2000 — 2004 |
Anderson, Matthew P |
K08Activity Code Description: To provide the opportunity for promising medical scientists with demonstrated aptitude to develop into independent investigators, or for faculty members to pursue research aspects of categorical areas applicable to the awarding unit, and aid in filling the academic faculty gap in these shortage areas within health profession's institutions of the country. |
Ca Channels in Thalamic &Hippocampal Rhythmic Activity @ Brigham and Women's Hospital
DESCRIPTION (applicant's abstract): During the transition from the awake to the sleep state, neuronal activity in the neocortex is dramatically altered, previously chaotic activity becomes rhythmic and globally synchronous. This so-called slow-wave sleep, which includes sleep spindles and delta rhythms, requires thalamic input to the neocortex via thalamocortical cells. The thalamocortical cells themselves contain specialized ion channels whose voltage-gating properties allow rhythmic membrane potential oscillations. EEG recordings of the hippocampus have revealed that behavioral exploration is marked by theta rhythm, while slow wave sleep and awake immobility are marked by synchronous rhythmic bursts called sharp wave/ripple activity. Individual neurons of hippocampal areas CA1 and CA3 also generate membrane potential oscillations and rhythmic bursts of action potentials. Synchronization of these single neuronal oscillators in the thalamus and hippocampus is thought to occur through GABAergic interneurons. Current models suggest that these membrane potential oscillations and their entrainment by interneurons requires T-type calcium channels. Yet, the lack of specific T-type calcium channel blockers has prevented direct tests of this hypothesis. New technologies for targeted gene knockout and recent cloning of T-type calcium channels now make such work possible. Our laboratory has developed technologies for gene disruption in restricted populations of postmitotic neurons in the murine brain. This method permitted the deletion of NR1, a component of the NMDA receptor, exclusively in pyramidal neurons of hippocampal area CA1. The resulting conditional knockout mice were deficient in hippocampal long term potentiation, hippocampal place cell synchronization, and spatial learning and memory. The results demonstrated a critical role for synaptic plasticity in area CA1 in spatial learning. We propose to employ similar methods to test the hypothesis that T-type calcium channels are required for intrinsic neuronal oscillations in the hippocampal and thalamic neurons using slice electrophysiology. We then propose to examine the role of these oscillations in the production of thalamocortical sleep rhythms, hippocampal theta rhythm, and hippocampal sharp wave/ripple activity using ensemble multielectrode recording techniques. Lastly, we will begin to explore the role of these rhythmic modes of neuronal activity in sleep/wake cycles, attention, motivation, elementary sensory and motor skills, and learning and memory. Such work may also begin to explain the cellular and molecular basis for neuropsychiatric disorders like temporal lobe epilepsy and absence seizures where these physiologic rhythms become pathologic.
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0.922 |
2005 — 2006 |
Anderson, Matthew P |
R03Activity Code Description: To provide research support specifically limited in time and amount for studies in categorical program areas. Small grants provide flexibility for initiating studies which are generally for preliminary short-term projects and are non-renewable. |
Modeling Childhhood Absence Epilepsy in Mice @ Beth Israel Deaconess Medical Center
DESCRIPTION (provided by applicant): Due to the multiplicity of neuron subtypes in the brain, solving the cellular basis of a complex neurologic disease such as childhood absence epilepsy could not be achieved until recently. Development of the bacteriophage PI-derived Cre/loxP recombination system enabled significant progress towards solving the cellular basis of memory and should also facilitate our goal of solving the cellular basis of childhood absence epilepsy. We will use this method to target human absence epilepsy gene mutations to specific neuron subtypes in the murine brain. We will focus on the childhood absence epilepsy-associated mutations recently discovered in the T-type calcium channel Cav3.2 gene. T-type calcium channels have been implicated in absence epilepsy. Furthermore, some disease mutations alter channel gating. Based on these findings, we hypothesize Cav3.2 mutations alter the firing properties of specific neuron subtypes in the brain to cause the characteristic 3Hz rhythmic discharge of spike-and-wave complexes, and the behavioral arrests afflicting children with absence epilepsy. To test this hypothesis, we will first, recreate the disease in mice using an epitope-tagged CACNA1H transgene (224 kb, genomic DNA) that encodes Cav3.2. Nucleotide mutations will be made to recreate the epilepsy-associated amino acid changes F161L and V831M, which alter Cav3.2 channel gating. Second, we will develop technologies for targeting the disease gene to specific neuron subtypes by adding a Cre recombinase delete-able transcriptional and translation silencing element to the transgene. We will assess gene silencing by breeding to mice with neuron subtype specific Cre recombinase transgenes. Because they contain cell-type specific promoters, the Cre transgenes express Cre recombinase protein in limited neuron subtypes. Only in these neurons will Cre delete the silencing element, cause transgene expression, and generate epitope tag staining. With this tool we plan to test whether abnormal burst firing in cortical pyramidal or reticular thalamic neurons cause absence epilepsy. If the characteristic signs of epilepsy are reproduced, the results will establish that mutations in Cav3.2 cause absence epilepsy. Once the silencing element system is created, future work to determine the specific neuron subtype whose dysfunction produces absence epilepsy will become possible. Identifying the neural substrate of absence epilepsy will facilitate work to identify other disease genes and potential drug targets.
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2006 — 2010 |
Anderson, Matthew P |
K02Activity Code Description: Undocumented code - click on the grant title for more information. |
Engineering the Mouse Nervous System to Decipher Network Mechanisms of Epilepsy @ Beth Israel Deaconess Medical Center
[unreadable] DESCRIPTION (provided by applicant): Candidate and Environment: This candidate has completed extensive neuroscience training at Harvard and MIT. Beth Israel Neurology has provided an independent laboratory and start-up funds. The candidate's K08 funding ends in 11/05 and he needs continued salary support to protect his research time. This Award would enable him to obtain the preliminary data necessary to obtain an R01 grant. His long term goal is to continue his full-time biomedical research career at Beth Israel/ Harvard Medical School. In the career development plan, the candidate proposes to apply his training and experience to the study of epilepsy. Research Project Summary: The molecular mechanisms in the brain that underlie the spike-and-wave seizures of childhood absence epilepsy (CAE) have long been debated. This proposal uses new bacteriophage P1-derived Cre/loxP recombination techniques to target absence epilepsy gene mutations to specific neuron subtypes in the murine brain. Childhood absence epilepsy-associated mutations were recently discovered in the T-type calcium channel Cav3.2 gene. The project's hypothesis is that Cav3.2 mutations alter the firing properties of specific neuron subtypes to cause the characteristic 3-5 Hz rhythmic discharge of spike-and-wave complexes, and the behavioral arrests afflicting children with absence epilepsy. To test this hypothesis, the candidate will recreate the disease in mice using an epitope-tagged CACNA1H transgene that encodes Cav3.2. Nucleotide mutations will be made to recreate the epilepsy-associated amino acid changes F161L and V831M, which alter Cav3.2 channel gating. Second, he will target the gene to specific neuron subtypes by adding a Cre recombinase delete-able trancriptional and translational silencing element to the transgene. Because they contain cell-type specific promoters, the Cre transgenes express Cre recombinase protein in limited neuron subtypes. Only in these neurons will Cre delete the silencing element, cause transgene expression, and generate epitope tag staining. In this study, the candidate will test whether abnormal burst firing in cortical pyramidal or reticular thalamic neurons cause absence epilepsy. If the characteristic signs of epilepsy are reproduced, it will establish that mutations in Cav3.2 cause absence epilepsy. Targeted expression of this mutant gene will identify the responsible neurons. Identifying the neural substrate will facilitate work to identify other disease genes and potential drug targets. [unreadable] [unreadable] [unreadable]
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2008 — 2011 |
Anderson, Matthew P |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Role of Lgi1 in Autosomal Dominant Lateral Temporal Lobe Epilepsy @ Beth Israel Deaconess Medical Center
DESCRIPTION (provided by applicant): A recently discovered human epilepsy gene, LGI1 (leucine-rich glioma-inactivated;mutated to cause human autosomal dominant lateral temporal lobe epilepsy or ADLTE) encodes a protein secreted at glutamate synapses during postnatal glutamate synapse development. Consequently, we hypothesize that LGI1 might promote epilepsy through a novel mechanism, by regulating postnatal glutamate synapse maturation. We propose ADLTE mutant LGI1 acts as a dominant negative to inhibit native LGI1 function and arrest maturation. To directly address our hypothesis and contrast the functional effects of epilepsy-associated mutant LGI1 with those of excess wild-type LGI1 on native neural circuits, we created transgenic mice using bacterial artificial chromosomes (BAC) carrying a large 226 kb fragment of mouse genomic DNA encoding the full-length LGI1 gene. The ADLTE 835delC mutation introduced a premature translational stop codon to generate a truncated LGI1 protein. The full-length gene BAC transgenic approach is important to maintain native patterns of gene expression and transcript splicing in order to assess the genes effects on the glutamate synapse development process in vivo. LGI1 is heavily expressed presynaptically at medial entorhinal cortex perforant pathway glutamate synapses innervating dentate granule neurons (MPP- dentate) and also separately in a synapse targeting thalamus. Our overall goal is to define the cellular basis for human ADLT epilepsy. We specifically test whether excess LGI1 magnifies and mutant LGI1 blocks maturation of the following glutamate synapse properties during the postnatal periods when it becomes expressed and throughout adulthood in dentate gyrus and thalamus. We examine: 1) presynaptic glutamate release down-regulation and role of Kv1.1 K+ channel activity;2) postsynaptic NR2B NMDA receptor current and synaptic plasticity down-regulation, PSD95-Src complex formation, and the role of Src kinase activity;and 3) dendrite branch (e.g., dentate) and axon input (e.g., thalamus) pruning. This murine model of human ADLT epilepsy could link a novel human epilepsy gene to the arrest of glutamate synapse maturation and potentially defining a cellular basis for human seizure disorders beyond ADLTE. PUBLIC HEALTH RELEVANCE: This project seeks to identify the cellular basis of the inherited human epilepsy disorder caused by mutations in LGI1, a secreted synaptic protein. The results should provide new insights into the cellular and molecular basis of human epilepsy, and help identify new potential therapeutic targets to treat this common brain disorder.
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2009 — 2016 |
Anderson, Matthew P |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Neurobiological Mechanism of 15q11-13 Duplication Autism Spectrum Disorder @ Beth Israel Deaconess Medical Center
DESCRIPTION (provided by applicant): The long-term objective of this project is to compare and contrast the defects in neuronal mRNA expression and circuit functions produced by altered Ube3a gene dosage that may underlie the behavioral phenotypes of Autism Spectrum Disorder (ASD) with maternal 15q11-13 duplication and Angelman's Syndrome (AS). Cells from 15q11-13 ASD and AS patients have excess and deficient E3 ubiquitin ligase, Ube3a, respectively. Ube3a is the sole gene expressed selectively from the maternal allele in brain. The majority of children who inherit 15q11-13 duplications from their mothers develop ASD and the more copies inherited, the more severe the impairment. Recently, we established that increasing Ube3a gene dosage alone reconstitutes the triad of autism-related behavioral deficits in mice. Angelman's Syndrome (AS), by contrast, results when children inherit maternal Ube3a gene mutations. Importantly, Ube3a also acts as a nuclear receptor co-activator regulating gene expression independent of ligase activity. Thus we hypothesized that excess Ube3a (15q dup model) acts in the nucleus to perturb the normal expression of specific neuronal genes and encoded proteins to alter circuit function and thereby generate autism-related behavioral deficits. The logical corollary is that deficiencies of nuclear Ube3a may alter gene expression to change circuit function and produce Angelman-related behavioral deficits through the same, but opposite mechanisms. Because the brain's circuitries are designed for quantitative assessment of sensory information and quantitative motor responses, it is likely that many molecules controlling circuit functions can cause graded changes in behavior when their quantities are altered. We propose Ube3a do so through a dose-dependent regulation of neuronal gene expression. Such molecular quantity variations likely underlie the intrinsic heterogeneity of behavioral disorders like ASD. The specific aims of this R01 grant follow: (1 and 2) determine if Ube3a gene dosage causes ASD (excess Ube3a) and AS (deficient Ube3a) related behavioral deficits through its actions within the nucleus; (3) identify the cortical neuron mRNAs quantitatively regulated by excesses or deficiencies of Ube3a; and (4) identify the cortical circui dysfunctions quantitatively induced by excesses and deficiencies of Ube3a. Our methods include a novel nuclear-targeted Ube3a transgene, a neuron cell-type specific expression of Ube3a, genome wide analysis of transcripts, and identification of consensus Ube3a-gene promoter binding sites. Slice electrophysiology and neuronal morphology will examine the effects of global and cell-type specific changes and nuclear targeted changes of Ube3a gene dosage on cortical circuit function in living brain slices. This analysis will facilitate our effors to bridge from genes to circuits to behavior in the two contrasting human neurological diseases. The project promotes the agency's mission to further a deeper understanding of the neuronal cells, circuits, and genes involved in ASD and AS via genetic models. The novel molecular insights and genetic tools will facilitate development of treatments for these life-long behavioral disabilities.
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2013 — 2014 |
Anderson, Matthew P |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Neurobiology of Aggression Co-Morbidity in Mouse Model of Idic15 Autism @ Beth Israel Deaconess Medical Center
DESCRIPTION (provided by applicant): Individuals diagnosed with autism spectrum disorders (ASDs) are, in addition to signature traits, often burdened by excess aggression (~70% incidence), but knowledge on how this co-morbidity develops and current treatment options are limited. Brain masculinization, the organization of sexually dimorphic regions, is thought to occur during a critical period of brain development during perinatal life. In males this period is identified by a testosterone surge that declines rapidly soon after birth. This testosterone is mostly converted to estradiol locally in the brain by neurons that synthesize the enzyme aromatase (cyp19). Estrogen then activates its cognate receptors in these neurons, where the nuclear hormone transcriptional factor induces changes in gene expression that underlie functional and structural changes in the neuronal circuits. These critical hormonal events orchestrate masculinization of these aromatase-expressing brain circuits, making a canvas for the expression of male specific behaviors later in life. Indeed it will be mostly androgen receptors and secondary testosterone surges that ultimately determine the activity of these brain regions and the extent of male-specific behaviors, such as aggression in adulthood. Recently we described a mouse model of human isodicentric chromosome 15 (idic15) that in addition to the core autism-related traits reported in Smith et al. 2011 also exhibits increased aggressive behavior. This represents the first known animal model of a human genetic autism displaying the co-morbidity of increased aggression. As in human idic15, the mice have a tripled gene and protein dosage of Ube3a, a known co- activator at nuclear hormone receptors, including those for estrogen and androgens. In the light of these findings, we propose to test the novel idea (appropriate for an exploratory R21 grant) that excess Ube3a in idic15 individuals and in our mouse model of the disorder causes abnormally strong estrogen receptors signaling during the key period of brain development to hypermasculinize the brain generating excess aggression in adulthood. The idea is congruent with existing hypermale theory of autism (Baron-Cohen), but provides a concrete biological explanation. To verify this new biological idea, we will perform the following studies: 1) Use our newly created conditional Ube3a ON transgenic mice for temporally-induced over- expression of the idic15 gene dosage of Ube3a to determine the developmental time period when excess Ube3a generates the exaggerated aggression behaviors and predicted hyper-male transcriptional and neuroanatomical (aromatase expressing neuron) brain phenotypes. 2) Use our second newly created conditional Ube3a OFF transgenic mice for induced rescue of the hyper-masculine behavioral and brain phenotypes. Pharmacological agents that inhibit the testosterone-aromatase-estrogen signaling pathway will also be tested for their ability to rescue these phenotypes. These studies provide a biological example and molecular mechanism for the hypermale brain in autism and explain increased aggression in idic15 autism.
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2014 — 2015 |
Anderson, Matthew P |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Conditional Genetics Rescue of Angelman Syndrome @ Beth Israel Deaconess Medical Center
DESCRIPTION (provided by applicant): Angelman syndrome results when maternally-inherited 15q11-13 is deleted or imprinted 15q11-13 gene Ube3a is mutated. Autism results when maternal 15q11-13 is triplicated. The parental inheritance patterns are explained by Ube3a the only 15q11-13 gene expressed solely from the maternal allele in neurons. The countervalent 15q disorders display some contrasting behavioral changes. Angelman syndrome presents with intellectual and motor deficits, but also a hypersocial demeanor, while 15q triplication displays impaired social behavior. Interestingly, in additional to the other previousl characterized deficits, we recently established the Angelman syndrome mice display increased social interaction and ultrasonic vocalization. By contrast, tripling Ube3a gene dosage reduced social interaction and vocalization providing a model of autism. The results establish a Goldilock effect for Ube3a gene dosage and social behavior. Reciprocal gene dose-dependent effects also argue some Ube3a effects could arise from ongoing regulatory rather than remote developmental defects. Ube3a acts as an E3 ubiquitin protein ligase to promote protein degradation and as a nuclear receptor co-activator. To test the hypothesis that Ube3a deficiency in Angelman syndrome causes deficits in behavior and circuit function via ongoing regulatory rather than developmental defects, we will test for reversal of the behavioral and circuit deficits when Ube3a is genetically reactivated in adulthood. To achieve this goal, we generated mice carrying a single extra copy of Ube3a-ON transgene that is silenced by a loxP-flanked STOP cassette. The Ube3a-ON transgene is inactive until the loxP-flanked STOP cassette is deleted by Cre recombinase. Crossing Ube3a-ON transgenic to Cre-ER fusion protein transgenic mice enables tamoxifen- induced Ube3a gene expression. ERTM is mutated, responding to tamoxifen but not estrogen. Cre recombinase is tethered to heat shock proteins in the cytoplasm by ERTM. Tamoxifen penetrates the CNS and binds ERTM, permitting Cre to enter the nucleus and delete the loxP-flanked STOP cassette. If adult rescue is not achieved, we will perform temporal mapping to postnatal or embryonic developmental periods. We also created an Ube3a-OFF transgene where loxP sequences flank Ube3a exon 2 so tamoxifen causes Cre-ERTM to inactivate Ube3a. Crossing Ube3a-OFF/Cre-ERTM into the Angelman model, we will determine if inactivating Ube3a in adulthood or at specific developmental times recreates the disorder. The result will establish the feasibility of rescuing Angelman syndrome and provide insights into the pathophysiological basis and treatment options for the disorder.
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2017 — 2021 |
Anderson, Matthew P |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Neurobiology of Aggression Comorbidity in Autism @ Beth Israel Deaconess Medical Center
PROJECT SUMMARY Aggression is a frequent comorbidity in autism spectrum disorders (ASD). The problem is one of the major reasons families seek medical therapy. Understanding the molecular basis and deciphering the neural circuits that contribute to the development of this aggression comorbidity could inform novel targeted therapeutics. Increased copies of maternal chromosome 15q11-13 region [interstitial duplication with a single extra copy and extranumerary isodicentric chromosome 15q (Idic15) with two extra copies] are frequent and strongly penetrant (Idic15) causes of ASD. We have recently established that extra copies of Ube3a alone (15q11-13 gene expressed exclusively from maternal allele in neurons) are sufficient to reproduce ASD-like deficits in mice (Smith et al. 2011). Interestingly, mice with extra copies of Ube3a also show increased aggression. Taken together, these observations indicate that aberrant expression of Ube3a underlies multiple ASD-associated behavioral problems. In this project we will dissect Ube3a's role in controlling the aggression-comorbidity of ASD: 1) Identify specific neuronal cell types where increased Ube3a gene dosage increase aggression and identify underlying transcriptional and electrophysiological changes; and 2) Identify synaptic connections that are disrupted by increased Ube3a gene dosage to increase aggression within those neuronal cell types. The project promotes the agency's mission to further a deeper understanding of the neuronal cells, circuits, and genes involved in ASD via genetic models. The novel molecular insights and genetic tools will facilitate development of treatments for these life-long behavioral disabilities.
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0.922 |
2018 — 2021 |
Anderson, Matthew P |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Vta Vglut2 Sociability Circuit in Genetic Autism @ Beth Israel Deaconess Medical Center
PROJECT SUMMARY Autism spectrum disorder (ASD) is characterized by its deficits in social interactions. Oxytocin is a hypothalamic neuropeptide known to increase social interactions through its oxytocin receptor (Oxtr) but where this occurs remains undefined. Maternal 15q11-13 triplications (extranumerary isodicentric chromosome 15, idic15) cause a highly penetrant autism that we have linked to the increased dosage of UBE3A. UBE3A encodes an ubiquitin-ligase and transcriptional co-regulator expressed exclusively from the maternal allele in mature neurons. Seizures are a frequent comorbidity in ASD including in idic15. In our recent study (Krishnan et al. Nature 2017), we established that a previously enigmatic population of glutamatergic neurons in the brainstem ventral tegmental area (VTA) drives sociability and found increases of UBE3A and seizures converge to repress expression of autism network gene Cbln1 to impair sociability within these neurons. In Aim 1, we investigate a new concept, that oxytocin receptors mark the specific population of VTA glutamatergic neurons that promote sociability and that oxytocin receptor activity in these neurons is necessary for normal sociability. In Aim 2, we investigate the target site where VTA glutamatergic neurons promote sociability by testing if chemogenetically-controlled activity and Grid1 expression (Cbln1's postsynaptic binding partner that is deleted in autism) in the nucleus accumbens are necessary and sufficient to promote sociability. VTA glutamatergic neurons form excitatory synapses onto nucleus accumbens neurons and we have shown these synapses are impaired by Cbln1 deletion and by seizures. In Aim 3, we test if increases of UBE3A and seizures converge on the specific VTA glutamatergic neurons that express oxytocin receptors to impair sociability and glutamategic transmission if these defects can rescued by adding back Cbln1 to these specialized neurons. In Aim 4, we investigate whether in vivo chemogenetic increases of oxytocin signaling can rescue the VTA glutamatergic neuron to nucleus accumbens synaptic defects and sociability impairments produced by increased UBE3A and seizures. In this study, we combine conditional mouse genetics, stereotaxic viral vector-based gene deliveries methods including VGluT2 and Oxtr promoter intersectional genetics, behavioral chemogenetics, and brain slice optogenetics electrophysiology techniques to uncover a convergent molecular autism gene network and neuronal circuitry where three models of human autism spectrum disorder impair sociability. (1) Increased Ube3a gene dosage (maternal 15q11-13 triplication) and (2) epilepsy convergence to repress Cbln1 in VTA glutamatergic neurons and (3) loss of Grid1, Cbln1's postsynaptic binding partner in nucleus accumbens all impair sociability. We also perform a series of in vivo preclinical tests of the efficacy of therapeutic interventions using viral vector-based methods aimed at these molecules and circuits and the oxytocin system.
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