKEC can store biochemical information in small subcellular compartments, thus potentially serving as a general mechanism for prolonged and compartmentalized signaling.
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Affiliation(s)
- Takeo Saneyoshi
- Brain Science Institute, RIKEN, Wako, Saitama 351-0198, Japan; Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan.
| | - Hitomi Matsuno
- Brain Science Institute, RIKEN, Wako, Saitama 351-0198, Japan
| | - Akio Suzuki
- Brain Science Institute, RIKEN, Wako, Saitama 351-0198, Japan
| | - Hideji Murakoshi
- National Institute of Physiological Science, Okazaki, Aichi 444-8585, Japan; Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA; Duke University Medical Center, Durham, NC 27703, USA
| | - Nathan G Hedrick
- Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA; Duke University Medical Center, Durham, NC 27703, USA
| | - Emily Agnello
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Rory O'Connell
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Margaret M Stratton
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Ryohei Yasuda
- Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA
| | - Yasunori Hayashi
- Brain Science Institute, RIKEN, Wako, Saitama 351-0198, Japan; Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan; Brain and Body System Science Institute, Saitama University, Saitama 338-8570, Japan; School of Life Science, South China Normal University, Guangzhou 510631, China.
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