proliferation

The role of GPR132 in regulating T cell responses in infection and cancer

PROJECT SUMMARY. CD8 T cells play a critical role in protection from a variety of infectious microorganisms, and pathogen-specific CD8 T cells undergo robust expansion, with an individual T cell clones expanding up to 10,000-fold in a matter of days. After infection is resolved, the majority of these T cells die, leaving a small population of memory cells to provide protective immunity from secondary challenge. T cell expansion and contraction are tightly orchestrated processes that involve a delicate balance between stimulatory and inhibitory signals to ensure proper immune function. Dysregulation of the T cell response can have detrimental effects; too little proliferation and the host fails to mount a successful immune response, while excessive proliferation and persistence of effector T cell populations can lead to tissue damage. This proposal aims to determine the role of the G protein coupled receptor GPR132 in the regulation of CD8 T cell responses during infection and tumorigenesis. GPR132 detects oxidized endogenous and microbial lipids, and this can lead to cell cycle arrest; however, the role of GPR132 in CD8 T cells remains unexplored. Here we identify GPR132 as a critical regulator of CD8 T cell expansion and memory differentiation. Completion of the proposed aims will: 1) uncover the temporal role of GPR132 in regulating T cell accumulation and function during infection and tumorigenesis, 2) examine the abundance of GPR132-activating ligands within the tissue during health and disease, and 3) determine how altering GPR132 ligand availability could be used to enhance/inhibit T cell responses. Overall, these studies will provide fundamental insights into the regulatory mechanisms that dictate the magnitude of T cell responses and how they can be modulated therapeutically, which would allow us to boost responses to pathogens/tumors or inhibit pathogenic responses in the context of autoimmune disease.

Airway Epithelial Defense Mechanisms in Combating STAT3-Deficiency-Related Lung Infections

Airway Epithelial Defense Mechanisms in Combating STAT3-Deficiency-Related Lung Infections Signal transducer and activator of transcription 3 (STAT3) regulates the expression of genes essential for various cellular processes, including survival, proliferation, differentiation, self-renewal, angiogenesis, and immune response. Abnormal and persistent STAT3 activation is detected in diverse human cancers, driving multiple pro- oncogenic functions. Multiple antitumor drug development targets the inhibition of STAT3 to treat various types of cancer. Unfortunately, downregulated STAT3 significantly increases host susceptibility to recurrent infections, especially pneumonia. Additionally, individuals with genetic polymorphisms associated with lower STAT3 expression are more susceptible to severe tuberculosis. Furthermore, patients with autosomal dominant hyper- IgE syndrome (AD-HIES), also known as Job Syndrome, which is caused by de novo STAT3 mutations and substantially decreased STAT3 expression, have a significantly increased susceptibility to bacterial and fungal infections, with high mortality rates and a shortened life span often associated with Pseudomonas aeruginosa infections. Gram-negative bacteria, particularly P. aeruginosa, are opportunistic pathogens that frequently cause hospital-acquired infections. The problems are worsened by the emerging P. aeruginosa with multidrug resistance (MDR), especially in patients with repeated antibiotic treatments, such as Job Syndrome sufferers. Notably, airway epithelial cell-derived proteins play a significant role in the antimicrobial milieu, promoting effective host defense against invading pathogens. One of the most critical STAT3-regulated antimicrobial molecules is bactericidal permeability-increasing protein fold A1 (BPIFA1, also known as SPLUNC1), a multifunctional innate immunity molecule and indispensable host defense protein that is abundantly secreted in the lungs. This application aims to elucidate how STAT3 deficiency impairs host epithelial defense against microbial infections and whether BPIFA1-mediated innate immune responses can sufficiently restore effective antimicrobial protection to prevent pneumonia. The long-term objective is to advance our understanding of the respiratory innate immune response, particularly in relation to epithelial cell-specific antimicrobial defense. We characterized BPIFA1 as an airway lining fluid protein secreted apically in the airway lumen and in primary human airway epithelial cultures. In this study, we hypothesize that mucosal BPIFA1 is an essential antimicrobial protein that plays a critical role in host defense against microbial infections in STAT3-deficiency- associated pneumonia. Our proposed studies will assess innate immunity mechanisms regulating the antimicrobial activity of the airway epithelium in STAT3 deficiency-associated lung infections. By focusing on the crucial epithelial-derived protein product, BPIFA1, our study will provide an alternative treatment for respiratory infections by augmenting native host defense mechanisms in high-risk individuals, including AD-HIES, cancer, and immunocompromised patients.

Neutralizing persistent IFN-I to improve HIV-specific CAR T cell therapy

PROJECT SUMMARY A critical hurdle to further improving the quality of life for people living with HIV (PLWH) is the need to resolve the residual immune activation and inflammation that persists even in those taking effective antiretroviral therapy (ART), which suppresses HIV replication. This unresolved and persistent immune activation is associated with increased type-I interferon (IFN-I) signaling, and increased incidence of comorbidities. Encouragingly, reports demonstrate that blocking IFN-I signaling in animal models of HIV infection can reduce HIV reservoirs and restore T cell immune function. We hypothesize that blocking IFN-I would likewise augment engineered T cell-based therapies against HIV, such as chimeric antigen receptor (CAR) T cells. Our prior work has demonstrated that when engineered to express both the 4-1BB and CD28 costimulatory domains and protected from HIV infection, HIV-specific CD4 ectodomain CAR T cells can reduce acute viremia, prevent CD4+ T cell loss, and reduce viral burden in the tissues of HIV-infected humanized mice. However, the reduction of plasma viral loads was ultimately transient, suggesting that the potency of HIV-specific CAR T cells should be further optimized for clinical translation. Our preliminary data highlights interferon-beta (IFNb) as a key immunosuppressive IFN-I negatively regulating CAR T cell proliferation, and we demonstrate that neutralizing IFNb in vivo enhanced the engraftment and persistence of HIV-specific CAR T cells adoptively transferred into HIV-infected ART- suppressed humanized mice. This proposal will interrogate whether IFNb neutralization augments CAR T cell therapy through 1) identifying the mechanism(s) by which chronic IFNb exposure mediates HIV-specific CAR T cell dysfunction, and 2) determining the effect of neutralizing IFNb on CAR T cell function and persistence in HIV infection in vivo. The proposed aims seek to develop the neutralization of IFNb as a novel immunotherapy approach to maximize the potency of HIV-specific CAR T cells aimed at achieving a functional HIV cure.

Identifying host-interacting proteins of Sneathia vaginalis

PROJECT SUMMARY AND ABSTRACT Sneathia vaginalis is a member of the human normal flora of the vagina. It is also a human pathogen that is associated with preterm birth and amniotic fluid infections as well as the most common bacterial species associated with HPV infection and cervical cancer. The identification of S. vaginalis as a human pathogen is recent and little is known about how this bacterium interacts with the host in either its commensal or pathogenic lifestyles. With the exception of a single toxin, no additional virulence factors have been identified. Our preliminary data demonstrates that S. vaginalis grows to high cell density in rich media; however, it fails to grow planktonically in other media unless host cells are present indicating that S. vaginalis relies on host cells for nutrients. This is consistent with its reduced genome. In addition, bacterial proliferation requires close proximity with the host cells and previous studies demonstrate that S. vaginalis can bind a variety of host cells. The proteins that mediate contact are unknown. We hypothesize that proteins on the surface of S. vaginalis are critical for host cell adhesion. We will use two Aims to examine this. Aim 1 will use mass spectrometry to identify S. vaginalis surface proteins. Aim 2 generates deletion strains of potential adhesins identified in Aim 1 as well as predicted host-interacting proteins that have already been identified bioinformatically based on those in other bacteria. The mutant bacteria are then tested in host-cell adhesion assays. Together, these aims will identify for the first time the proteins found on the surface of S. vaginalis while identifying proteins that interact with host cells that would be expected to contribute to either its commensal or pathogenic lifestyles or both. Moreover, these studies would be used to inform clinical lab practice as surface-expressed proteins could be used to identify identifying markers of S. vaginalis detection.

Primary cilia protein IFT88 governs smooth muscle phenotype and vascular remodeling

Project Summary/Abstract Cardiovascular disease remains the leading cause of death in the United States, accounting for nearly 1 million deaths in 2022. Vascular diseases such as atherosclerosis, aneurysm, and coronary artery disease are regulated largely by smooth muscle cells (SMCs) residing in the blood vessel wall. The central dogma of vascular SMC biology is that differentiated cells can de-differentiate and give rise to a spectrum of alternative phenotypes promoting invasion, proliferation, fibrosis, and inflammation, but the mechanisms regulating SMC phenotypic transitions are poorly understood. Intraflagellar transport 88 (IFT88) is an essential protein for the formation of primary cilia, centriole-associated plasma membrane organelles that project into the extracellular milieu and regulate cell cycle reentry and responses to stimuli like growth factors and mechanical strain. Non- ciliary functions of IFT88 also include progression of the cell cycle checkpoint and polarized motility, both of which are functionally critical for SMC-mediated vascular remodeling. Little is known about the functional role of the primary cilia in SMCs and the role of the essential cilia protein IFT88 in regulating SMC phenotype. To address this gap in knowledge, my postdoctoral studies focus on the role of IFT88 in the context of intimal hyperplasia (K99). During the independent phase (R00), I will apply these findings to arteriovenous fistula (AVF) maturation, a surgical intervention often required for dialysis individuals with polycystic kidney disease (PKD), an IFT88 loss-of-function disease. I will test my central hypothesis that cilia are key regulators of SMC phenotype in three Specific Aims: 1) determine the role of IFT88-dependent SMC primary cilia in mechanotransduction of extracellular matrix (ECM) stiffness (K99), 2) determine the role of IFT88 in pathological intimal hyperplasia (K99), and 3) test whether SMC IFT88 expression is required for adaptive remodeling of grafted veins following AVF placement (R00). Overall, we propose that IFT88+ ciliated SMC represent an unidentified subclass of the SMC phenotype spectrum that is primarily responsible for vascular remodeling and is an attractive potential target for treatment of vascular diseases. Building on strong existing collaborations, we have formed a research and mentoring team with expertise in SMC pathophysiology, primary cilia biology, mechanobiology, AVF surgery, and PKD to complete the proposed aims. The additional training in cell-ECM interactions (Aim 1, K99), in vivo murine ligation injury and in vivo cilia imaging (Aim 2, K99), and AVF surgery and PKD pathology (Aim 3, R00) will be indispensable for preparing the PI, Dr. O’Brien, for his career as an independent investigator. Completion of the proposed aims will also contribute directly to an understanding of the function of IFT88-dependent primary cilia in SMCs and may likely identify novel therapeutic targets for treatment of vascular diseases.

The multiciliation cycle: a variant cell cycle coordinating centriole biogenesis and ciliogenesis

Project summary/Abstract Differentiating multiciliated cells line the mammalian airway and are critical for protecting the lungs from inhaled pathogens and particulates. Multiciliated cells have a distinct architecture from other cell types, having hundreds of centrioles, each of which matures into a basal body and nucleates a motile cilium. Defects in multiciliation cause a form of Primary Ciliary Dyskinesia (PCD), a lung disease. Most cells generate two centrioles and one cilium per cell cycle. We found that differentiating multiciliated cells redeploy cell cycle regulators into a novel cell cycle variant, which we refer to as the multiciliation cycle, to break these rules, generate hundreds of centrioles and cilia, and coordinate their differentiation. The multiciliation cycle redeploys many mitotic cell cycle regulators, including cyclin-dependent kinases (CDKs) and their cognate cyclins. For example, Cyclin D1-CDK4/6, regulators of mitotic G1 to S progression, is required for multiciliated cell fate initiation and entry into the multiciliation cycle. While we have focused on lung multiciliated cells, others have found that cell cycle regulators similarly participate in multiciliation of ependymal cells of the brain. Some cells, such as mammalian trophoblast giant cells, employ cell cycle variants like the endocycle to bypass mitosis. We propose that the multiciliation cycle is another cell cycle variant that augments some aspects of the canonical cell cycle, such as centriole synthesis, and blocks others, such as DNA replication. During the multiciliation cycle, E2F7, a transcriptional regulator of canonical S to G2 progression, is expressed at high levels. During multiciliated cell differentiation, E2F7 directly dampens expression of genes encoding DNA replication machinery and terminates the S phase-like gene expression program. Loss of E2F7 causes a reacquisition of DNA synthesis in multiciliated cells and dysregulation of multiciliation cycle progression, disrupting centriole maturation and ciliogenesis. We propose that multiciliated cell differentiation is coordinated by an alternative cell cycle that organizes, instead of cell proliferation, the steps of cell differentiation. In this project, we investigate how the multiciliation cycle redeploys the mitotic cell cycle regulatory framework to generate many centrioles without undergoing DNA synthesis or cytokinesis. More specifically, we seek to uncover how CDKs and cyclins are regulated to control the amount and timing of basal body synthesis, how Retinoblastoma (RB) protein controls the transcriptional program of multiciliation, and how E2Fs advance the multiciliation cycle. This work will test the hypothesis that multiciliation is organized by a variant cell cycle that uncouples centriole synthesis from DNA replication and mitosis. We propose that his variant cell cycle orchestrates progression through sequential phases required to construct the multiciliated cells that protect the lungs.

Cellular Crosstalk in Brain Development, Evolution and Disease

Cellular crosstalk is an essential process during brain development and is influenced by numerous factors, including cell morphology, adhesion, the local extracellular matrix and secreted vesicles. Inspired by mutations associated with neurodevelopmental disorders, we focus on understanding the role of extracellular mechanisms essential for the proper development of the human brain. Therefore, we combine 2D and 3D in vitro human models to better understand the molecular and cellular mechanisms involved in progenitor proliferation and fate, migration and maturation of excitatory and inhibitory neurons during human brain development and tackle the causes of neurodevelopmental disorders.

Cellular and genetic mechanisms of cerebral cortex folding

One of the most prominent features of the human brain is the fabulous size of the cerebral cortex and its intricate folding, both of which emerge during development. Over the last few years, work from my lab has shown that specific cellular and genetic mechanisms play central roles in cortex folding, particularly linked to neural stem and progenitor cells. Key mechanisms include high rates of neurogenesis, high abundance of basal Radial Glia Cells (bRGCs), and neuron migration, all of which are intertwined during development. We have also shown that primary cortical folds follow highly stereotyped patterns, defined by a spatial-temporal protomap of gene expression within germinal layers of the developing cortex. I will present recent findings from my laboratory revealing novel cellular and genetic mechanisms that regulate cortex expansion and folding. We have uncovered the contribution of epigenetic regulation to the establishment of the cortex folding protomap, modulating the expression levels of key transcription factors that control progenitor cell proliferation and cortex folding. At the single cell level, we have identified an unprecedented diversity of cortical progenitor cell classes in the ferret and human embryonic cortex. These are differentially enriched in gyrus versus sulcus regions and establish parallel cell lineages, not observed in mouse. Our findings show that genetic and epigenetic mechanisms in gyrencephalic species diversify cortical progenitor cell types and implement parallel cell linages, driving the expansion of neurogenesis and patterning cerebral cortex folds.

Gut/Body interactions in health and disease

The adult intestine is a major barrier epithelium and coordinator of multi-organ functions. Stem cells constantly repair the intestinal epithelium by adjusting their proliferation and differentiation to tissue intrinsic as well as micro- and macro-environmental signals. How these signals integrate to control intestinal and whole-body homeostasis is largely unknown. Addressing this gap in knowledge is central to an improved understanding of intestinal pathophysiology and its systemic consequences. Combining Drosophila and mammalian model systems my laboratory has discovered fundamental mechanisms driving intestinal regeneration and tumourigenesis and outlined complex inter-organ signaling regulating health and disease. During my talk, I will discuss inter-related areas of research from my lab, including:1- Interactions between the intestine and its microenvironment influencing intestinal regeneration and tumourigenesis. 2- Long-range signals from the intestine impacting whole-body in health and disease.

Cellular crosstalk in Neurodevelopmental Disorders

Cellular crosstalk is an essential process during brain development and it is influenced by numerous factors, including the morphology of the cells, their adhesion molecules, the local extracellular matrix and the secreted vesicles. Inspired by mutations associated with neurodevelopmental disorders, we focus on understanding the role of extracellular mechanisms essential for the correct development of the human brain. Hence, we combine the in vivo mouse model and the in vitro human-derived neurons, cerebral organoids, and dorso-ventral assembloids in order to better comprehend the molecular and cellular mechanisms involved in ventral progenitors’ proliferation and fate as well as migration and maturation of inhibitory neurons during human brain development and tackle the causes of neurodevelopmental disorders. We particularly focus on mutations in genes influencing cell-cell contacts, extracellular matrix, and secretion of vesicles and therefore study intrinsic and extrinsic mechanisms contributing to the formation of the brain. Our data reveal an important contribution of cell non-autonomous mechanisms in the development of neurodevelopmental disorders.

Integration of 3D human stem cell models derived from post-mortem tissue and statistical genomics to guide schizophrenia therapeutic development

Schizophrenia is a neuropsychiatric disorder characterized by positive symptoms (such as hallucinations and delusions), negative symptoms (such as avolition and withdrawal) and cognitive dysfunction1. Schizophrenia is highly heritable, and genetic studies are playing a pivotal role in identifying potential biomarkers and causal disease mechanisms with the hope of informing new treatments. Genome-wide association studies (GWAS) identified nearly 270 loci with a high statistical association with schizophrenia risk; however each locus confers only a small increase in risk therefore it is difficult to translate these findings into understanding disease biology that can lead to treatments. Induced pluripotent stem cell (iPSC) models are a tractable system to translate genetic findings and interrogate mechanisms of pathogenesis. Mounting research with patient-derived iPSCs has proposed several neurodevelopmental pathways altered in SCZ, such as neural progenitor cell (NPC) proliferation, imbalanced differentiation of excitatory and inhibitory cortical neurons. However, it is unclear what exactly these iPS models recapitulate, how potential perturbations of early brain development translates into illness in adults and how iPS models that represent fetal stages can be utilized to further drug development efforts to treat adult illness. I will present the largest transcriptome analysis of post-mortem caudate nucleus in schizophrenia where we discovered that decreased presynaptic DRD2 autoregulation is the causal dopamine risk factor for schizophrenia (Benjamin et al, Nature Neuroscience 2022 https://doi.org/10.1038/s41593-022-01182-7). We developed stem cell models from a subset of the postmortem cohort to better understand the molecular underpinnings of human psychiatric disorders (Sawada et al, Stem Cell Research 2020). We established a method for the differentiation of iPS cells into ventral forebrain organoids and performed single cell RNAseq and cellular phenotyping. To our knowledge, this is the first study to evaluate iPSC models of SZ from the same individuals with postmortem tissue. Our study establishes that striatal neurons in the patients with SCZ carry abnormalities that originated during early brain development. Differentiation of inhibitory neurons is accelerated whereas excitatory neuronal development is delayed, implicating an excitation and inhibition (E-I) imbalance during early brain development in SCZ. We found a significant overlap of genes upregulated in the inhibitory neurons in SCZ organoids with upregulated genes in postmortem caudate tissues from patients with SCZ compared with control individuals, including the donors of our iPS cell cohort. Altogether, we demonstrate that ventral forebrain organoids derived from postmortem tissue of individuals with schizophrenia recapitulate perturbed striatal gene expression dynamics of the donors’ brains (Sawada et al, biorxiv 2022 https://doi.org/10.1101/2022.05.26.493589).

Neuron-glial interactions in health and disease: from cognition to cancer

In the central nervous system, neuronal activity is a critical regulator of development and plasticity. Activity-dependent proliferation of healthy glial progenitors, oligodendrocyte precursor cells (OPCs), and the consequent generation of new oligodendrocytes contributes to adaptive myelination. This plasticity of myelin tunes neural circuit function and contributes to healthy cognition. The robust mitogenic effect of neuronal activity on normal oligodendroglial precursor cells, a putative cellular origin for many forms of glioma, suggests that dysregulated or “hijacked” mechanisms of myelin plasticity might similarly promote malignant cell proliferation in this devastating group of brain cancers. Indeed, neuronal activity promotes progression of both high-grade and low-grade glioma subtypes in preclinical models. Crucial mechanisms mediating activity-regulated glioma growth include paracrine secretion of BDNF and the synaptic protein neuroligin-3 (NLGN3). NLGN3 induces multiple oncogenic signaling pathways in the cancer cell, and also promotes glutamatergic synapse formation between neurons and glioma cells. Glioma cells integrate into neural circuits synaptically through neuron-to-glioma synapses, and electrically through potassium-evoked currents that are amplified through gap-junctional coupling between tumor cells This synaptic and electrical integration of glioma into neural circuits is central to tumor progression in preclinical models. Thus, neuron-glial interactions not only modulate neural circuit structure and function in the healthy brain, but paracrine and synaptic neuron-glioma interactions also play important roles in the pathogenesis of glial cancers. The mechanistic parallels between normal and malignant neuron-glial interactions underscores the extent to which mechanisms of neurodevelopment and plasticity are subverted by malignant gliomas, and the importance of understanding the neuroscience of cancer.

Epigenome regulation in neocortex expansion and generation of neuronal subtypes

Evolutionarily, the expansion of the human neocortex accounts for many of the unique cognitive abilities of humans. This expansion appears to reflect the increased proliferative potential of basal progenitors (BPs) in mammalian evolution. Further cortical progenitors generate both glutamatergic excitatory neurons (ENs) and GABAergic inhibitory interneurons (INs) in human cortex, whereas they produce exclusively ENs in rodents. The increased proliferative capacity and neuronal subtype generation of cortical progenitors in mammalian evolution may have evolved through epigenetic alterations. However, whether or how the epigenome in cortical progenitors differs between humans and other species is unknown. Here, we report that histone H3 acetylation is a key epigenetic regulation in BP profiling of sorted BPs, we show that H3K9 acetylation is low in murine BPs and high in amplification, neuronal subtype generation and cortical expansion. Through epigenetic profiling of sorted BPs, we show that H3K9 acetylation is low in murine BPs and high in human BPs. Elevated H3K9ac preferentially increases BP proliferation, increasing the size and folding of the normally smooth mouse neocortex. Furthermore, we found that the elevated H3 acetylation activates expression of IN genes in in developing mouse cortex and promote proliferation of IN progenitor-like cells in cortex of Pax6 mutant mouse models. Mechanistically, H3K9ac drives the BP amplification and proliferation of these IN progenitor-like cells by increasing expression of the evolutionarily regulated gene, TRNP1. Our findings demonstrate a previously unknown mechanism that controls neocortex expansion and generation of neuronal subtypes. Keywords: Cortical development, neurogenesis, basal progenitors, cortical size, gyrification, excitatory neuron, inhibitory interneuron, epigenetic profiling, epigenetic regulation, H3 acetylation, H3K9ac, TRNP1, PAX6

Malignant synaptic plasticity in pediatric high-grade gliomas

Pediatric high-grade gliomas (pHGG) are a devastating group of diseases that urgently require novel therapeutic options. We have previously demonstrated that pHGGs directly synapse onto neurons and the subsequent tumor cell depolarization, mediated by calcium-permeable AMPA channels, promotes their proliferation. The regulatory mechanisms governing these postsynaptic connections are unknown. Here, we investigated the role of BDNF-TrkB signaling in modulating the plasticity of the malignant synapse. BDNF ligand activation of its canonical receptor, TrkB (which is encoded for by the gene NTRK2), has been shown to be one important modulator of synaptic regulation in the normal setting. Electrophysiological recordings of glioma cell membrane properties, in response to acute neurotransmitter stimulation, demonstrate in an inward current resembling AMPA receptor (AMPAR) mediated excitatory neurotransmission. Extracellular BDNF increases the amplitude of this glutamate-induced tumor cell depolarization and this effect is abrogated in NTRK2 knockout glioma cells. Upon examining tumor cell excitability using in situ calcium imaging, we found that BDNF increases the intensity of glutamate-evoked calcium transients in GCaMP6s expressing glioma cells. Western blot analysis indicates the tumors AMPAR properties are altered downstream of BDNF induced TrkB activation in glioma. Cell membrane protein capture (via biotinylation) and live imaging of pH sensitive GFP-tagged AMPAR subunits demonstrate an increase of calcium permeable channels at the tumors postsynaptic membrane in response to BDNF. We find that BDNF-TrkB signaling promotes neuron-to-glioma synaptogenesis as measured by high-resolution confocal and electron microscopy in culture and tumor xenografts. Our analysis of published pHGG transcriptomic datasets, together with brain slice conditioned medium experiments in culture, indicates the tumor microenvironment as the chief source of BDNF ligand. Disruption of the BDNF-TrkB pathway in patient-derived orthotopic glioma xenograft models, both genetically and pharmacologically, results in an increased overall survival and reduced tumor proliferation rate. These findings suggest that gliomas leverage normal mechanisms of plasticity to modulate the excitatory channels involved in synaptic neurotransmission and they reveal the potential to target the regulatory components of glioma circuit dynamics as a therapeutic strategy for these lethal cancers.

Faking emotions and a therapeutic role for robots and chatbots: Ethics of using AI in psychotherapy

In recent years, there has been a proliferation of social robots and chatbots that are designed so that users make an emotional attachment with them. This talk will start by presenting the first such chatbot, a program called Eliza designed by Joseph Weizenbaum in the mid 1960s. Then we will look at some recent robots and chatbots with Eliza-like interfaces and examine their benefits as well as various ethical issues raised by deploying such systems.

Modulation of oligodendrocyte development and myelination by voltage-gated Ca++ channels

The oligodendrocyte generates CNS myelin, which is essential for normal nervous system function. Thus, investigating the regulatory and signaling mechanisms that control its differentiation and the production of myelin is relevant to our understanding of brain development and of adult pathologies such as multiple sclerosis. We have recently established that the activity of voltage-gated Ca++ channels is crucial for the adequate migration, proliferation and maturation of oligodendrocyte progenitor cells (OPCs). Furthermore, we have found that voltage-gated Ca++ channels that function in synaptic communication between neurons also mediate synaptic signaling between neurons and OPCs. Thus, we hypothesize that voltage-gated Ca++ channels are central components of OPC-neuronal synapses and are the principal ion channels mediating activity-dependent myelination.

Malformation of cortical development: the genesis of epileptogenic networks

Malformations of cortical development (MCDs) result from alterations of one or combined developmental steps, including progenitors proliferation, neuronal migration and differentiation. They are important cause of childhood epilepsy and frequently associate cognitive deficits and behavioral alterations. Though the genetic basis of MCDs have known prominent progress during the past decade, including the identification of somatic, mosaic mutations responsible for focal MCDs, the pathophysiological mechanisms linking malformations to epileptogenesis remain elusive. In this seminar I will present data from my team and from the literature addressing this topic in two different MCDs types, the subcortical band heterotopia as a model of cortical migration defect and mTOR- dependent MCDs , that characterize by cortical dyslamination and neuronal differentiation defects.

Neuroendocrine control of female germline stem cell increase in the fruit fly Drosophila melanogaster

The development and maintenance of many tissues are fueled by stem cells. Many studies have addressed how intrinsic factors and local signals from neighboring niche cells maintain stem cell identity and proliferative potential. In contrast, it is poorly understood how stem cell activity is controlled by systemic, tissue-extrinsic signals in response to environmental cues and changes in physiological status. Our laboratory has been focusing on female germline stem cells (fGSCs) in the fruit fly Drosophila melanogaster as a model system and studying neuroendocrine control of fGSC increase. The increase of fGSCs is induced by mating stimuli. We have previously reported that mating-induced fGSC increase is regulated by the ovarian steroid hormone and the enteroendocrine peptide hormone [Ameku & Niwa, PLOS Genetics 2016; Ameku et al. PLOS Biology 2018]. In this presentation, we report our recent finding showing a neuronal mechanism of mating-induced fGSC increase. We first found that the ovarian somatic cell-specific RNAi for Oamb, a G protein-coupled receptor for the neurotransmitter octopamine, failed to induce fGSC proliferation after mating. Both ex vivo and in vivo experiments revealed that octopamine and Oamb positively regulated mating-induced fGSC increase via intracellular Ca 2+ signaling. We also found that a small subset of octopaminergic neurons directly projected to the ovary, and neuronal activity of these neurons was required for mating-induced fGSC increase. This study provides a mechanism describing how the neuronal system controls stem cell behavior through stem cell niche signaling [Yoshinari et al. eLife 2020]. Here I will also present our recent data showing how the neuroendocrine system couples fGSC behavior to multiple environmental cues, such as mating and nutrition.

Microglia function and dysfunction in Alzheimer’s disease

Emerging genetic studies of late-onset Alzheimer’s Disease implicate the brain’s resident macrophages in the pathogenesis of AD. More than half the risk genes associated with late-onset AD are selectively expressed in microglia and peripheral myeloid cells; yet we know little about the underlying biology or how myeloid cells contribute to AD pathogenesis. Using single-cell RNA sequencing and spatial transcriptomics we identified molecular signatures that can be used to localize and monitor distinct microglia functional states in the human and mouse brain. Our results show that microglia assume diverse functional states in development, aging and injury, including populations corresponding to known microglial functions including proliferation, migration, inflammation, and synaptic phagocytosis. We identified several innate immune pathways by which microglia recognize and prune synapses during development and in models of Alzheimer’s disease, including the classical complement cascade. Illuminating the mechanisms by which developing synaptic circuits are sculpted is providing important insight on understanding how to protect synapses in Alzheimer’s and other neurodegenerative diseases of synaptic dysfunction.

Theory of gating in recurrent neural networks

Recurrent neural networks (RNNs) are powerful dynamical models, widely used in machine learning (ML) for processing sequential data, and also in neuroscience, to understand the emergent properties of networks of real neurons. Prior theoretical work in understanding the properties of RNNs has focused on models with additive interactions. However, real neurons can have gating i.e. multiplicative interactions, and gating is also a central feature of the best performing RNNs in machine learning. Here, we develop a dynamical mean-field theory (DMFT) to study the consequences of gating in RNNs. We use random matrix theory to show how gating robustly produces marginal stability and line attractors – important mechanisms for biologically-relevant computations requiring long memory. The long-time behavior of the gated network is studied using its Lyapunov spectrum, and the DMFT is used to provide a novel analytical expression for the maximum Lyapunov exponent demonstrating its close relation to relaxation-time of the dynamics. Gating is also shown to give rise to a novel, discontinuous transition to chaos, where the proliferation of critical points (topological complexity) is decoupled from the appearance of chaotic dynamics (dynamical complexity), contrary to a seminal result for additive RNNs. Critical surfaces and regions of marginal stability in the parameter space are indicated in phase diagrams, thus providing a map for principled parameter choices for ML practitioners. Finally, we develop a field-theory for gradients that arise in training, by incorporating the adjoint sensitivity framework from control theory in the DMFT. This paves the way for the use of powerful field-theoretic techniques to study training/gradients in large RNNs.

Association of canonical NF-κB signaling pathway with apoptotic cell death and cell proliferation in glucocorticoid-induced neurotoxicity and after vitamin D3 supplementation

Defective intracellular cholesterol mobilization deranges the proliferation/differentiation balance of neuronal precursors in a mouse model of Niemann Pick C disease

Embryonic nutritional hyperglycemia inhibits cell proliferation in the zebrafish retina

Hippocampus proteomics profiling of major depression and antidepressant treatment reveals pathways involved in cell proliferation, differentiation and connectivity

Intranasal Delivery of Galanin 2 and Neuropeptide Y1 Agonists Enhanced Spatial Memory Performance and antidepressant effects through Neuronal Precursor Cells Proliferation in the hippocampus

Nwd1 controls NSPCs proliferation through purinosome formation

Repeated anodal transcranial direct current stimulation (RA-tDCS) increases hippocampal cell proliferation in young-adult mice

Secreted factors modulating damage-induced proliferation in the adult fly brain after traumatic injury

CETN3 deficiency perturbs proliferation and differentiation of neural stem cells in the developing human cerebral organoids

FENS Forum 2024

Control of neural precursor cells proliferation and differentiation by the Fragile X messenger ribonucleoprotein 1 (FMRP): Insights into the etiology of Fragile X Syndrome

FENS Forum 2024

The impact of autism spectrum disorder-risk genes on human neural stem cell proliferation and survival

FENS Forum 2024

LRIG1 regulates the balance between proliferation and quiescence in glioblastoma stem cells

FENS Forum 2024

Possible role of NKCC1 in the proliferation of hippocampal neural stem cells during Alzheimer's disease

FENS Forum 2024