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Jiang SZ, Shahoha M, Zhang HY, Brancaleone W, Elkahloun A, Tejeda HA, Ashery U, Eiden LE. The guanine nucleotide exchange factor RapGEF2 is required for ERK-dependent immediate-early gene (Egr1) activation during fear memory formation. Cell Mol Life Sci 2024; 81:48. [PMID: 38236296 PMCID: PMC11071968 DOI: 10.1007/s00018-023-04999-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 09/16/2023] [Accepted: 10/04/2023] [Indexed: 01/19/2024]
Abstract
The MAP kinase ERK is important for neuronal plasticity underlying associative learning, yet specific molecular pathways for neuronal ERK activation are undetermined. RapGEF2 is a neuron-specific cAMP sensor that mediates ERK activation. We investigated whether it is required for cAMP-dependent ERK activation leading to other downstream neuronal signaling events occurring during associative learning, and if RapGEF2-dependent signaling impairments affect learned behavior. Camk2α-cre+/-::RapGEF2fl/fl mice with depletion of RapGEF2 in hippocampus and amygdala exhibit impairments in context- and cue-dependent fear conditioning linked to corresponding impairment in Egr1 induction in these two brain regions. Camk2α-cre+/-::RapGEF2fl/fl mice show decreased RapGEF2 expression in CA1 and dentate gyrus associated with abolition of pERK and Egr1, but not of c-Fos induction, following fear conditioning, impaired freezing to context after fear conditioning, and impaired cAMP-dependent long-term potentiation at perforant pathway and Schaffer collateral synapses in hippocampal slices ex vivo. RapGEF2 expression is largely eliminated in basolateral amygdala, also involved in fear memory, in Camk2α-cre+/-::RapGEF2fl/fl mice. Neither Egr1 nor c-fos induction in BLA after fear conditioning, nor cue-dependent fear learning, are affected by ablation of RapGEF2 in BLA. However, Egr1 induction (but not that of c-fos) in BLA is reduced after restraint stress-augmented fear conditioning, as is freezing to cue after restraint stress-augmented fear conditioning, in Camk2α-cre+/-::RapGEF2fl/fl mice. Cyclic AMP-dependent GEFs have been genetically associated as risk factors for schizophrenia, a disorder associated with cognitive deficits. Here we show a functional link between one of them, RapGEF2, and cognitive processes involved in associative learning in amygdala and hippocampus.
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Affiliation(s)
- Sunny Zhihong Jiang
- Section On Molecular Neuroscience, NIMH Intramural Research Program, 9000 Rockville Pike, Building 49, Room 5A38, Bethesda, MD, 20892, USA
| | - Meishar Shahoha
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, and Sagol School of Neuroscience, Tel Aviv University, Sherman Building Rm 719, Ramat Aviv, 69978, Tel Aviv, Israel
| | - Hai-Ying Zhang
- Section On Molecular Neuroscience, NIMH Intramural Research Program, 9000 Rockville Pike, Building 49, Room 5A38, Bethesda, MD, 20892, USA
| | - William Brancaleone
- Section On Molecular Neuroscience, NIMH Intramural Research Program, 9000 Rockville Pike, Building 49, Room 5A38, Bethesda, MD, 20892, USA
| | | | - Hugo A Tejeda
- Unit on Neuromodulation and Synaptic Integration, NIMH-IRP, Bethesda, MD, USA
| | - Uri Ashery
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, and Sagol School of Neuroscience, Tel Aviv University, Sherman Building Rm 719, Ramat Aviv, 69978, Tel Aviv, Israel.
| | - Lee E Eiden
- Section On Molecular Neuroscience, NIMH Intramural Research Program, 9000 Rockville Pike, Building 49, Room 5A38, Bethesda, MD, 20892, USA.
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Xu W, Dahlke SP, Sung M, Samal B, Emery AC, Elkahloun A, Eiden LE. ERK-dependent induction of the immediate-early gene Egr1 and the late gene Gpr50 contribute to two distinct phases of PACAP Gs-GPCR signaling for neuritogenesis. J Neuroendocrinol 2022; 34:e13182. [PMID: 35841324 PMCID: PMC9529758 DOI: 10.1111/jne.13182] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 06/07/2022] [Accepted: 06/08/2022] [Indexed: 11/28/2022]
Abstract
Gs-coupled GPCR-stimulated neuritogenesis in PC12 and NS-1 - cells depends on activation of the MAP kinase ERK. Here, we examine changes in ERK activation (phosphorylation), and the time course of ERK-dependent gene induction, to seek transcriptional determinants for this process. Quenching of ERK activation by inhibition of MEK with U0126 at any time point for at least 24 h following addition of PACAP resulted in arrest of neurite formation. Changes in the transcriptome profile throughout this time period revealed at least two phases of gene induction: an early phase dominated by induction of immediate-early genes, and a later phase of gene induction after 4-6 h of exposure to PACAP with persistent elevation of phospho-ERK levels. Genes induced by PACAP in both phases consisted in those whose induction was dependent on ERK (i.e., blocked by U0126), and some whose induction was blocked by the protein kinase A inhibitor H89. ERK-dependent "late gene" transcripts included Gpr50, implicated earlier in facilitation of NGF-induced neurite formation in NS-1 cells. Gpr50 induction by PACAP, but not NGF, was dependent on the guanine nucleotide exchange factor RapGEF2, which has been shown to be required for PACAP-induced neuritogenesis in NS-1 cells. Expression of a Gpr50-directed shRNA lowered basal levels of Gpr50 mRNA and attenuated Gpr50 mRNA and GPR50 protein induction by PACAP, with a corresponding attenuation of PACAP-induced neuritogenesis. Gs-GPCR-stimulated neuritogenesis first requires immediate-early gene induction, including that of Egr1 (Zif268/NGF1A/Krox24) as previously reported. This early phase of gene induction, however, is insufficient to maintain the neuritogenic process without ERK-dependent induction of additional late genes, including Gpr50, upon continuous exposure to neurotrophic neuropeptide. Early (Egr1) and late (Gpr50) gene induction by NGF, like that for PACAP, was inhibited by U0126, but was independent of RapGEF2, confirming distinct modes of ERK activation by Gs-coupled GPCRs and neurotrophic tyrosine receptor kinases, converging on a final common ERK-dependent signaling pathway for neuritogenesis.
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Affiliation(s)
- Wenqin Xu
- Section on Molecular Neuroscience, National Institute of Mental Health-Intramural Research Program
| | - Sam P. Dahlke
- Section on Molecular Neuroscience, National Institute of Mental Health-Intramural Research Program
| | - Michelle Sung
- Section on Molecular Neuroscience, National Institute of Mental Health-Intramural Research Program
| | - Babru Samal
- Section on Molecular Neuroscience, National Institute of Mental Health-Intramural Research Program
| | - Andrew C. Emery
- Section on Molecular Neuroscience, National Institute of Mental Health-Intramural Research Program
| | - Abdel Elkahloun
- Microarray Core, National Human Genome Research Institute, Bethesda, MD, USA
| | - Lee E. Eiden
- Section on Molecular Neuroscience, National Institute of Mental Health-Intramural Research Program
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