| 1. |
- Spelat, R., et al.
(författare)
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Metabolic reprogramming and membrane glycan remodeling as potential drivers of zebrafish heart regeneration
- 2022
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- The ability of the zebrafish heart to regenerate following injury makes it a valuable model to deduce why this capability in mammals is limited to early neonatal stages. Although metabolic reprogramming and glycosylation remodeling have emerged as key aspects in many biological processes, how they may trigger a cardiac regenerative response in zebrafish is still a crucial question. Here, by using an up-to-date panel of transcriptomic, proteomic and glycomic approaches, we identify a metabolic switch from mitochondrial oxidative phosphorylation to glycolysis associated with membrane glycosylation remodeling during heart regeneration. Importantly, we establish the N- and O-linked glycan structural repertoire of the regenerating zebrafish heart, and link alterations in both sialylation and high mannose structures across the phases of regeneration. Our results show that metabolic reprogramming and glycan structural remodeling are potential drivers of tissue regeneration after cardiac injury, providing the biological rationale to develop novel therapeutics to elicit heart regeneration in mammals.
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| 2. |
- Floriddia, Elisa M., et al.
(författare)
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Distinct oligodendrocyte populations have spatial preference and different responses to spinal cord injury
- 2020
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Mature oligodendrocytes (MOLs) show transcriptional heterogeneity, the functional consequences of which are unclear. MOL heterogeneity might correlate with the local environment or their interactions with different neuron types. Here, we show that distinct MOL populations have spatial preference in the mammalian central nervous system (CNS). We found that MOL type 2 (MOL2) is enriched in the spinal cord when compared to the brain, while MOL types 5 and 6 (MOL5/6) increase their contribution to the OL lineage with age in all analyzed regions. MOL2 and MOL5/6 also have distinct spatial preference in the spinal cord regions where motor and sensory tracts run. OL progenitor cells (OPCs) are not specified into distinct MOL populations during development, excluding a major contribution of OPC intrinsic mechanisms determining MOL heterogeneity. In disease, MOL2 and MOL5/6 present different susceptibility during the chronic phase following traumatic spinal cord injury. Our results demonstrate that the distinct MOL populations have different spatial preference and different responses to disease.
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| 3. |
- Ciralli, Barbara, et al.
(författare)
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Unraveling the role of Slc10a4 in auditory processing and sensory motor gating : Implications for neuropsychiatric disorders?
- 2024
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Ingår i: Progress in Neuro-psychopharmacology and Biological Psychiatry. - : Elsevier. - 0278-5846 .- 1878-4216. ; 131
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundPsychiatric disorders, such as schizophrenia, are complex and challenging to study, partly due to the lack of suitable animal models. However, the absence of the Slc10a4 gene, which codes for a monoaminergic and cholinergic associated vesicular transporter protein, in knockout mice (Slc10a4−/−), leads to the accumulation of extracellular dopamine. A major challenge for studying schizophrenia is the lack of suitable animal models that accurately represent the disorder. We sought to overcome this challenge by using Slc10a4−/− mice as a potential model, considering their altered dopamine levels. This makes them a potential animal model for schizophrenia, a disorder known to be associated with altered dopamine signaling in the brain.MethodsThe locomotion, auditory sensory filtering and prepulse inhibition (PPI) of Slc10a4−/− mice were quantified and compared to wildtype (WT) littermates. Intrahippocampal electrodes were used to record auditory event-related potentials (aERPs) for quantifying sensory filtering in response to paired-clicks. The channel above aERPs phase reversal was chosen for reliably comparing results between animals, and aERPs amplitude and latency of click responses were quantified. WT and Slc10a4−/− mice were also administered subanesthetic doses of ketamine to provoke psychomimetic behavior.ResultsBaseline locomotion during auditory stimulation was similar between Slc10a4−/− mice and WT littermates. In WT animals, normal auditory processing was observed after i.p saline injections, and it was maintained under the influence of 5 mg/kg ketamine, but disrupted by 20 mg/kg ketamine. On the other hand, Slc10a4−/− mice did not show significant differences between N40 S1 and S2 amplitude responses in saline or low dose ketamine treatment. Auditory gating was considered preserved since the second N40 peak was consistently suppressed, but with increased latency. The P80 component showed higher amplitude, with shorter S2 latency under saline and 5 mg/kg ketamine treatment in Slc10a4−/− mice, which was not observed in WT littermates. Prepulse inhibition was also decreased in Slc10a4−/− mice when the longer interstimulus interval of 100 ms was applied, compared to WT littermates.ConclusionThe Slc10a4−/− mice responses indicate that cholinergic and monoaminergic systems participate in the PPI magnitude, in the temporal coding (response latency) of the auditory sensory gating component N40, and in the amplitude of aERPs P80 component. These results suggest that Slc10a4−/− mice can be considered as potential models for neuropsychiatric conditions.
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| 4. |
- Enjin, Anders, et al.
(författare)
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Developmental disruption of recurrent inhibitory feedback results in compensatory adaptation in the Renshaw cell-motor neuron circuit
- 2017
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Ingår i: Journal of Neuroscience. - 0270-6474 .- 1529-2401. ; 37:23, s. 5634-5647
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Tidskriftsartikel (refereegranskat)abstract
- When activating muscles, motor neurons in the spinal cord also activate Renshaw cells, which provide recurrent inhibitory feedback to the motor neurons. The tight coupling with motor neurons suggests that Renshaw cells have an integral role in movement, a role that is yet to be elucidated. Here we used the selective expression of the nicotinic cholinergic receptor α2 (Chrna2) in mice to genetically target the vesicular inhibitory amino acid transporter (VIAAT) in Renshaw cells. Loss of VIAAT from Chrna2Cre-expressing Renshaw cells did not impact any aspect of drug-induced fictive locomotion in the neonatal mouse or change gait, motor coordination, or grip strength in adult mice of both sexes. However, motor neurons from neonatal mice lacking VIAAT in Renshaw cells received spontaneous inhibitory synaptic input with a reduced frequency, showed lower input resistance, and had an increased number of proprioceptive glutamatergic and calbindin-labeled putative Renshaw cell synapses on their soma and proximal dendrites. Concomitantly, Renshaw cells developed with increased excitability and a normal number of cholinergic motor neuron synapses, indicating a compensatory mechanism within the recurrent inhibitory feedback circuit. Our data suggest an integral role for Renshaw cell signaling in shaping the excitability and synaptic input to motor neurons.
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| 5. |
- Gyllborg, Daniel, et al.
(författare)
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Hybridization-based in situ sequencing (HybISS) for spatially resolved transcriptomics in human and mouse brain tissue
- 2020
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Ingår i: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 48:19
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Tidskriftsartikel (refereegranskat)abstract
- Visualization of the transcriptome in situ has proven to be a valuable tool in exploring single-cell RNA-sequencing data, providing an additional spatial dimension to investigate multiplexed gene expression, cell types, disease architecture or even data driven discoveries. In situ sequencing (ISS) method based on padlock probes and rolling circle amplification has been used to spatially resolve gene transcripts in tissue sections of various origins. Here, we describe the next iteration of ISS, HybISS, hybridization-based in situ sequencing. Modifications in probe design allows for a new barcoding system via sequence-by-hybridization chemistry for improved spatial detection of RNA transcripts. Due to the amplification of probes, amplicons can be visualized with standard epifluorescence microscopes for high-throughput efficiency and the new sequencing chemistry removes limitations bound by sequence-by-ligation chemistry of ISS. HybISS design allows for increased flexibility and multiplexing, increased signal-to-noise, all without compromising throughput efficiency of imaging large fields of view. Moreover, the current protocol is demonstrated to work on human brain tissue samples, a source that has proven to be difficult to work with image-based spatial analysis techniques. Overall, HybISS technology works as a targeted amplification detection method for improved spatial transcriptomic visualization, and importantly, with an ease of implementation.
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| 6. |
- Hilscher, Markus M., et al.
(författare)
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Chrna2-Martinotti Cells Synchronize Layer 5 Type A Pyramidal Cells via Rebound Excitation
- 2017
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Ingår i: PLoS biology. - : PUBLIC LIBRARY SCIENCE. - 1544-9173 .- 1545-7885. ; 15:2
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Tidskriftsartikel (refereegranskat)abstract
- Martinotti cells are the most prominent distal dendrite-targeting interneurons in the cortex, but their role in controlling pyramidal cell ( PC) activity is largely unknown. Here, we show that the nicotinic acetylcholine receptor alpha 2 subunit (Chrna2) specifically marks layer 5 (L5) Martinotti cells projecting to layer 1. Furthermore, we confirm that Chrna2-expressing Martinotti cells selectively target L5 thick-tufted type A PCs but not thin-tufted type B PCs. Using optogenetic activation and inhibition, we demonstrate how Chrna2-Martinotti cells robustly reset and synchronize type A PCs via slow rhythmic burst activity and rebound excitation. Moreover, using optical feedback inhibition, in which PC spikes controlled the firing of surrounding Chrna2-Martinotti cells, we found that neighboring PC spike trains became synchronized by Martinotti cell inhibition. Together, our results show that L5 Martinotti cells participate in defined cortical circuits and can synchronize PCs in a frequency-dependent manner. These findings suggest that Martinotti cells are pivotal for coordinated PC activity, which is involved in cortical information processing and cognitive control.
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| 7. |
- Hilscher, Markus M, et al.
(författare)
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Chrna2-OLM interneurons display different membrane properties and h-current magnitude depending on dorsoventral location
- 2019
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Ingår i: Hippocampus. - : Wiley. - 1050-9631 .- 1098-1063. ; 29:12, s. 1224-1237
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Tidskriftsartikel (refereegranskat)abstract
- The hippocampus is an extended structure displaying heterogeneous anatomical cell layers along its dorsoventral axis. It is known that dorsal and ventral regions show different integrity when it comes to functionality, innervation, gene expression, and pyramidal cell properties. Still, whether hippocampal interneurons exhibit different properties along the dorsoventral axis is not known. Here, we report electrophysiological properties of dorsal and ventral oriens lacunosum moleculare (OLM) cells from coronal sections of the Chrna2-cre mouse line. We found dorsal OLM cells to exhibit a significantly more depolarized resting membrane potential compared to ventral OLM cells, while action potential properties were similar between the two groups. We found ventral OLM cells to show a higher initial firing frequency in response to depolarizing current injections but also to exhibit a higher spike-frequency adaptation than dorsal OLM cells. Additionally, dorsal OLM cells displayed large membrane sags in response to negative current injections correlating with our results showing that dorsal OLM cells have more hyperpolarization-activated current (I-h) compared to ventral OLM cells. Immunohistochemical examination indicates the h-current to correspond to hyperpolarization-activated cyclic nucleotide-gated subunit 2 (HCN2) channels. Computational studies suggest that I-h in OLM cells is essential for theta oscillations in hippocampal circuits, and here we found dorsal OLM cells to present a higher membrane resonance frequency than ventral OLM cells. Thus, our results highlight regional differences in membrane properties between dorsal and ventral OLM cells allowing this interneuron to differently participate in the generation of hippocampal theta rhythms depending on spatial location along the dorsoventral axis of the hippocampus.
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| 8. |
- Hilscher, Markus M., et al.
(författare)
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Spatial and temporal heterogeneity in the lineage progression of fine oligodendrocyte subtypes
- 2022
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Ingår i: BMC Biology. - : Springer Science and Business Media LLC. - 1741-7007. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Oligodendrocytes are glial cells that support and insulate axons in the central nervous system through the production of myelin. Oligodendrocytes arise throughout embryonic and early postnatal development from oligodendrocyte precursor cells (OPCs), and recent work demonstrated that they are a transcriptional heterogeneous cell population, but the regional and functional implications of this heterogeneity are less clear. Here, we apply in situ sequencing (ISS) to simultaneously probe the expression of 124 marker genes of distinct oligodendrocyte populations, providing comprehensive maps of the corpus callosum, cingulate, motor, and somatosensory cortex in the brain, as well as gray matter (GM) and white matter (WM) regions in the spinal cord, at postnatal (P10), juvenile (P20), and young adult (P60) stages. We systematically compare the abundances of these populations and investigate the neighboring preference of distinct oligodendrocyte populations.Results: We observed that oligodendrocyte lineage progression is more advanced in the juvenile spinal cord compared to the brain, corroborating with previous studies. We found myelination still ongoing in the adult corpus callosum while it was more advanced in the cortex. Interestingly, we also observed a lateral-to-medial gradient of oligodendrocyte lineage progression in the juvenile cortex, which could be linked to arealization, as well as a deep-to-superficial gradient with mature oligodendrocytes preferentially accumulating in the deeper layers of the cortex. The ISS experiments also exposed differences in abundances and population dynamics over time between GM and WM regions in the brain and spinal cord, indicating regional differences within GM and WM, and we found that neighboring preferences of some oligodendroglia populations are altered from the juvenile to the adult CNS.Conclusions: Overall, our ISS experiments reveal spatial heterogeneity of oligodendrocyte lineage progression in the brain and spinal cord and uncover differences in the timing of oligodendrocyte differentiation and myelination, which could be relevant to further investigate functional heterogeneity of oligodendroglia, especially in the context of injury or disease.
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| 9. |
- Hilscher, Markus M., et al.
(författare)
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Synchronization through nonreciprocal connections in a hybrid hippocampus microcircuit
- 2013
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Ingår i: Frontiers in Neural Circuits. - : Frontiers Media SA. - 1662-5110. ; 7, s. 120-
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Tidskriftsartikel (refereegranskat)abstract
- Synchronization among neurons is thought to arise from the interplay between excitation and inhibition; however, the connectivity rules that contribute to synchronization are still unknown. We studied these issues in hippocampal CA1 microcircuits using paired patch clamp recordings and real time computing. By virtually connecting a model interneuron with two pyramidal cells (PCs), we were able to test the importance of connectivity in synchronizing pyramidal cell activity. Our results show that a circuit with a nonreciprocal connection between pyramidal cells and no feedback from PCs to the virtual interneuron produced the greatest level of synchronization and mutual information between PC spiking activity. Moreover, we investigated the role of intrinsic membrane properties contributing to synchronization where the application of a specific ion channel blocker, ZD7288 dramatically impaired PC synchronization. Additionally, background synaptic activity, in particular arising from NMDA receptors, has a large impact on the synchrony observed in the aforementioned circuit. Our results give new insights to the basic connection paradigms of microcircuits that lead to coordination and the formation of assemblies.
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| 10. |
- Hilscher, Markus M., 1987-, et al.
(författare)
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The alpha2 nicotinic acetylcholine receptor, a subunit with unique and selective expression in inhibitory interneurons associated with principal cells
- 2023
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Ingår i: Pharmacological Research. - : Elsevier. - 1043-6618 .- 1096-1186. ; 196
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Tidskriftsartikel (refereegranskat)abstract
- Nicotinic acetylcholine receptors (nAChRs) play crucial roles in various human disorders, with the α7, α4, α6, and α3-containing nAChR subtypes extensively studied in relation to conditions such as Alzheimer's disease, Parkinson's disease, nicotine dependence, mood disorders, and stress disorders. In contrast, the α2-nAChR subunit has received less attention due to its more restricted expression and the scarcity of specific agonists and antagonists for studying its function. Nevertheless, recent research has shed light on the unique expression pattern of the Chrna2 gene, which encodes the α2-nAChR subunit, and its involvement in distinct populations of inhibitory interneurons. This review highlights the structure, pharmacology, localization, function, and disease associations of α2-containing nAChRs and points to the unique expression pattern of the Chrna2 gene and its role in different inhibitory interneuron populations. These populations, including the oriens lacunosum moleculare (OLM) cells in the hippocampus, Martinotti cells in the neocortex, and Renshaw cells in the spinal cord, share common features and contribute to recurrent inhibitory microcircuits. Thus, the α2-nAChR subunit's unique expression pattern in specific interneuron populations and its role in recurrent inhibitory microcircuits highlight its importance in various physiological processes. Further research is necessary to uncover the comprehensive functionality of α2-containing nAChRs, delineate their specific contributions to neuronal circuits, and investigate their potential as therapeutic targets for related disorders.
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