Preferential Pharmacological Inhibition of Nav1.6, but not Nav1.1, Abolishes Epileptiform Activity Induced by 4-AP in Mouse Cortical Slices

ABSTRACTBrain isoforms of voltage-gated sodium channels (VGSCs) have distinct cellular and subcellular expression patterns as well as functional roles that are critical for normal physiology as aberrations in their expression or activity lead to pathophysiological conditions. In this study, we asked how inhibition of select isoforms of VGSCs alters epileptiform activity to further parse out the roles of VGSCs in the brain. We first determined the relative selectivity of recently discovered small molecule, aryl sulfonamide, inhibitors (ICA-121431 and Compound 801) against Nav1.1, Nav1.2, and Nav1.6 activity using whole-cell patch clamp recordings obtained from HEK293 cells. To test the effects of these inhibitors on epileptiform activity, we obtained multielectrode array (MEA) recordings from mouse cortical slices in the presence of 4-aminopyridine (4-AP) to induce epileptiform activity. We found that the ICA-121431 and Compound 801 compounds are relatively selective for Nav1.1 and Nav1.6, respectively. From the MEA recordings, we found that inhibition of Nav1.6 and Nav1.2 with 500nM of the Compound 801 compound completely abolishes ictal local field potentials induced by 4-AP, whereas inhibition of Nav1.1 with 500nM of the ICA-121431 compound had minimal effect on epileptiform activity induced by 4-AP. Due to the prominent expression of Nav1.1 in inhibitory neurons, we asked whether inhibition of Nav1.1 alone alters activity. We found that, indeed, inhibition of Nav1.1 with the ICA-121431 compound increased basal activity in the absence of 4-AP. These findings expand our current understanding of the roles of VGSC isoforms in the brain and suggest that selective targeting of Nav1.6 may be a more efficacious treatment strategy for epileptic syndromes.

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Shared Blood Transcriptomic Signatures between Alzheimer’s Disease and Diabetes Mellitus

Biomedicines ◽

10.3390/biomedicines9010034 ◽

2021 ◽

Vol 9 (1) ◽

pp. 34

Author(s):

Taesic Lee ◽

Hyunju Lee

Keyword(s):

Diabetes Mellitus ◽

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Protein Interactions ◽

Expression Patterns ◽

Protein Protein Interactions ◽

Hub Genes ◽

Gene Modules ◽

Gene Regulatory ◽

The Brain

Alzheimer’s disease (AD) and diabetes mellitus (DM) are known to have a shared molecular mechanism. We aimed to identify shared blood transcriptomic signatures between AD and DM. Blood expression datasets for each disease were combined and a co-expression network was used to construct modules consisting of genes with similar expression patterns. For each module, a gene regulatory network based on gene expression and protein-protein interactions was established to identify hub genes. We selected one module, where COPS4, PSMA6, GTF2B, GTF2F2, and SSB were identified as dysregulated transcription factors that were common between AD and DM. These five genes were also differentially co-expressed in disease-related tissues, such as the brain in AD and the pancreas in DM. Our study identified gene modules that were dysregulated in both AD and DM blood samples, which may contribute to reveal common pathophysiology between two diseases.

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Macrophages and microglia: the cerberus of glioblastoma

Acta Neuropathologica Communications ◽

10.1186/s40478-021-01156-z ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Alice Buonfiglioli ◽

Dolores Hambardzumyan

Keyword(s):

Tumor Cells ◽

Innate Immune System ◽

Tumor Heterogeneity ◽

Expression Profiles ◽

Brain Parenchyma ◽

Innate Immune ◽

Malignant Growth ◽

Neoplastic Cells ◽

Functional Roles ◽

The Brain

AbstractGlioblastoma (GBM) is the most aggressive and deadliest of the primary brain tumors, characterized by malignant growth, invasion into the brain parenchyma, and resistance to therapy. GBM is a heterogeneous disease characterized by high degrees of both inter- and intra-tumor heterogeneity. Another layer of complexity arises from the unique brain microenvironment in which GBM develops and grows. The GBM microenvironment consists of neoplastic and non-neoplastic cells. The most abundant non-neoplastic cells are those of the innate immune system, called tumor-associated macrophages (TAMs). TAMs constitute up to 40% of the tumor mass and consist of both brain-resident microglia and bone marrow-derived myeloid cells from the periphery. Although genetically stable, TAMs can change their expression profiles based upon the signals that they receive from tumor cells; therefore, heterogeneity in GBM creates heterogeneity in TAMs. By interacting with tumor cells and with the other non-neoplastic cells in the tumor microenvironment, TAMs promote tumor progression. Here, we review the origin, heterogeneity, and functional roles of TAMs. In addition, we discuss the prospects of therapeutically targeting TAMs alone or in combination with standard or newly-emerging GBM targeting therapies.

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Neuron-specific spinal cord translatomes reveal a neuropeptide code for mouse dorsal horn excitatory neurons

Scientific Reports ◽

10.1038/s41598-021-84667-y ◽

2021 ◽

Vol 11 (1) ◽

Cited By ~ 1

Author(s):

Rebecca Rani Das Gupta ◽

Louis Scheurer ◽

Pawel Pelczar ◽

Hendrik Wildner ◽

Hanns Ulrich Zeilhofer

Keyword(s):

Spinal Cord ◽

Dorsal Horn ◽

Functional Organization ◽

Affinity Purification ◽

Expression Patterns ◽

Inhibitory Neurons ◽

Dorsal Horn Neurons ◽

Expression Of Genes ◽

Excitatory Neurons ◽

Genes Encoding

AbstractThe spinal dorsal horn harbors a sophisticated and heterogeneous network of excitatory and inhibitory neurons that process peripheral signals encoding different sensory modalities. Although it has long been recognized that this network is crucial both for the separation and the integration of sensory signals of different modalities, a systematic unbiased approach to the use of specific neuromodulatory systems is still missing. Here, we have used the translating ribosome affinity purification (TRAP) technique to map the translatomes of excitatory glutamatergic (vGluT2+) and inhibitory GABA and/or glycinergic (vGAT+ or Gad67+) neurons of the mouse spinal cord. Our analyses demonstrate that inhibitory and excitatory neurons are not only set apart, as expected, by the expression of genes related to the production, release or re-uptake of their principal neurotransmitters and by genes encoding for transcription factors, but also by a differential engagement of neuromodulator, especially neuropeptide, signaling pathways. Subsequent multiplex in situ hybridization revealed eleven neuropeptide genes that are strongly enriched in excitatory dorsal horn neurons and display largely non-overlapping expression patterns closely adhering to the laminar and presumably also functional organization of the spinal cord grey matter.

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Characterization of microglial transcriptomes in the brain and spinal cord of mice in early and late experimental autoimmune encephalomyelitis using a RiboTag strategy

Scientific Reports ◽

10.1038/s41598-021-93590-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Shaona Acharjee ◽

Paul M. K. Gordon ◽

Benjamin H. Lee ◽

Justin Read ◽

Matthew L. Workentine ◽

...

Keyword(s):

Gene Expression ◽

Spinal Cord ◽

Experimental Autoimmune Encephalomyelitis ◽

Expression Patterns ◽

Immune Functions ◽

Autoimmune Encephalomyelitis ◽

Transcriptional Changes ◽

Brain And Spinal Cord ◽

The Brain ◽

Experimental Autoimmune

AbstractMicroglia play an important role in the pathogenesis of multiple sclerosis and the mouse model of MS, experimental autoimmune encephalomyelitis (EAE). To more fully understand the role of microglia in EAE we characterized microglial transcriptomes before the onset of motor symptoms (pre-onset) and during symptomatic EAE. We compared the transcriptome in brain, where behavioral changes are initiated, and spinal cord, where damage is revealed as motor and sensory deficits. We used a RiboTag strategy to characterize ribosome-bound mRNA only in microglia without incurring possible transcriptional changes after cell isolation. Brain and spinal cord samples clustered separately at both stages of EAE, indicating regional heterogeneity. Differences in gene expression were observed in the brain and spinal cord of pre-onset and symptomatic animals with most profound effects in the spinal cord of symptomatic animals. Canonical pathway analysis revealed changes in neuroinflammatory pathways, immune functions and enhanced cell division in both pre-onset and symptomatic brain and spinal cord. We also observed a continuum of many pathways at pre-onset stage that continue into the symptomatic stage of EAE. Our results provide additional evidence of regional and temporal heterogeneity in microglial gene expression patterns that may help in understanding mechanisms underlying various symptomology in MS.

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Microglial Function and Regulation during Development, Homeostasis and Alzheimer’s Disease

Cells ◽

10.3390/cells10040957 ◽

2021 ◽

Vol 10 (4) ◽

pp. 957

Author(s):

Brad T. Casali ◽

Erin G. Reed-Geaghan

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Immune Cells ◽

Expression Patterns ◽

Brain Parenchyma ◽

Primary Role ◽

And Function ◽

Inflammatory Milieu ◽

The Brain ◽

Homeostatic State

Microglia are the resident immune cells of the brain, deriving from yolk sac progenitors that populate the brain parenchyma during development. During development and homeostasis, microglia play critical roles in synaptogenesis and synaptic plasticity, in addition to their primary role as immune sentinels. In aging and neurodegenerative diseases generally, and Alzheimer’s disease (AD) specifically, microglial function is altered in ways that significantly diverge from their homeostatic state, inducing a more detrimental inflammatory environment. In this review, we discuss the receptors, signaling, regulation and gene expression patterns of microglia that mediate their phenotype and function contributing to the inflammatory milieu of the AD brain, as well as strategies that target microglia to ameliorate the onset, progression and symptoms of AD.

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SOS2 Comes to the Fore: Differential Functionalities in Physiology and Pathology

International Journal of Molecular Sciences ◽

10.3390/ijms22126613 ◽

2021 ◽

Vol 22 (12) ◽

pp. 6613

Author(s):

Fernando C. Baltanás ◽

Rósula García-Navas ◽

Eugenio Santos

Keyword(s):

Expression Patterns ◽

Critical Role ◽

Ras Signaling ◽

Epidermal Stem Cell ◽

Functional Specificity ◽

Functional Roles ◽

Signaling Axis ◽

Therapy Target ◽

External Stimuli

The SOS family of Ras-GEFs encompasses two highly homologous and widely expressed members, SOS1 and SOS2. Despite their similar structures and expression patterns, early studies of constitutive KO mice showing that SOS1-KO mutants were embryonic lethal while SOS2-KO mice were viable led to initially viewing SOS1 as the main Ras-GEF linking external stimuli to downstream RAS signaling, while obviating the functional significance of SOS2. Subsequently, different genetic and/or pharmacological ablation tools defined more precisely the functional specificity/redundancy of the SOS1/2 GEFs. Interestingly, the defective phenotypes observed in concomitantly ablated SOS1/2-DKO contexts are frequently much stronger than in single SOS1-KO scenarios and undetectable in single SOS2-KO cells, demonstrating functional redundancy between them and suggesting an ancillary role of SOS2 in the absence of SOS1. Preferential SOS1 role was also demonstrated in different RASopathies and tumors. Conversely, specific SOS2 functions, including a critical role in regulation of the RAS–PI3K/AKT signaling axis in keratinocytes and KRAS-driven tumor lines or in control of epidermal stem cell homeostasis, were also reported. Specific SOS2 mutations were also identified in some RASopathies and cancer forms. The relevance/specificity of the newly uncovered functional roles suggests that SOS2 should join SOS1 for consideration as a relevant biomarker/therapy target.

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