A deep learning-based approach for unbiased kinematic analysis in CNS injury.

Traumatic spinal cord injury (SCI) is a devastating condition that impacts over 300,000 individuals in the US alone. Depending on the severity of the injury, SCI can lead to varying degrees of sensorimotor deficits and paralysis. Despite advances in our understanding of the underlying pathological mechanisms of SCI and the identification of promising molecular targets for repair and functional restoration, few therapies have made it into clinical use.

Cognitive dysfunction following brain trauma results from sex-specific reactivation of the developmental pruning processes.

Cognitive losses resulting from severe brain trauma have long been associated with the focal region of tissue damage, leading to devastating functional impairment. For decades, researchers have focused on the sequelae of cellular alterations that exist within the perilesional tissues; however, few clinical trials have been successful. Here, we employed a mouse brain injury model that resulted in expansive synaptic damage to regions outside the focal injury.

Loss of Sigma-2 Receptor/TMEM97 Is Associated with Neuropathic Injury-Induced Depression-Like Behaviors in Female Mice.

Previous studies have shown that ligands that bind to sigma-2 receptor/TMEM97 (sR/TMEM97), a transmembrane protein, have anxiolytic/antidepressant-like properties and relieve neuropathic pain-like effects in rodents. Despite medical interest in sR/TMEM97, little affective and pain behavioral characterization has been done using transgenic mice, which limits the development of sR/TMEM97 as a viable therapeutic target. Using wild-type (WT) and global knock-out (KO) mice, we sought to identify the contribution of in modulating affective and pain-like behaviors using a battery of affective and pain assays, including open field, light/dark preference, elevated plus maze, forced swim test, tail suspension test, and the mechanical sensitivity tests.

A new type of blood-brain barrier aminoacidopathy underlies metabolic microcephaly associated with SLC1A4 mutations.

Mutations in the SLC1A4 transporter lead to neurodevelopmental impairments, spastic tetraplegia, thin corpus callosum and microcephaly in children. SLC1A4 catalyses obligatory amino acid exchange between neutral amino acids, but the physiopathology of SLC1A4 disease mutations and progressive microcephaly remain unclear. Here, we examined the phenotype and metabolic profile of three Slc1a4 mouse models: a constitutive Slc1a4-knockout mouse; a knock-in mouse with the major human Slc1a4 mutation (Slc1a4-K256E); and a selective knockout of Slc1a4 in brain endothelial cells (Slc1a4tie2-cre).

A deep learning-based approach for unbiased kinematic analysis in CNS injury.

Unlabelled: Traumatic spinal cord injury (SCI) is a devastating condition that impacts over 300,000 individuals in the US alone. Depending on the severity of the injury, SCI can lead to varying degrees of sensorimotor deficits and paralysis. Despite advances in our understanding of the underlying pathological mechanisms of SCI and the identification of promising molecular targets for repair and functional restoration, few therapies have made it into clinical use.

Highly specific σR/TMEM97 ligand FEM-1689 alleviates neuropathic pain and inhibits the integrated stress response.

The sigma 2 receptor (σR) was described pharmacologically more than three decades ago, but its molecular identity remained obscure until recently when it was identified as transmembrane protein 97 (TMEM97). We and others have shown that σR/TMEM97 ligands alleviate mechanical hypersensitivity in mouse neuropathic pain models with a time course wherein maximal antinociceptive effect is approximately 24 h following dosing. We sought to understand this unique antineuropathic pain effect by addressing two key questions: do these σR/TMEM97 compounds act selectively via the receptor, and what is their downstream mechanism on nociceptive neurons? Using male and female conventional knockout mice for we find that a σR/TMEM97 binding compound, FEM-1689, requires the presence of the gene to produce antinociception in the spared nerve injury model in mice.

Cross species review of the physiological role of D-serine in translationally relevant behaviors.

Bridging the gap between preclinical models of neurological and psychiatric disorders with their human manifestations is necessary to understand their underlying mechanisms, identify biomarkers, and develop novel therapeutics. Cognitive and social impairments underlie multiple neuropsychiatric and neurological disorders and are often comorbid with sleep disturbances, which can exacerbate poor outcomes. Importantly, many symptoms are conserved between vertebrates and invertebrates, although they may have subtle differences.

Highly specific σR/TMEM97 ligand alleviates neuropathic pain and inhibits the integrated stress response.

The Sigma 2 receptor (σR) was described pharmacologically more than three decades ago, but its molecular identity remained obscure until recently when it was identified as transmembrane protein 97 (TMEM97). We and others have shown that σR/TMEM97 ligands alleviate mechanical hypersensitivity in mouse neuropathic pain models with a time course wherein maximal anti-nociceptive effect is approximately 24 hours following dosing. We sought to understand this unique anti-neuropathic pain effect by addressing two key questions: do these σR/TMEM97 compounds act selectively via the receptor, and what is their downstream mechanism on nociceptive neurons? Using male and female conventional knockout (KO) mice for we find that a new σR/TMEM97 binding compound, FEM-1689, requires the presence of the gene to produce anti-nociception in the spared nerve injury model in mice.

DCC/netrin-1 regulates cell death in oligodendrocytes after brain injury.

Hallmark pathological features of brain trauma are axonal degeneration and demyelination because myelin-producing oligodendrocytes (OLs) are particularly vulnerable to injury-induced death signals. To reveal mechanisms responsible for this OL loss, we examined a novel class of "death receptors" called dependence receptors (DepRs). DepRs initiate pro-death signals in the absence of their respective ligand(s), yet little is known about their role after injury.

Inhibition of glial D-serine release rescues synaptic damage after brain injury.

Synaptic damage is one of the most prevalent pathophysiological responses to traumatic CNS injury and underlies much of the associated cognitive dysfunction; however, it is poorly understood. The D-amino acid, D-serine, serves as the primary co-agonist at synaptic NMDA receptors (NDMARs) and is a critical mediator of NMDAR-dependent transmission and synaptic plasticity. In physiological conditions, D-serine is produced and released by neurons from the enzymatic conversion of L-serine by serine racemase (SRR).

Reducing acetylated tau is neuroprotective in brain injury.

Traumatic brain injury (TBI) is the largest non-genetic, non-aging related risk factor for Alzheimer's disease (AD). We report here that TBI induces tau acetylation (ac-tau) at sites acetylated also in human AD brain. This is mediated by S-nitrosylated-GAPDH, which simultaneously inactivates Sirtuin1 deacetylase and activates p300/CBP acetyltransferase, increasing neuronal ac-tau.

EphB3 interacts with initiator caspases and FHL-2 to activate dependence receptor cell death in oligodendrocytes after brain injury.

Clinical trials examining neuroprotective strategies after brain injury, including those targeting cell death mechanisms, have been underwhelming. This may be in part due to an incomplete understanding of the signalling mechanisms that induce cell death after traumatic brain injury. The recent identification of a new family of death receptors that initiate pro-cell death signals in the absence of their ligand, called dependence receptors, provides new insight into the factors that contribute to brain injury.

Time series modeling of cell cycle exit identifies Brd4 dependent regulation of cerebellar neurogenesis.

Cerebellar neuronal progenitors undergo a series of divisions before irreversibly exiting the cell cycle and differentiating into neurons. Dysfunction of this process underlies many neurological diseases including ataxia and the most common pediatric brain tumor, medulloblastoma. To better define the pathways controlling the most abundant neuronal cells in the mammalian cerebellum, cerebellar granule cell progenitors (GCPs), we performed RNA-sequencing of GCPs exiting the cell cycle.

Validation study of neurotrophin-3-releasing chitosan facilitation of neural tissue generation in the severely injured adult rat spinal cord.

It was previously reported that a tube holding chitosan carriers loaded with neurotrophin-3 (NT-3), after insertion into a 5 mm long transection gap in the adult rat spinal cord, triggered de novo neural tissue generation and functional recovery. Here, we report an effort to validate these findings using stringent blinding methodologies, which are crucial for robustness in reproducing biomedical studies. Radio frequency identification (RFID) chips were utilized to label rats that were randomly assigned into three experimental groups: transection with chitosan-NT-3 implant (C-NT3), transection only (T-controls), and laminectomy only (S-controls), blinding the experimenters to the treatments.

Neuroprotective Efficacy of a Sigma 2 Receptor/TMEM97 Modulator (DKR-1677) after Traumatic Brain Injury.

Compounds targeting the sigma 2 receptor, which we recently cloned and showed to be identical with transmembrane protein 97 (σ2R/TMEM97), are broadly applicable therapeutic agents currently in clinical trials for imaging in breast cancer and for treatment of Alzheimer's disease and schizophrenia. These promising applications coupled with our previous observation that the σ2R/TMEM97 modulator SAS-0132 has neuroprotective attributes and improves cognition in wild-type mice suggests that modulating σ2R/TMEM97 may also have therapeutic benefits in other neurodegenerative conditions such as traumatic brain injury (TBI). Herein, we report that DKR-1677, a novel derivative of SAS-0132 with increased affinity and selectivity for σ2R/Tmem97 ( K = 5.

EphB3 signaling induces cortical endothelial cell death and disrupts the blood-brain barrier after traumatic brain injury.

Damage to the cerebrovascular network is a major contributor to dysfunction in patients suffering from traumatic brain injury (TBI). Vessels are composed of lumen-forming endothelial cells that associate closely with both glial and neuronal units to establish a functional blood-brain barrier (BBB). Under normal physiological conditions, these vascular units play important roles in central nervous system (CNS) homeostasis by delivering oxygen and nutrients while filtering out molecules and cells that could be harmful; however, after TBI this system is disrupted.

Explant Methodology for Analyzing Neuroblast Migration.

The subventricular zone (SVZ) in the mammalian forebrain contains stem/progenitor cells that migrate through the rostral migratory stream (RMS) to the olfactory bulb throughout adulthood. SVZ-derived explant cultures provide a convenient method to assess factors regulating the intermediary stage of neural stem/progenitor cell migration. Here, we describe the isolation of SVZ-derived RMS explants from the neonatal mouse brain, and the conditions required to culture and evaluate their migration.

Enhanced astrocytic d-serine underlies synaptic damage after traumatic brain injury.

After traumatic brain injury (TBI), glial cells have both beneficial and deleterious roles in injury progression and recovery. However, few studies have examined the influence of reactive astrocytes in the tripartite synapse following TBI. Here, we have demonstrated that hippocampal synaptic damage caused by controlled cortical impact (CCI) injury in mice results in a switch from neuronal to astrocytic d-serine release.

Eph/Ephrin Signaling Controls Progenitor Identities In The Ventral Spinal Cord.

Background: In the vertebrate spinal cord, motor neurons (MN) are generated in stereotypical numbers from a pool of dedicated progenitors (pMN) whose number depends on signals that control their specification but also their proliferation and differentiation rates. Although the initial steps of pMN specification have been extensively studied, how pMN numbers are regulated over time is less well characterized.

Results: Here, we show that ephrinB2 and ephrinB3 are differentially expressed in progenitor domains in the ventral spinal cord with several Eph receptors more broadly expressed.

Ephrin-B3 supports glioblastoma growth by inhibiting apoptosis induced by the dependence receptor EphA4.

EphA4, an Ephrins tyrosine kinase receptor, behaves as a dependence receptor (DR) by triggering cell apoptosis in the absence of its ligand Ephrin-B3. DRs act as conditional tumor suppressors, engaging cell death based on ligand availability; this mechanism is bypassed by overexpression of DRs ligands in some aggressive cancers. The pair EphA4/Ephrin-B3 favors survival of neuronal progenitors of the brain subventricular zone, an area where glioblastoma multiform (GBM) are thought to originate.

EphrinB3 restricts endogenous neural stem cell migration after traumatic brain injury.

Traumatic brain injury (TBI) leads to a series of pathological events that can have profound influences on motor, sensory and cognitive functions. Conversely, TBI can also stimulate neural stem/progenitor cell proliferation leading to increased numbers of neuroblasts migrating outside their restrictive neurogenic zone to areas of damage in support of tissue integrity. Unfortunately, the factors that regulate migration are poorly understood.

EphB3 signaling propagates synaptic dysfunction in the traumatic injured brain.

Traumatic brain injury (TBI), ranging from mild concussion to severe penetrating wounds, can involve brain regions that contain damaged or lost synapses in the absence of neuronal death. These affected regions significantly contribute to sensory, motor and/or cognitive deficits. Thus, studying the mechanisms responsible for synaptic instability and dysfunction is important for protecting the nervous system from the consequences of progressive TBI.

A flow cytometric approach to analyzing mature and progenitor endothelial cells following traumatic brain injury.

Background: Traumatic brain injury (TBI) continues to be a major source of death and disability worldwide, and one of the earliest and most profound deficits comes from vascular damage and breakdown of the blood-brain barrier (BBB). Cerebral vascular endothelial cells (cvECs) and endothelial progenitor cells (EPCs) have been shown to play essential roles in vessel repair and BBB stability, although their individual contributions remain poorly defined.

New Method: We employ TruCount beads with flow cytometry to precisely quantify cvECs, EPCs, and peripheral leukocytes in the murine cortex after controlled cortical impact (CCI) injury.

Endogenous neural stem/progenitor cells stabilize the cortical microenvironment after traumatic brain injury.

Although a myriad of pathological responses contribute to traumatic brain injury (TBI), cerebral dysfunction has been closely linked to cell death mechanisms. A number of therapeutic strategies have been studied in an attempt to minimize or ameliorate tissue damage; however, few studies have evaluated the inherent protective capacity of the brain. Endogenous neural stem/progenitor cells (NSPCs) reside in distinct brain regions and have been shown to respond to tissue damage by migrating to regions of injury.