2006 — 2010 |
Novitch, Bennett G |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Function of Olig2-Regulated Genes in Spinal Motor Neuron Development @ University of Michigan At Ann Arbor
[unreadable] DESCRIPTION (provided by applicant): The formation of neural circuits in the central nervous system (CNS) depends on the ability of undifferentiated stem and progenitor cells to produce distinct classes of neurons and glial cells in a stereotyped manner. Our main objective is to understand the molecular details of how general aspects of cell cycle regulation and differentiation are coordinated with cell fate decisions. Previously, we identified a bHLH class transcriptional represser called Olig2 that is selectively expressed by motor neuron (MN) progenitors in the spinal cord, and involved in coordinating three key features of MN development: MN- specific gene expression, cell cycle exit, and general neuronal differentiation. Since Olig2 functions as a represser, we hypothesize that Olig2 must direct MN formation through its ability to shut off the expression of other important regulatory genes that themselves control the fate, proliferation, and differentiation of stem and progenitor cells in the CNS. The identity of these genes is currently not known. Using in vitro and in vivo assays of gene function in chick and mouse spinal cord, we will examine the regulated expression of three newly identified Olig2 targets and determine how these genes control different aspects of MN differentiation. First, we will determine the role of Hes genes in controlling the expression of the proneural bHLH protein Neurogenin2 and the overall capacity of MN progenitors to differentiate. Second, we will examine the role that Id genes play in inhibiting the function of Olig2 and Ngn2 to control the timing of MN differentiation. Third, we will test the role of PLZF, a transcription factor that controls stem cell self-renewal in other tissues, in maintaining spinal cord progenitors in an undifferentiated state. Together, these studies will provide significant insight into how stem and progenitor cells become specialized to generate specific cell types in the CNS, and provide a detailed understanding of how the processes of cellular division and differentiation are controlled. Insights into this process are important for our understanding of how different cell types in the nervous system are initially formed, and critical for current and future efforts to develop stem cell therapies to repair injured or diseased neural tissue. [unreadable] [unreadable]
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0.958 |
2010 — 2014 |
Novitch, Bennett G |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Transcriptional Regulation of Neuronal Differentiation @ University of California Los Angeles
DESCRIPTION (provided by applicant): The development of the central nervous system depends upon the ability of neural stem and progenitor cells to produce an array of distinct neurons and glia that carry out highly specialized functions in mature neural networks. Errors in this process can result in devastating developmental abnormalities that disrupt the integrity of the nervous system or cause more subtle defects that affect learning, behavior, communication, and movement. In our proposed research, we will investigate the genetic pathways that regulate the formation of motor neurons in the spinal cord during embryonic development. We have recently found that members of the Foxp transcription factor family are progressively expressed as motor neuron differentiation proceeds, beginning with Foxp2 in dividing progenitors, followed by Foxp4 as the cells differentiate, and then Foxp1 in subsets of postmitotic motor neurons. Foxp proteins are required for the development of many tissues in the body and alterations in their function contributes to cancerous growth. Foxps are also broadly expressed throughout the CNS, and their function has been implicated in the development of brain regions associated with language. However, at the cellular and molecular level, the functions of Foxp proteins in the nervous system remain largely unknown. Previously, we have shown that Foxp1 is essential for the formation of the MN subtypes that innervate the limbs and sympathetic nervous system, raising the question of what role(s) do the other Foxp proteins play in neural development? In Aim 1 of the proposed research, we will investigate the actions of Foxp2 and Foxp4 in regulating neuroepithelial integrity and neural stem/progenitor cell maintenance. In Aim 2, we will test the contributions of each Foxp protein to MN fate specification and differentiation. Through these studies, we will provide important new insights into how motor circuits are formed in developing embryos, and how this process may eventually be recapitulated for the repair of injured or diseased neural tissue. In addition, given the broad expression of Foxps in the nervous system and their association with neurological disorders, we anticipate that our studies will further provide more general information on how this transcription factor family contributes to the formation and function of the CNS. )
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0.958 |
2015 — 2019 |
Novitch, Bennett G |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Molecular Pathways Controlling Respiratory Motor Neuron Formation and Function @ University of California Los Angeles
? DESCRIPTION (provided by applicant): Breathing is the most essential of our motor activities that starts at birth and persists until death. At the core of this vital function are respiratory mtor neurons (MNs) in the spinal cord that innervate distinct muscle targets such as the diaphragm, intercostals, and abdominals to produce alternating inspiratory and expiratory movements. These activities are principally driven by descending inputs provided by rhythm generating neurons in the brainstem that selectively form monosynaptic synapses with respiratory MNs while avoiding other MN classes. Defects in respiratory motor circuit formation can result in a variety of breathing disorders ranging from sleep apneas to potentially fatal respiratory distress syndromes. Moreover, respiratory motor loss or dysfunction is the primary cause of death in many neurodegenerative diseases and traumatic injuries. Despite the importance of respiratory MNs function for survival, remarkably little is known about the developmental origins of these cells and the mechanisms that guide their assembly into functional motor circuits. In our previous work, we identified a novel population of spinal MNs termed the hypaxial motor column (HMC) associated with innervation of body wall muscles and the diaphragm. We further discovered that HMC MN formation is actively suppressed by the transcription factor Foxp1. In Foxp1 mutants, MNs acquire HMC characteristics and display exuberant growth towards respiratory muscle targets. From these findings we conclude first that respiratory MNs are likely the mature derivatives of the HMC, and second that Foxp1 plays a critical role suppressing the program of respiratory MN formation. We build upon these observations to elucidate the developmental program through which respiratory motor circuits are constructed. In Aim 1, we will examine the organizational features of the HMC, particularly its subdivision into pools associated with inspiratory and expiratory motor activities. We will also examine the function of transcription factors that our preliminary studies show are reciprocally expressed by inspiratory and expiratory MN subpopulations and thus candidates for conveying these MN activities. Lastly, in Aim 2, we will examine how descending respiratory premotor inputs from the brainstem respond to changes in either the molecular identity of different MN subtypes or their settling position within the spinal cord in terms of axonal targeting and selection of synaptic partners. Through these studies we hope to gain fundamental insights into how respiratory motor circuits are constructed and the organizational principles of descending pathways in the CNS. This information will be invaluable for understanding the basis of disorders that impair respiratory functions, and future efforts to evoke repair of the diseased or damaged spinal cord by harnessing these developmental mechanisms.
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0.958 |
2015 — 2019 |
Novitch, Bennett G |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Regulation of Neural Progenitor Functions Underlying Cortical Growth & Complexity @ University of California Los Angeles
? DESCRIPTION (provided by applicant): A notable determinant of human intellectual capacity is the enormous size and complexity of our neocortex. The neocortex forms during embryogenesis and then expands during fetal development when progenitors differentiate to populate the cortical plate. Defects in brain growth and morphogenesis result in a host of neurodevelopmental disorders, neuropsychiatric diseases, and intellectual disabilities. A key step towards understanding the normal and abnormal functions of the brain thus lies in defining the mechanisms driving neocortical growth. Progress towards this goal has been made though the identification of functionally distinct neural progenitor populations, most prominently ventricular radial glia (vRG), intermediate progenitor (IP), and basal/outer radial glia (bRG) cell. These classes of progenitors are common to both rodents and humans. However, recent studies have proposed that the neocortical enlargement and complexity seen in humans may result in part from a substantial increase in the genesis of bRG and IP cells that is not seen in rodents. Remarkably little is known about the mechanisms behind this human-specific expansion. Our preliminary experiments implicate Foxp transcription factors as important components to this process. Foxp1 and Foxp4 are expressed in the human neocortex as vRG cells transform into bRG and IP cells, and altering Foxp1 and Foxp4 functions in mouse changes cortical development in a manner suggesting that they play pivotal roles controlling the production of bRG and IP cells respectively. In this proposal, we will determine the function of Foxp proteins in both mouse and human cortical development. In Aim 1 we will characterize the expression of Foxp proteins in the developing mouse and human neocortex. In Aim 2, we will determine how manipulation of Foxp functions alters the generation of bRG and IP cells, and the overall size and structure of the cerebral cortex. Lastly, in Aim 3 we will define the genomic targets of Foxp proteins mediating their contributions to neocortical growth.
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0.958 |
2020 — 2021 |
Fregoso, Oliver I (co-PI) [⬀] Novitch, Bennett G |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Integrative Modeling of Hiv-Associated Neurocognitive Disorder in Human Brain Organoids @ University of California Los Angeles
PROJECT SUMMARY Approximately 40 million people are currently infected by HIV, with an additional 1.7 million people newly infected each year. While only a single person has been functionally cured of HIV, advances in antiretroviral therapy (ART) have drastically decreased AIDS-related illnesses and deaths for individuals on ART. However, HIV+ patients on ART still face debilitating AIDS-independent diseases, including HIV-associated neurocognitive disorders (HAND). HAND refers to a spectrum of three neurocognitive disorders that influence survival, quality of life, and everyday function: asymptomatic neurocognitive impairment (ANI), mild neurocognitive disorder (MND), and HIV-associated dementia (HAD). While the number of patients with the more severe forms of HAND have declined since the introduction of ART, an estimated 15-55% of HIV+ patients taking ART still develop a neurocognitive disorder. Patients with ANI are two to six times more likely to progress to a more severe form of HAND when compared to HIV+ patients who are neurocognitively normal. Thus, HAND remains an important and prevalent HIV-associated disease to affect individuals in the ART era. It is now thought that HAND develops because of functional changes in neurons caused by chronic inflammation and HIV infection of an immune cell in the brain, microglia. Though they are not a neuronal cell, microglia do play an important role in the general health and function of neural tissue. The immune responses of microglia are thought to be tightly regulated and controlled as to not normally harm the surrounding neurons. We do know that HIV can infect microglia. However, little is known about the progression of acute and chronic HIV infection in microglia nor how and what impact these infected cells have on surrounding neuronal tissue. Moreover, HIV infection is frequently associated with intravenous drug us such as heroin along with the growing abuse of prescription opioids. It remains unclear how the use of these drugs alters both neuronal and innate immune signaling and further contributes to HAND. One major roadblock in understanding infection of microglia has been the lack of systems for analysis in culture, as well as means for studying their impact on human brain functions. Recent developments in human pluripotent stem cell (hPSC)-derived microglia and 3D-brain organoids have opened new doors to understand HIV infection in these otherwise intractable cells. We have begun to bridge this knowledge gap by leveraging our strengths in HIV and brain organoid biology to model HAND in culture, where we can finally begin to answer important questions in the roles of HIV, opioids, and microglia and other cells in this debilitating HIV- associated disease. Success of our proposed research will 1) define the response of microglia to HIV infection and opioid treatment, 2) characterize how dysregulated microglia affect brain organoid structure, neural network health, and signaling, and 3) establish a foundation for therapeutic discovery to reduce neuroinflammation and HAND.
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0.958 |
2020 — 2021 |
Novitch, Bennett G |
P50Activity Code Description: To support any part of the full range of research and development from very basic to clinical; may involve ancillary supportive activities such as protracted patient care necessary to the primary research or R&D effort. The spectrum of activities comprises a multidisciplinary attack on a specific disease entity or biomedical problem area. These grants differ from program project grants in that they are usually developed in response to an announcement of the programmatic needs of an Institute or Division and subsequently receive continuous attention from its staff. Centers may also serve as regional or national resources for special research purposes. |
Mechanisms Underlying Non-Rem Sleep and Neural Oscillation Abnormalities in Dup15q and Rett Syndrome: Effects On Intellectual Disability @ University of California Los Angeles
ABSTRACT Sleep impairments are ubiquitous in IDDs, and sleep problems profoundly impact quality of life and neurodevelopmental outcomes. The Center proposes a model research project, focused on the mechanisms underlying sleep impairments in IDDs using a multidisciplinary approach that includes a clinical component, animal models, and brain organoid models using patient-derived induced pluripotent stem cells. This project builds on findings from our previous IDDRC model project and the cells and circuits core, inspired by two striking findings: (1) in Dup15q syndrome, our investigators discovered profoundly abnormal sleep physiology, characterized by abnormal sleep spindles and attenuated slow-wave sleep (SWS), among patients who had undergone overnight clinical, with magnitude of these EEG abnormalities correlated with the degree of intellectual disability and (2) in Rett syndrome organoid models, our investigators quantified abnormal oscillatory activity in the earliest stages of development. For this project, we take a fully translational approach to study mechanisms underlying neural oscillations and sleep in Dup15q and Rett syndrome. In Aim 1 (Clinical), we verify abnormalities in sleep physiology (SWS and sleep spindle density) in clinical EEGs of young children with Dup15q syndrome and examine their relation to cognitive function. In Aim 2 (Preclinical model), we examine sleep physiology (SWS and spindles) and its effect on hippocampal and prefrontal ensemble activity in mouse models of Dup15q and Rett syndrome, performing EEG and simultaneous electrophysiological recordings and calcium imaging using a novel miniaturized microscope. In Aim 3 (Preclinical model), we investigate early neural network function in human cortical, subcortical, and hippocampal organoids from derived from Dup15q and Rett Syndrome iPSC using calcium imaging, electrophysiological recordings techniques, and transcriptomic analyses. This project leverages our center's strengths in both clinical and preclinical investigation of syndromic IDDs and capitalizes on active scientific collaborations between basic and clinical researchers in our center to understand sleep physiology, a fundamental and understudied problem in IDDs. By verifying the relationship between NREM sleep abnormalities and behavior in children with these syndromes and then, in model systems, determining the network and cellular basis of abnormal neural oscillations that are critical for memory formation and learning, this project will directly inform next steps for development of timely, effective treatments that may modulate sleep and, in turn, improve neurodevelopmental outcomes.
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0.958 |
2020 — 2021 |
Novitch, Bennett G |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Notch-Mediated Modulation of Sonic Hedgehog Signaling in Neural Fate Specification and Differentiation @ University of California Los Angeles
PROJECT SUMMARY The formation of complex tissue and organs systems in developing organisms depends on the ability of dividing stem and progenitor cells to properly integrate extracellular signals present in the embryonic environment. The combined actions of these signals in turn direct diverse processes such as progenitor maintenance, differentiation, and assignment of specific cell fates. A key step towards understanding the basis of and means for preventing birth defect thus lies in defining how different signaling pathways mechanistically intersect, permitting the activation of one signaling pathway to influence responses to other signals. Moreover, the combinatorial activities have the potential to extend the range of outcomes possible from a limited range of developmental signals. Our studies in the developing spinal cord have identified an unexpected role for Notch receptor signaling in modulating the response of cells to the tissue morphogen Sonic hedgehog (Shh). Both activation and inactivation of the Notch pathway alters the dorsoventral register of neural progenitors, leading to corresponding changes in neuronal and glial cell fates (Kong et al. Dev Cell, 2015). In tracking down the mechanism behind these effects, we discovered that Notch signaling influences the trafficking of the Shh receptor Patched1 (Ptch1) and the key downstream Shh effector Smoothened (Smo) to primary cilia, leading to changes in downstream Shh pathway activities. Importantly, this role for Notch can be seen in multiple cell types including mouse and human neural progenitors, fibroblasts, and skeletal myoblasts, suggesting it may be a general feature of mammalian cells. Collectively, our studies reveal a novel and surprisingly proximal role for Notch in shaping the interpretation of the Shh morphogen gradient and thereby impacting cell fate determination. The means by which Notch influences the trafficking of Shh signaling proteins, however, remains unknown. Our preliminary data suggest that these actions of Notch are most likely transcriptionally mediated, raising the questions of what are the target genes regulated by Notch, and how do they impact the trafficking of Shh pathway components, and possibly other signaling proteins, to primary cilia? Moreover, do defects in this Notch-mediated pathway contribute to congenital defects affecting ciliary transport, collectively termed ciliopathies? Our proposed studies will address these questions, first by identifying the transcriptional targets of Notch and its downstream effector Hes1 that coincide with changes in ciliary trafficking, and second by developing a platform for investigating the function of these newly identified Notch target genes in Shh signaling through CRISPR/Cas9-mediated deletions. With this approach, we will: a) reveal the nature of the functional intersection between the Notch and Shh transduction pathways in neural fate selection and b) identify new regulators of Shh signaling and protein trafficking to primary cilia more generally.
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0.958 |