Pub Date : 2024-09-12DOI: 10.1101/2024.09.09.612115
Benjamin W Fait, Bianca Cotto, Tatsuya C Murakami, Michael Hagemann-Jensen, Huiqing Zhan, Corinne Freivald, Isadora Turbek, Yuan Gao, Zizhen Yao, Sharon W Way, Hongkui Zeng, Bosiljka Tasic, Oswald Steward, Nathaniel Heintz, Eric F Schmidt
The spinal cord receives inputs from the cortex via corticospinal neurons (CSNs). While predominantly a contralateral projection, a less-investigated minority of its axons terminate in the ipsilateral spinal cord. We analyzed the spatial and molecular properties of these ipsilateral axons and their post-synaptic targets in mice and found they project primarily to the ventral horn, including directly to motor neurons. Barcode-based reconstruction of the ipsilateral axons revealed a class of primarily bilaterally-projecting CSNs with a distinct cortical distribution. The molecular properties of these ipsilaterally-projecting CSNs (IP-CSNs) are strikingly similar to the previously described molecular signature of embryonic-like regenerating CSNs. Finally, we show that IP-CSNs are spontaneously regenerative after spinal cord injury. The discovery of a class of spontaneously regenerative CSNs may prove valuable to the study of spinal cord injury. Additionally, this work suggests that the retention of juvenile-like characteristics may be a widespread phenomenon in adult nervous systems.
{"title":"Spontaneously regenerative corticospinal neurons in mice","authors":"Benjamin W Fait, Bianca Cotto, Tatsuya C Murakami, Michael Hagemann-Jensen, Huiqing Zhan, Corinne Freivald, Isadora Turbek, Yuan Gao, Zizhen Yao, Sharon W Way, Hongkui Zeng, Bosiljka Tasic, Oswald Steward, Nathaniel Heintz, Eric F Schmidt","doi":"10.1101/2024.09.09.612115","DOIUrl":"https://doi.org/10.1101/2024.09.09.612115","url":null,"abstract":"The spinal cord receives inputs from the cortex via corticospinal neurons (CSNs). While predominantly a contralateral projection, a less-investigated minority of its axons terminate in the ipsilateral spinal cord. We analyzed the spatial and molecular properties of these ipsilateral axons and their post-synaptic targets in mice and found they project primarily to the ventral horn, including directly to motor neurons. Barcode-based reconstruction of the ipsilateral axons revealed a class of primarily bilaterally-projecting CSNs with a distinct cortical distribution. The molecular properties of these ipsilaterally-projecting CSNs (IP-CSNs) are strikingly similar to the previously described molecular signature of embryonic-like regenerating CSNs. Finally, we show that IP-CSNs are spontaneously regenerative after spinal cord injury. The discovery of a class of spontaneously regenerative CSNs may prove valuable to the study of spinal cord injury. Additionally, this work suggests that the retention of juvenile-like characteristics may be a widespread phenomenon in adult nervous systems.","PeriodicalId":501581,"journal":{"name":"bioRxiv - Neuroscience","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-12DOI: 10.1101/2024.09.11.612421
Anna Maria Ostenrath, Nicholas Faturos, Yagnur Isik Ciftci Cobanoglu, Bram Serneels, Inyoung Jeong, Anja Enz, Francisca Hinrichsen, Aytac Kadir Mutlu, Ricarda Bardenhewer, Suresh Kumar Jetti, Stephan C. F. Neuhauss, Nathalie Jurisch-Yaksi, Emre Yaksi
Inhibition contributes to various brain computations from sensory motor transformations to cognitive operations. While most studies on inhibition focus on GABA, the main excitatory neurotransmitter of the brain, glutamate, can also elicit inhibition via metabotropic glutamate receptors (mGluRs). The function of mGluR-mediated inhibition remains largely elusive. Here, we investigated the role of group III mGluR-dependent inhibition in the habenula. This primarily glutamatergic and conserved forebrain region acts as a hub between multiple forebrain inputs and neuromodulatory mid- and hindbrain targets that regulate adaptive behaviors. We showed that both zebrafish and mice habenula express group III mGluRs. We identified that group III mGluRs regulate the membrane potential and calcium activity of zebrafish dorsal habenula. Pharmacological and genetic perturbation of group III mGluRs increased sensory-evoked excitation and reduced selectivity of habenular neurons to different sensory modalities. We also observed that inhibition is the main channel of communication between primarily glutamatergic habenula neurons. Blocking group III mGluRs reduced inhibition within habenula and increased correlations during spontaneous activity. In line with such inhibition within habenula, we identified that multi-sensory information is integrated mainly through competition and suppression across habenular neurons, which in part relies on group III mGluRs. Finally, genetic perturbation of a habenula-specific group III mGluR, mGluR6a, amplified neural responses and defensive behaviors evoked by sensory stimulation and environmental changes. Altogether, our results revealed that mGluR driven inhibition is essential in encoding, integration, and communication of information between Hb neurons, ultimately playing a critical role in regulating defensive and adaptive behaviors.
抑制有助于从感官运动转换到认知操作的各种大脑计算。虽然有关抑制的研究大多集中在 GABA 上，但大脑的主要兴奋性神经递质谷氨酸也能通过代谢型谷氨酸受体（mGluRs）引起抑制。mGluR 介导的抑制功能在很大程度上仍然难以捉摸。在这里，我们研究了第 III 组 mGluR 依赖性抑制在哈氏脑中的作用。这个主要由谷氨酸能和保守的前脑区域是多个前脑输入和调节适应行为的中脑和后脑神经调节靶点之间的枢纽。我们发现斑马鱼和小鼠的哈文鱼都表达第 III 组 mGluRs。我们发现 III 组 mGluRs 可调控斑马鱼背侧哈氏神经节的膜电位和钙离子活性。药理和基因扰乱 III 组 mGluRs 会增加感觉诱发的兴奋，并降低背神经元对不同感觉模式的选择性。我们还观察到，抑制是主要是谷氨酸能神经元之间交流的主要渠道。阻断第三组 mGluRs 可减少哈氏神经元内部的抑制作用，并增加自发活动期间的相关性。与这种抑制作用相一致，我们发现多感觉信息主要是通过不同神经元之间的竞争和抑制来整合的，而这在一定程度上依赖于III群mGluRs。最后，通过基因扰乱一种兔神经元特异的第三组 mGluR（mGluR6a），可以放大由感觉刺激和环境变化引起的神经反应和防御行为。总之，我们的研究结果表明，mGluR驱动的抑制作用在哈贝神经元之间的信息编码、整合和交流中至关重要，最终在调节防御和适应行为中发挥关键作用。
{"title":"Inhibition mediated by group III mGluRs regulates habenula activity and defensive behaviors","authors":"Anna Maria Ostenrath, Nicholas Faturos, Yagnur Isik Ciftci Cobanoglu, Bram Serneels, Inyoung Jeong, Anja Enz, Francisca Hinrichsen, Aytac Kadir Mutlu, Ricarda Bardenhewer, Suresh Kumar Jetti, Stephan C. F. Neuhauss, Nathalie Jurisch-Yaksi, Emre Yaksi","doi":"10.1101/2024.09.11.612421","DOIUrl":"https://doi.org/10.1101/2024.09.11.612421","url":null,"abstract":"Inhibition contributes to various brain computations from sensory motor transformations to cognitive operations. While most studies on inhibition focus on GABA, the main excitatory neurotransmitter of the brain, glutamate, can also elicit inhibition via metabotropic glutamate receptors (mGluRs). The function of mGluR-mediated inhibition remains largely elusive. Here, we investigated the role of group III mGluR-dependent inhibition in the habenula. This primarily glutamatergic and conserved forebrain region acts as a hub between multiple forebrain inputs and neuromodulatory mid- and hindbrain targets that regulate adaptive behaviors. We showed that both zebrafish and mice habenula express group III mGluRs. We identified that group III mGluRs regulate the membrane potential and calcium activity of zebrafish dorsal habenula. Pharmacological and genetic perturbation of group III mGluRs increased sensory-evoked excitation and reduced selectivity of habenular neurons to different sensory modalities. We also observed that inhibition is the main channel of communication between primarily glutamatergic habenula neurons. Blocking group III mGluRs reduced inhibition within habenula and increased correlations during spontaneous activity. In line with such inhibition within habenula, we identified that multi-sensory information is integrated mainly through competition and suppression across habenular neurons, which in part relies on group III mGluRs. Finally, genetic perturbation of a habenula-specific group III mGluR, mGluR6a, amplified neural responses and defensive behaviors evoked by sensory stimulation and environmental changes. Altogether, our results revealed that mGluR driven inhibition is essential in encoding, integration, and communication of information between Hb neurons, ultimately playing a critical role in regulating defensive and adaptive behaviors.","PeriodicalId":501581,"journal":{"name":"bioRxiv - Neuroscience","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maternal prenatal depressive symptoms are linked to neurodevelopmental impairments in offspring. Maternal cortisol levels are hypothesized to moderate this association, but its relationship with depressive symptoms is inconsistent. This study examined how maternal prenatal depressive symptoms and cortisol levels predict infant brain development, focusing on neonatal corpus callosum (CC) integrity. Using data from the FinnBrain Birth Cohort Study, we analyzed 37 mother-infant dyads. MRI data were collected from 2 to 5 weeks old infants, and DTI imaging estimated fractional anisotropy (FA) in CC regions (Genu, Body, and Splenium). Maternal cortisol levels were assessed through hair cortisol concentration (HCC) from a 5cm hair segment, reflecting cortisol over the last five months of pregnancy. A factor score of maternal depressive symptoms was computed from EPDS questionnaire data collected at gestational weeks 14, 24, and 34. We employed multivariate regression models with a Bayesian approach for statistical testing, controlling for maternal and infant attributes. Results indicated that maternal prenatal depressive symptoms and HCC interact negatively in predicting infants' FA across all CC regions. Infants exposed to high prenatal depressive symptoms and low HCC (1 SD below the mean) showed higher FA in all CC regions. These findings highlight the complex dynamics between maternal prenatal cortisol levels and depressive symptoms, revealing a nuanced impact of those factors on the structural integrity of infants' CC.
{"title":"Association between maternal depressive symptoms and hair cortisol concentration during pregnancy with corpus callosum integrity in newborns","authors":"Isabella Lucia Chiara Mariani Wigley, Paula Mustonen, Linnea Karlsson, Saara Nolvi, Noora Scheinin, Susanna Kortesluoma, Massimiliano Pastore, Katja Tervahartiala, Bárbara Coimbra, Ana J Rodrigues, Nuno Sousa, Hasse Karlsson, Jetro J Tuulari","doi":"10.1101/2024.09.06.610927","DOIUrl":"https://doi.org/10.1101/2024.09.06.610927","url":null,"abstract":"Maternal prenatal depressive symptoms are linked to neurodevelopmental impairments in offspring. Maternal cortisol levels are hypothesized to moderate this association, but its relationship with depressive symptoms is inconsistent. This study examined how maternal prenatal depressive symptoms and cortisol levels predict infant brain development, focusing on neonatal corpus callosum (CC) integrity. Using data from the FinnBrain Birth Cohort Study, we analyzed 37 mother-infant dyads. MRI data were collected from 2 to 5 weeks old infants, and DTI imaging estimated fractional anisotropy (FA) in CC regions (Genu, Body, and Splenium). Maternal cortisol levels were assessed through hair cortisol concentration (HCC) from a 5cm hair segment, reflecting cortisol over the last five months of pregnancy. A factor score of maternal depressive symptoms was computed from EPDS questionnaire data collected at gestational weeks 14, 24, and 34. We employed multivariate regression models with a Bayesian approach for statistical testing, controlling for maternal and infant attributes. Results indicated that maternal prenatal depressive symptoms and HCC interact negatively in predicting infants' FA across all CC regions. Infants exposed to high prenatal depressive symptoms and low HCC (1 SD below the mean) showed higher FA in all CC regions. These findings highlight the complex dynamics between maternal prenatal cortisol levels and depressive symptoms, revealing a nuanced impact of those factors on the structural integrity of infants' CC.","PeriodicalId":501581,"journal":{"name":"bioRxiv - Neuroscience","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-12DOI: 10.1101/2024.09.03.611040
Mohammad Hassan Yaghoubi, Andres Nieto-Pasadas, Coralie-Anne Mosser, Thomas Gisiger, Emmanuel Wilson, Sylvain Williams, Mark P Brandon
A fundamental objective of the brain is to anticipate future outcomes. This process requires learning the states of the world as well as the transitional relationships between those states. The hippocampal cognitive map is believed to be one such internal model. However, evidence for predictive coding and reward sensitivity in the hippocampal neuronal representation suggests that its role extends beyond purely spatial representation. In fact, it raises the question of what kind of spatial representation is most useful for learning and maximizing future rewards? Here, we track the evolution of reward representation over weeks as mice learn to solve a cognitively demanding reward-based task. Our findings reveal a highly organized restructuring of hippocampal reward representations during the learning process. Specifically, we found multiple lines of evidence, both at the population and single-cell levels, that hippocampal representation becomes predictive of reward over weeks. Namely, both population-level information about reward and the percentage of reward-tuned neurons decrease over time. At the same time, the representation of the animals' choice and reward approach period (the period between choice and reward) increased over time. By tracking individual reward cells across sessions, we found that neurons initially tuned for reward shifted their tuning towards choice and reward approach periods, indicating that reward cells backpropagate their tuning to anticipate reward with experience. These findings underscore the dynamic nature of hippocampal representations, highlighting their critical role in learning through the prediction of future outcomes.
{"title":"Predictive Coding of Reward in the Hippocampus","authors":"Mohammad Hassan Yaghoubi, Andres Nieto-Pasadas, Coralie-Anne Mosser, Thomas Gisiger, Emmanuel Wilson, Sylvain Williams, Mark P Brandon","doi":"10.1101/2024.09.03.611040","DOIUrl":"https://doi.org/10.1101/2024.09.03.611040","url":null,"abstract":"A fundamental objective of the brain is to anticipate future outcomes. This process requires learning the states of the world as well as the transitional relationships between those states. The hippocampal cognitive map is believed to be one such internal model. However, evidence for predictive coding and reward sensitivity in the hippocampal neuronal representation suggests that its role extends beyond purely spatial representation. In fact, it raises the question of what kind of spatial representation is most useful for learning and maximizing future rewards? Here, we track the evolution of reward representation over weeks as mice learn to solve a cognitively demanding reward-based task. Our findings reveal a highly organized restructuring of hippocampal reward representations during the learning process. Specifically, we found multiple lines of evidence, both at the population and single-cell levels, that hippocampal representation becomes predictive of reward over weeks. Namely, both population-level information about reward and the percentage of reward-tuned neurons decrease over time. At the same time, the representation of the animals' choice and reward approach period (the period between choice and reward) increased over time. By tracking individual reward cells across sessions, we found that neurons initially tuned for reward shifted their tuning towards choice and reward approach periods, indicating that reward cells backpropagate their tuning to anticipate reward with experience. These findings underscore the dynamic nature of hippocampal representations, highlighting their critical role in learning through the prediction of future outcomes.","PeriodicalId":501581,"journal":{"name":"bioRxiv - Neuroscience","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-12DOI: 10.1101/2024.09.11.612440
Carlos Fernandez-Pena, Rachel L Pace, Lourds M Fernando, Brittany G Pittman, Lindsay A Schwarz
Anxiety is an emotional state precipitated by the anticipation of real or potential threats. Anxiety disorders are the most prevalent psychiatric illnesses globally and increase the risk of developing comorbid conditions that negatively impact the brain and body. The etiology of anxiety disorders remains unresolved, limiting improvement of therapeutic strategies to alleviate anxiety-related symptoms with increased specificity and efficacy. Here, we applied novel intersectional tools to identify a discrete population of brainstem adrenergic neurons, named C1 cells, that promote aversion and anxiety-related behaviors via projections to the periaqueductal gray matter (PAG). While C1 cells have traditionally been implicated in modulation of autonomic processes, rabies tracing revealed that they receive input from brain areas with diverse functions. Calcium-based in vivo imaging showed that activation of C1 cells enhances excitatory responses in vlPAG, activity that is exacerbated in times of heightened stress. Furthermore, inhibition of C1 cells impedes the development of anxiety-like behaviors in response to stressful situations. Overall, these findings suggest that C1 neurons are positioned to integrate complex information from the brain and periphery for the promotion of anxiety-like behaviors.
{"title":"Adrenergic C1 neurons enhance anxiety via projections to PAG","authors":"Carlos Fernandez-Pena, Rachel L Pace, Lourds M Fernando, Brittany G Pittman, Lindsay A Schwarz","doi":"10.1101/2024.09.11.612440","DOIUrl":"https://doi.org/10.1101/2024.09.11.612440","url":null,"abstract":"Anxiety is an emotional state precipitated by the anticipation of real or potential threats. Anxiety disorders are the most prevalent psychiatric illnesses globally and increase the risk of developing comorbid conditions that negatively impact the brain and body. The etiology of anxiety disorders remains unresolved, limiting improvement of therapeutic strategies to alleviate anxiety-related symptoms with increased specificity and efficacy. Here, we applied novel intersectional tools to identify a discrete population of brainstem adrenergic neurons, named C1 cells, that promote aversion and anxiety-related behaviors via projections to the periaqueductal gray matter (PAG). While C1 cells have traditionally been implicated in modulation of autonomic processes, rabies tracing revealed that they receive input from brain areas with diverse functions. Calcium-based in vivo imaging showed that activation of C1 cells enhances excitatory responses in vlPAG, activity that is exacerbated in times of heightened stress. Furthermore, inhibition of C1 cells impedes the development of anxiety-like behaviors in response to stressful situations. Overall, these findings suggest that C1 neurons are positioned to integrate complex information from the brain and periphery for the promotion of anxiety-like behaviors.","PeriodicalId":501581,"journal":{"name":"bioRxiv - Neuroscience","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-12DOI: 10.1101/2024.09.12.612649
Avika Chopra, Mary Xylaki, Fanzheng Yin, Ricardo Castro-Hernandez, Madiha Merghani, Valentina Grande, Brit Mollenhauer, Andre Fischer, Tiago Fleming Outeiro
N6-methyladenosine (m6A) is the most abundant and conserved transcriptional modification in eukaryotic RNA, regulating RNA fate. While the functions of m6A in the development of the mammalian brain have been extensively studied, its roles in synaptic plasticity, cognitive decline, motor function, or other brain circuits remain underexplored. To date, the role of this modification in Parkinson's disease (PD) and other synucleinopathies has been largely unknown. Here, we investigated the m6A epitranscriptome in a mouse model of synucleinopathy. We performed m6A RNA immunoprecipitation sequencing (meRIP-seq) to obtain the m6A epitranscriptome of the midbrain in young (3 mo) and aged (15 mo) A30P-aSyn transgenic mice (aSyn Tg) and C57BL6 control wild type (Wt) mice. We observed hypermethylation of synaptic genes in 3 mo aSyn Tg mice compared to age-matched Wt mice. This methylation was reduced during ageing, with synaptic genes becoming increasingly hypomethylated. Using immunofluorescence imaging alongside biochemical analysis, we further investigated the expression of m6A regulatory enzymes writer, N6-Adenosine-Methyltransferase Complex Catalytic Subunit (METTL3); reader, YTH N6-methyladenosine RNA-binding protein (YTHDF1); and eraser, fat mass and obesity-associated protein (FTO) in the cortex, striatum, hippocampus, and cerebellum of Wt and aSyn Tg mice, as well as in primary cortical neuronal cultures. We observed that the levels of METTL3, YTHDF1 and FTO were similar between Wt and aSyn Tg mice. Interestingly, the writer protein METTL3 was found in both the nucleus and in the post-synaptic compartment in neuronal cultures. Our findings suggest that alterations in the regulation of m6A RNA methylation may be associated with neurodegeneration and ageing and that this level of epitranscriptomic regulation plays a significant role at the synapse.
{"title":"The epitranscriptomic m6A RNA modification modulates synaptic function in ageing and in a mouse model of synucleinopathy","authors":"Avika Chopra, Mary Xylaki, Fanzheng Yin, Ricardo Castro-Hernandez, Madiha Merghani, Valentina Grande, Brit Mollenhauer, Andre Fischer, Tiago Fleming Outeiro","doi":"10.1101/2024.09.12.612649","DOIUrl":"https://doi.org/10.1101/2024.09.12.612649","url":null,"abstract":"N6-methyladenosine (m6A) is the most abundant and conserved transcriptional modification in eukaryotic RNA, regulating RNA fate. While the functions of m6A in the development of the mammalian brain have been extensively studied, its roles in synaptic plasticity, cognitive decline, motor function, or other brain circuits remain underexplored. To date, the role of this modification in Parkinson's disease (PD) and other synucleinopathies has been largely unknown. Here, we investigated the m6A epitranscriptome in a mouse model of synucleinopathy. We performed m6A RNA immunoprecipitation sequencing (meRIP-seq) to obtain the m6A epitranscriptome of the midbrain in young (3 mo) and aged (15 mo) A30P-aSyn transgenic mice (aSyn Tg) and C57BL6 control wild type (Wt) mice. We observed hypermethylation of synaptic genes in 3 mo aSyn Tg mice compared to age-matched Wt mice. This methylation was reduced during ageing, with synaptic genes becoming increasingly hypomethylated. Using immunofluorescence imaging alongside biochemical analysis, we further investigated the expression of m6A regulatory enzymes writer, N6-Adenosine-Methyltransferase Complex Catalytic Subunit (METTL3); reader, YTH N6-methyladenosine RNA-binding protein (YTHDF1); and eraser, fat mass and obesity-associated protein (FTO) in the cortex, striatum, hippocampus, and cerebellum of Wt and aSyn Tg mice, as well as in primary cortical neuronal cultures. We observed that the levels of METTL3, YTHDF1 and FTO were similar between Wt and aSyn Tg mice. Interestingly, the writer protein METTL3 was found in both the nucleus and in the post-synaptic compartment in neuronal cultures. Our findings suggest that alterations in the regulation of m6A RNA methylation may be associated with neurodegeneration and ageing and that this level of epitranscriptomic regulation plays a significant role at the synapse.","PeriodicalId":501581,"journal":{"name":"bioRxiv - Neuroscience","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-12DOI: 10.1101/2024.09.07.611810
Ravinder Naik Dharavath, Ashley Bernardo, Cassandra Marceau-Linhares, Michael Marcotte, Kayla Wong, Celeste Pina-Leblanc, Adrien Bouchet, Dishary Sharmin, James Cook, Kamal Prasad Pandey, Thomas Damien Prevot, Etienne Sibille
Background: Dysregulated tau phosphorylation is one of the hallmarks of Alzheimer's disease (AD), and it results in cognitive impairments, neuronal atrophy, and neurofibrillary tangle accumulation. Evidence shows that impaired somatostatin (SST) expression, particularly in SST-expressing GABAergic neurons, significantly contributes to AD-related pathophysiology and may increase cognitive burden. Additionally, SST+ interneurons in cortical layers and the hippocampus inhibit the dendrites of excitatory neurons, primarily through α5-GABAA receptors involved in cognitive regulation. Leveraging the potential of a newly developed small molecule that targets the α5-GABAA receptors via positive allosteric modulation (α5-PAM), we aim to assess its effects on tau phosphorylation-related neuronal morphology, cognitive deficits and protein expression. Methods: In the PS19 transgenic mouse mode, we administered the α5-PAM, GL-II-73, either acutely or chronically at 3 and 6 months. We assessed spatial working memory using the Y-maze. Golgi staining analyzed dendritic morphology in chronically exposed mice to α5-PAM. Western blotting was used to quantify p-Tau and Tau expression. Results: α5-PAM effectively reverses spatial working memory deficits induced by tau phosphorylation both acutely and chronically. Chronic treatment at 3and 6 months mitigates tau-induced loss of spine density. However, α5-PAM does not directly influence p-Tau levels, suggesting cognitive and neurotrophic benefits of GL-II-73s are independent of Tau burden. Conclusions: These results demonstrate the potential for both symptomatic and disease-modifying effects, highlighting the promise of α5-GABAA receptor positive allosteric modulation as a novel therapeutic strategy for addressing cognitive deficits associated with tau phosphorylation in AD pathology.
背景：tau 磷酸化失调是阿尔茨海默病（AD）的特征之一，它会导致认知障碍、神经元萎缩和神经纤维缠结累积。有证据表明，体生长抑素（SST）表达受损，尤其是在SST表达的GABA能神经元中，是导致阿尔茨海默病相关病理生理学的重要原因，并可能加重认知负担。此外，皮层和海马中的SST+中间神经元主要通过参与认知调节的α5-GABAA受体抑制兴奋性神经元的树突。一种新开发的小分子通过正异位调节作用靶向α5-GABAA受体（α5-PAM），我们利用这种小分子的潜力，旨在评估其对与tau磷酸化相关的神经元形态学、认知障碍和蛋白质表达的影响：在PS19转基因小鼠模式中，我们在3个月和6个月时急性或慢性给予α5-PAM GL-II-73。我们使用 Y 型迷宫对空间工作记忆进行了评估。高尔基体染色分析了长期暴露于α5-PAM的小鼠的树突形态。结果：α5-PAM能有效逆转急性和慢性tau磷酸化引起的空间工作记忆缺陷。3个月和6个月的慢性治疗可减轻tau诱导的脊柱密度损失。然而，α5-PAM 并不直接影响 p-Tau 水平，这表明 GL-II-73s 在认知和神经营养方面的益处与 Tau 负担无关：这些结果表明，α5-GABAA 受体正异位调节具有改善症状和疾病的潜在作用，有望成为一种新型治疗策略，用于解决注意力缺失症病理中与 tau 磷酸化相关的认知障碍。
{"title":"Positive Allosteric Modulation of the α5-GABAA receptors prevents neuronal atrophy and cognitive decline independently of tau tangle accumulation in the PS19 mouse model","authors":"Ravinder Naik Dharavath, Ashley Bernardo, Cassandra Marceau-Linhares, Michael Marcotte, Kayla Wong, Celeste Pina-Leblanc, Adrien Bouchet, Dishary Sharmin, James Cook, Kamal Prasad Pandey, Thomas Damien Prevot, Etienne Sibille","doi":"10.1101/2024.09.07.611810","DOIUrl":"https://doi.org/10.1101/2024.09.07.611810","url":null,"abstract":"Background: Dysregulated tau phosphorylation is one of the hallmarks of Alzheimer's disease (AD), and it results in cognitive impairments, neuronal atrophy, and neurofibrillary tangle accumulation. Evidence shows that impaired somatostatin (SST) expression, particularly in SST-expressing GABAergic neurons, significantly contributes to AD-related pathophysiology and may increase cognitive burden. Additionally, SST+ interneurons in cortical layers and the hippocampus inhibit the dendrites of excitatory neurons, primarily through α5-GABAA receptors involved in cognitive regulation. Leveraging the potential of a newly developed small molecule that targets the α5-GABAA receptors via positive allosteric modulation (α5-PAM), we aim to assess its effects on tau phosphorylation-related neuronal morphology, cognitive deficits and protein expression.\u0000Methods: In the PS19 transgenic mouse mode, we administered the α5-PAM, GL-II-73, either acutely or chronically at 3 and 6 months. We assessed spatial working memory using the Y-maze. Golgi staining analyzed dendritic morphology in chronically exposed mice to α5-PAM. Western blotting was used to quantify p-Tau and Tau expression.\u0000Results: α5-PAM effectively reverses spatial working memory deficits induced by tau phosphorylation both acutely and chronically. Chronic treatment at 3and 6 months mitigates tau-induced loss of spine density. However, α5-PAM does not directly influence p-Tau levels, suggesting cognitive and neurotrophic benefits of GL-II-73s are independent of Tau burden.\u0000Conclusions: These results demonstrate the potential for both symptomatic and disease-modifying effects, highlighting the promise of α5-GABAA receptor positive allosteric modulation as a novel therapeutic strategy for addressing cognitive deficits associated with tau phosphorylation in AD pathology.","PeriodicalId":501581,"journal":{"name":"bioRxiv - Neuroscience","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-12DOI: 10.1101/2024.09.10.612361
Chun Chien, Kaikai He, Sarah Perry, Elizabeth Tchitchkan, Yifu Han, Xiling Li, Dion Dickman
Synapses are endowed with the flexibility to change through experience, but must be sufficiently stable to last a lifetime. This tension is illustrated at the Drosophila neuromuscular junction (NMJ), where two motor inputs that differ in structural and functional properties co-innervate most muscles to coordinate locomotion. To stabilize NMJ activity, motor neurons augment neurotransmitter release following diminished postsynaptic glutamate receptor functionality, termed presynaptic homeostatic potentiation (PHP). How these distinct inputs contribute to PHP plasticity remains enigmatic. We have used a botulinum neurotoxin to selectively silence each input and resolve their roles in PHP, demonstrating that PHP is input-specific: Chronic (genetic) PHP selectively targets the tonic MN-Ib, where active zone remodeling enhances Ca2+ influx to promote increased glutamate release. In contrast, acute (pharmacological) PHP selectively increases vesicle pools to potentiate phasic MN-Is. Thus, distinct homeostatic modulations in active zone nanoarchitecture, vesicle pools, and Ca2+ influx collaborate to enable input-specific PHP expression.
{"title":"Distinct input-specific mechanisms enable presynaptic homeostatic plasticity","authors":"Chun Chien, Kaikai He, Sarah Perry, Elizabeth Tchitchkan, Yifu Han, Xiling Li, Dion Dickman","doi":"10.1101/2024.09.10.612361","DOIUrl":"https://doi.org/10.1101/2024.09.10.612361","url":null,"abstract":"Synapses are endowed with the flexibility to change through experience, but must be sufficiently stable to last a lifetime. This tension is illustrated at the Drosophila neuromuscular junction (NMJ), where two motor inputs that differ in structural and functional properties co-innervate most muscles to coordinate locomotion. To stabilize NMJ activity, motor neurons augment neurotransmitter release following diminished postsynaptic glutamate receptor functionality, termed presynaptic homeostatic potentiation (PHP). How these distinct inputs contribute to PHP plasticity remains enigmatic. We have used a botulinum neurotoxin to selectively silence each input and resolve their roles in PHP, demonstrating that PHP is input-specific: Chronic (genetic) PHP selectively targets the tonic MN-Ib, where active zone remodeling enhances Ca2+ influx to promote increased glutamate release. In contrast, acute (pharmacological) PHP selectively increases vesicle pools to potentiate phasic MN-Is. Thus, distinct homeostatic modulations in active zone nanoarchitecture, vesicle pools, and Ca2+ influx collaborate to enable input-specific PHP expression.","PeriodicalId":501581,"journal":{"name":"bioRxiv - Neuroscience","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Neurodegenerative clinical trials often fail due to insufficient drug doses in reaching targeted cells and the unintended delivery to non-targeted cells. This study demonstrates an alternative neuron-selective drug delivery system, which utilizes the synaptic vesicle release and recycling mechanism (SVRM) by antibody shuttles targeting synaptic vesicle transmembrane proteins for molecule delivery. Using Synaptotagmin-2 (SYT2), we exemplify that intravenously administered anti-SYT2 antibodies localize to neuromuscular junctions, undergo uptake, and retrograde transport to ChAT-positive motor neurons (MNs) in the spinal cord and brainstem. The delivery of anti-microtubule agent and Malat1 gapmer antisense oligonucleotide to MNs with anti-SYT2 antibodies induces axon degeneration and reduction of Malat1 RNA expression, respectively. This approach circumvents the blood-spinal cord barrier, enabling selective delivery of therapeutic molecules to neurons while minimizing effects in non-targeted cells. Thus harnessing SVRM presents a promising strategy for enhancing drug concentrations in neurons and improving treatment efficacy for neurodegenerative diseases.
{"title":"Harnessing Synaptic Vesicle Release and Recycling Mechanism for Molecule Delivery to Neurons","authors":"Karen KL Yee, Junichi Kumamoto, Daijiro Inomata, Naoki Suzuki, Ryuhei Harada, Norihiro Yumoto","doi":"10.1101/2024.09.11.612569","DOIUrl":"https://doi.org/10.1101/2024.09.11.612569","url":null,"abstract":"Neurodegenerative clinical trials often fail due to insufficient drug doses in reaching targeted cells and the unintended delivery to non-targeted cells. This study demonstrates an alternative neuron-selective drug delivery system, which utilizes the synaptic vesicle release and recycling mechanism (SVRM) by antibody shuttles targeting synaptic vesicle transmembrane proteins for molecule delivery. Using Synaptotagmin-2 (SYT2), we exemplify that intravenously administered anti-SYT2 antibodies localize to neuromuscular junctions, undergo uptake, and retrograde transport to ChAT-positive motor neurons (MNs) in the spinal cord and brainstem. The delivery of anti-microtubule agent and Malat1 gapmer antisense oligonucleotide to MNs with anti-SYT2 antibodies induces axon degeneration and reduction of Malat1 RNA expression, respectively. This approach circumvents the blood-spinal cord barrier, enabling selective delivery of therapeutic molecules to neurons while minimizing effects in non-targeted cells. Thus harnessing SVRM presents a promising strategy for enhancing drug concentrations in neurons and improving treatment efficacy for neurodegenerative diseases.","PeriodicalId":501581,"journal":{"name":"bioRxiv - Neuroscience","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-12DOI: 10.1101/2024.09.06.611738
Bikash Sahoo, Adam Snyder
The unfolding of neural population activity can be approximated as a dynamical system. Stability in the latent dynamics that characterize neural population activity has been linked with consistency in animal behavior, such as motor control or value-based decision-making. However, whether similar dynamics characterize perceptual activity and decision-making in the visual cortex is not well understood. To test this, we recorded V4 populations in monkeys engaged in a non-match-to-sample visual change-detection task that required sustained engagement. We measured how the stability in the latent dynamics in V4 might affect monkeys' perceptual behavior. Specifically, we reasoned that unstable sensory neural activity around dynamic attractor boundaries may make animals susceptible to taking incorrect actions when withholding action would have been correct ("false alarms"). We made three key discoveries: 1) greater stability was associated with longer trial sequences; 2) false alarm rate decreased (and reaction times slowed) when neural dynamics were more stable; and, 3) low stability predicted false alarms on a single-trial level, and this relationship depended on the elapsed time during the trial, consistent with the latent neural state approaching an attractor boundary. Our results suggest the same outward false alarm behavior can be attributed to two different potential strategies that can be disambiguated by examining neural stability: 1) premeditated false alarms that might lead to greater stability in population dynamics and faster reaction time and 2) false alarms due to unstable sensory activity consistent with misperception.
{"title":"Neural Dynamics Underlying False Alarms in Extrastriate Cortex","authors":"Bikash Sahoo, Adam Snyder","doi":"10.1101/2024.09.06.611738","DOIUrl":"https://doi.org/10.1101/2024.09.06.611738","url":null,"abstract":"The unfolding of neural population activity can be approximated as a dynamical system. Stability in the latent dynamics that characterize neural population activity has been linked with consistency in animal behavior, such as motor control or value-based decision-making. However, whether similar dynamics characterize perceptual activity and decision-making in the visual cortex is not well understood. To test this, we recorded V4 populations in monkeys engaged in a non-match-to-sample visual change-detection task that required sustained engagement. We measured how the stability in the latent dynamics in V4 might affect monkeys' perceptual behavior. Specifically, we reasoned that unstable sensory neural activity around dynamic attractor boundaries may make animals susceptible to taking incorrect actions when withholding action would have been correct (\"false alarms\"). We made three key discoveries: 1) greater stability was associated with longer trial sequences; 2) false alarm rate decreased (and reaction times slowed) when neural dynamics were more stable; and, 3) low stability predicted false alarms on a single-trial level, and this relationship depended on the elapsed time during the trial, consistent with the latent neural state approaching an attractor boundary. Our results suggest the same outward false alarm behavior can be attributed to two different potential strategies that can be disambiguated by examining neural stability: 1) premeditated false alarms that might lead to greater stability in population dynamics and faster reaction time and 2) false alarms due to unstable sensory activity consistent with misperception.","PeriodicalId":501581,"journal":{"name":"bioRxiv - Neuroscience","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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