Project description:Since many years, we are interested in the regulation of the intraneuronal chloride concentration. We were the first group reporting a full knockout of the KCl-co-transporter KCC2, which dies immediately after birth due to respiratory failure. Notably, KCC2 loss-of-function mutations are associated with inherited febrile seizures, severe genetic generalized epilepsy and epilepsy of infancy with migrating focal seizures. Here, we used our floxed line to study the consequences of the disruption of KCC2 within parvalbumin-positive interneurons in mice. Remarkably, this leads to the disinhibition of PV-positive interneurons as evidenced by a decrease of E-S-Coupling and an increase in the sIPSC frequency. Nevertheless, these mice develop fatal epilepsy with progressive loss of parvalbumin-positive interneurons thus increasing network excitability.
Project description:Purpose: To identify genes differentially expressed in parvalbumin-positive (PV) interneurons of the hippocampus in non-defetaed (CTRL), stress-susceptible and stress-resilient mice. Method: Translating Ribosome Affinity Purification (TRAP) to isolate RNA from PV+ cells, cDNA synthesis and next generation RNAseq using Illumina Nextseq 500 sequencer. Results: RNA-seq revealed 458 DEGs between non-defeated and resilient mice, 1976 DEGs in non-defeated and susceptible mice, and 3475 DEGs in resilient and susceptible mice.
Project description:This experiment was designed to compare the transcriptomic differences between two parvalbumin (PV) interneuron population of the mouse brain. These two populations have the same embryological origin and share several neurochemical and electrophysiological properties, but differ in their ability to express the glial cell line-derived neurotrophic factor GDNF (negative in cortex and positive in striatum). Two different reporters for PV expressing cells were used: i) a constitutive tdTomato gene inserted in the Pvalb locus, and ii) a PV-Cre; tdTomato model in which fluorescent cells are PV cells expressing Cre recombinase. The comparative gene expression analysis between PV neurons captured from striatum and cortex allowed unraveling differential molecular characteristics of GDNF-synthesizing striatal PV interneurons and their potential role in endogenous GDNF modulation. The specific expression of several genes of interest in the striatal PV interneurons has been validated by other methods (real-time RT-PCR, in situ hibridization, immunohistochemistry).
Project description:We developed an affinity purification approach to isolate tagged nuclei in mice (similar to INTACT; [Deal R.B. and Henikoff S. A simple method for gene expression and chromatin profiling of individual cell types within a tissue. Dev. Cell 18,1030-1040. (2010)]) and used it to characterize genome-wide patterns of transcription, DNA methylation, and chromatin accessibility in 3 major neuron classes of the neocortex (excitatory pyramidal neurons, parvalbumin (PV)-positive GABAergic interneurons, and vasoactive intestinal peptide (VIP)-positive GABAergic interneurons). By combining cell purification and integrative analysis, our findings relate the phenotypic and functional complexity of neocortical neurons to their underlying transcriptional and epigenetic diversity. RNA-seq, MethylC-seq, ATAC-seq, and ChIP-seq for histone modifications using INTACT-purified nuclei from the mouse neocortex
Project description:People with schizophrenia show hyperactivity in the ventral hippocampus (vHipp) and we have previously demonstrated distinct behavioral roles for vHipp cell populations. Here, we test the hypothesis that parvalbumin (PV) and somatostatin (SST) interneurons differentially innervate and regulate hippocampal pyramidal neurons based on their projection target. First, we use eGRASP to show that PV-positive interneurons form a similar number of synaptic connections with pyramidal cells regardless of their projection target while SST-positive interneurons preferentially target nucleus accumbens (NAc) projections. To determine if these anatomical differences result in functional changes, we used in vivo opto-electrophysiology to show that SST cells also preferentially regulate the activity of NAc-projecting cells. These results suggest vHipp interneurons differentially regulate that vHipp neurons that project to the medial prefrontal cortex (mPFC) and NAc. Characterization of these cell populations may provide potential molecular targets for the treatment schizophrenia and other psychiatric disorders associated with vHipp dysfunction.
Project description:Schizophrenia is associated with dysfunction of the dorsolateral prefrontal cortex (DLPFC). This dysfunction is manifest as cognitive deficits that appear to arise from disturbances in gamma frequency oscillations. These oscillations are generated in DLPFC layer 3 via reciprocal connections between pyramidal cells and parvalbumin (PV)-containing interneurons. The density of cortical PV neurons is not altered in schizophrenia, but expression levels of several transcripts involved in PV cell function, including PV, are lower in the disease.
Project description:One of the earliest pathophysiological perturbations in Alzheimer’s Disease (AD) may arise from dysfunction of fast-spiking parvalbumin (PV) interneurons (PV-INs). Defining early protein-level (proteomic) alterations in PV-INs can provide key biological and translationally relevant insights. Here, we use cell-type-specific in vivo biotinylation of proteins (CIBOP) coupled with mass spectrometry to obtain native-state proteomes of PV interneurons. PV-INs exhibited proteomic signatures of high metabolic, mitochondrial, and translational activity, with over-representation of causally linked AD genetic risk factors. Analyses of bulk brain proteomes indicated strong correlations between PV-IN proteins with cognitive decline in humans, and with progressive neuropathology in humans and mouse models of Aβ pathology. Furthermore, PV-IN-specific proteomes revealed unique signatures of increased mitochondrial and metabolic proteins, but decreased synaptic and mTOR signaling proteins in response to early Aβ pathology. PV-specific changes were not apparent in whole-brain proteomes. These findings showcase the first nativestate PV-IN proteomes in mammalian brain, revealing a molecular basis for their unique vulnerabilities in AD
Project description:We developed an affinity purification approach to isolate tagged nuclei in mice (similar to INTACT; [Deal R.B. and Henikoff S. A simple method for gene expression and chromatin profiling of individual cell types within a tissue. Dev. Cell 18,1030-1040. (2010)]) and used it to characterize genome-wide patterns of transcription, DNA methylation, and chromatin accessibility in 3 major neuron classes of the neocortex (excitatory pyramidal neurons, parvalbumin (PV)-positive GABAergic interneurons, and vasoactive intestinal peptide (VIP)-positive GABAergic interneurons). By combining cell purification and integrative analysis, our findings relate the phenotypic and functional complexity of neocortical neurons to their underlying transcriptional and epigenetic diversity.
Project description:Mutations in the solute carrier family 6-member 8 (Slc6a8) gene, encoding the protein responsible for cellular creatine (Cr) uptake, cause Creatine Transporter Deficiency (CTD), an X-linked neurometabolic disorder presenting with intellectual disability, autistic-like features, and epilepsy. The pathological determinants of CTD are still poorly understood, hindering the development of therapies. In this study, we generated an extensive transcriptomic profile of CTD showing that Cr deficiency causes perturbations of gene expression in excitatory neurons, inhibitory cells, and oligodendrocytes which result in remodeling of circuit excitability and synaptic wiring. We also identified specific alterations of parvalbumin-expressing (PV+) interneurons, exhibiting a reduction in cellular and synaptic density, and a hypofunctional electrophysiological phenotype. Mice lacking Slc6a8 only in PV+ interneurons recapitulated numerous CTD features, including cognitive deterioration, impaired cortical processing and hyperexcitability of brain circuits, demonstrating that Cr deficit in PV+ interneurons is sufficient to determine the neurological phenotype of CTD. Moreover, a pharmacological treatment targeted to restore the efficiency of PV+ synapses significantly improved cortical activity in Slc6a8 knock-out animals. Altogether, these data demonstrate that Slc6a8 is critical for the normal function of PV+ interneurons and that impairment of these cells is central in the disease pathogenesis, suggesting a novel therapeutic venue for CTD.