Showing papers by "Daniel Choquet published in 2022"
TL;DR: In this paper , the authors show that the induction of long-term depression via activation of NMDA receptors or metabotropic glutamate receptors initiates autophagy in the postsynaptic dendrites in mice.
Abstract: The pruning of dendritic spines during development requires autophagy. This process is facilitated by long-term depression (LTD)-like mechanisms, which has led to speculation that LTD, a fundamental form of synaptic plasticity, also requires autophagy. Here, we show that the induction of LTD via activation of NMDA receptors or metabotropic glutamate receptors initiates autophagy in the postsynaptic dendrites in mice. Dendritic autophagic vesicles (AVs) act in parallel with the endocytic machinery to remove AMPA receptor subunits from the membrane for degradation. During NMDAR-LTD, key postsynaptic proteins are sequestered for autophagic degradation, as revealed by quantitative proteomic profiling of purified AVs. Pharmacological inhibition of AV biogenesis, or conditional ablation of atg5 in pyramidal neurons abolishes LTD and triggers sustained potentiation in the hippocampus. These deficits in synaptic plasticity are recapitulated by knockdown of atg5 specifically in postsynaptic pyramidal neurons in the CA1 area. Conducive to the role of synaptic plasticity in behavioral flexibility, mice with autophagy deficiency in excitatory neurons exhibit altered response in reversal learning. Therefore, local assembly of the autophagic machinery in dendrites ensures the degradation of postsynaptic components and facilitates LTD expression.
28 citations
TL;DR: In this paper , the authors show that the induction of long-term depression via activation of NMDA receptors or metabotropic glutamate receptors initiates autophagy in the postsynaptic dendrites in mice.
Abstract: The pruning of dendritic spines during development requires autophagy. This process is facilitated by long-term depression (LTD)-like mechanisms, which has led to speculation that LTD, a fundamental form of synaptic plasticity, also requires autophagy. Here, we show that the induction of LTD via activation of NMDA receptors or metabotropic glutamate receptors initiates autophagy in the postsynaptic dendrites in mice. Dendritic autophagic vesicles (AVs) act in parallel with the endocytic machinery to remove AMPA receptor subunits from the membrane for degradation. During NMDAR-LTD, key postsynaptic proteins are sequestered for autophagic degradation, as revealed by quantitative proteomic profiling of purified AVs. Pharmacological inhibition of AV biogenesis, or conditional ablation of atg5 in pyramidal neurons abolishes LTD and triggers sustained potentiation in the hippocampus. These deficits in synaptic plasticity are recapitulated by knockdown of atg5 specifically in postsynaptic pyramidal neurons in the CA1 area. Conducive to the role of synaptic plasticity in behavioral flexibility, mice with autophagy deficiency in excitatory neurons exhibit altered response in reversal learning. Therefore, local assembly of the autophagic machinery in dendrites ensures the degradation of postsynaptic components and facilitates LTD expression.
26 citations
TL;DR: In this paper , the role of AMPAR lateral diffusion in long-term potentiation (LTP) was investigated and it was shown that there are multiple solutions for achieving the diffusional trapping of AmPAR during LTP, mainly mediated by the interaction between interchangeable AMPAR auxiliary subunits and cell-adhesion molecules containing PDZ-binding domains.
6 citations
TL;DR: In this article , a simple and low-cost active image optimization (AIO) method is proposed to recover high resolution imaging inside thick biological samples, which is based on a light-sheet autofocus step followed by an adaptive optics image-based optimization.
Abstract: Lattice light-sheet microscopy (LLSM) is a very efficient technique for high resolution 3D imaging of dynamic phenomena in living biological samples. However, LLSM imaging remains limited in depth due to optical aberrations caused by sample-based refractive index mismatch. Here, we propose a simple and low-cost active image optimization (AIO) method to recover high resolution imaging inside thick biological samples. AIO is based on (1) a light-sheet autofocus step (AF) followed by (2) an adaptive optics image-based optimization. We determine the optimum AIO parameters to provide a fast, precise and robust aberration correction on biological samples. Finally, we demonstrate the performances of our approach on sub-micrometric structures in brain slices and plant roots.
2 citations
TL;DR: This work analyzes how interactions between GluA1 and 4.1N or SAP97 regulate IT and exocytosis at the plasma membrane in basal condition and after cLTP induction to identify the differential roles of 4.
Abstract: Changes in the number of synaptic AMPA subtypes of glutamate receptors (AMPAR) underlie many forms of synaptic plasticity. These variations are controlled by a complex interplay between their intracellular transport (IT), export to the plasma membrane, stabilization at synaptic sites, and recycling. The differential molecular mechanisms involved in these various trafficking pathways and their regulation remains partly unknown. We have recently reported the visualization of AMPAR IT in cultured hippocampal neurons and demonstrated its regulation during synaptic plasticity inducing protocols (Hangen, Cordelieres et al., 2018), opening the path to the differential analysis of the mechanisms controlling AMPAR transport and exocytosis. The cytosolic C-terminal (C-ter.) domain of AMPAR GluA1 subunit is specifically associated with cytoplasmic proteins that could be implicated in the regulation of their IT such as 4.1N and SAP97. Here we analyze how interactions between GluA1 and 4.1N or SAP97 regulate IT and exocytosis at the plasma membrane in basal condition and after cLTP induction. We use sh-RNA against 4.1N and SAP97 and specific mutations and deletions of GluA1 C-ter. domain to characterize how these interactions are involved in coupling AMPAR to the transport machinery. The down-regulation of both 4.1N or SAP97 by shRNAs decrease GluA1 containing vesicle number, modify their transport properties and decrease GluA1 export to the PM, indicating their role in GluA1 IT. The total deletion of the C-ter. domain of GluA1 fully suppresses its IT. Disruption of GluA1 binding to 4.1N decreases the number of GluA1 containing transport vesicles, inhibits GluA1 externalization but does not affect the transport properties of the remaining GluA1 containing vesicles. This indicates a role of the 4.1N-GluA1 interaction during exocytosis of the receptor in basal transmission. In contrast, disrupting the binding between SAP97 and GluA1 modifies the basal transport properties of GluA1 containing vesicles and decreases GluA1 export to the plasma membrane. Importantly, disrupting GluA1 interaction with either 4.1N or SAP97 prevents both the cLTP induced increase in the number of GluA1 containing vesicles observed in control and GluA1 externalization. Our results demonstrate that specific interactions between 4.1N or SAP97 with GluA1 have different roles in GluA1 IT and exocytosis. During basal transmission, the binding of 4.1N to GluA1 allows the fusion/fission membrane exocytosis whereas the interaction with SAP97 is essential for GluA1 IT. During cLTP the interaction of 4.1N with GluA1 allows both IT and exocytosis of the receptor in hippocampal cultured neurons. Altogether, our results identify the differential roles of 4.1N and SAP97 in the control of various phases of GluA1 IT.