Neurosciences Commons^™

Synaptic Dysfunction Induced By Glycine-Alanine Dipeptides In C9orf72-Als/Ftd Is Rescued By Sv2 Replenishment., Brigid K Jensen, Martin H Schuldi, Kevin Mcavoy, Katelyn A Russell, Ashley Boehringer, Bridget M Curran, Karthik Krishnamurthy, Xinmei Wen, Thomas Westergard, Le Ma, Aaron R. Haeusler, Dieter Edbauer, Piera Pasinelli, Davide Trotti

Department of Neuroscience Faculty Papers

The most common cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) is an intronic hexanucleotide repeat expansion in the C9orf72 gene. In disease, RNA transcripts containing this expanded region undergo repeat-associated non-AUG translation to produce dipeptide repeat proteins (DPRs), which are detected in brain and spinal cord of patients and are neurotoxic both in vitro and in vivo paradigms. We reveal here a novel pathogenic mechanism for the most abundantly detected DPR in ALS/FTD autopsy tissues, poly-glycine-alanine (GA). Previously, we showed motor dysfunction in a GA mouse model without loss of motor neurons. Here, we demonstrate that mobile …

Antagonistic Regulation Of Circadian Output And Synaptic Development By Jetlag And The Dyschronic-Slowpoke Complex, Angelique Lamaze, James E.C. Jepson, Oghenerukevwe Akpoghiran, Kyunghee Koh

Department of Neuroscience Faculty Papers

Circadian output genes act downstream of the clock to promote rhythmic changes in behavior and physiology, yet their molecular and cellular functions are not well understood. Here we characterize an interaction between regulators of circadian entrainment, output, and synaptic development in Drosophila that influences clock-driven anticipatory increases in morning and evening activity. We previously showed the JETLAG (JET) E3 ubiquitin ligase resets the clock upon light exposure, whereas the PDZ protein DYSCHRONIC (DYSC) regulates circadian locomotor output and synaptic development. Surprisingly, we find that JET and DYSC antagonistically regulate synaptic development at the larval neuromuscular junction, and reduced JET activity …

Positive Surface Charge Of Glun1 N-Terminus Mediates The Direct Interaction With Ephb2 And Nmdar Mobility., Halley R. Washburn, Nan L. Xia, Wei Zhou, Yu-Ting Mao, Matthew B. Dalva

Department of Neuroscience Faculty Papers

Localization of the N-methyl-D-aspartate type glutamate receptor (NMDAR) to dendritic spines is essential for excitatory synaptic transmission and plasticity. Rather than remaining trapped at synaptic sites, NMDA receptors undergo constant cycling into and out of the postsynaptic density. Receptor movement is constrained by protein-protein interactions with both the intracellular and extracellular domains of the NMDAR. The role of extracellular interactions on the mobility of the NMDAR is poorly understood. Here we demonstrate that the positive surface charge of the hinge region of the N-terminal domain in the GluN1 subunit of the NMDAR is required to maintain NMDARs at dendritic spine …

A Crucial Role For The Protein Quality Control System In Motor Neuron Diseases., Riccardo Cristofani, Valeria Crippa, Maria Elena Cicardi, Barbara Tedesco, Veronica Ferrari, Marta Chierichetti, Elena Casarotto, Margherita Piccolella, Elio Messi, Mariarita Galbiati, Paola Rusmini, Angelo Poletti

Department of Neuroscience Faculty Papers

Motor neuron diseases (MNDs) are fatal diseases characterized by loss of motor neurons in the brain cortex, in the bulbar region, and/or in the anterior horns of the spinal cord. While generally sporadic, inherited forms linked to mutant genes encoding altered RNA/protein products have also been described. Several different mechanisms have been found altered or dysfunctional in MNDs, like the protein quality control (PQC) system. In this review, we will discuss how the PQC system is affected in two MNDs-spinal and bulbar muscular atrophy (SBMA) and amyotrophic lateral sclerosis (ALS)-and how this affects the clearance of aberrantly folded proteins, which …

Understanding The Axonal Response To Injury By In Vivo Imaging In The Mouse Spinal Cord: A Tale Of Two Branches., Binhai Zheng, Ariana O Lorenzana, Le Ma

Department of Neuroscience Faculty Papers

Understanding the basic properties of how axons respond to injury in the mammalian central nervous system (CNS) is of fundamental value for developing strategies to promote neural repair. Axons possess complex morphologies with stereotypical branching patterns. However, current knowledge of the axonal response to injury gives little consideration to axonal branches, nor do strategies to promote axon regeneration. This article reviews evidence from in vivo spinal cord imaging that axonal branches markedly impact the degenerative and regenerative responses to injury. At a major bifurcation point, depending on whether one or both axonal branches are injured, neurons may choose either a …

Ephrin-B3 Controls Excitatory Synapse Density Through Cell-Cell Competition For Ephbs., Nathan T. Henderson, Sylvain J. Le Marchand, Martin Hruska, Simon Hippenmeyer, Liqun Luo, Matthew B. Dalva

Department of Neuroscience Faculty Papers

Cortical networks are characterized by sparse connectivity, with synapses found at only a subset of axo-dendritic contacts. Yet within these networks, neurons can exhibit high connection probabilities, suggesting that cell-intrinsic factors, not proximity, determine connectivity. Here, we identify ephrin-B3 (eB3) as a factor that determines synapse density by mediating a cell-cell competition that requires ephrin-B-EphB signaling. In a microisland culture system designed to isolate cell-cell competition, we find that eB3 determines winning and losing neurons in a contest for synapses. In a Mosaic Analysis with Double Markers (MADM) genetic mouse model system in vivo the relative levels of eB3 control …

The Tenets Of Teneurin: Conserved Mechanisms Regulate Diverse Developmental Processes In The Drosophila Nervous System, Alison T. Depew, Michael A. Aimino, Timothy J. Mosca

Department of Neuroscience Faculty Papers

To successfully integrate a neuron into a circuit, a myriad of developmental events must occur correctly and in the correct order. Neurons must be born and grow out toward a destination, responding to guidance cues to direct their path. Once arrived, each neuron must segregate to the correct sub-region before sorting through a milieu of incorrect partners to identify the correct partner with which they can connect. Finally, the neuron must make a synaptic connection with their correct partner; a connection that needs to be broadly maintained throughout the life of the animal while remaining responsive to modes of plasticity …

Propofol Inhibits The Voltage-Gated Sodium Channel Nachbac At Multiple Sites., Yali Wang, Elaine Yang, Marta M. Wells, Vasyl Bondarenko, Kellie Woll, Vincenzo Carnevale, Daniele Granata, Michael L. Klein, Roderic G. Eckenhoff, William P. Dailey, Manuel Covarrubias, Pei Tang, Yan Xu

Department of Neuroscience Faculty Papers

Voltage-gated sodium (Na_V) channels are important targets of general anesthetics, including the intravenous anesthetic propofol. Electrophysiology studies on the prokaryotic Na_V channel NaChBac have demonstrated that propofol promotes channel activation and accelerates activation-coupled inactivation, but the molecular mechanisms of these effects are unclear. Here, guided by computational docking and molecular dynamics simulations, we predict several propofol-binding sites in NaChBac. We then strategically place small fluorinated probes at these putative binding sites and experimentally quantify the interaction strengths with a fluorinated propofol analogue, 4-fluoropropofol. In vitro and in vivo measurements show that 4-fluoropropofol and propofol have similar effects …

Propofol Inhibits Prokaryotic Voltage-Gated Na+ Channels By Promoting Activation-Coupled Inactivation, Elaine Yang, Daniele Granata, Roderic G. Eckenhoff, Vincenzo Carnevale, Manuel Covarrubias

Department of Neuroscience Faculty Papers

Propofol is widely used in the clinic for the induction and maintenance of general anesthesia. As with most general anesthetics, however, our understanding of its mechanism of action remains incomplete. Local and general anesthetics largely inhibit voltage-gated Na⁺ channels (Navs) by inducing an apparent stabilization of the inactivated state, associated in some instances with pore block. To determine the biophysical and molecular basis of propofol action in Navs, we investigated NaChBac and NavMs, two prokaryotic Navs with distinct voltage dependencies and gating kinetics, by whole-cell patch clamp electrophysiology in the absence and presence of propofol at clinically relevant concentrations …

Map7 Regulates Axon Morphogenesis By Recruiting Kinesin-1 To Microtubules And Modulating Organelle Transport., Stephen R. Tymanskyj, Benjamin Yang, Kristen J. Verhey, Le Ma

Department of Neuroscience Faculty Papers

Neuronal cell morphogenesis depends on proper regulation of microtubule-based transport, but the underlying mechanisms are not well understood. Here, we report our study of MAP7, a unique microtubule-associated protein that interacts with both microtubules and the motor protein kinesin-1. Structure-function analysis in rat embryonic sensory neurons shows that the kinesin-1 interacting domain in MAP7 is required for axon and branch growth but not for branch formation. Also, two unique microtubule binding sites are found in MAP7 that have distinct dissociation kinetics and are both required for branch formation. Furthermore, MAP7 recruits kinesin-1 dynamically to microtubules, leading to alterations in organelle …

A-Type Kv Channels In Dorsal Root Ganglion Neurons: Diversity, Function, And Dysfunction, Benjamin M. Zemel, David M. Ritter, Manuel Covarrubias, Tanziyah Muqeem

Department of Neuroscience Faculty Papers

A-type voltage-gated potassium (Kv) channels are major regulators of neuronal excitability that have been mainly characterized in the central nervous system. By contrast, there is a paucity of knowledge about the molecular physiology of these Kv channels in the peripheral nervous system, including highly specialized and heterogenous dorsal root ganglion (DRG) neurons. Although all A-type Kv channels display pore-forming subunits with similar structural properties and fast inactivation, their voltage-, and time-dependent properties and modulation are significantly different. These differences ultimately determine distinct physiological roles of diverse A-type Kv channels, and how their dysfunction might contribute to neurological disorders. The importance …

Evolution Of Cortical Neurogenesis In Amniotes Controlled By Robo Signaling Levels., Adrián Cárdenas, Ana Villalba, Camino De Juan Romero, Esther Picó, Christina Kyrousi, Athanasia C Tzika, Marc Tessier-Lavigne, Le Ma, Micha Drukker, Silvia Cappello, Víctor Borrell

Department of Neuroscience Faculty Papers

Cerebral cortex size differs dramatically between reptiles, birds, and mammals, owing to developmental differences in neuron production. In mammals, signaling pathways regulating neurogenesis have been identified, but genetic differences behind their evolution across amniotes remain unknown. We show that direct neurogenesis from radial glia cells, with limited neuron production, dominates the avian, reptilian, and mammalian paleocortex, whereas in the evolutionarily recent mammalian neocortex, most neurogenesis is indirect via basal progenitors. Gain- and loss-of-function experiments in mouse, chick, and snake embryos and in human cerebral organoids demonstrate that high Slit/Robo and low Dll1 signaling, via Jag1 and Jag2, are necessary and …

Regional Microglia Are Transcriptionally Distinct But Similarly Exacerbate Neurodegeneration In A Culture Model Of Parkinson's Disease., Eric Wildon Kostuk, Jingli Cai, Lorraine Iacovitti

Department of Neuroscience Faculty Papers

BACKGROUND: Parkinson's disease (PD) is characterized by selective degeneration of dopaminergic (DA) neurons of the substantia nigra pars compacta (SN) while neighboring ventral tegmental area (VTA) DA neurons are relatively spared. Mechanisms underlying the selective protection of the VTA and susceptibility of the SN are still mostly unknown. Here, we demonstrate the importance of balance between astrocytes and microglia in the susceptibility of SN DA neurons to the PD mimetic toxin 1-methyl-4-phenylpyridinium (MPP

METHODS: Previously established methods were used to isolate astrocytes and microglia from the cortex (CTX), SN, and VTA, as well as embryonic midbrain DA neurons from the …

Synaptic Nanomodules Underlie The Organization And Plasticity Of Spine Synapses., Martin Hruska, Nathan T. Henderson, Sylvain J. Le Marchand, Haani Jafri, Matthew B. Dalva

Department of Neuroscience Faculty Papers

Experience results in long-lasting changes in dendritic spine size, yet how the molecular architecture of the synapse responds to plasticity remains poorly understood. Here a combined approach of multicolor stimulated emission depletion microscopy (STED) and confocal imaging in rat and mouse demonstrates that structural plasticity is linked to the addition of unitary synaptic nanomodules to spines. Spine synapses in vivo and in vitro contain discrete and aligned subdiffraction modules of pre- and postsynaptic proteins whose number scales linearly with spine size. Live-cell time-lapse super-resolution imaging reveals that NMDA receptor-dependent increases in spine size are accompanied both by enhanced mobility of …

Representing Diversity In The Dish: Using Patient-Derived In Vitro Models To Recreate The Heterogeneity Of Neurological Disease, Layla T. Ghaffari, Alexander Starr, Andrew T. Nelson, Rita Sattler

Department of Neuroscience Faculty Papers

Neurological diseases, including dementias such as Alzheimer's disease (AD) and fronto-temporal dementia (FTD) and degenerative motor neuron diseases such as amyotrophic lateral sclerosis (ALS), are responsible for an increasing fraction of worldwide fatalities. Researching these heterogeneous diseases requires models that endogenously express the full array of genetic and epigenetic factors which may influence disease development in both familial and sporadic patients. Here, we discuss the two primary methods of developing patient-derived neurons and glia to model neurodegenerative disease: reprogramming somatic cells into induced pluripotent stem cells (iPSCs), which are differentiated into neurons or glial cells, or directly converting (DC) somatic …

Genome-Wide Profiling Reveals Functional Diversification Of ∆Fosb Gene Targets In The Hippocampus Of An Alzheimer's Disease Mouse Model., Jason C. You, Gabriel S. Stephens, Chia-Hsuan Fu, Xiaohong Zhang, Yin Liu, Jeannie Chin

Department of Neuroscience Faculty Papers

The activity-induced transcription factor ∆FosB has been implicated in Alzheimer's disease (AD) as a critical regulator of hippocampal function and cognition downstream of seizures and network hyperexcitability. With its long half-life (> 1 week), ∆FosB is well-poised to modulate hippocampal gene expression over extended periods of time, enabling effects to persist even during seizure-free periods. However, the transcriptional mechanisms by which ∆FosB regulates hippocampal function are poorly understood due to lack of identified hippocampal gene targets. To identify putative ∆FosB gene targets, we employed high-throughput sequencing of genomic DNA bound to ∆FosB after chromatin immunoprecipitation (ChIP-sequencing). We compared ChIP-sequencing results …

Epigenetic Suppression Of Hippocampal Calbindin-D28k By Δfosb Drives Seizure-Related Cognitive Deficits., Jason C. You, Kavitha Muralidharan, Jin W. Park, Iraklis Petrof, Mark S. Pyfer, Brian F. Corbett, John J. Lafrancois, Yi Zheng, Xiaohong Zhang, Carrie A. Mohila, Daniel Yoshor, Robert A. Rissman, Eric J. Nestler, Helen E. Scharfman, Jeannie Chin

Department of Neuroscience Faculty Papers

The calcium-binding protein calbindin-D28k is critical for hippocampal function and cognition, but its expression is markedly decreased in various neurological disorders associated with epileptiform activity and seizures. In Alzheimer's disease (AD) and epilepsy, both of which are accompanied by recurrent seizures, the severity of cognitive deficits reflects the degree of calbindin reduction in the hippocampal dentate gyrus (DG). However, despite the importance of calbindin in both neuronal physiology and pathology, the regulatory mechanisms that control its expression in the hippocampus are poorly understood. Here we report an epigenetic mechanism through which seizures chronically suppress hippocampal calbindin expression and impair cognition. …

Rabies Screen Reveals Gpe Control Of Cocaine-Triggered Plasticity., Kevin T. Beier, Christina K. Kim, Paul Hoerbelt, Lin Wai Hung, Boris D. Heifets, Katherine E. Deloach, Timothy J. Mosca, Sophie Neuner, Karl Deisseroth, Liqun Luo, Robert C. Malenka

Department of Neuroscience Faculty Papers

Identification of neural circuit changes that contribute to behavioural plasticity has routinely been conducted on candidate circuits that were preselected on the basis of previous results. Here we present an unbiased method for identifying experience-triggered circuit-level changes in neuronal ensembles in mice. Using rabies virus monosynaptic tracing, we mapped cocaine-induced global changes in inputs onto neurons in the ventral tegmental area. Cocaine increased rabies-labelled inputs from the globus pallidus externus (GPe), a basal ganglia nucleus not previously known to participate in behavioural plasticity triggered by drugs of abuse. We demonstrated that cocaine increased GPe neuron activity, which accounted for the …

Calcineurin Dysregulation Underlies Spinal Cord Injury-Induced K(+) Channel Dysfunction In Drg Neurons., Benjamin M. Zemel, Tanziyah Muqeem, Eric V. Brown, Miguel Goulão, Mark W Urban, Stephen R. Tymanskyj, Angelo C. Lepore, Manuel Covarrubias

Department of Neuroscience Faculty Papers

Dysfunction of the fast-inactivating Kv3.4 potassium current in dorsal root ganglion (DRG) neurons contributes to the hyperexcitability associated with persistent pain induced by spinal cord injury (SCI). However, the underlying mechanism is not known. In light of our previous work demonstrating modulation of the Kv3.4 channel by phosphorylation, we investigated the role of the phosphatase calcineurin (CaN) using electrophysiological, molecular, and imaging approaches in adult female Sprague Dawley rats. Pharmacological inhibition of CaN in small-diameter DRG neurons slowed repolarization of the somatic action potential (AP) and attenuated the Kv3.4 current. Attenuated Kv3.4 currents also exhibited slowed inactivation. We observed similar …

Δfosb Regulates Gene Expression And Cognitive Dysfunction In A Mouse Model Of Alzheimer's Disease., Brian F Corbett, Jason C You, Xiaohong Zhang, Mark S Pyfer, Umberto Tosi, Daniel M Iascone, Iraklis Petrof, Anupam Hazra, Chia-Hsuan Fu, Gabriel S Stephens, Annie Ashok, Suzan Aschmies, Lijuan Zhao, Eric J Nestler, Jeannie Chin

Department of Neuroscience Faculty Papers

Alzheimer's disease (AD) is characterized by cognitive decline and 5- to 10-fold increased seizure incidence. How seizures contribute to cognitive decline in AD or other disorders is unclear. We show that spontaneous seizures increase expression of ΔFosB, a highly stable Fos-family transcription factor, in the hippocampus of an AD mouse model. ΔFosB suppressed expression of the immediate early gene c-Fos, which is critical for plasticity and cognition, by binding its promoter and triggering histone deacetylation. Acute histone deacetylase (HDAC) inhibition or inhibition of ΔFosB activity restored c-Fos induction and improved cognition in AD mice. Administration of seizure-inducing agents to nontransgenic …

A Role For Ankyring In Maturation And Maintenance Of The Nodes Of Ranvier., Benjamin Yang, Bridget M. Curran, Stephen R. Tymanskyj

Department of Neuroscience Faculty Papers

No abstract provided.

Presynaptic Lrp4 Promotes Synapse Number And Function Of Excitatory Cns Neurons., Timothy J. Mosca, David J. Luginbuhl, Irving E. Wang, Liqun Luo

Department of Neuroscience Faculty Papers

Precise coordination of synaptic connections ensures proper information flow within circuits. The activity of presynaptic organizing molecules signaling to downstream pathways is essential for such coordination, though such entities remain incompletely known. We show that LRP4, a conserved transmembrane protein known for its postsynaptic roles, functions presynaptically as an organizing molecule. In the Drosophila brain, LRP4 localizes to the nerve terminals at or near active zones. Loss of presynaptic LRP4 reduces excitatory (not inhibitory) synapse number, impairs active zone architecture, and abolishes olfactory attraction - the latter of which can be suppressed by reducing presynaptic GABAB receptors. LRP4 overexpression increases …

Identification Of Octopaminergic Neurons That Modulate Sleep Suppression By Male Sex Drive., Daniel R. Machado, Dinis Afonso, Alexandra R. Kenny, Arzu Öztürk-Çolak, Emilia H. Moscato, Benjamin Mainwaring, Matthew Kayser, Kyunghee Koh

Department of Neuroscience Faculty Papers

Molecular and circuit mechanisms for balancing competing drives are not well understood. While circadian and homeostatic mechanisms generally ensure sufficient sleep at night, other pressing needs can overcome sleep drive. Here, we demonstrate that the balance between sleep and sex drives determines whether male flies sleep or court, and identify a subset of octopaminergic neurons (MS1) that regulate sleep specifically in males. When MS1 neurons are activated, isolated males sleep less, and when MS1 neurons are silenced, the normal male sleep suppression in female presence is attenuated and mating behavior is impaired. MS1 neurons do not express the sexually dimorphic …

Map7 Regulates Axon Collateral Branch Development In Dorsal Root Ganglion Neurons., Stephen R Tymanskyj, Benjamin Yang, Aditi Falnikar, Angelo C Lepore, Le Ma

Department of Neuroscience Faculty Papers

Collateral branches from axons are key components of functional neural circuits that allow neurons to connect with multiple synaptic targets. Like axon growth and guidance, formation of collateral branches depends on the regulation of microtubules, but how such regulation is coordinated to ensure proper circuit development is not known. Based on microarray analysis, we have identified a role for microtubule-associated protein 7 (MAP7) during collateral branch development of dorsal root ganglion (DRG) sensory neurons. We show that MAP7 is expressed at the onset of collateral branch formation. Perturbation of its expression by overexpression or shRNA knockdown alters axon branching in …

Regulation Of Sleep Plasticity By A Thermo-Sensitive Circuit In Drosophila., Angelique Lamaze, Arzu Öztürk-Çolak, Robin Fischer, Nicolai Peschel, Kyunghee Koh, James E.C. Jepson

Department of Neuroscience Faculty Papers

Sleep is a highly conserved and essential behaviour in many species, including the fruit fly Drosophila melanogaster. In the wild, sensory signalling encoding environmental information must be integrated with sleep drive to ensure that sleep is not initiated during detrimental conditions. However, the molecular and circuit mechanisms by which sleep timing is modulated by the environment are unclear. Here we introduce a novel behavioural paradigm to study this issue. We show that in male fruit flies, onset of the daytime siesta is delayed by ambient temperatures above 29 °C. We term this effect Prolonged Morning Wakefulness (PMW). We show that …

Pathogenic Determinants And Mechanisms Of Als/Ftd Linked To Hexanucleotide Repeat Expansions In The C9orf72 Gene., Xinmei Wen, Thomas Westergard, Piera Pasinelli, Davide Trotti

Department of Neuroscience Faculty Papers

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are two apparently distinct neurodegenerative diseases, the former characterized by selective loss of motor neurons in the brain and spinal cord and the latter characterized by selective atrophy of frontal and temporal lobes. Over the years, however, growing evidence from clinical, pathological and genetic findings has suggested that ALS and FTD belong to the same clinic-pathological spectrum disorder. This concept has been further supported by the identification of the most common genetic cause for both diseases, an aberrantly expanded hexanucleotide repeat GGGGCC/ CCCCGG sequence located in a non-coding region of the gene …

Harnessing The Power Of Cell Transplantation To Target Respiratory Dysfunction Following Spinal Cord Injury., Brittany A. Charsar, Mark W. Urban, Angelo C. Lepore

Department of Neuroscience Faculty Papers

The therapeutic benefit of cell transplantation has been assessed in a host of central nervous system (CNS) diseases, including disorders of the spinal cord such as traumatic spinal cord injury (SCI). The promise of cell transplantation to preserve and/or restore normal function can be aimed at a variety of therapeutic mechanisms, including replacement of lost or damaged CNS cell types, promotion of axonal regeneration or sprouting, neuroprotection, immune response modulation, and delivery of gene products such as neurotrophic factors, amongst other possibilities. Despite significant work in the field of transplantation in models of SCI, limited attention has been directed at …

Assessment Of The Effects Of Mptp And Paraquat On Dopaminergic Neurons And Microglia In The Substantia Nigra Pars Compacta Of C57bl/6 Mice., Richard Jay Smeyne, Charles B. Breckenridge, Melissa Beck, Yun Jiao, Mark T. Butt, Jeffrey C. Wolf, Dan Zadory, Daniel J. Minnema, Nicholas C. Sturgess, Kim Z. Travis, Andrew R. Cook, Lewis L. Smith, Philip A. Botham

Department of Neuroscience Faculty Papers

The neurotoxicity of paraquat dichloride (PQ) was assessed in two inbred strains of 9- or 16-week old male C57BL/6 mice housed in two different laboratories and compared to the effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). PQ was administered by intraperitoneal injections; either once (20 mg/kg) or twice (10 mg/kg) weekly for 3 weeks, while MPTP-HCl was injected 4 times on a single day (20 mg/kg/dose). Brains were collected 8, 16, 24, 48, 96 or 168 hours after the last PQ treatment, and 48 or 168 hours after MPTP treatment. Dopamine neurons in the substantia nigra pars compacta (SNpc) were identified by antibodies …

Tau Phosphorylation At Alzheimer's Disease-Related Ser356 Contributes To Tau Stabilization When Par-1/Mark Activity Is Elevated., Kanae Ando, Mikiko Oka, Yosuke Ohtake, Motoki Hayashishita, Sawako Shimizu, Shin-Ichi Hisanaga, Koichi M. Iijima

Department of Neuroscience Faculty Papers

Abnormal phosphorylation of the microtubule-associated protein tau is observed in many neurodegenerative diseases, including Alzheimer's disease (AD). AD-related phosphorylation of two tau residues, Ser262 and Ser356, by PAR-1/MARK stabilizes tau in the initial phase of mismetabolism, leading to subsequent phosphorylation events, accumulation, and toxicity. However, the relative contribution of phosphorylation at each of these sites to tau stabilization has not yet been elucidated. In a Drosophila model of human tau toxicity, we found that tau was phosphorylated at Ser262, but not at Ser356, and that blocking Ser262 phosphorylation decreased total tau levels. By contrast, when PAR-1 was co-overexpressed with tau, …

Closed-State Inactivation Involving An Internal Gate In Kv4.1 Channels Modulates Pore Blockade By Intracellular Quaternary Ammonium Ions., Jeffrey D. Fineberg, Tibor G. Szanto, Gyorgy Panyi, Manuel Covarrubias

Department of Neuroscience Faculty Papers

Voltage-gated K(+) (Kv) channel activation depends on interactions between voltage sensors and an intracellular activation gate that controls access to a central pore cavity. Here, we hypothesize that this gate is additionally responsible for closed-state inactivation (CSI) in Kv4.x channels. These Kv channels undergo CSI by a mechanism that is still poorly understood. To test the hypothesis, we deduced the state of the Kv4.1 channel intracellular gate by exploiting the trap-door paradigm of pore blockade by internally applied quaternary ammonium (QA) ions exhibiting slow blocking kinetics and high-affinity for a blocking site. We found that inactivation gating seemingly traps benzyl-tributylammonium …