Biology subjects

Abebe, D.

Publications and source records attributed to Abebe, D..

6 recordsLinked to original sources

bioRxiv2025

Discrete interneuron subsets participate in GluN1/GluN3A excitatory glycine receptor (eGlyR)-mediated regulation of hippocampal network activity throughout development and evolution.

Decades of studies implicating GluN3A N-methyl-D-aspartate receptor (NMDAR) subunits in physiological and pathological function have largely been interpreted through direct regulation of conventional glutamatergic NMDARs. However, emerging evidence indicates that GluN3A frequently assembles with GluN1 forming unconventional glutamate-insensitive NMDARs that operate as native excitatory glycine receptors (eGlyRs). Here we demonstrate that hippocampal somatostatin and neurogliaform interneurons (Sst-INs and NGFCs) express functional eGlyRs from early postnatal through adult ages. In the developing hippocampus eGlyR-mediated excitation of NGFCs with ambient glycine dramatically increases GABAergic tone, with consequences for the generation of giant depolarizing potentials (GDPs). In the mature hippocampus, eGlyR- mediated excitation of Sst-INs regulates sharp wave ripples (SWRs). Finally, we reveal evolutionary conservation of hippocampal Sst-IN eGlyRs and eGlyR- mediated SWR regulation in non-human primates confirming functional eGlyR availability for therapeutic potential in higher species. Our findings underscore that eGlyR mediated regulation of cell and circuit excitability through both cell autonomous and cell non-autonomous mechanisms must be considered to understand GluN3A roles in brain development, plasticity, and disease.

neuroscience↗

bioRxiv2025

IRF8 deficiency causes anxiety-like behavior in a sex-dependent manner

Anxiety disorder is a serious psychiatric disease that affects women twice more than men and disrupts patients daily lives. It is often comorbid with major depression and other mental diseases. Various underlying mechanisms have been proposed, such as neurotransmitters and neuroanatomical disruptions, and more recently, oxidative stress; however, much remained unclear, including the role of glial cells. Here, we investigated the role of IRF8 in anxiety disorders in the mouse model. IRF8 is a transcription factor expressed primarily in microglia in the brain. A battery of behavioral tests revealed that female IRF8 knockout (IRF8KO) mice show increased anxiety relative to male IRF8KO and wild-type mice. Female IRF8KO mice also exhibited a higher tendency for obsessive-compulsive disorder. However, these behavioral abnormalities were not observed when IRF8 was deleted postnatally, indicating that it acts during the fetal stage to control anxiety. Transcriptome analysis revealed that IRF8 deficiency leads to redox dysregulation. Further, 2,7-dichlorofluorescin diacetate (DCFDA) staining for microglia demonstrated that female IRF8KO microglia produce higher levels of reactive oxygen species (ROS) compared to WT and male IRF8KO counterparts. Detailed RNA-seq analysis, however, did not reveal specific genes that cause high ROS production in female cells. In sum, this work demonstrates that IRF8 in microglia plays a major role in controlling anxiety in a sex dependent manner.

neuroscience↗

bioRxiv2025

Mature interneuron subtypes arise from distinct spatial and temporal subdomains within the caudal ganglionic eminence

Forebrain inhibitory interneurons are born from transient structures during embryogenesis known as the medial and caudal ganglionic eminences (MGE and CGE, respectively). The MGE and CGE generate distinct, non-overlapping cohorts of interneurons that can be defined by their transcriptomic, morphological, and electrophysiological characteristics. In the MGE, somatostatin-expressing (SST+) cells arise predominantly from the dorsal-posterior MGE from E12-E16 whereas parvalbumin-expressing (PV+) cells are born in the ventral-anterior MGE throughout embryogenesis. This relationship between spatiotemporal origin and mature interneuron subtypes has led to genetic insights regarding fate and maturation of these MGE-derived cells. A similar organization has never been explored in the CGE, despite the significant increase in CGE-derived interneurons in primates compared to rodents. Here we harvested fluorescent cells from distinct CGE subdomains at E13.5 and E15.5 and grafted them into WT neonatal mice cortices. One month post-transplantation, brains were immunostained for interneuron markers to relate mature CGE-derived interneurons with spatiotemporal origins within the CGE. Our results indicate that there are significant spatial biases in the CGE, with specific interneuron subtypes preferentially arising from distinct CGE subdomains. These biases are relatively stable over time, implying a minimal relationship between temporal birthdate and interneuron subtype. In the future, combining these insights with spatial transcriptome profiles will generate critical insights into gene regulation of CGE-derived interneurons.

neuroscience↗

bioRxiv2025

Neurotrophic Factor-α1/carboxypeptidase E regulates critical protein networks to rescue neurodegeneration, defective synaptogenesis and impaired autophagy in Alzheimer's Disease mice

BackgroundThe global aging population is increasingly inflicted with Alzheimers disease (AD), but a cure is still unavailable. Neurotrophic Factor-1/carboxypeptidase E (NF-1/CPE) gene therapy has been shown to prevent and reverse memory loss and pathology AD mouse models However, the mechanisms of action of NF-1/CPE are not fully understood. We investigated if a non-enzymatic form of NF-1/CPE-E342Q is efficient in reversing AD pathology and carried out a proteomic study to uncover the mechanisms of action of NF-1/CPE in AD mice. MethodsAAV-human NF-1/CPE and a non-enzymatic form, NF-1/CPE -E342Q were delivered into hippocampus of 3xTg-AD mice and effects on cognitive function, neurodegeneration, synaptogenesis and autophagy were investigated. A quantitative proteomic analysis of hippocampus of 3xTg-AD mice with and without AAV-NF-1/CPE treatment was carried out. ResultsHippocampal delivery of AAV-NF-1/CPE-E342Q prevented memory loss, neurodegeneration and increase in activated microglia in 3xTg-AD mice, indicating its action is independent of its enzymatic activity. Quantitative proteomic analysis of hippocampus of 3xTg-AD mice that underwent NF-1/CPE gene therapy revealed differential expression of >2000 proteins involving many metabolic pathways. Of these, two new proteins down-regulated by NF-1/CPE: Nexin4 (SNX4) and Trim28 which increase A{beta} production and tau levels, respectively were identified. Western blot analysis verified that they were reduced in AAV-NF-1/CPE treated 3xTg-AD mice compared to untreated mice. Our proteomic analysis indicated synaptic organization as top signaling pathway altered as a response to CPE expression. Synaptic markers PSD95 and Synapsin1 were decreased in 3xTg-AD mice and were restored with AAV-NF-1/CPE treatment. Proteomic analysis hypothesized involvement of autophagic signaling pathway. Indeed, multiple proteins known to be markers of autophagy were down-regulated in 3xTg-AD mice, accounting for impaired autophagy. Expression of these proteins were upregulated in 3xTg-AD mice with NF-1/CPE gene therapy, thereby reversing autophagic impairment. ConclusionsThis study uncovered vast actions of NF-1/CPE in restoring expression of networks of critical proteins including those necessary for maintaining neuronal survival, synaptogenesis and autophagy, while down-regulating many proteins that promote tau and A{beta} accumulation to reverse memory loss and AD pathology in 3xTg-AD mice. AAV-NF-1/CPE gene therapy uniquely targets many metabolic levels, offering a promising holistic approach for AD treatment. Graphic abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=113 SRC="FIGDIR/small/657876v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@10e468forg.highwire.dtl.DTLVardef@3a78adorg.highwire.dtl.DTLVardef@c8d62forg.highwire.dtl.DTLVardef@165d118_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2025

Reducing methylation of histone 3.3 lysine 4 in the medial ganglionic eminence and hypothalamus recapitulates neurodevelopmental disorder phenotypes

Methylation of lysine 4 on histone H3 (H3K4) is enriched on active promoters and enhancers and correlates with gene activation. Disruption of H3K4 methylation is associated with numerous neurodevelopmental diseases (NDDs) that display intellectual disability and abnormal body growth. Here, we perturb H3K4 methylation in the medial ganglionic eminence (MGE) and the hypothalamus, two brain regions associated with these disease phenotypes. These mutant mice have fewer forebrain interneurons, deficient network rhythmogenesis, and increased spontaneous seizures and seizure susceptibility. Mutant mice are significantly smaller than control littermates, but they eventually became obese due to striking changes in the genetic and cellular hypothalamus environment in these mice. Perturbation of H3K4 methylation in these cells produces deficits in numerous NDD-associated behaviors, with a bias for more severe phenotypes in female mice. Single cell sequencing reveals transcriptional changes in the embryonic and adult brain that underlie many of these phenotypes. In sum, our findings highlight the critical role of H3K4 methylation in regulating survival and cell-specific gene regulatory mechanisms in forebrain GABAergic and hypothalamic cells during neurodevelopment to control network excitability and body size homoeostasis.

neuroscience↗

bioRxiv2024

Complex opioid driven modulation of glutamatergic and cholinergic neurotransmission in a GABAergic brain nucleus associated with emotion, reward and addiction.

The medial habenula (mHb)/interpeduncular nucleus (IPN) circuitry is resident to divergent molecular, neurochemical and cellular components which, in concert, perform computations to drive emotion, reward and addiction behaviors. Although housing one of the most prominent mu opioid receptor (mOR) expression levels in the brain, remarkably little is known as to how they impact mHb/IPN circuit function at the granular level. In this study, our systematic functional and pharmacogenetic analyses demonstrate that mOR activation attenuates glutamatergic signaling whilst producing an opposing potentiation of glutamatergic/cholinergic co-transmission mediated by mHb substance P and cholinergic neurons, respectively. Intriguingly, this latter non-canonical augmentation is developmentally regulated only emerging during later postnatal stages. In addition, we reveal that specific potassium channels act as a molecular brake on nicotinic receptor signaling in the IPN with the opioid mediated potentiation of this arm of neurotransmission being operational only following attenuation of Kv1 function. Thus, mORs play a complex role in shaping the salience of distinct afferent inputs and transmitter modalities that ultimately influences synaptic recruitment of downstream GABAergic IPN neurons. Together, these observations provide a framework for future investigations aimed at identifying the neural underpinnings of maladaptive behaviors that can emerge when opioids, including potent synthetic analogs such as fentanyl, modulate or hijack this circuitry during the vulnerable stages of adolescence and in adulthood.

neuroscience↗