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1.
Cell ; 186(8): 1689-1707, 2023 04 13.
Article in English | MEDLINE | ID: mdl-37059069

ABSTRACT

The nervous system governs both ontogeny and oncology. Regulating organogenesis during development, maintaining homeostasis, and promoting plasticity throughout life, the nervous system plays parallel roles in the regulation of cancers. Foundational discoveries have elucidated direct paracrine and electrochemical communication between neurons and cancer cells, as well as indirect interactions through neural effects on the immune system and stromal cells in the tumor microenvironment in a wide range of malignancies. Nervous system-cancer interactions can regulate oncogenesis, growth, invasion and metastatic spread, treatment resistance, stimulation of tumor-promoting inflammation, and impairment of anti-cancer immunity. Progress in cancer neuroscience may create an important new pillar of cancer therapy.


Subject(s)
Neoplasms , Neurosciences , Humans , Immune System , Neoplasms/pathology , Neurons/pathology , Tumor Microenvironment
2.
Cell ; 185(16): 2899-2917.e31, 2022 08 04.
Article in English | MEDLINE | ID: mdl-35914528

ABSTRACT

Glioblastomas are incurable tumors infiltrating the brain. A subpopulation of glioblastoma cells forms a functional and therapy-resistant tumor cell network interconnected by tumor microtubes (TMs). Other subpopulations appear unconnected, and their biological role remains unclear. Here, we demonstrate that whole-brain colonization is fueled by glioblastoma cells that lack connections with other tumor cells and astrocytes yet receive synaptic input from neurons. This subpopulation corresponds to neuronal and neural-progenitor-like tumor cell states, as defined by single-cell transcriptomics, both in mouse models and in the human disease. Tumor cell invasion resembled neuronal migration mechanisms and adopted a Lévy-like movement pattern of probing the environment. Neuronal activity induced complex calcium signals in glioblastoma cells followed by the de novo formation of TMs and increased invasion speed. Collectively, superimposing molecular and functional single-cell data revealed that neuronal mechanisms govern glioblastoma cell invasion on multiple levels. This explains how glioblastoma's dissemination and cellular heterogeneity are closely interlinked.


Subject(s)
Brain Neoplasms , Glioblastoma , Animals , Astrocytes/pathology , Brain/pathology , Brain Neoplasms/pathology , Glioblastoma/genetics , Glioblastoma/pathology , Humans , Mice , Neoplasm Invasiveness , Neurons/physiology
3.
Physiol Rev ; 102(1): 269-318, 2022 01 01.
Article in English | MEDLINE | ID: mdl-34727002

ABSTRACT

Chemical synapses are commonly known as a structurally and functionally highly diverse class of cell-cell contacts specialized to mediate communication between neurons. They represent the smallest "computational" unit of the brain and are typically divided into excitatory and inhibitory as well as modulatory categories. These categories are subdivided into diverse types, each representing a different structure-function repertoire that in turn are thought to endow neuronal networks with distinct computational properties. The diversity of structure and function found among a given category of synapses is referred to as heterogeneity. The main building blocks for this heterogeneity are synaptic vesicles, the active zone, the synaptic cleft, the postsynaptic density, and glial processes associated with the synapse. Each of these five structural modules entails a distinct repertoire of functions, and their combination specifies the range of functional heterogeneity at mammalian excitatory synapses, which are the focus of this review. We describe synapse heterogeneity that is manifested on different levels of complexity ranging from the cellular morphology of the pre- and postsynaptic cells toward the expression of different protein isoforms at individual release sites. We attempt to define the range of structural building blocks that are used to vary the basic functional repertoire of excitatory synaptic contacts and discuss sources and general mechanisms of synapse heterogeneity. Finally, we explore the possible impact of synapse heterogeneity on neuronal network function.


Subject(s)
Neuronal Plasticity/physiology , Synapses/physiology , Synaptic Transmission/physiology , Synaptic Vesicles/physiology , Animals , Glutamates/metabolism , Humans , Neurons/physiology
4.
Nature ; 613(7942): 179-186, 2023 01.
Article in English | MEDLINE | ID: mdl-36517594

ABSTRACT

Diffuse gliomas, particularly glioblastomas, are incurable brain tumours1. They are characterized by networks of interconnected brain tumour cells that communicate via Ca2+ transients2-6. However, the networks' architecture and communication strategy and how these influence tumour biology remain unknown. Here we describe how glioblastoma cell networks include a small, plastic population of highly active glioblastoma cells that display rhythmic Ca2+ oscillations and are particularly connected to others. Their autonomous periodic Ca2+ transients preceded Ca2+ transients of other network-connected cells, activating the frequency-dependent MAPK and NF-κB pathways. Mathematical network analysis revealed that glioblastoma network topology follows scale-free and small-world properties, with periodic tumour cells frequently located in network hubs. This network design enabled resistance against random damage but was vulnerable to losing its key hubs. Targeting of autonomous rhythmic activity by selective physical ablation of periodic tumour cells or by genetic or pharmacological interference with the potassium channel KCa3.1 (also known as IK1, SK4 or KCNN4) strongly compromised global network communication. This led to a marked reduction of tumour cell viability within the entire network, reduced tumour growth in mice and extended animal survival. The dependency of glioblastoma networks on periodic Ca2+ activity generates a vulnerability7 that can be exploited for the development of novel therapies, such as with KCa3.1-inhibiting drugs.


Subject(s)
Brain Neoplasms , Glioblastoma , Animals , Mice , Brain/metabolism , Brain/pathology , Brain Neoplasms/genetics , Brain Neoplasms/metabolism , Brain Neoplasms/pathology , Glioblastoma/genetics , Glioblastoma/metabolism , Glioblastoma/pathology , NF-kappa B/metabolism , MAP Kinase Signaling System , Calcium Signaling , Cell Death , Survival Analysis , Calcium/metabolism
5.
Physiol Rev ; 101(1): 213-258, 2021 01 01.
Article in English | MEDLINE | ID: mdl-32525759

ABSTRACT

Chronic, pathological pain remains a global health problem and a challenge to basic and clinical sciences. A major obstacle to preventing, treating, or reverting chronic pain has been that the nature of neural circuits underlying the diverse components of the complex, multidimensional experience of pain is not well understood. Moreover, chronic pain involves diverse maladaptive plasticity processes, which have not been decoded mechanistically in terms of involvement of specific circuits and cause-effect relationships. This review aims to discuss recent advances in our understanding of circuit connectivity in the mammalian brain at the level of regional contributions and specific cell types in acute and chronic pain. A major focus is placed on functional dissection of sub-neocortical brain circuits using optogenetics, chemogenetics, and imaging technological tools in rodent models with a view towards decoding sensory, affective, and motivational-cognitive dimensions of pain. The review summarizes recent breakthroughs and insights on structure-function properties in nociceptive circuits and higher order sub-neocortical modulatory circuits involved in aversion, learning, reward, and mood and their modulation by endogenous GABAergic inhibition, noradrenergic, cholinergic, dopaminergic, serotonergic, and peptidergic pathways. The knowledge of neural circuits and their dynamic regulation via functional and structural plasticity will be beneficial towards designing and improving targeted therapies.


Subject(s)
Acute Pain/physiopathology , Brain/physiopathology , Chronic Pain/physiopathology , Nerve Net/physiopathology , Animals , Humans , Neural Pathways , Neurotransmitter Agents , Signal Transduction/physiology
6.
Nature ; 606(7912): 137-145, 2022 06.
Article in English | MEDLINE | ID: mdl-35614217

ABSTRACT

Nerve injury leads to chronic pain and exaggerated sensitivity to gentle touch (allodynia) as well as a loss of sensation in the areas in which injured and non-injured nerves come together1-3. The mechanisms that disambiguate these mixed and paradoxical symptoms are unknown. Here we longitudinally and non-invasively imaged genetically labelled populations of fibres that sense noxious stimuli (nociceptors) and gentle touch (low-threshold afferents) peripherally in the skin for longer than 10 months after nerve injury, while simultaneously tracking pain-related behaviour in the same mice. Fully denervated areas of skin initially lost sensation, gradually recovered normal sensitivity and developed marked allodynia and aversion to gentle touch several months after injury. This reinnervation-induced neuropathic pain involved nociceptors that sprouted into denervated territories precisely reproducing the initial pattern of innervation, were guided by blood vessels and showed irregular terminal connectivity in the skin and lowered activation thresholds mimicking low-threshold afferents. By contrast, low-threshold afferents-which normally mediate touch sensation as well as allodynia in intact nerve territories after injury4-7-did not reinnervate, leading to an aberrant innervation of tactile end organs such as Meissner corpuscles with nociceptors alone. Genetic ablation of nociceptors fully abrogated reinnervation allodynia. Our results thus reveal the emergence of a form of chronic neuropathic pain that is driven by structural plasticity, abnormal terminal connectivity and malfunction of nociceptors during reinnervation, and provide a mechanistic framework for the paradoxical sensory manifestations that are observed clinically and can impose a heavy burden on patients.


Subject(s)
Hyperalgesia , Neuralgia , Nociceptors , Skin , Animals , Chronic Pain/physiopathology , Hyperalgesia/physiopathology , Mechanoreceptors/pathology , Mice , Neuralgia/physiopathology , Nociceptors/pathology , Skin/innervation , Skin/physiopathology
7.
PLoS Biol ; 21(11): e3002357, 2023 Nov.
Article in English | MEDLINE | ID: mdl-37943858

ABSTRACT

Comprehensive analysis of tissue cell type composition using microscopic techniques has primarily been confined to ex vivo approaches. Here, we introduce NuCLear (Nucleus-instructed tissue composition using deep learning), an approach combining in vivo two-photon imaging of histone 2B-eGFP-labeled cell nuclei with subsequent deep learning-based identification of cell types from structural features of the respective cell nuclei. Using NuCLear, we were able to classify almost all cells per imaging volume in the secondary motor cortex of the mouse brain (0.25 mm3 containing approximately 25,000 cells) and to identify their position in 3D space in a noninvasive manner using only a single label throughout multiple imaging sessions. Twelve weeks after baseline, cell numbers did not change yet astrocytic nuclei significantly decreased in size. NuCLear opens a window to study changes in relative density and location of different cell types in the brains of individual mice over extended time periods, enabling comprehensive studies of changes in cell type composition in physiological and pathophysiological conditions.


Subject(s)
Brain , Neural Networks, Computer , Mice , Animals , Brain/physiology , Diagnostic Imaging
8.
Nature ; 573(7775): 532-538, 2019 09.
Article in English | MEDLINE | ID: mdl-31534219

ABSTRACT

A network of communicating tumour cells that is connected by tumour microtubes mediates the progression of incurable gliomas. Moreover, neuronal activity can foster malignant behaviour of glioma cells by non-synaptic paracrine and autocrine mechanisms. Here we report a direct communication channel between neurons and glioma cells in different disease models and human tumours: functional bona fide chemical synapses between presynaptic neurons and postsynaptic glioma cells. These neurogliomal synapses show a typical synaptic ultrastructure, are located on tumour microtubes, and produce postsynaptic currents that are mediated by glutamate receptors of the AMPA subtype. Neuronal activity including epileptic conditions generates synchronised calcium transients in tumour-microtube-connected glioma networks. Glioma-cell-specific genetic perturbation of AMPA receptors reduces calcium-related invasiveness of tumour-microtube-positive tumour cells and glioma growth. Invasion and growth are also reduced by anaesthesia and the AMPA receptor antagonist perampanel, respectively. These findings reveal a biologically relevant direct synaptic communication between neurons and glioma cells with potential clinical implications.


Subject(s)
Brain Neoplasms/physiopathology , Disease Progression , Glioma/physiopathology , Synapses/pathology , Animals , Brain Neoplasms/ultrastructure , Disease Models, Animal , Glioma/ultrastructure , Humans , Mice , Microscopy, Electron, Transmission , Neurons/physiology , Receptors, AMPA/genetics , Receptors, AMPA/metabolism
9.
EMBO J ; 38(6)2019 03 15.
Article in English | MEDLINE | ID: mdl-30643018

ABSTRACT

Adult neurogenesis is involved in cognitive performance but studies that manipulated this process to improve brain function are scarce. Here, we characterized a genetic mouse model in which neural stem cells (NSC) of the subventricular zone (SVZ) were temporarily expanded by conditional expression of the cell cycle regulators Cdk4/cyclinD1, thus increasing neurogenesis. We found that supernumerary neurons matured and integrated in the olfactory bulb similarly to physiologically generated newborn neurons displaying a correct expression of molecular markers, morphology and electrophysiological activity. Olfactory performance upon increased neurogenesis was unchanged when mice were tested on relatively easy tasks using distinct odor stimuli. In contrast, intriguingly, increasing neurogenesis improved the discrimination ability of mice when challenged with a difficult task using mixtures of highly similar odorants. Together, our study provides a mammalian model to control the expansion of somatic stem cells that can in principle be applied to any tissue for basic research and models of therapy. By applying this to NSC of the SVZ, we highlighted the importance of adult neurogenesis to specifically improve performance in a challenging olfactory task.


Subject(s)
Discrimination Learning , Neural Stem Cells/physiology , Neurogenesis/physiology , Odorants/analysis , Olfactory Bulb/physiology , Animals , Cyclin D1/physiology , Cyclin-Dependent Kinase 4/physiology , Disease Models, Animal , Male , Mice , Mice, Transgenic , Neural Stem Cells/cytology , Neural Stem Cells/drug effects , Neurogenesis/drug effects , Olfactory Bulb/cytology , Olfactory Bulb/drug effects
10.
Mol Psychiatry ; 26(4): 1376-1398, 2021 04.
Article in English | MEDLINE | ID: mdl-31444474

ABSTRACT

Aberrant fear is a cornerstone of several psychiatric disorders. Consequently, there is large interest in elucidation of signaling mechanisms that link extracellular cues to changes in neuronal function and structure in brain pathways that are important in the generation and maintenance of fear memory and its behavioral expression. Members of the Plexin-B family of receptors for class 4 semaphorins play important roles in developmental plasticity of neurons, and their expression persists in some areas of the adult nervous system. Here, we aimed to elucidate the role of Semaphorin 4C (Sema4C) and its cognate receptor, Plexin-B2, in the expression of contextual and cued fear memory, setting a mechanistic focus on structural plasticity and exploration of contributing signaling pathways. We observed that Plexin-B2 and Sema4C are expressed in forebrain areas related to fear memory, such as the anterior cingulate cortex, amygdala and the hippocampus, and their expression is regulated by aversive stimuli that induce fear memory. By generating forebrain-specific Plexin-B2 knockout mice and analyzing fear-related behaviors, we demonstrate that Sema4C-PlexinB2 signaling plays a crucial functional role in the recent and remote recall of fear memory. Detailed neuronal morphological analyses revealed that Sema4C-PlexinB2 signaling largely mediates fear-induced structural plasticity by enhancing dendritic ramifications and modulating synaptic density in the adult hippocampus. Analyses on signaling-related mutant mice showed that these functions are mediated by PlexinB2-dependent RhoA activation. These results deliver important insights into the mechanistic understanding of maladaptive plasticity in fear circuits and have implications for novel therapeutic strategies against fear-related disorders.


Subject(s)
Fear , Memory , Nerve Tissue Proteins , Semaphorins , Animals , Cell Adhesion Molecules , Mice , Nerve Tissue Proteins/genetics , Neurons , Semaphorins/genetics
11.
Cell Tissue Res ; 383(1): 495-506, 2021 Jan.
Article in English | MEDLINE | ID: mdl-33404844

ABSTRACT

The role of granule cells in olfactory processing is surrounded by several enigmatic observations, such as the purpose of reciprocal spines and the mechanisms for GABA release, the apparently low firing activity and recurrent inhibitory drive of granule cells, the missing proof for functional reciprocal connectivity, and the apparently negligible contribution to lateral inhibition. Here, we summarize recent results with regard to both the mechanisms of GABA release and the behavioral relevance of granule cell activity during odor discrimination. We outline a novel hypothesis that has the potential to resolve most of these enigmas and allows further predictions on the function of granule cells in odor processing. Briefly, recent findings imply that GABA release from the reciprocal spine requires a local spine action potential and the cooperative action of NMDA receptors and high voltage-activated Ca2+ channels. Thus, lateral inhibition is conditional on activity in the principal neurons connected to a granule cell and tightly intertwined with recurrent inhibition. This notion allows us to infer that lateral inhibition between principal neurons occurs "on demand," i.e., selectively on coactive mitral and tufted cells, and thus can provide directed, dynamically switched lateral inhibition in a sensory system with 1000 input channels organized in glomerular columns. The mechanistic underpinnings of this hypothesis concur with findings from odor discrimination behavior in mice with synaptic proteins deleted in granule cells. In summary, our hypothesis explains the unusual microcircuit of the granule cell reciprocal spine as a means of olfactory combinatorial coding.


Subject(s)
Odorants , Olfactory Bulb/physiology , Animals
12.
PLoS Biol ; 16(8): e2003816, 2018 08.
Article in English | MEDLINE | ID: mdl-30125271

ABSTRACT

Dendrodendritic synaptic interactions between olfactory bulb mitral and granule cells represent a key neuronal mechanism of odor discrimination. Dendritic release of gamma-aminobutyric acid (GABA) from granule cells contributes to stimulus-dependent, rapid, and accurate odor discrimination, yet the physiological mechanisms governing this release and its behavioral relevance are unknown. Here, we show that granule cells express the voltage-gated sodium channel α-subunit NaV1.2 in clusters distributed throughout the cell surface including dendritic spines. Deletion of NaV1.2 in granule cells abolished spiking and GABA release as well as inhibition of synaptically connected mitral cells (MCs). As a consequence, mice required more time to discriminate highly similar odorant mixtures, while odor discrimination learning remained unaffected. In conclusion, we show that expression of NaV1.2 in granule cells is crucial for physiological dendritic GABA release and rapid discrimination of similar odorants with high accuracy. Hence, our data indicate that neurotransmitter-releasing dendritic spines function just like axon terminals.


Subject(s)
Axons/physiology , Dendrites/physiology , NAV1.2 Voltage-Gated Sodium Channel/genetics , Odorants/analysis , Olfactory Bulb/physiology , Olfactory Perception/physiology , Action Potentials/physiology , Animals , Axons/ultrastructure , Dendrites/ultrastructure , Discrimination Learning/physiology , Gene Expression , Mice , Mice, Inbred C57BL , Microtomy , NAV1.2 Voltage-Gated Sodium Channel/metabolism , Neurotransmitter Agents/metabolism , Olfactory Bulb/cytology , RNA, Small Interfering/genetics , RNA, Small Interfering/metabolism , Sensory Receptor Cells/physiology , Sensory Receptor Cells/ultrastructure , Synapses/physiology , Synaptic Transmission/physiology , Tissue Culture Techniques , gamma-Aminobutyric Acid/metabolism
13.
Nature ; 528(7580): 93-8, 2015 Dec 03.
Article in English | MEDLINE | ID: mdl-26536111

ABSTRACT

Astrocytic brain tumours, including glioblastomas, are incurable neoplasms characterized by diffusely infiltrative growth. Here we show that many tumour cells in astrocytomas extend ultra-long membrane protrusions, and use these distinct tumour microtubes as routes for brain invasion, proliferation, and to interconnect over long distances. The resulting network allows multicellular communication through microtube-associated gap junctions. When damage to the network occurred, tumour microtubes were used for repair. Moreover, the microtube-connected astrocytoma cells, but not those remaining unconnected throughout tumour progression, were protected from cell death inflicted by radiotherapy. The neuronal growth-associated protein 43 was important for microtube formation and function, and drove microtube-dependent tumour cell invasion, proliferation, interconnection, and radioresistance. Oligodendroglial brain tumours were deficient in this mechanism. In summary, astrocytomas can develop functional multicellular network structures. Disconnection of astrocytoma cells by targeting their tumour microtubes emerges as a new principle to reduce the treatment resistance of this disease.


Subject(s)
Astrocytoma/pathology , Brain Neoplasms/pathology , Gap Junctions/metabolism , Animals , Astrocytoma/metabolism , Astrocytoma/radiotherapy , Brain Neoplasms/metabolism , Brain Neoplasms/radiotherapy , Cell Communication/radiation effects , Cell Death/radiation effects , Cell Proliferation/radiation effects , Cell Surface Extensions/metabolism , Cell Surface Extensions/radiation effects , Cell Survival/radiation effects , Connexin 43/metabolism , Disease Progression , GAP-43 Protein/metabolism , Gap Junctions/radiation effects , Glioma/metabolism , Glioma/pathology , Glioma/radiotherapy , Humans , Male , Mice , Mice, Nude , Neoplasm Invasiveness , Radiation Tolerance/drug effects
14.
Proc Natl Acad Sci U S A ; 115(10): E2246-E2253, 2018 03 06.
Article in English | MEDLINE | ID: mdl-29463719

ABSTRACT

The centrosome linker proteins C-Nap1, rootletin, and CEP68 connect the two centrosomes of a cell during interphase into one microtubule-organizing center. This coupling is important for cell migration, cilia formation, and timing of mitotic spindle formation. Very little is known about the structure of the centrosome linker. Here, we used stimulated emission depletion (STED) microscopy to show that each C-Nap1 ring at the proximal end of the two centrioles organizes a rootletin ring and, in addition, multiple rootletin/CEP68 fibers. Rootletin/CEP68 fibers originating from the two centrosomes form a web-like, interdigitating network, explaining the flexible nature of the centrosome linker. The rootletin/CEP68 filaments are repetitive and highly ordered. Staggered rootletin molecules (N-to-N and C-to-C) within the filaments are 75 nm apart. Rootletin binds CEP68 via its C-terminal spectrin repeat-containing region in 75-nm intervals. The N-to-C distance of two rootletin molecules is ∼35 to 40 nm, leading to an estimated minimal rootletin length of ∼110 nm. CEP68 is important in forming rootletin filaments that branch off centrioles and to modulate the thickness of rootletin fibers. Thus, the centrosome linker consists of a vast network of repeating rootletin units with C-Nap1 as ring organizer and CEP68 as filament modulator.


Subject(s)
Centrioles/metabolism , Centrosome/metabolism , Cytoskeletal Proteins/metabolism , Microtubule-Associated Proteins/metabolism , Proteins/metabolism , Amino Acid Motifs , Centrioles/chemistry , Centrioles/genetics , Centrosome/chemistry , Cytoskeletal Proteins/chemistry , Cytoskeletal Proteins/genetics , HeLa Cells , Humans , Interphase , Microscopy , Microtubule-Associated Proteins/chemistry , Microtubule-Associated Proteins/genetics , Protein Binding , Proteins/chemistry , Proteins/genetics , tRNA Methyltransferases
15.
J Neurosci ; 38(14): 3507-3519, 2018 04 04.
Article in English | MEDLINE | ID: mdl-29483279

ABSTRACT

Cue-reward associations form distinct memories that can drive appetitive behaviors and are involved in craving for both drugs and natural rewards. Distinct sets of neurons, so-called neuronal ensembles, in the infralimbic area (IL) of the medial prefrontal cortex (mPFC) play a key role in alcohol seeking. Whether this ensemble is specific for alcohol or controls reward seeking in general remains unclear. Here, we compared IL ensembles formed upon recall of drug (alcohol) or natural reward (saccharin) memories in male Wistar rats. Using an experimental framework that allows identification of two distinct reward-associated ensembles within the same animal, we found that cue-induced seeking of either alcohol or saccharin activated ensembles of similar size and organization, whereby these ensembles consist of largely overlapping neuronal populations. Thus, the IL seems to act as a general integration hub for reward seeking behavior, but also contains subsets of neurons that encode for the different rewards.SIGNIFICANCE STATEMENT Cue-reward associations form distinct memories that can act as drivers of appetitive behaviors and are involved in craving for natural rewards as well as for drugs. Distinct sets of neurons, so-called neuronal ensembles, in the infralimbic area of the mPFC play a key role in cue-triggered reward seeking. However, it is unclear whether these ensembles act as broadly tuned controllers of approach behavior or represent the learned associations between specific cues and rewards. Using an experimental framework that allows identification of two distinct reward-associated ensembles within the same animal we find largely overlapping neuronal populations. Repeated activation by two distinct events could reflect the linking of the two memory traces within the same neuron.


Subject(s)
Choice Behavior , Drug-Seeking Behavior , Prefrontal Cortex/physiology , Reward , Animals , Male , Neurons/physiology , Prefrontal Cortex/cytology , Rats , Rats, Wistar
16.
Nat Methods ; 13(4): 319-21, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26928761

ABSTRACT

Super-resolution fluorescence microscopy has become a widely used tool in many areas of research. However, designing and validating super-resolution experiments to address a research question in a technically feasible and scientifically rigorous manner remains a fundamental challenge. We developed SuReSim, a software tool that simulates localization data of arbitrary three-dimensional structures represented by ground truth models, allowing users to systematically explore how changing experimental parameters can affect potential imaging outcomes.


Subject(s)
Image Processing, Computer-Assisted/methods , Imaging, Three-Dimensional/methods , Microscopy, Fluorescence/methods , Software , Synaptic Vesicles/ultrastructure , Algorithms , Computational Biology , Humans , Microscopy, Fluorescence/instrumentation
17.
J Neurosci ; 37(35): 8534-8548, 2017 08 30.
Article in English | MEDLINE | ID: mdl-28765333

ABSTRACT

Phosphorylation of AMPA receptor GluA1 plays important roles in synaptic potentiation. Most previous studies have been performed in the hippocampus, while the roles of GluA1 phosphorylation in the cortex remain unknown. Here we investigated the involvement of the phosphorylation of GluA1 in the LTP in the anterior cingulate cortex (ACC) using mice with a GluA1 knock-in mutation at the PKA phosphorylation site serine 845 (s845A) or CaMKII/PKC phosphorylation site serine 831 (s831A). The network LTP, which is constructed by multiple recordings of LTP at different locations within the ACC, was also investigated. We found that the expression of LTP and network LTP was significantly impaired in the s845A mice, but not in the s831A mice. By contrast, basal synaptic transmission and NMDA receptor-mediated responses were not affected. Furthermore, to uncover potential information under the current acquired data, a new method for reconstruction and better visualization of the signals was developed to observe the spatial localizations and dynamic temporal changes of fEPSP signals and multiple LTP responses within the ACC circuit. Our results provide strong evidence that PKA phosphorylation of the GluA1 is important for the network LTP expression in the ACC.SIGNIFICANCE STATEMENT Previous studies have shown that PKA and PKC phosphorylation of AMPA receptor GluA1 plays critical roles in LTP in the hippocampus, while the roles of GluA1 phosphorylation in the cortex remain unknown. In the present study, by combining a 64-channel multielectrode system and a novel analysis and visualization method, we observed the accurate spatial localization and dynamic temporal changes of network fEPSP signals and LTP responses within the ACC circuit and found that PKA phosphorylation, but not PKC phosphorylation, of the GluA1 is required for LTP in the ACC.


Subject(s)
Cyclic AMP-Dependent Protein Kinases/metabolism , Gyrus Cinguli/physiology , Nerve Net/physiology , Receptors, AMPA/metabolism , Signal Transduction/physiology , Animals , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , Phosphorylation , Protein Kinase C/metabolism
18.
J Physiol ; 596(8): 1485-1499, 2018 04 15.
Article in English | MEDLINE | ID: mdl-29194628

ABSTRACT

KEY POINTS: Bassoon and Piccolo do not mediate basal synaptic vesicle release at a high-frequency synapse. Knockdown of Bassoon increases short-term depression at the calyx of Held. Both Bassoon and Piccolo have shared functions in synaptic vesicle replenishment during high-frequency synaptic transmission. Piccolo organizes the readily releasable pool of synaptic vesicles. It safeguards a fraction of them to be not immediately available for action potential-induced release. This enables the synapse to sustain high-frequency synaptic transmission over long periods. ABSTRACT: Synaptic vesicles (SVs) are released at the active zone (AZ), a specialized region of the presynaptic plasma membrane organized by a highly interconnected network of multidomain proteins called the cytomatrix of the active zone (CAZ). Two core components of the CAZ are the large, highly homologous scaffolding proteins Bassoon and Piccolo, whose function is not well understood. To investigate their role in synaptic transmission, we established the small hairpin RNA (shRNA)-mediated in vivo knockdown (KD) of Bassoon and Piccolo at the rat calyx of Held synapse. KD of Bassoon and Piccolo, separately or simultaneously, did not affect basic SV release. However, short-term depression (STD) was prominently increased by the KD of Bassoon, whereas KD of Piccolo only had a minor effect. The observed alterations in STD were readily explained by reduced SV replenishment in synapses deficient in either of the proteins. Thus, the regulation of SV refilling during ongoing synaptic activity is a shared function of Bassoon and Piccolo, although Bassoon appears to be more efficient. Moreover, we observed the recruitment of slowly-releasing SVs of the readily-releasable pool (RRP), which are normally not available for action potential-induced release, during high-frequency stimulation in Piccolo-deficient calyces. Therefore, the results obtained in the present study suggest a novel and specific role for Piccolo in the organization of the subpools of the RRP.


Subject(s)
Cytoskeletal Proteins/metabolism , Neuropeptides/metabolism , Synapses/metabolism , Synaptic Potentials , Synaptic Vesicles/metabolism , Animals , Cytoskeletal Proteins/genetics , Female , Male , Nerve Tissue Proteins/genetics , Nerve Tissue Proteins/metabolism , Neuropeptides/genetics , Rats , Rats, Sprague-Dawley , Synapses/physiology , Trapezoid Body/cytology , Trapezoid Body/metabolism
19.
J Physiol ; 596(16): 3759-3773, 2018 08.
Article in English | MEDLINE | ID: mdl-29873393

ABSTRACT

KEY POINTS: Despite their immense physiological and pathophysiological importance, we know very little about the biology of dense core vesicle (DCV) trafficking in the intact mammalian brain. DCVs are transported at similar average speeds in the anaesthetized and awake mouse brain compared to neurons in culture, yet maximal speed and pausing fraction of transport were higher. Microtubule plus (+)-end extension imaging visualized microtubular growth at 0.12 µm/s and revealed that DCVs were transported faster in the anterograde direction. DCV transport slowed down upon presynaptic bouton approach, possibly promoting synaptic localization and cargo release. Our work provides a basis to extrapolate DCV transport properties determined in cultured neurons to the intact mouse brain and reveals novel features such as slowing upon bouton approach and brain state-dependent trafficking directionality. ABSTRACT: Neuronal dense core vesicles (DCVs) transport many cargo molecules like neuropeptides and neurotrophins to their release sites in dendrites or axons. The transport properties of DCVs in axons of the intact mammalian brain are unknown. We used viral expression of a DCV cargo reporter (NPY-Venus/Cherry) in the thalamus and two-photon in vivo imaging to visualize axonal DCV trafficking in thalamocortical projections of anaesthetized and awake mice. We found an average speed of 1 µm/s, maximal speeds of up to 5 µm/s and a pausing fraction of ∼11%. Directionality of transport differed between anaesthetized and awake mice. In vivo microtubule +-end extension imaging using MACF18-GFP revealed microtubular growth at 0.12 µm/s and provided positive identification of antero- and retrograde axonal transport. Consistent with previous reports, anterograde transport was faster (∼2.1 µm/s) than retrograde transport (∼1.4 µm/s). In summary, DCVs are transported with faster maximal speeds and lower pausing fraction in vivo compared to previous results obtained in vitro. Finally, we found that DCVs slowed down upon presynaptic bouton approach. We propose that this mechanism promotes synaptic localization and cargo release.


Subject(s)
Anesthesia , Axonal Transport , Axons/physiology , Secretory Vesicles/physiology , Synapses/physiology , Synaptic Transmission , Wakefulness , Animals , Axons/drug effects , Male , Mice , Mice, Inbred C57BL , Microtubules/physiology , Neurons/cytology , Neurons/drug effects , Neurons/physiology , Neuropeptides/metabolism , Presynaptic Terminals/drug effects , Presynaptic Terminals/physiology , Secretory Vesicles/drug effects , Somatosensory Cortex/cytology , Somatosensory Cortex/drug effects , Somatosensory Cortex/physiology , Synapses/drug effects , Thalamus/cytology , Thalamus/drug effects , Thalamus/physiology
20.
Eur Radiol ; 28(7): 2838-2844, 2018 Jul.
Article in English | MEDLINE | ID: mdl-29383525

ABSTRACT

OBJECTIVES: To establish contrast-enhanced (CE) cadaver-specific post-mortem computed tomography (PMCT) in first-year gross anatomy teaching and quantitatively evaluate its learning benefit. METHODS: 132 first-year medical students were included in this IRB-approved study and randomly assigned to an intervention group (n=59) provided with continuous access to CE and non-enhanced (NE) cadaver-specific PMCT-scans during the first-semester gross anatomy course, and a control group (n=73) that had only NE cadaver-specific PMCT data available. Four multiple-choice tests were carried out (15 questions each) subsequent to completion of the corresponding anatomy module: Head and neck anatomy, extremities, thorax, and abdomen. Median test results were compared in each module between the groups using the Wilcoxon rank-sum test. Additionally, participants of the intervention group answered a 15-item feedback-questionnaire. RESULTS: The intervention group achieved significantly higher test scores in head and neck anatomy (median=12.0, IQR=10.0-13.0) versus the control group (median=10.5, IQR=9.0-12.0) (p<0.01). There were no significant differences in the comparison of other modules. CEPMCT was highly appreciated by undergraduate medical students. CONCLUSIONS: The incorporation of contrast-enhanced cadaver-specific PMCT-scans in gross anatomy teaching was proven to be feasible in the framework of the medical curriculum and significantly improved the students' learning performance in head and neck anatomy. KEY POINTS: • Cadaver-specific contrast-enhanced post-mortem CT (CEPMCT) is feasible in the medical curriculum. • CEPMCT yields significantly improved learning performance in head and neck anatomy (p<0.01). • CEPMCT is highly appreciated by medical students and used in tutor- or self-guided modes.


Subject(s)
Anatomy/education , Education, Medical, Undergraduate/methods , Head/anatomy & histology , Neck/anatomy & histology , Teaching , Tomography, X-Ray Computed/methods , Autopsy/methods , Cadaver , Clinical Competence/standards , Contrast Media , Curriculum , Educational Measurement/methods , Feasibility Studies , Humans , Learning , Prospective Studies , Students, Medical , Surveys and Questionnaires
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