Molecular and Cellular Neuroscience Commons^™

Synaptic Transmission At The Photoreceptor Ribbon Synapse, Chris Mesnard

Theses & Dissertations

Synaptic transmission relies on the Ca²⁺-dependent release of neurotransmitters packaged into synaptic vesicles. Ribbon synapses have the capability to release multiple vesicles at a time in a highly coordinated and synchronized manner. Glutamate release from rod and cone photoreceptor cells involves presynaptic ribbons composed largely of the protein RIBEYE. To examine roles of ribbons in rods and cones, we studied mice in which GCamP3 replaced the B-domain of RIBEYE. We discovered that ribbons were absent from rods and cones of both knock-in mice possessing GCamP3 and conditional RIBEYE knockout mice. Mice lacking ribbons showed reduced temporal resolution and …

The Role Of Parkin In Mitochondrial Dna, Eliezer Lichter

Theses & Dissertations

Mitochondria are at the center of biological phenomena such as aging and diseases, especially neurodegenerative diseases. While the discovery of mitochondria only came approximately 200 years after the cell was discovered, a lot of progress has been made since. The mitochondrial genome encodes proteins vital for mitochondrial function. These proteins are only a subset of the proteins present in mitochondria; the rest are nuclear encoded. The nucleus also encodes cytosolic proteins vital for mitochondrial maintenance. One of these is Parkin, an E3 ubiquitin ligase that ubiquitinates mitochondrial proteins as mitochondria become depolarized. Its activity has been shown to be involved …

Metoprolol Disrupts Sterol Biosynthesis Through Inhibition Of 7-Dehydrocholesterol Reductase (Dhcr7), Luke B. Allen

Theses & Dissertations

Cholesterol is essential for life. It is particularly important in the brain as it relies on de novo synthesis of cholesterol following the formation of the blood brain barrier (BBB). As such, disrupting sterol biosynthesis during neurodevelopment can have devastating outcomes. The most common post-lanosterol sterol biosynthesis disorder, Smith-Lemli-Opitz Syndrome, arises from a faulty DHCR7 enzyme. DHCR7 has also been shown to be inhibited by several psychotropic medications. Here we assess six beta-blockers and their effects on sterol biosynthesis in vitro. Two beta-blockers, metoprolol and nebivolol strongly inhibit DHCR7 in four separate in vitro models of both mouse and …

Innate Immunity In The Pathobiology And Treatment Of Infectious And Neurodegenerative Diseases, Mai Mostafa

Theses & Dissertations

Mononuclear phagocytes (MPs; monocytes, macrophages, and dendritic cells) are the governors of innate immunity which is the body’s first line of defense against microbial pathogens. They act beneficial or detrimental. They are crucial for an effective non-specific immune response to invading pathogens by engulfing, destroying, then eliciting an adaptive specific immune response. Given their pivotal functions in the host immune defense, studying MP immune responses in disease is paramount important for understanding disease pathobiology and uncovering therapeutic strategies.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the driver of acute respiratory distress syndrome (ARDS) in coronavirus disease 2019 (COVID-19) amongst …

In Utero And Postnatal Oxycodone Exposure: Implications For Intergenerational Effects, Katherine E. Odegaard

Theses & Dissertations

Prescription opioid abuse during and after pregnancy is a rising public health concern. Adding a layer of complexity is the role of heredity in the overall development of these exposed offspring. The present work uses a preclinical rat model mimicking oxycodone (oxy) exposure in utero (IUO) and postnatally (PNO) to investigate comparative and intergenerational effects in the two different exposure groups.

To understand the direct effects of IUO and PNO exposure on the F1 generation, we employed a systems biology approach encompassing proton magnetic resonance spectroscopy (¹H-MRS), electrophysiology RNA-sequencing, and pain assessment to elucidate molecular and behavioral changes …

Roles Of Autism Gene Arid1b In Murine Brain Development And Behavior, Amanda L. Smith

Theses & Dissertations

Autism spectrum disorder (ASD) and intellectual disability (ID) are highly prevalent neurodevelopmental disorders characterized by social and communication deficits, stereotyped behaviors, cognitive dysfunction, and deficits in adaptive behaviors. The pathogenesis underlying these disorders remains unknown, and thus no pharmacologic or genetic therapies are currently available. Recent progress in the field has shown that haploinsufficiency of the AT-rich interactive domain-containing 1B (ARID1B) gene is a genetic cause of ASD and ID. Our lab recently developed an Arid1b knockout mouse model to better study its role in the pathogenesis of these disorders. One theory regarding the cause of neurodevelopmental disorders …

Cholesterol Biosynthesis In The Nervous System With An Emphasis On Desmosterolosis, Luke Allen

Theses & Dissertations

Cholesterol biosynthesis is integral to proper neurodevelopment due to the reliance on de novo synthesis of cholesterol in the brain. Disruptions in this process have devastating outcomes for human life characterized by several phenotypic manifestations concomitant with developmental delay. The cholesterol biosynthesis disorder desmosterolosis is an extremely rare disorder with a severe clinical phenotype, however, the models used to study this disease are not well characterized. In addition to genetic disruptions in cholesterol biosynthesis, pharmacological perturbation is an understudied side effect of many commonly prescribed drugs. Here we present a characterization of the sterol profile of the mouse model of …

Role Of Astrocyte-Derived Extracellular Vesicles In Neuroinflammation Mediated By Drug Abuse, Ke Liao

Theses & Dissertations

Neuronal damage and neuroinflammation is a hallmark feature of HIV-associated neurological disorders (HANDs). Opioids abuse accelerates the incidence and progression of HAND; however, the mechanisms underlying the potentiation of neuropathogenesis by these drugs remain elusive. Extracellular vesicles (EVs) are essential conduits in HIV and drug abuse-mediated synaptodendritic injury and neuroinflammation. Findings from our group have demonstrated that astrocyte-derived EV (ADEV)-miRNA-29b mediates HIV Tat and morphine-induced neuronal injury, thus underscoring the importance of such interactions in NeuroHIV.

Besides, HIV Tat and morphine-mediated synaptodendritic injury via ADEVs, we are also interested in whether ADEVs contributes to neuroinflammation. Microglia are critical players in …

Novel Antiviral Effect Of A Small Molecule Onc201 And Its Potential Application In Hiv-1 Eradication, Runze Zhao

Theses & Dissertations

Despite the success of antiretroviral therapy (ART), eradication of HIV-1 from brain reservoirs remains elusive. HIV-1 brain reservoirs include perivascular macrophages that are behind the blood-brain barrier and difficult to access by ART. Macrophages express transcription factor FOXO3a and the TNF superfamily cytokine TRAIL, which are known to target HIV-1-infected macrophages for viral suppression. ONC201 is a novel and potent FOXO3a activator capable of inducing TRAIL. It can cross the blood-brain barrier, and has shown an antitumor effect in clinical trials. We hypothesized that activation of FOXO3a/TRAIL by ONC201 will reduce the size of HIV-1 brain reservoirs. Using primary human …

Mechanisms Of Calcium-Dependent Neurotransmission In Photoreceptors, Justin J. Grassmeyer

Theses & Dissertations

Rod and cone photoreceptors initiate vision by transforming light into graded membrane voltage changes that in turn dictate the rate of continuous Ca²⁺-dependent neurotransmission to postsynaptic neurons. Continuous release relies on synaptic ribbons at photoreceptor active zones, which organize exocytotic proteins and deliver vesicles to release sites near voltage-gated Ca²⁺ channels. Individual cones possess multiple ribbon synapses at which they contact postsynaptic neurons. We examined heterogeneity in signaling at individual ribbon synapses in salamander cones by measuring the voltage dependence of Ca²⁺ currents (I_Ca) and Ca²⁺ influx at individual ribbon release sites. Ca …

T Cell Mediated Cytotoxicity In The Mptp Mouse Model Of Parkinson's Disease, Rebecca A. Wilshusen

Theses & Dissertations

Increasing evidence suggests that neurotoxic inflammatory activities affect the pathogenesis and progression of PD. Neuroinflammatory processes also produce oxidized and modified self-central nervous system (CNS) proteins which lead to dysfunction, mis-folding, aggregation, and retention of those oxidized products. In PD, nitrated α-synuclein (N-α-syn) is found aggregated within the cytoplasm and Lewy bodies of dopaminergic neurons within the substantia nigra and is released to the extraneuronal environment by dying and damaged neurons. Previous studies have shown that after 1-methyl 4-phenyl 1,2,3,6-tetrahydropyridine (MPTP) intoxication, adoptive transfer of effector T cells (Teff) exacerbates microglial-mediated neuroinflammation and amplifies dopaminergic neurodegeneration with accelerated and prolonged …

Novel Therapeutic Approaches For Juvenile Neuronal Ceroid Lipofuscinosis (Cln3), Megan Elizabeth Bosch

Theses & Dissertations

Juvenile Neuronal Ceroid Lipofuscinosis (JNCL) is a lysosomal storage disease caused by autosomal recessive mutations in CLN3. Neuronal loss is thought to occur via glutamate excitotoxicity; however, little is known about neuron-astrocyte glutamate regulation in JNCL. We discovered that Cln3^Δex7/8 astrocytes have significantly lower basal spontaneous Ca²⁺ oscillations and decreased responses to glutamate, indicating a disrupted signaling network. Cln3^Δex7/8 astrocytes also displayed significantly lower basal mitochondrial respiration and ATP production, suggesting impaired metabolic functions. Concurrent with diminished astrocyte metabolism and Ca²⁺ signaling, Cln3^Δex7/8 neurons were hyper-responsive to glutamate stimulation. These studies suggest that CLN3 …

Pattern Recognition Receptors, Immune Proteins, And Nf-Κb Signaling Regulate Behaviors Associated With Aging Phenotypes, Nicholas W. Dekorver

Theses & Dissertations

The aging process is accompanied by functional impairments, including reduced locomotor function, fragmentation of active states, and alterations in energy balance. Our lab has demonstrated that immune proteins are increased in specific regions of the mouse brain that correlate with strain specific deficits. These immune proteins include toll-like receptors (Tlr), class I major histocompatibility complex proteins (MHC I), and complement proteins. There is an increasing appreciation for the role of immune proteins in neurodevelopment; however, their involvement in age-associated deficits is poorly understood. Here, we present data demonstrating that 1) activation of a specific immune receptor (Tlr2) leads to changes …

Inflammasome Activation By Methamphetamine Potentiates Lipopolysaccharide Stimulation Of Il-1Β Production In Microglia, Enquan Xu

Theses & Dissertations

Methamphetamine (Meth) is a psychostimulant drug that is widely abused all around the world. The administration of Meth causes a strong instant euphoria effect, and long-term of abuse is correlative of drug-dependence and neurotoxicity. The neuroimaging studies demonstrated that the long-term abuse of Meth is associated with the reduction of the dopamine transporter (DAT) and vesicular monoamine transporter (VMAT2) in the striatum. Neuroinflammation is well-accepted as an important mechanism underlying the Meth-induced neurotoxicity. The over-activated microglia were found both in Meth human abusers and animal models.

NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome is the most predominant Nod-like …

Basal And Experience Dependent Ampar And Synapse Dynamics: Alterations In A Mouse Model Of Fragile X Syndrome, Anand Suresh

Theses & Dissertations

Dendritic spines are the principal sites of excitatory synapses in the neurons of mammalian central nervous system. Spine are plastic, undergoing structural and functional changes under basal and experience dependent conditions. Spine properties are altered in a number of neurodevelopmental disorders including the Fragile X syndrome (FXS) which is the most common inherited form of intellectual disability. The structural reorganization of dendritic spines is thought to be associated with synaptic plasticity mechanisms that are deficient in FXS. A number of synaptic plasticity mechanisms involve modulation of synaptic strength via insertion or removal of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPAR). However, the link …

Mitogen And Morphogen Signaling Dysregulation: Pathophysiological Influence In Pancreatic Cancer And Alzheimer’S Disease, Eric Cruz

Theses & Dissertations

Although the etiology of a particular disease will vary, there are genetic and epigenetic bottlenecks that frequently converge resulting in dysregulation of mitogenic and morphogenetic signaling. This propensity is acutely experienced in malignancy and neurodegenerative disease.

Here, we have first investigated the role of dysregulated signaling in the context of pancreatic cancer (PC). Morphogenetic signaling has been regarded as a pleiotropic pathway with the potential to promote and inhibit metastatic features. Our investigation of bone morphogenetic protein 2 (BMP-2), an archetypical member of the BMP superfamily, has revealed the presence of extracellular, intracellular, and long non-coding RNA products. Our findings …

Voltage-Gated K+ Channels And Hiv-1-Induced Neural Injury: Implications For Pathogenesis Of Hiv-1-Associated Neurocognitive Disorders, Han Liu

Theses & Dissertations

Human immunodeficiency virus-1 (HIV-1)-associated neurocognitive disorder (HAND) is a subcortical disease involving neuronal loss and myelin damage. Myelin is deposited by oligodendrocytes through a complex process including oligodendrocyte progenitor cell (OPC) proliferation and maturation. Oligodendrocytes/OPCs are susceptible to viral proteins such as Tat and that myelin damage is associated with oligodendrocyte number decrease. It has been shown that activation of voltage-gated K⁺ (K_V) channels mediates apoptosis in various cell types. K_V1.3 is the most predominant K_V channel expressed in OPCs/oligodendrocytes and potentially involved in OPC developmental regulation. We studied the involvement of K_{V …}

Expression And Function Of Inflammation-Associated Micrornas In Traumatic Brain Injury, Emily Harrison

Theses & Dissertations

MicroRNAs (miRNAs) are important regulators of gene expression. Many neurological diseases, including traumatic brain injury alter expression of miRNAs in the brain. However, the function of these molecules in the context of TBI is largely unknown. Here we report multiple potential roles for miRNAs in TBI, some of which extend beyond the traditional model of post-transcriptional regulation, highlighting that these RNA molecules may have broader implications for the neurobiology of disease. We found that miR-155 plays an essential role in interferon expression after CCI and that miR-155 contributes to TBI induced anxiety, potentially through regulation of interferons. Expression of miR-155 …

Characteristics Of Exocytosis And Endocytosis In Photoreceptors, Karlene M. Cork

Theses & Dissertations

Photoreceptors signal changes in light intensity to downstream retinal neurons through the exocytosis of glutamate-containing synaptic vesicles. The maintenance of the vesicle exocytosis and endocytosis process is essential for ongoing synaptic signaling. This study investigated the properties of exocytosis and endocytosis in photoreceptors and their role in ongoing neurotransmission.

I used electrophysiology and imaging techniques to study the properties of vesicle exocytosis and endocytosis in photoreceptors. First, we examined baseline release in photoreceptors that occurs in the absence of depolarizing stimulation. We measured mEPSCs in whole cell patch clamp recordings from horizontal cells. After inhibiting Ca²⁺ influx and efflux …