The Experts below are selected from a list of 16179 Experts worldwide ranked by ideXlab platform
Tobias M. Boeckers - One of the best experts on this subject based on the ideXlab platform.
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Altered Intestinal Morphology and Microbiota Composition in the Autism Spectrum Disorders Associated SHANK3 Mouse Model
MDPI AG, 2019Co-Authors: Ann Katrin Sauer, Juergen Bockmann, Tobias M. Boeckers, Konrad Steinestel, Andreas M. GrabruckerAbstract:Autism spectrum disorders (ASD) are a group of neurodevelopmental disorders characterized by deficits in social interaction and communication, and repetitive behaviors. In addition, co-morbidities such as gastro-intestinal problems have frequently been reported. Mutations and deletion of proteins of the SH3 and multiple ankyrin repeat domains (SHANK) gene-family were identified in patients with ASD, and Shank knock-out mouse models display autism-like phenotypes. SHANK3 proteins are not only expressed in the central nervous system (CNS). Here, we show expression in gastrointestinal (GI) epithelium and report a significantly different GI morphology in Shank3 knock-out (KO) mice. Further, we detected a significantly altered microbiota composition measured in feces of Shank3 KO mice that may contribute to inflammatory responses affecting brain development. In line with this, we found higher E. coli lipopolysaccharide levels in liver samples of Shank3 KO mice, and detected an increase in Interleukin-6 and activated astrocytes in Shank3 KO mice. We conclude that apart from its well-known role in the CNS, SHANK3 plays a specific role in the GI tract that may contribute to the ASD phenotype by extracerebral mechanisms
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heterogeneity of cell surface glutamate and gaba receptor expression in shank and cntn4 autism mouse models
Frontiers in Molecular Neuroscience, 2018Co-Authors: Christopher Heise, Jonathan M Preuss, Jan C Schroeder, Chiara R Battaglia, Jonas Kolibius, Rebecca Schmid, Peter J H Burbach, Michael R. Kreutz, Tobias M. BoeckersAbstract:Autism spectrum disorder (ASD) refers to a large set of neurodevelopmental disorders, which have in common both repetitive behavior and abnormalities in social interactions and communication. Interestingly, most forms of ASD have a strong genetic contribution. However, the molecular underpinnings of this disorder remain elusive. The SHANK3 gene (and to a lesser degree SHANK2) which encode for the postsynaptic density (PSD) proteins SHANK3/SHANK2 and the CONTACTIN 4 gene which encodes for the neuronal glycoprotein CONTACTIN4 (CNTN4) exhibit mutated variants which are associated with ASD. Like many of the other genes associated with ASD, both SHANKs and CNTN4 affect synapse formation and function and are therefore related to the proper development and signaling capability of excitatory and inhibitory neuronal networks in the adult mammal brain. In this study we used mutant/knock-out mice of SHANK2 (SHANK2-/-), Shank3 (Shank3αβ-/-), and Cntn4 (Cntn4-/-) as ASD-models to explore whether these mice share a molecular signature in glutamatergic and GABAergic synaptic transmission in ASD-related brain regions. Using a biotinylation assay and subsequent western blotting we focused our analysis on cell surface expression of classical several ionotropic glutamate and GABA receptor subunits: GluA1, GluA2, and NR1GluN1 were analyzed for excitatory synaptic transmission, and the α1 subunit of the GABAA receptor was analyzed for inhibitory synaptic transmission. We found that both SHANK2-/- and Shank3αβ-/- mice exhibit reduced levels of several cell surface glutamate receptors in most of the analyzed brain regions – especially in the striatum and thalamus – when compared to wildtype controls. Interestingly, even though Cntn4-/- mice also show reduced levels of some cell surface glutamate receptors in the cortex and hippocampus, increased levels of cell surface glutamate receptors were found in the striatum. Moreover, Cntn4-/- mice do not only show brain region-specific alterations in cell surface glutamate receptors but also a downregulation of cell surface GABA receptors in several of the analyzed brain regions. The results of this study suggest that even though mutations in defined genes can be associated with ASD this does not necessarily result in a common molecular phenotype in surface expression of glutamatergic and GABAergic receptor subunits in defined brain regions.
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Hyperactivity and Hypermotivation Associated With Increased Striatal mGluR1 Signaling in a SHANK2 Rat Model of Autism.
Frontiers in molecular neuroscience, 2018Co-Authors: Meera E. Modi, Dominik Reim, Tobias M. Boeckers, Michael J. Schmeisser, Julie M. Brooks, Edward Guilmette, Mercedes Beyna, Radka Graf, Patricio O'donnell, Derek L. BuhlAbstract:Mutations in the SHANK family of genes have been consistently identified in genetic and genomic screens of autism spectrum disorder (ASD). The functional overlap of SHANK with several other ASD-associated genes suggests synaptic dysfunction as a convergent mechanism of pathophysiology in ASD. Although many ASD-related mutations result in alterations to synaptic function, the nature of those dysfunctions and the consequential behavioral manifestations are highly variable when expressed in genetic mouse models. To investigate the phylogenetic conservation of phenotypes resultant of SHANK2 loss-of-function in a translationally relevant animal model, we generated and characterized a novel transgenic rat with a targeted mutation of the SHANK2 gene, enabling an evaluation of gene-associated phenotypes, the elucidation of complex behavioral phenotypes, and the characterization of potential translational biomarkers. The SHANK2 loss-of-function mutation resulted in a notable phenotype of hyperactivity encompassing hypermotivation, increased locomotion, and repetitive behaviors. Mutant rats also expressed deficits in social behavior throughout development and in the acquisition of operant tasks. The hyperactive phenotype was associated with an upregulation of mGluR1 expression, increased dendritic branching, and enhanced long-term depression in the striatum but opposing morphological and cellular alterations in the hippocampus. Administration of the mGluR1 antagonist JNJ16259685 selectively normalized the expression of striatally mediated repetitive behaviors and physiology but had no effect on social deficits. Finally, SHANK2 mutant animals also exhibited alterations in electroencephalography (EEG) spectral power and event-related potentials, which may serve as translatable EEG biomarkers of synaptopathic alterations. Our results show a novel hypermotivation phenotype that is unique to the rat model of SHANK2 dysfunction, in addition to the traditional hyperactive and repetitive behaviors observed in mouse models. The hypermotivated and hyperactive phenotype is associated with striatal dysfunction, which should be explored further as a targetable mechanism for impairment in ASD.
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Structural basis for PDZ domain interactions in the post‐synaptic density scaffolding protein Shank3
Journal of Neurochemistry, 2018Co-Authors: Srinivas Kumar Ponna, Corinna Keller, Salla Ruskamo, Matti Myllykoski, Tobias M. Boeckers, Petri KursulaAbstract:: The Shank proteins are crucial scaffolding elements of the post-synaptic density (PSD). One of the best-characterized domains in Shank is the PDZ domain, which binds to C-terminal segments of several other PSD proteins. We carried out a detailed structural analysis of Shank3 PDZ domain-peptide complexes, to understand determinants of binding affinity towards different ligand proteins. Ligand peptides from four different proteins were cocrystallized with the Shank3 PDZ domain, and binding affinities were determined calorimetrically. In addition to conserved class I interactions between the first and third C-terminal peptide residue and Shank3, side chain interactions of other residues in the peptide with the PDZ domain are important factors in defining affinity. Structural conservation suggests that the binding specificities of the PDZ domains from different Shanks are similar. Two conserved buried water molecules in PDZ domains may affect correct local folding of ligand recognition determinants. The solution structure of a tandem Shank3 construct containing the SH3 and PDZ domains showed that the two domains are close to each other, which could be of relevance, when recognizing and binding full target proteins. The SH3 domain did not affect the affinity of the PDZ domain towards short target peptides, and the schizophrenia-linked Shank3 mutation R536W in the linker between the domains had no effect on the structure or peptide interactions of the Shank3 SH3-PDZ unit. Our data show the spatial arrangement of two adjacent Shank domains and pinpoint affinity determinants for short PDZ domain ligands with limited sequence homology.
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Structure of an unconventional SH3 domain from the postsynaptic density protein Shank3 at ultrahigh resolution.
Biochemical and Biophysical Research Communications, 2017Co-Authors: Srinivas Kumar Ponna, Matti Myllykoski, Tobias M. Boeckers, Petri KursulaAbstract:Abstract The Shank family comprises three large multi-domain proteins playing central roles as protein scaffolds in the neuronal postsynaptic density. The Shank proteins are closely linked to neuropsychiatric diseases, such as autism spectrum disorders. One characteristic domain in the Shank family is the SH3 domain, assumed to play a role in protein-protein interactions; however, no specific ligand binding to any Shank SH3 domain has been described. We solved the crystal structure of the SH3 domain from Shank3 at sub-atomic resolution. While the structure presents the canonical SH3 domain fold, the binding site for proline-rich peptides is not conserved. In line with this, no binding of Pro-rich sequences by the Shank3 SH3 domain was observed. Sequence comparisons indicate that all Shank isoforms have similarly lost the classical Pro-rich peptide binding site from the SH3 domain. Whether the corresponding site in the Shank SH3 domains has evolved to bind a non-poly-Pro target sequence is currently not known. Our work provides an intriguing example of the evolution of a well-characterized protein-protein interaction domain within the context of multi-domain protein scaffolds, allowing the conservation of structural features, but losing canonical functional sites. The data are further discussed in light of known mutations in the SH3 domain or its vicinity in the different Shank isoforms.
Michael R. Kreutz - One of the best experts on this subject based on the ideXlab platform.
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heterogeneity of cell surface glutamate and gaba receptor expression in shank and cntn4 autism mouse models
Frontiers in Molecular Neuroscience, 2018Co-Authors: Christopher Heise, Jonathan M Preuss, Jan C Schroeder, Chiara R Battaglia, Jonas Kolibius, Rebecca Schmid, Peter J H Burbach, Michael R. Kreutz, Tobias M. BoeckersAbstract:Autism spectrum disorder (ASD) refers to a large set of neurodevelopmental disorders, which have in common both repetitive behavior and abnormalities in social interactions and communication. Interestingly, most forms of ASD have a strong genetic contribution. However, the molecular underpinnings of this disorder remain elusive. The SHANK3 gene (and to a lesser degree SHANK2) which encode for the postsynaptic density (PSD) proteins SHANK3/SHANK2 and the CONTACTIN 4 gene which encodes for the neuronal glycoprotein CONTACTIN4 (CNTN4) exhibit mutated variants which are associated with ASD. Like many of the other genes associated with ASD, both SHANKs and CNTN4 affect synapse formation and function and are therefore related to the proper development and signaling capability of excitatory and inhibitory neuronal networks in the adult mammal brain. In this study we used mutant/knock-out mice of SHANK2 (SHANK2-/-), Shank3 (Shank3αβ-/-), and Cntn4 (Cntn4-/-) as ASD-models to explore whether these mice share a molecular signature in glutamatergic and GABAergic synaptic transmission in ASD-related brain regions. Using a biotinylation assay and subsequent western blotting we focused our analysis on cell surface expression of classical several ionotropic glutamate and GABA receptor subunits: GluA1, GluA2, and NR1GluN1 were analyzed for excitatory synaptic transmission, and the α1 subunit of the GABAA receptor was analyzed for inhibitory synaptic transmission. We found that both SHANK2-/- and Shank3αβ-/- mice exhibit reduced levels of several cell surface glutamate receptors in most of the analyzed brain regions – especially in the striatum and thalamus – when compared to wildtype controls. Interestingly, even though Cntn4-/- mice also show reduced levels of some cell surface glutamate receptors in the cortex and hippocampus, increased levels of cell surface glutamate receptors were found in the striatum. Moreover, Cntn4-/- mice do not only show brain region-specific alterations in cell surface glutamate receptors but also a downregulation of cell surface GABA receptors in several of the analyzed brain regions. The results of this study suggest that even though mutations in defined genes can be associated with ASD this does not necessarily result in a common molecular phenotype in surface expression of glutamatergic and GABAergic receptor subunits in defined brain regions.
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Selective Localization of Shanks to VGLUT1-Positive Excitatory Synapses in the Mouse Hippocampus
Frontiers in Cellular Neuroscience, 2016Co-Authors: Christopher Heise, Jan C Schroeder, Sarah Woelfle, Michael Schoen, Michael R. Kreutz, Dominik Reim, Sonja Halbedl, Michael J. Schmeisser, Tobias M. BoeckersAbstract:Abstract Members of the Shank family of multidomain proteins (Shank1, SHANK2, and Shank3) are core components of the postsynaptic density (PSD) of excitatory synapses. At synaptic sites Shanks serve as scaffolding molecules that cluster neurotransmitter receptors as well as cell adhesion molecules attaching them to the actin cytoskeleton. In this study we investigated the synapse specific localization of Shank1-3 and focused on well-defined synaptic contacts within the hippocampal formation. We found that all three family members are present only at VGLUT1-positive synapses, which is particularly visible at mossy fiber contacts. No costaining was found at VGLUT2-positive contacts indicating that the molecular organization of VGLUT2-associated PSDs diverges from classical VGLUT1-positive excitatory contacts in the hippocampus. In light of SHANK mutations in neuropsychiatric disorders, this study indicates which glutamatergic networks within the hippocampus will be primarily affected by shankopathies.
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Concerted action of zinc and ProSAP/Shank in synaptogenesis and synapse maturation
The EMBO Journal, 2011Co-Authors: Andreas M. Grabrucker, Mary Jane Knight, Marisa K. Joubert, Magali Rowan, G Uirich Nienhaus, Christian Proepper, Juergen Bockmann, James U. Bowie, Craig C Garner, Michael R. KreutzAbstract:Neuronal morphology and number of synapses is not static, but can change in response to a variety of factors, a process called synaptic plasticity. These structural and molecular changes are believed to represent the basis for learning and memory, thereby underling both the developmental and activity-dependent remodelling of excitatory synapses. Here, we report that Zn2+ ions, which are highly enriched within the postsynaptic density (PSD), are able to influence the recruitment of ProSAP/Shank proteins to PSDs in a family member-specific manner during the course of synaptogenesis and synapse maturation. Through selectively overexpressing each family member at excitatory postsynapses and comparing this to shRNA-mediated knockdown, we could demonstrate that only the overexpression of zinc-sensitive ProSAP1/SHANK2 or ProSAP2/Shank3 leads to increased synapse density, although all of them cause a decrease upon knockdown. Furthermore, depletion of synaptic Zn2+ along with the knockdown of zinc-insensitive Shank1 causes the rapid disintegration of PSDs and the loss of several postsynaptic molecules including Homer1, PSD-95 and NMDA receptors. These findings lead to the model that the concerted action of ProSAP/Shank and Zn2+ is essential for the structural integrity of PSDs and moreover that it is an important element of synapse formation, maturation and structural plasticity.
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C-terminal synaptic targeting elements for postsynaptic density proteins ProSAP1/SHANK2 and ProSAP2/Shank3
Journal of Neurochemistry, 2005Co-Authors: Tobias M. Boeckers, Christina Spilker, Thomas Liedtke, Thomas Dresbach, Jürgen Bockmann, Michael R. Kreutz, Eckart D GundelfingerAbstract:Synapses are specialized contact sites mediating communication between neurons. Synaptogenesis requires the specific assembly of protein clusters at both sides of the synaptic contact by mechanisms that are barely understood. We studied the synaptic targeting of multi-domain proteins of the ProSAP/Shank family thought to serve as master scaffolding molecules of the postsynaptic density. In contrast to Shank1, expression of green-fluorescent protein (GFP)-tagged ProSAP1/SHANK2 and ProSAP2/Shank3 deletion constructs in hippocampal neurons revealed that their postsynaptic localization relies on the integrity of the C-termini. The shortest construct that was perfectly targeted to synaptic sites included the last 417 amino acids of ProSAP1/SHANK2 and included the C-terminal sterile alpha motif (SAM) domain. Removal of 54 residues from the N-terminus of this construct resulted in a diffuse distribution in the cytoplasm. Altogether, our data delineate a hitherto unknown targeting signal in both ProSAP1/SHANK2 and ProSAP2/Shank3 and provide evidence for an implication of these proteins and their close homologue, Shank1, in distinct molecular pathways.
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c terminal synaptic targeting elements for postsynaptic density proteins prosap1 SHANK2 and prosap2 shank3
Journal of Neurochemistry, 2005Co-Authors: Tobias M. Boeckers, Christina Spilker, Thomas Liedtke, Thomas Dresbach, Jürgen Bockmann, Michael R. Kreutz, Eckart D GundelfingerAbstract:Synapses are specialized contact sites mediating communication between neurons. Synaptogenesis requires the specific assembly of protein clusters at both sides of the synaptic contact by mechanisms that are barely understood. We studied the synaptic targeting of multi-domain proteins of the ProSAP/Shank family thought to serve as master scaffolding molecules of the postsynaptic density. In contrast to Shank1, expression of green-fluorescent protein (GFP)-tagged ProSAP1/SHANK2 and ProSAP2/Shank3 deletion constructs in hippocampal neurons revealed that their postsynaptic localization relies on the integrity of the C-termini. The shortest construct that was perfectly targeted to synaptic sites included the last 417 amino acids of ProSAP1/SHANK2 and included the C-terminal sterile alpha motif (SAM) domain. Removal of 54 residues from the N-terminus of this construct resulted in a diffuse distribution in the cytoplasm. Altogether, our data delineate a hitherto unknown targeting signal in both ProSAP1/SHANK2 and ProSAP2/Shank3 and provide evidence for an implication of these proteins and their close homologue, Shank1, in distinct molecular pathways.
Michael J. Schmeisser - One of the best experts on this subject based on the ideXlab platform.
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Hyperactivity and Hypermotivation Associated With Increased Striatal mGluR1 Signaling in a SHANK2 Rat Model of Autism.
Frontiers in molecular neuroscience, 2018Co-Authors: Meera E. Modi, Dominik Reim, Tobias M. Boeckers, Michael J. Schmeisser, Julie M. Brooks, Edward Guilmette, Mercedes Beyna, Radka Graf, Patricio O'donnell, Derek L. BuhlAbstract:Mutations in the SHANK family of genes have been consistently identified in genetic and genomic screens of autism spectrum disorder (ASD). The functional overlap of SHANK with several other ASD-associated genes suggests synaptic dysfunction as a convergent mechanism of pathophysiology in ASD. Although many ASD-related mutations result in alterations to synaptic function, the nature of those dysfunctions and the consequential behavioral manifestations are highly variable when expressed in genetic mouse models. To investigate the phylogenetic conservation of phenotypes resultant of SHANK2 loss-of-function in a translationally relevant animal model, we generated and characterized a novel transgenic rat with a targeted mutation of the SHANK2 gene, enabling an evaluation of gene-associated phenotypes, the elucidation of complex behavioral phenotypes, and the characterization of potential translational biomarkers. The SHANK2 loss-of-function mutation resulted in a notable phenotype of hyperactivity encompassing hypermotivation, increased locomotion, and repetitive behaviors. Mutant rats also expressed deficits in social behavior throughout development and in the acquisition of operant tasks. The hyperactive phenotype was associated with an upregulation of mGluR1 expression, increased dendritic branching, and enhanced long-term depression in the striatum but opposing morphological and cellular alterations in the hippocampus. Administration of the mGluR1 antagonist JNJ16259685 selectively normalized the expression of striatally mediated repetitive behaviors and physiology but had no effect on social deficits. Finally, SHANK2 mutant animals also exhibited alterations in electroencephalography (EEG) spectral power and event-related potentials, which may serve as translatable EEG biomarkers of synaptopathic alterations. Our results show a novel hypermotivation phenotype that is unique to the rat model of SHANK2 dysfunction, in addition to the traditional hyperactive and repetitive behaviors observed in mouse models. The hypermotivated and hyperactive phenotype is associated with striatal dysfunction, which should be explored further as a targetable mechanism for impairment in ASD.
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Selective Localization of Shanks to VGLUT1-Positive Excitatory Synapses in the Mouse Hippocampus
Frontiers in Cellular Neuroscience, 2016Co-Authors: Christopher Heise, Jan C Schroeder, Sarah Woelfle, Michael Schoen, Michael R. Kreutz, Dominik Reim, Sonja Halbedl, Michael J. Schmeisser, Tobias M. BoeckersAbstract:Abstract Members of the Shank family of multidomain proteins (Shank1, SHANK2, and Shank3) are core components of the postsynaptic density (PSD) of excitatory synapses. At synaptic sites Shanks serve as scaffolding molecules that cluster neurotransmitter receptors as well as cell adhesion molecules attaching them to the actin cytoskeleton. In this study we investigated the synapse specific localization of Shank1-3 and focused on well-defined synaptic contacts within the hippocampal formation. We found that all three family members are present only at VGLUT1-positive synapses, which is particularly visible at mossy fiber contacts. No costaining was found at VGLUT2-positive contacts indicating that the molecular organization of VGLUT2-associated PSDs diverges from classical VGLUT1-positive excitatory contacts in the hippocampus. In light of SHANK mutations in neuropsychiatric disorders, this study indicates which glutamatergic networks within the hippocampus will be primarily affected by shankopathies.
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Shank3 is localized in axons and presynaptic specializations of developing hippocampal neurons and involved in the modulation of NMDA receptor levels at axon terminals
Journal of Neurochemistry, 2016Co-Authors: Sonja Halbedl, Marisa S. Feiler, Michael Schoen, Tobias M. Boeckers, Michael J. SchmeisserAbstract:Autism-related Shank1, SHANK2, and Shank3 are major postsynaptic scaffold proteins of excitatory glutamatergic synapses. A few studies, however, have already indicated that within a neuron, the presence of Shank family members is not limited to the postsynaptic density. By separating axons from dendrites of developing hippocampal neurons in microfluidic chambers, we show that RNA of all three Shank family members is present within axons. Immunostaining confirms these findings as all three Shanks are indeed found within separated axons and further co-localize with well-known proteins of the presynaptic specialization in axon terminals. Therefore, Shank proteins might not only serve as postsynaptic scaffold proteins, but also play a crucial role during axonal outgrowth and presynaptic development and function. This is supported by our findings that shRNA-mediated knockdown of Shank3 results in up-regulation of the NMDA receptor subunit GluN1 in axon terminals. Taken together, our findings will have major implications for the future analysis of neuronal Shank biology in both health and disease. Shank1, SHANK2, and Shank3 are major postsynaptic scaffold proteins of excitatory glutamatergic synapses strongly related to several neuropsychiatric disorders. However, a few studies have already implicated a functional role of the Shanks beyond the postsynaptic density (PSD). We here show that all three Shanks are localized in both axons and pre-synaptic specializiations of developing hippocampal neurons in culture. We further provide evidence that Shank3 is involved in the modulation of NMDA receptor levels at axon terminals. Taken together, our study will open up novel avenues for the future analysis of neuronal Shank biology in both health and disease.
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SHANK Mutations in Intellectual Disability and Autism Spectrum Disorder
Neuronal and Synaptic Dysfunction in Autism Spectrum Disorder and Intellectual Disability, 2016Co-Authors: Michael J. Schmeisser, Chiara VerpelliAbstract:Abstract Mutations in the three human SHANK genes, which encode the postsynaptic scaffold proteins SHANK1, SHANK2, and SHANK3, are directly responsible for certain types of intellectual disability (ID) and in general for autism spectrum disorder (ASD). These neuropsychiatric conditions are caused by a generalized dysfunction of the brain, most probably owing to altered formation and plasticity of synaptic connections, thus leading to dysfunctional neuronal communication. Most interestingly, SHANK mutations affect individuals with a different grade of severity: that is, patients with SHANK3 mutations exhibit a strong ID and ASD phenotype, whereas patients with SHANK2 or SHANK1 mutations characteristically exhibit milder phenotypes. To summarize current knowledge about the effects of SHANK mutations on the pathogenesis of ID and ASD, we will discuss the impact of SHANK on synaptic function and highlight genotypic and phenotypic variations among mutations. Whereas the foundation of our knowledge on SHANK function began with in vitro studies, in vivo investigation of Shank mutant mice has further advanced our studies. Functional analysis of rodent Shank family members allows us to understand the role of these proteins better in brain development and in the pathogenesis of ID and ASD with the ultimate aim of identifying novel targets to develop effective therapies. With the recent discovery of human induced pluripotent stem cells, the ability to work on human neurons has opened up, potentially allowing for precise genetic mapping and possibly even personalized therapies to be developed. In this chapter, we will present an overview of SHANK function and SHANK mutations from the perspective of both in vitro and in vivo studies pointing to future directions where research on SHANK will likely go.
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Translational neurobiology in Shank mutant mice - Model systems for neuropsychiatric disorders
Annals of Anatomy-anatomischer Anzeiger, 2015Co-Authors: Michael J. SchmeisserAbstract:Abstract The Shank family comprises three core postsynaptic scaffold proteins of excitatory synapses in the mammalian brain: Shank1, SHANK2 and Shank3. Since mutations in all three human SHANK genes are linked to neuropsychiatric disorders such as autism and schizophrenia, Shank mutant mice serve as corresponding in vivo model systems. Besides intriguing alterations in behavior, dysfunction of glutamatergic synapses has emerged as a pathological hallmark among several Shank mutant lines. However, there is very limited knowledge of the underlying pathomechanisms. Therefore, precise neurobiological evaluation of morphological, molecular and electrophysiological phenotypes in Shank mutants is crucially needed. In this brief review, I will focus on the Shank mutant mouse lines we have generated so far and discuss how they might help us to develop translational treatment studies in the future.
Andreas M. Grabrucker - One of the best experts on this subject based on the ideXlab platform.
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Altered Intestinal Morphology and Microbiota Composition in the Autism Spectrum Disorders Associated SHANK3 Mouse Model
MDPI AG, 2019Co-Authors: Ann Katrin Sauer, Juergen Bockmann, Tobias M. Boeckers, Konrad Steinestel, Andreas M. GrabruckerAbstract:Autism spectrum disorders (ASD) are a group of neurodevelopmental disorders characterized by deficits in social interaction and communication, and repetitive behaviors. In addition, co-morbidities such as gastro-intestinal problems have frequently been reported. Mutations and deletion of proteins of the SH3 and multiple ankyrin repeat domains (SHANK) gene-family were identified in patients with ASD, and Shank knock-out mouse models display autism-like phenotypes. SHANK3 proteins are not only expressed in the central nervous system (CNS). Here, we show expression in gastrointestinal (GI) epithelium and report a significantly different GI morphology in Shank3 knock-out (KO) mice. Further, we detected a significantly altered microbiota composition measured in feces of Shank3 KO mice that may contribute to inflammatory responses affecting brain development. In line with this, we found higher E. coli lipopolysaccharide levels in liver samples of Shank3 KO mice, and detected an increase in Interleukin-6 and activated astrocytes in Shank3 KO mice. We conclude that apart from its well-known role in the CNS, SHANK3 plays a specific role in the GI tract that may contribute to the ASD phenotype by extracerebral mechanisms
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Prospects of Zinc Supplementation in Autism Spectrum Disorders and Shankopathies Such as Phelan McDermid Syndrome.
Frontiers in Synaptic Neuroscience, 2018Co-Authors: Simone Hagmeyer, Ann Katrin Sauer, Andreas M. GrabruckerAbstract:The loss of one copy of SHANK3 (SH3 and multiple ankyrin repeat domains 3) in humans highly contributes to Phelan McDermid syndrome (PMDS). In addition, SHANK3 was identified as a major autism candidate gene. Interestingly, the protein encoded by the SHANK3 gene is regulated by zinc. While zinc deficiency depletes synaptic pools of Shank3, increased zinc levels were shown to promote synaptic scaffold formation. Therefore, the hypothesis arises that patients with PMDS and Autism caused by Shankopathies, having one intact copy of SHANK3 left, may benefit from zinc supplementation, as elevated zinc may drive remaining Shank3 into the post-synaptic density (PSD) and may additional recruit SHANK2, a second zinc-dependent member of the SHANK gene family. Further, elevated synaptic zinc levels may modulate E/I ratios affecting other synaptic components such as NMDARs. However, several factors need to be considered in relation to zinc supplementation such as the role of Shank3 in the gastrointestinal (GI) system-the location of zinc absorption in humans. Therefore, here, we briefly discuss the prospect and impediments of zinc supplementation in disorders affecting Shank3 such as PMDS and propose a model for most efficacious supplementation.
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Actin-Dependent Alterations of Dendritic Spine Morphology in Shankopathies
Neural Plasticity, 2016Co-Authors: Tasnuva Sarowar, Andreas M. GrabruckerAbstract:Shank proteins (Shank1, SHANK2, and Shank3) act as scaffolding molecules in the postsynaptic density of many excitatory neurons. Mutations in SHANK genes, in particular SHANK2 and SHANK3, lead to autism spectrum disorders (ASD) in both human and mouse models. Shank3 proteins are made of several domains—the Shank/ProSAP N-terminal (SPN) domain, ankyrin repeats, SH3 domain, PDZ domain, a proline-rich region, and the sterile alpha motif (SAM) domain. Via various binding partners of these domains, Shank3 is able to bind and interact with a wide range of proteins including modulators of small GTPases such as RICH2, a RhoGAP protein, and βPIX, a RhoGEF protein for Rac1 and Cdc42, actin binding proteins and actin modulators. Dysregulation of all isoforms of Shank proteins, but especially Shank3, leads to alterations in spine morphogenesis, shape, and activity of the synapse via altering actin dynamics. Therefore, here, we highlight the role of Shank proteins as modulators of small GTPases and, ultimately, actin dynamics, as found in multiple in vitro and in vivo models. The failure to mediate this regulatory role might present a shared mechanism in the pathophysiology of autism-associated mutations, which leads to dysregulation of spine morphogenesis and synaptic signaling.
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concerted action of zinc and prosap shank in synaptogenesis and synapse maturation
The EMBO Journal, 2011Co-Authors: Mary Jane Knight, Marisa K. Joubert, Magali Rowan, Christian Proepper, Juergen Bockmann, Andreas M. Grabrucker, Craig C Garner, Uirich G Nienhaus, James U. BowieAbstract:Neuronal morphology and number of synapses is not static, but can change in response to a variety of factors, a process called synaptic plasticity. These structural and molecular changes are believed to represent the basis for learning and memory, thereby underling both the developmental and activity-dependent remodelling of excitatory synapses. Here, we report that Zn2+ ions, which are highly enriched within the postsynaptic density (PSD), are able to influence the recruitment of ProSAP/Shank proteins to PSDs in a family member-specific manner during the course of synaptogenesis and synapse maturation. Through selectively overexpressing each family member at excitatory postsynapses and comparing this to shRNA-mediated knockdown, we could demonstrate that only the overexpression of zinc-sensitive ProSAP1/SHANK2 or ProSAP2/Shank3 leads to increased synapse density, although all of them cause a decrease upon knockdown. Furthermore, depletion of synaptic Zn2+ along with the knockdown of zinc-insensitive Shank1 causes the rapid disintegration of PSDs and the loss of several postsynaptic molecules including Homer1, PSD-95 and NMDA receptors. These findings lead to the model that the concerted action of ProSAP/Shank and Zn2+ is essential for the structural integrity of PSDs and moreover that it is an important element of synapse formation, maturation and structural plasticity.
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Concerted action of zinc and ProSAP/Shank in synaptogenesis and synapse maturation
The EMBO Journal, 2011Co-Authors: Andreas M. Grabrucker, Mary Jane Knight, Marisa K. Joubert, Magali Rowan, G Uirich Nienhaus, Christian Proepper, Juergen Bockmann, James U. Bowie, Craig C Garner, Michael R. KreutzAbstract:Neuronal morphology and number of synapses is not static, but can change in response to a variety of factors, a process called synaptic plasticity. These structural and molecular changes are believed to represent the basis for learning and memory, thereby underling both the developmental and activity-dependent remodelling of excitatory synapses. Here, we report that Zn2+ ions, which are highly enriched within the postsynaptic density (PSD), are able to influence the recruitment of ProSAP/Shank proteins to PSDs in a family member-specific manner during the course of synaptogenesis and synapse maturation. Through selectively overexpressing each family member at excitatory postsynapses and comparing this to shRNA-mediated knockdown, we could demonstrate that only the overexpression of zinc-sensitive ProSAP1/SHANK2 or ProSAP2/Shank3 leads to increased synapse density, although all of them cause a decrease upon knockdown. Furthermore, depletion of synaptic Zn2+ along with the knockdown of zinc-insensitive Shank1 causes the rapid disintegration of PSDs and the loss of several postsynaptic molecules including Homer1, PSD-95 and NMDA receptors. These findings lead to the model that the concerted action of ProSAP/Shank and Zn2+ is essential for the structural integrity of PSDs and moreover that it is an important element of synapse formation, maturation and structural plasticity.
Eckart D Gundelfinger - One of the best experts on this subject based on the ideXlab platform.
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C-terminal synaptic targeting elements for postsynaptic density proteins ProSAP1/SHANK2 and ProSAP2/Shank3
Journal of Neurochemistry, 2005Co-Authors: Tobias M. Boeckers, Christina Spilker, Thomas Liedtke, Thomas Dresbach, Jürgen Bockmann, Michael R. Kreutz, Eckart D GundelfingerAbstract:Synapses are specialized contact sites mediating communication between neurons. Synaptogenesis requires the specific assembly of protein clusters at both sides of the synaptic contact by mechanisms that are barely understood. We studied the synaptic targeting of multi-domain proteins of the ProSAP/Shank family thought to serve as master scaffolding molecules of the postsynaptic density. In contrast to Shank1, expression of green-fluorescent protein (GFP)-tagged ProSAP1/SHANK2 and ProSAP2/Shank3 deletion constructs in hippocampal neurons revealed that their postsynaptic localization relies on the integrity of the C-termini. The shortest construct that was perfectly targeted to synaptic sites included the last 417 amino acids of ProSAP1/SHANK2 and included the C-terminal sterile alpha motif (SAM) domain. Removal of 54 residues from the N-terminus of this construct resulted in a diffuse distribution in the cytoplasm. Altogether, our data delineate a hitherto unknown targeting signal in both ProSAP1/SHANK2 and ProSAP2/Shank3 and provide evidence for an implication of these proteins and their close homologue, Shank1, in distinct molecular pathways.
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c terminal synaptic targeting elements for postsynaptic density proteins prosap1 SHANK2 and prosap2 shank3
Journal of Neurochemistry, 2005Co-Authors: Tobias M. Boeckers, Christina Spilker, Thomas Liedtke, Thomas Dresbach, Jürgen Bockmann, Michael R. Kreutz, Eckart D GundelfingerAbstract:Synapses are specialized contact sites mediating communication between neurons. Synaptogenesis requires the specific assembly of protein clusters at both sides of the synaptic contact by mechanisms that are barely understood. We studied the synaptic targeting of multi-domain proteins of the ProSAP/Shank family thought to serve as master scaffolding molecules of the postsynaptic density. In contrast to Shank1, expression of green-fluorescent protein (GFP)-tagged ProSAP1/SHANK2 and ProSAP2/Shank3 deletion constructs in hippocampal neurons revealed that their postsynaptic localization relies on the integrity of the C-termini. The shortest construct that was perfectly targeted to synaptic sites included the last 417 amino acids of ProSAP1/SHANK2 and included the C-terminal sterile alpha motif (SAM) domain. Removal of 54 residues from the N-terminus of this construct resulted in a diffuse distribution in the cytoplasm. Altogether, our data delineate a hitherto unknown targeting signal in both ProSAP1/SHANK2 and ProSAP2/Shank3 and provide evidence for an implication of these proteins and their close homologue, Shank1, in distinct molecular pathways.
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the neuronal scaffold protein shank3 mediates signaling and biological function of the receptor tyrosine kinase ret in epithelial cells
Journal of Cell Biology, 2004Co-Authors: Gunnar Schuetz, Tobias M. Boeckers, Eckart D Gundelfinger, Marta Rosario, Jan Grimm, Walter BirchmeierAbstract:Shank proteins, initially also described as ProSAP proteins, are scaffolding adaptors that have been previously shown to integrate neurotransmitter receptors into the cortical cytoskeleton at postsynaptic densities. We show here that Shank proteins are also crucial in receptor tyrosine kinase signaling. The PDZ domain–containing Shank3 protein was found to represent a novel interaction partner of the receptor tyrosine kinase Ret, which binds specifically to a PDZ-binding motif present in the Ret9 but not in the Ret51 isoform. Furthermore, we show that Ret9 but not Ret51 induces epithelial cells to form branched tubular structures in three-dimensional cultures in a Shank3-dependent manner. Ret9 but not Ret51 has been previously shown to be required for kidney development. Shank3 protein mediates sustained Erk–MAPK and PI3K signaling, which is crucial for tubule formation, through recruitment of the adaptor protein Grb2. These results demonstrate that the Shank3 adaptor protein can mediate cellular signaling, and provide a molecular mechanism for the biological divergence between the Ret9 and Ret51 isoform.
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differential expression and dendritic transcript localization of shank family members identification of a dendritic targeting element in the 3 untranslated region of shank1 mrna
Molecular and Cellular Neuroscience, 2004Co-Authors: Tobias M Bockers, Mailin Seggerjunius, Peter Iglauer, Stefan Kindler, Jürgen Bockmann, Michael R. Kreutz, Dietmar Richter, Eckart D Gundelfinger, Hans Jurgen KreienkampAbstract:Abstract Shank proteins are scaffolding proteins in the postsynaptic density of excitatory synapses in the mammalian brain. In situ hybridization revealed that Shank1/SSTRIP and SHANK2/ProSAP1 mRNAs are widely expressed early in postnatal brain development whereas Shank3/ProSAP2 expression increases during postnatal development especially in the cerebellum and thalamus. Shank1 and Shank3 (but not SHANK2) mRNAs are present in the molecular layers of the hippocampus, consistent with a dendritic transcript localization. Shank1 and SHANK2 transcripts are detectable in the dendritic fields of Purkinje cells, whereas Shank3 mRNA is restricted to cerebellar granule cells. The appearance of dendritic Shank mRNAs in cerebellar Purkinje cells coincides with the onset of dendrite formation. Expression of reporter transcripts in hippocampal neurons identifies a 200-nucleotide dendritic targeting element (DTE) in the Shank1 mRNA. The widespread presence of Shank mRNAs in dendrites suggests a role for local synthesis of Shanks in response to stimuli that induce alterations in synaptic morphology.
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Differential expression and dendritic transcript localization of Shank family members: identification of a dendritic targeting element in the 3′ untranslated region of Shank1 mRNA
Molecular and Cellular Neuroscience, 2004Co-Authors: Tobias M Bockers, Peter Iglauer, Stefan Kindler, Mailin Segger-junius, Jürgen Bockmann, Michael R. Kreutz, Dietmar Richter, Eckart D Gundelfinger, Hans Jurgen KreienkampAbstract:Abstract Shank proteins are scaffolding proteins in the postsynaptic density of excitatory synapses in the mammalian brain. In situ hybridization revealed that Shank1/SSTRIP and SHANK2/ProSAP1 mRNAs are widely expressed early in postnatal brain development whereas Shank3/ProSAP2 expression increases during postnatal development especially in the cerebellum and thalamus. Shank1 and Shank3 (but not SHANK2) mRNAs are present in the molecular layers of the hippocampus, consistent with a dendritic transcript localization. Shank1 and SHANK2 transcripts are detectable in the dendritic fields of Purkinje cells, whereas Shank3 mRNA is restricted to cerebellar granule cells. The appearance of dendritic Shank mRNAs in cerebellar Purkinje cells coincides with the onset of dendrite formation. Expression of reporter transcripts in hippocampal neurons identifies a 200-nucleotide dendritic targeting element (DTE) in the Shank1 mRNA. The widespread presence of Shank mRNAs in dendrites suggests a role for local synthesis of Shanks in response to stimuli that induce alterations in synaptic morphology.
