Porter Neuroscience Research Center
Porter Neuroscience Research Center
Tricoire L.,Porter Neuroscience Research Center |
Pelkey K.A.,Porter Neuroscience Research Center |
Erkkila B.E.,U.S. National Institutes of Health |
Jeffries B.W.,U.S. National Institutes of Health |
And 2 more authors.
Journal of Neuroscience | Year: 2011
Although vastly out numbered, inhibitory interneurons critically pace and synchronize excitatory principal cell populations to coordinate cortical information processing. Precision in this control relies upon a remarkable diversity of interneurons primarily determined during embryogenesis by genetic restriction of neuronal potential at the progenitor stage. Like their neocortical counterparts, hippocampal interneurons arise from medial and caudal ganglionic eminence (MGE and CGE) precursors. However, while studies of the early specification of neocortical interneurons are rapidly advancing, similar lineage analyses of hippocampal interneurons have lagged. A "hip-pocampocentric" investigation is necessary as several hippocampal interneuron subtypes remain poorly represented in the neocortical literature. Thus, we investigated the spatiotemporal origins of hippocampal interneurons using transgenic mice that specifically report MGE- and CGE-derived interneurons either constitutively or inducibly. We found that hippocampal interneurons are produced in two neurogenic waves between E9-E12 and E12-E16 from MGE and CGE, respectively, and invade the hippocampus by E14. In the mature hippocampus, CGE-derived interneurons primarily localize to superficial layers in strata lacunosum moleculare and deep radiatum, while MGE-derived interneurons readily populate all layers with preference for strata pyramidale and oriens. Combined molecular, anatomical, and electrophysiological interrogation of MGE/CGE-derived interneurons revealed that MGE produces parvalbumin-, somatostatin-, and nitric oxide synthase-expressing interneurons including fast-spiking basket, bistratified, axo-axonic, oriens-lacunosum moleculare, neurogliaform, and ivy cells. In contrast, CGE-derived interneurons contain cholecystokinin, calretinin, vasoac-tive intestinal peptide, and reelin including non-fast-spiking basket, Schaffer collateral-associated, mossy fiber-associated, trilaminar, and additional neurogliaform cells. Our findings provide a basic blueprint of the developmental origins of hippocampal interneuron diversity. © 2011 the authors.
Fenster C.,Ashland University |
Fenster C.,Porter Neuroscience Research Center |
Vullhorst D.,Porter Neuroscience Research Center |
Buonanno A.,Porter Neuroscience Research Center
Brain Research Bulletin | Year: 2012
Neuregulin-1 (NRG1) is a trophic and differentiation factor that signals through ErbB receptor tyrosine kinases to regulate nervous system development. Previous studies have demonstrated that NRG1 affects plasticity at glutamatergic synapses in principal glutamatergic neurons of the hippocampus and frontal cortex; however, immunohistochemical and genetic analyses strongly suggest these effects are indirect and mediated via ErbB4 receptors on GABAergic interneurons. Here, we used cultured cerebellar granule cells (CGCs) that express ErbB4 to analyze the cell-autonomous effects of NRG1 stimulation on glutamatergic function. These cultures have the advantage that they are relatively homogenous and consist primarily of granule neurons that express ErbB4. We show that acute NRG1 treatment does not affect whole-cell AMPA or NMDA receptor (NMDAR) mediated currents in CGCs at 10-12 days in vitro. NRG1 also does not affect the frequency or amplitude of spontaneous AMPAR or NMDAR mediated miniature excitatory post-synaptic currents (mEPSCs). To further investigate the effects of NRG1 on activity-dependent plasticity of glutamatergic synapses in CGCs, we characterized the effects of high-glyine/0 Mg 2+ (which activates synaptic NMDARs) on AMPAR-mEPSC frequency and amplitude. We show that high-glycine induces a form of chemical long-term potentiation (chemLTP) in CGCs characterized by an increase in AMPAR-mEPSC frequency but not amplitude. Moreover, NRG1 induces a decrease in AMPAR-mEPSC frequency following chemLTP, but does not affect AMPAR-mEPSC amplitude. CGCs in our cultures conditions express low levels of GluR1, in contrast to dissociated hippocampal cultures, but do express the long isoform of GluR4. This study provides first evidence that (1) high-glycine can induce plasticity at glutamatergic synapses in CGCs, and (2) that acute NRG1/ErbB-signaling can regulate glutamatergic plasticity in CGCs. Taken together with previous reports, our results suggest that, similar to Schaeffer collateral to CA1 synapses, NRG1 effects are activity dependent and mediated via modulation of synaptic AMPARs. © 2011 Elsevier Inc.
Zukosky K.,U.S. National Institutes of Health |
Meilleur K.,U.S. National Institutes of Health |
Traynor B.J.,U.S. National Institute on Aging |
Dastgir J.,Columbia University |
And 21 more authors.
JAMA Neurology | Year: 2015
IMPORTANCE: New genomic strategies can now be applied to identify a diagnosis in patients and families with previously undiagnosed rare genetic conditions. The large family evaluated in the present study was described in 1966 and now expands the phenotype of a known neuromuscular gene. OBJECTIVE: To determine the genetic cause of a slowly progressive, autosomal dominant, scapuloperoneal neuromuscular disorder by using linkage and exome sequencing. DESIGN, SETTING, AND PARTICIPANTS: Fourteen affected individuals in a 6-generation family with a progressive scapuloperoneal disorder were evaluated. Participants were examined at pediatric, neuromuscular, and research clinics from March 1, 2005, toMay 31, 2014. Exome and linkage were performed in genetics laboratories of research institutions. MAIN OUTCOMES AND MEASURES: Examination and evaluation by magnetic resonance imaging, ultrasonography, electrodiagnostic studies, and muscle biopsies (n = 3). Genetic analysis included linkage analysis (n = 17) with exome sequencing (n = 7). RESULTS: Clinical findings included progressive muscle weakness in an initially scapuloperoneal and distal distribution, including wrist extensor weakness, finger and foot drop, scapular winging, mild facial weakness, Achilles tendon contractures, and diminished or absent deep tendon reflexes. Both age at onset and progression of the disease showed clinical variability within the family. Muscle biopsy specimens demonstrated type I fiber atrophy and trabeculated fibers without nemaline rods. Analysis of exome sequences within the linkage region (4.8 megabases) revealed missense mutation c.591C>A p.Glu197Asp in a highly conserved residue in exon 4 of ACTA1. The mutation cosegregated with disease in all tested individuals and was not present in unaffected individuals. CONCLUSIONS AND RELEVANCE: This family defines a new scapuloperoneal phenotype associated with an ACTA1 mutation. A highly conserved protein, ACTA1 is implicated in multiple muscle diseases, including nemalinemyopathy, actin aggregatemyopathy, fiber-type disproportion, and rod-coremyopathy. To our knowledge, mutations in Glu197 have not been reported previously. This residue is highly conserved and located in an exposed position in the protein; the mutation affects the intermolecular and intramolecular electrostatic interactions as shown by structural modeling. The mutation in this residue does not appear to lead to rod formation or actin accumulation in vitro or in vivo, suggesting a different molecular mechanism from that of other ACTA1 diseases.
Pierson T.M.,U.S. National Institutes of Health |
Pierson T.M.,Porter Neuroscience Research Center |
Simeonov D.R.,U.S. National Institutes of Health |
Sincan M.,U.S. National Institutes of Health |
And 13 more authors.
European Journal of Human Genetics | Year: 2012
Fatty acid hydroxylase-associated neurodegeneration due to fatty acid 2-hydroxylase deficiency presents with a wide range of phenotypes including spastic paraplegia, leukodystrophy, and/or brain iron deposition. All previously described families with this disorder were consanguineous, with homozygous mutations in the probands. We describe a 10-year-old male, from a non-consanguineous family, with progressive spastic paraplegia, dystonia, ataxia, and cognitive decline associated with a sural axonal neuropathy. The use of high-throughput sequencing techniques combined with SNP array analyses revealed a novel paternally derived missense mutation and an overlapping novel maternally derived ∼28-kb genomic deletion in FA2H. This patient provides further insight into the consistent features of this disorder and expands our understanding of its phenotypic presentation. The presence of a sural nerve axonal neuropathy had not been previously associated with this disorder and so may extend the phenotype. © 2012 Macmillan Publishers Limited All rights reserved.
PubMed | NCI Inc, FEI Company and Porter Neuroscience Research Center
Type: | Journal: Scientific reports | Year: 2014
Poor partitioning of macromolecules into the holes of holey carbon support grids frequently limits structural determination by single particle cryo-electron microscopy (cryo-EM). Here, we present a method to deposit, on gold-coated carbon grids, a self-assembled monolayer whose surface properties can be controlled by chemical modification. We demonstrate the utility of this approach to drive partitioning of ionotropic glutamate receptors into the holes, thereby enabling 3D structural analysis using cryo-EM methods.
Lomash S.,Porter Neuroscience Research Center |
Chittori S.,Porter Neuroscience Research Center |
Brown P.,Bioengineering and Physical Science Shared Resource |
Mayer M.L.,Porter Neuroscience Research Center
Structure | Year: 2013
AvGluR1, a glutamate receptor ion channel from the primitive eukaryote Adineta vaga, is activated by alanine, cysteine, methionine, and phenylalanine, which produce lectin-sensitive desensitizing responses like those to glutamate, aspartate, and serine. AvGluR1 LBD crystal structures reveal an unusual scheme for binding dissimilar ligands that may be utilized by distantly related odorant/chemosensory receptors. Arginine residues in domain 2 coordinate the γ-carboxyl group of glutamate, whereas in the alanine, methionine, and serine complexes a chloride ion acts as a surrogate ligand, replacing the γ-carboxyl group. Removal of Cl- lowers affinity for these ligands but not for glutamate or aspartate nor for phenylalanine, which occludes the anion binding site and binds with low affinity. AvGluR1 LBD crystal structures and sedimentation analysis also provide insights into the evolutionary link between prokaryotic and eukaryotic iGluRs and reveal features unique to both classes, emphasizing the need for additional structure-based studies on iGluR-ligand interactions. © 2013 Elsevier Ltd. All rights reserved.
Chittori S.,Indian Institute of Science |
Chittori S.,Porter Neuroscience Research Center |
Savithri H.S.,Indian Institute of Science |
Murthy M.R.N.,Indian Institute of Science
BMC Structural Biology | Year: 2012
Background: Bacteria such as Escherichia coli and Salmonella typhimurium can utilize acetate as the sole source of carbon and energy. Acetate kinase (AckA) and phosphotransacetylase (Pta), key enzymes of acetate utilization pathway, regulate flux of metabolites in glycolysis, gluconeogenesis, TCA cycle, glyoxylate bypass and fatty acid metabolism. Results: Here we report kinetic characterization of S. typhimurium AckA (StAckA) and structures of its unliganded (Form-I, 2.70 resolution) and citrate-bound (Form-II, 1.90 resolution) forms. The enzyme showed broad substrate specificity with k cat/Km in the order of acetate>propionate>formate. Further, the Km for acetyl-phosphate was significantly lower than for acetate and the enzyme could catalyze the reverse reaction (i.e. ATP synthesis) more efficiently. ATP and Mg2+ could be substituted by other nucleoside 5-triphosphates (GTP, UTP and CTP) and divalent cations (Mn 2+ and Co2+), respectively. Form-I StAckA represents the first structural report of an unliganded AckA. StAckA protomer consists of two domains with characteristic topology of ASKHA superfamily of proteins. These domains adopt an intermediate conformation compared to that of open and closed forms of ligand-bound Methanosarcina thermophila AckA (MtAckA). Spectroscopic and structural analyses of StAckA further suggested occurrence of inter-domain motion upon ligand-binding. Unexpectedly, Form-II StAckA structure showed a drastic change in the conformation of residues 230-300 compared to that of Form-I. Further investigation revealed electron density corresponding to a citrate molecule in a pocket located at the dimeric interface of Form-II StAckA. Interestingly, a similar dimeric interface pocket lined with largely conserved residues could be identified in Form-I StAckA as well as in other enzymes homologous to AckA suggesting that ligand binding at this pocket may influence the function of these enzymes. Conclusions: The biochemical and structural characterization of StAckA reported here provides insights into the biochemical specificity, overall fold, thermal stability, molecular basis of ligand binding and inter-domain motion in AckA family of enzymes. Dramatic conformational differences observed between unliganded and citrate-bound forms of StAckA led to identification of a putative ligand-binding pocket at the dimeric interface of StAckA with implications for enzymatic function. © 2012 Chittori et al.; licensee BioMed Central Ltd.
PubMed | Porter Neuroscience Research Center
Type: Comment | Journal: Neuron | Year: 2013
Voltage-activated proton (Hv1) channels are relatives of classical voltage-activated cation channels. In this issue of Neuron, Hong etal. (2013) and Qiu etal. (2013) investigate the functional mechanisms of Hv1 gating and uncover key relationships with Kv channels.