Biology subjects

LeDoux, J.

Publications and source records attributed to LeDoux, J..

3 recordsLinked to original sources

bioRxiv2021

Upregulation of eIF4E, but not other translation initiation factors, in dendritic spines during memory consolidation

Local translation can provide a rapid, spatially targeted supply of new proteins in distal dendrites to support synaptic changes that underlie learning. Learning and memory are especially sensitive to manipulations of translational control mechanisms, particularly those that target the initiation step, and translation initiation at synapses could be a means of maintaining synapse specificity during plasticity. Initiation predominantly occurs via recruitment of ribosomes to the 5 mRNA cap by complexes of eukaryotic initiation factors (eIFs), and the interaction between eIF4E and eIF4G1 is a particularly important target of translational control pathways. Pharmacological inhibition of eIF4E-eIF4G1 binding impairs consolidation of memory for aversive Pavlovian conditioning as well as the accompanying increase in polyribosomes in the heads of dendritic spines in the lateral amygdala (LA). This is consistent with a role for initiation at synapses in memory formation, but whether eIFs are even present near synapses is unknown. To determine whether dendritic spines contain eIFs and whether eIF distribution is affected by learning, we combined immunolabeling with serial section transmission electron microscopy (ssTEM) volume reconstructions of LA dendrites after Pavlovian conditioning. Labeling for eIF4E, eIF4G1, and eIF2 - another key target of regulation - occurred in roughly half of dendritic spines, but learning effects were only found for eIF4E, which was upregulated in the heads of dendritic spines. Our results support the possibility of regulated translation initiation as a means of synapse-specific protein targeting during learning and are consistent with the model of eIF4E availability as a central point of control.

neuroscience↗

bioRxiv2019

Chemogenetic evidence that rapid neuronal de novo protein synthesis is required for consolidation of long-term memory

Translational control of memory processes is a tightly regulated process where the coordinated interaction and modulation of translation factors provides a permissive environment for protein synthesis during memory formation. Existing methods used to block translation lack the spatiotemporal precision to investigate cell-specific contributions to consolidation of long-term memories. Here, we have developed a novel chemogenetic mouse resource for cell type-specific and drug-inducible protein synthesis inhibition (ciPSI) that utilizes an engineered version of the catalytic kinase domain of dsRNA-activated protein (PKR). ciPSI allows rapid and reversible phosphorylation of eIF2 causing a block on general translation by 50% in vivo. Using this resource, we discovered that temporally structured pan-neuronal protein synthesis is required for consolidation of long-term auditory threat memory. Targeted protein synthesis inhibition in CamK2 expressing glutamatergic neurons in lateral amygdala (LA) impaired long-term memory, which was recovered with artificial chemogenetic reactivation at the cost of stimulus generalization. Conversely, genetically reducing phosphorylation of eIF2 in CamK2 positive neurons in LA enhanced memory strength, but was accompanied with reduced memory fidelity and behavior inflexibility. Our findings provide evidence for a finely tuned translation program during consolidation of long-term threat memories.

neuroscience↗

bioRxiv2018

The translatome of adult cortical axons is regulated by learning in vivo

Local translation can support memory consolidation by supplying new proteins to synapses undergoing plasticity. Translation in adult forebrain dendrites is an established mechanism of synaptic plasticity and is regulated by learning, yet there is no evidence for learning-regulated protein synthesis in adult forebrain axons, which have traditionally been believed to be incapable of translation. Here we show that axons in the adult rat amygdala contain translation machinery, and use translating ribosome affinity purification (TRAP) with RNASeq to identify mRNAs in cortical axons projecting to the amygdala, over 1200 of which were regulated during consolidation of associative memory. Mitochondrial and translation-related genes were upregulated, whereas synaptic, cytoskeletal, and myelin-related genes were downregulated; the opposite effects were observed in the cortex. Our results demonstrate that learning-regulated axonal translation occurs in the adult forebrain, and support the likelihood that local translation is more a rule than an exception in neuronal processes.

neuroscience↗