scholarly journals FMRP regulates mRNAs encoding distinct functions in the cell body and dendrites of CA1 pyramidal neurons

2021 ◽  
Author(s):  
Caryn R Hale ◽  
Kirsty Sawicka ◽  
Kevin Mora ◽  
John J Fak ◽  
Jin Joo Kang ◽  
...  
Keyword(s):  
Pyramidal Neurons ◽  
Neuronal Cell ◽  
Synaptic Proteins ◽  
Translational Repression ◽  
Functional Modules ◽  
Cell Type ◽  
Ca1 Pyramidal Neurons ◽  
Splicing Isoforms ◽  
Activity Dependent ◽  
Ribosome Association

Neurons are believed to rely on dendritic localization and translation of mRNAs in order to generate activity-dependent changes in the synaptic plasticity. Here, we develop a strategy combining compartment-specific CLIP and TRAP in conditionally tagged mice to precisely define the ribosome bound dendritic transcriptome of CA1 pyramidal neurons. This revealed transcripts that have differentially localized alternative 3′UTR and splicing isoforms. FMRP targets are overrepresented among dendritic mRNAs, and compartment-specific FMRP-CLIP defined 383 dendritic FMRP targets, and also allowed for segregation of whole-cell FMRP targets into functional modules that are locally regulated by FMRP. In the absence of FMRP, dendritic FMRP targets show increased ribosome association, consistent with reported roles for FMRP in translational repression. Together, the data support a model in which distinct patterns of FMRP localization allow it to differentially regulate the expression of nuclear proteins and synaptic proteins within different compartments of a single neuronal cell type.

scholarly journals FMRP has a cell-type-specific role in CA1 pyramidal neurons to regulate autism-related transcripts and circadian memory

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Kirsty Sawicka ◽  
Caryn R Hale ◽  
Christopher Y Park ◽  
John J Fak ◽  
Jodi E Gresack ◽  
...  
Keyword(s):  
Pyramidal Neurons ◽  
Rna Binding ◽  
Fragile X ◽  
Neuronal Cell ◽  
Cell Types ◽  
Brain Regions ◽  
Cell Type ◽  
Ca1 Pyramidal Neurons ◽  
Mrna Targets ◽  
Specific Regulation

Loss of the RNA binding protein FMRP causes Fragile X Syndrome (FXS), the most common cause of inherited intellectual disability, yet it is unknown how FMRP function varies across brain regions and cell types and how this contributes to disease pathophysiology. Here we use conditional tagging of FMRP and CLIP (FMRP cTag CLIP) to examine FMRP mRNA targets in hippocampal CA1 pyramidal neurons, a critical cell type for learning and memory relevant to FXS phenotypes. Integrating these data with analysis of ribosome-bound transcripts in these neurons revealed CA1-enriched binding of autism-relevant mRNAs, and CA1-specific regulation of transcripts encoding circadian proteins. This contrasted with different targets in cerebellar granule neurons, and was consistent with circadian defects in hippocampus-dependent memory in Fmr1 knockout mice. These findings demonstrate differential FMRP-dependent regulation of mRNAs across neuronal cell types that may contribute to phenotypes such as memory defects and sleep disturbance associated with FXS.

scholarly journals FMRP regulates mRNAs encoding distinct functions in the cell body and dendrites of CA1 pyramidal neurons

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Caryn R Hale ◽  
Kirsty Sawicka ◽  
Kevin Mora ◽  
John J Fak ◽  
Jin Joo Kang ◽  
...  
Keyword(s):  
Cell Body ◽  
Pyramidal Neurons ◽  
Neuronal Cell ◽  
Alternative Polyadenylation ◽  
Cell Type ◽  
Mrna Isoforms ◽  
Protein Coding ◽  
Ca1 Pyramidal Neurons ◽  
Synaptic Functions ◽  
Cell Type Specific

Neurons rely on translation of synaptic mRNAs in order to generate activity-dependent changes in plasticity. Here we develop a strategy combining compartment-specific CLIP and TRAP in conditionally tagged mice to precisely define the ribosome-bound dendritic transcriptome of CA1 pyramidal neurons. We identify CA1 dendritic transcripts with differentially localized mRNA isoforms generated by alternative polyadenylation and alternative splicing, including many which have altered protein-coding capacity. Among dendritic mRNAs, FMRP targets were found to be overrepresented. Cell-type specific FMRP-CLIP and TRAP in microdissected CA1 neuropil revealed 383 dendritic FMRP targets and suggests that FMRP differentially regulates functionally distinct modules in CA1 dendrites and cell bodies. FMRP regulates ~15-20% of mRNAs encoding synaptic functions and 10% of chromatin modulators, in the dendrite and cell body, respectively. In the absence of FMRP, dendritic FMRP targets had increased ribosome association, consistent with a function for FMRP in synaptic translational repression. Conversely, downregulation of FMRP targets involved in chromatin regulation in cell bodies and suggest a role for FMRP in stabilizing mRNAs containing stalled ribosomes in this compartment. Together, the data support a model in which FMRP regulates the translation and expression of synaptic and nuclear proteins within different compartments of a single neuronal cell type.

scholarly journals Stability of excitatory structural connectivity predicts the probability of CA1 pyramidal neurons to become engram neurons

2019 ◽  
Author(s):  
Tim P. Castello-Waldow ◽  
Ghabiba Weston ◽  
Alireza Chenani ◽  
Yonatan Loewenstein ◽  
Alon Chen ◽  
...  
Keyword(s):  
Pyramidal Neurons ◽  
Structural Connectivity ◽  
Synaptic Connectivity ◽  
Two Photon ◽  
Ca1 Pyramidal Neurons ◽  
Trace Fear Conditioning ◽  
Hippocampal Ca1 ◽  
Trace Fear ◽  
Activity Dependent ◽  
Deep Brain

SUMMARYNeurons undergoing activity-dependent plasticity represent experience and are functional for learning and recall thus they are considered cellular engrams of memory. Although increase in excitability and stability of structural synaptic connectivity have been implicated in the formation and persistance of engrams, the mechanisms bringing engrams into existence are still largely unknown. To investigate this issue, we tracked the dynamics of structural excitatory synaptic connectivity of hippocampal CA1 pyramidal neurons over two weeks using deep-brain two-photon imaging in live mice. We found that neurons that will prospectively become part of an engram display higher stability of connectivity than neurons that will not. A novel experience significantly stabilizes the connectivity of non-engram neurons. Finally, the density and survival of dendritic spines negatively correlates to freezing to the context but not to the tone in a trace fear conditioning learning paradigm.

scholarly journals Reelin Improves Cognition and Extends the Lifespan of Mutant Ndel1 Mice with Postnatal CA1 Hippocampus Deterioration

2020 ◽  
Vol 30 (9) ◽  
pp. 4964-4978 ◽  
Author(s):  
Ivana Kiroski ◽  
Yulan Jiang ◽  
Cezar Gavrilovici ◽  
Fan Gao ◽  
Sukyoung Lee ◽  
...  
Keyword(s):  
Learning And Memory ◽  
Spatial Learning ◽  
Pyramidal Neurons ◽  
Neurological Diseases ◽  
Memory Function ◽  
Neuronal Cell ◽  
Adult Brain ◽  
Conditional Knockout ◽  
Spatial Learning And Memory ◽  
Ca1 Pyramidal Neurons

Abstract The glycoprotein Reelin maintains neuronal positioning and regulates neuronal plasticity in the adult brain. Reelin deficiency has been associated with neurological diseases. We recently showed that Reelin is depleted in mice with a targeted disruption of the Ndel1 gene in forebrain postnatal excitatory neurons (Ndel1 conditional knockout (CKO)). Ndel1 CKO mice exhibit fragmented microtubules in CA1 pyramidal neurons, profound deterioration of the CA1 hippocampus and a shortened lifespan (~10 weeks). Here we report that Ndel1 CKO mice (of both sexes) experience spatial learning and memory deficits that are associated with deregulation of neuronal cell adhesion, plasticity and neurotransmission genes, as assessed by genome-wide transcriptome analysis of the hippocampus. Importantly, a single injection of Reelin protein in the hippocampus of Ndel1 CKO mice improves spatial learning and memory function and this is correlated with reduced intrinsic hyperexcitability of CA1 pyramidal neurons, and normalized gene deregulation in the hippocampus. Strikingly, when treated with Reelin, Ndel1 CKO animals that die from an epileptic phenotype, live twice as long as nontreated, or vehicle-treated CKO animals. Thus, Reelin confers striking beneficial effects in the CA1 hippocampus, and at both behavioral and organismal levels.

scholarly journals Kv1.1 contributes to a rapid homeostatic plasticity of intrinsic excitability in CA1 pyramidal neurons in vivo

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Peter James Morgan ◽  
Romain Bourboulou ◽  
Caroline Filippi ◽  
Julie Koenig-Gambini ◽  
Jérôme Epsztein
Keyword(s):  
Pyramidal Neurons ◽  
Place Cells ◽  
Homeostatic Plasticity ◽  
Intrinsic Excitability ◽  
Memory Interference ◽  
Ca1 Pyramidal Neurons ◽  
Whole Cell Patch Clamp ◽  
Activity Dependent

In area CA1 of the hippocampus, the selection of place cells to represent a new environment is biased towards neurons with higher excitability. However, different environments are represented by orthogonal cell ensembles, suggesting that regulatory mechanisms exist. Activity-dependent plasticity of intrinsic excitability, as observed in vitro, is an attractive candidate. Here, using whole-cell patch-clamp recordings of CA1 pyramidal neurons in anesthetized rats, we have examined how inducing theta-bursts of action potentials affects their intrinsic excitability over time. We observed a long-lasting, homeostatic depression of intrinsic excitability which commenced within minutes, and, in contrast to in vitro observations, was not mediated by dendritic Ih. Instead, it was attenuated by the Kv1.1 channel blocker dendrotoxin K, suggesting an axonal origin. Analysis of place cells’ out-of-field firing in mice navigating in virtual reality further revealed an experience-dependent reduction consistent with decreased excitability. We propose that this mechanism could reduce memory interference.

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