1,721,197 research outputs found
EGFR Activates NFAT3 through Frequency Modulated Ca2+ Oscillations to Regulate the Proliferation of Transit-Amplifying (type C) Cells in the Adult SVZ
No full textAdult neurogenesis in the subventricular zone (SVZ) is a highly dynamic and finely-tuned process, subject to modulation by various physiological stimuli. Fast- dividing transit-amplifying (type C) cells are the immediate progeny of adult neural stem cells in the SVZ. These type C cells play a key role in neurogenesis by expanding cell numbers that eventually give rise to neuroblasts destined for the olfactory bulbs (OB). The size of the progenitor pool, and ultimately the number of neurons that engage in synaptic competition at the OB, is largely determined by the balance between proliferation and differentiation of these cells. Identifying the signalling mechanisms that regulate type C cell fate is an essential step towards understanding how intermediate progenitor pools are maintained in the adult neurogenic niches. A key feature of type C cells is their transient expression and activation of epidermal growth factor receptor (EGFR), which is a critical signal involved in regulating their undifferentiated and proliferative state in vitro, and in maintaining the number of neurons produced in vivo. EGFR activation leads to multiple complex signal transduction pathways, including Ca2+ liberation from the endoplasmic reticulum (ER). Biological systems can transduce information by initiating and/or altering the spatial and temporal dynamics of Ca2+ within the cell, allowing for distinct biological signals to be transmitted in a process known as Ca2+-encoding. In this study, the role Ca2+-encoding plays in EGFR signal transduction was examined.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)SChool of Natural SciencesScience, Environment, Engineering and TechnologyFull Tex
The De-ubiquitylating Enzyme USP9X is Essential for Normal Neural Development in Mouse
No full textThe ubiquitin system is involved in almost all aspects of protein function and cell fate and is thought to play an important role during neural development. Defects within the ubiquitin system have been linked to a range of neuro-degenerative diseases including Parkinson’s and Alzheimer’s disease. De-ubiquitylating enzymes function downstream in the ubiquitin pathway having potential to act as the final arbiters of substrate fate and function. Several studies have shown that de-ubiquitylating enzymes play important roles in the growth, function and maintenance of neurons.
The substrate-specific de-ubiquitylating enzyme USP9X is highly expressed in the developing central nervous system. In vitro analyses have shown that USP9X is highly expressed in neural stem cells while expression remains at lower levels in more differentiated neural cell types. As the human and mouse USP9X genes share a 97% nucleotide identity within the coding sequence, this study uses the mouse as a model to analyse the role of USP9X during mammalian neural development. Previous studies have shown that loss of USP9X in the pre-implantation mouse embryo results in pre-implantation lethality. To circumvent this early developmental stage and analyse USP9X function in the developing brain we utilized a conditional knockout strategy involving the Cre/loxP recombination system. Using the Cre/loxP recombination system we permanently disable USP9X via exon removal specifically in the CNS during embryonic development. Two models were utilised, the first disabling USP9X in the whole CNS using Nestin-Cre mediated deletion and the second disabling USP9X in the dorsal telencephalon (dorsal forebrain) using Emx1-Cre. Using these models, USP9X is targeted in neural stem cells / neural progenitor cells prior to differentiation. This approach presents the ability to examine the effects of loss of USP9X on neural progenitor cells as well as neuronal and glial cells that derive from these progenitors.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School of Biomolecular and Physical SciencesScience, Environment, Engineering and TechnologyFull Tex
Capacity of Neurotrophic Factors of the GDNF Family in Supporting the Survival of Dopaminergic Neurons in the Central Nervous System of the Aging Mouse
No full textDopaminergic neurons of the substantia nigra are vital for proper motor function. The Glial cell line-derived neurotrophic factor (GDNF) family of neurotrophic factors have been shown to promote the survival of dopaminergic neurons both in vitro and in vivo. GDNF and its related factor neurturin have both been trialled as a therapy for Parkinson’s patients for which degeneration of dopaminergic neurons is hallmark pathology. However, GDNF and neurturin are not required for proper development of dopaminergic neurons. Knockout of the GDNF gene in mice causes improper formation of the enteric nervous and kidneys causing death shortly after birth but does not cause any changes in dopaminergic phenotype. Knockout of the neurturin gene is non-lethal but causes abnormalities in enteric, parasympathetic and sensory neurons. No abnormalities in the brain of neurturin knockout have been reported however very little work has been done in this area. It appears that these two neurotrophic factors are not required for successful dopaminergic development.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)Griffith University School of Biomolecular and Physical SciencesScience, Environment, Engineering and TechnologyFull Tex
Vascular Endothelial Growth Factor (VEGF) and Platelet Derived Growth Factor (PDGF) in a Novel Model of Parkinson's Disease
No full textParkinson's disease is a progressive neurodegenerative disorder, characterised histopathologically by the degenerating nigrostriatal pathway. Previous studies have shown a decrease in neurogenesis, dopaminergic neurons and neurotrophic factor levels in the Parkinson brain. This thesis investigates the capability of vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF) to stimulate endogenous neurogenesis and offer direct or indirect neuroprotection in a novel model of Parkinson's disease. To assess the neurogenic capability of the postnatal substantia nigra, the effect of age and nigrostriatal circuitry function was examined. Animals were randomised into 2 cohorts; one cohort the control while the other received a partial unilateral 6-hydroxydopamine (6-OHDA; 4 [mcg]) lesion. All animals received 10 day exposure to 5-ethynyl-2'-deoxyuridine (EdU; 25 mg/kg body weight) after lesion to label proliferative cells. An increase in age decreased neurogenic potential of the substantia nigra and dentate gyrus of rats. A partial lesion increased cell proliferation; with the change showing an interaction between age and treatment. The current data shows the highest neurogenic potential at day 28 after weaning, with a near complete lack of neurogenesis at 2 years. With increasing age, a decrease in neurotrophic factors has been reported. The current data supports the hypothesis for neurotrophic factors influencing endogenous neurogenesis. A novel Parkinson's disease rat model that mimics human pathophysiology using a low dose rotenone induced intra-medial forebrain bundle lesion was developed. Rotenone is a highaffinity inhibitor of complex 1 of the mitochondrial electron transport chain. Complex 1 inhibition by rotenone causes the production of reactive oxygen species that result in oxidative damage of the dopaminergic neurons. The animal model demonstrated a glial response together with a slow degenerative change (cell stress; oxidative stress; [alpha]-synuclein production; cell death) similar to human Parkinson's disease. This is a useful model for testing therapeutic interventions, including neuroprotective and neurogenic agents for Parkinson's disease.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School of Biomolecular and Physical SciencesScience, Environment, Engineering and TechnologyFull Tex
Olfactory Stem Cells From Adult Rats
No full textThe formation of neurospheres was important in demonstrating that neurogenesis in the adult brain may be fuelled by a stem cell population. The olfactory mucosa is another site of neurogenesis which, in humans, has been observed to contain a stem cell population through the formation of neurospheres (Murrell et al., 2005). Stem cells can be defined as cells capable of self-renewal and multipotency. The aim of this study was to investigate the potential of rat olfactory stem cells growing as neurospheres. The hypothesis is that the rat olfactory mucosa contains a 'true' stem cell population that can be cultured as neurospheres and that will demonstrate multipotency by differentiating into 'non-olfactory' cell types and possess the capacity for self-renewal, if provided with the appropriate environmental niche. Here it was found that adult rat olfactory mucosa is capable of generating neurospheres when cultured in EGF and bFGF. Evidence of self-renewal was provided by the formation of six generations of neurospheres, the formation of neurospheres from single cells and the expression of markers associated with self-renewal by neurosphere cells. The multipotency of olfactory neurosphere cells was demonstrated through manipulation of the stem cell niche. In defined culture conditions, extracellular matrix molecules and growth factors were able to induce the differentiation of neurosphere cells down the dopaminergic lineage pathway. When co-cultured with differentiating cells, neonatal myoblasts and 3T3-L1 cells, olfactory neurosphere cells were able to differentiate and incorporate into a skeletal muscle myotube and differentiate into adipocytes, respectively. In conclusion it was found that the adult rat olfactory mucosa is capable of generating neurospheres. When presented with an appropriate niche neurosphere cells are able to self-renew and demonstrate multipotency.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School of Biomolecular and Biomedical SciencesFaculty of ScienceFull Tex
Investigating Cell Proliferation in the Nervous System
No full textCell proliferation is a strictly regulated process which is preceded by DNA synthesis and results in an increase in the number of new cells. It is essential for the development, regeneration and is upregulated in tumours. Whilst the study of cell proliferation is fundamental for many arms of biomedical investigation, the techniques used in its study have remained unchanged for decades. Neuroscience is one such field where cell proliferation in the adult can be a rare event and where molecular biology techniques are accelerating discoveries. Unfortunately, the limitations of studying cell proliferation have become a constraint in the field. This thesis examines the development of techniques to identify, characterise, quantify and profile proliferative cells in neural tissue. The techniques are provided in the context of a collection of studies that applied the techniques to secure data in a testable framework. The nervous system of the brain and olfactory mucosa were used to develop techniques to investigate cells on a histological and molecular scale. Initial investigation developed and improved tissue processing workflow and techniques to provide the optimal samples for histological analysis. The optical properties of the sample were improved, allowing deeper imaging in thick tissue sections. The embedding of frozen samples was altered to make use of gradients of OCT embedding media that minimised cell lysis. Embedment in the wax polyethelene glycol was used for sectioning at room temperature. Both techniques preserved tissue cytoarchitecture and antigenicity, allowing fluorescent labelling with multiple markers simultaneously in tissues with well conserved ultrastructure. These optimally prepared thick tissue samples provided a means of imaging multiple phenotypes and cell states in a single specimen (multiplexed), rather than multiple replicates of tissue sections, with different markers. The high optical clarity of the section facilitated high resolution 3D image acquisition, using optimised imaging techniques, further increasing the amount of information obtained from a sample set. These histological techniques were applied to the olfactory mucosa and substantia nigra to quantify cell proliferation and neurogenesis. EdU a thymidine analogue was used to label cells during the S-phase of the cell cycle, identifying cells that had undergone proliferation during exposure. It was shown that although neurogenesis was present in the olfactory mucosa, cell proliferation that occurred in the substantia nigra rarely gave rise to cells of a neural lineage. These techniques enabled the development of novel cell quantification methods, using stereology principles. Due to the ease and significantly less fragile nature, the substantia nigra as opposed to the olfactory system, was chosen to develop this technique. By quantifying subtypes of dopaminergic neurons in the substantia nira pars compacta of both the mouse and rat, an unbiased and accurate method of cell estimation was developed. The embedding method, multiple labelling immunofluorescence and serial optical sections obtained from thick specimens enabled significant improvements to stereological assessment. Thus, multiplexed cellular data was accurately quantified in brain tissue. These techniques were used to label multiple cell phenotypes during a defined period of exposure to EdU. This provided a powerful tool to investigate tissue where data on cell division and development was required together with cell – cell interaction of specific cell phenotypes that were labelled fluorescently. Specific tissue regions were quantified accurately and unbiasedly employing the advanced cell estimation technique. Expanding on the ability to effectively label and analyse cellular structures in tissue sections, in-situ, the capability to isolate and extract biomolecules from proliferating cells for analysis was developed. Thus, providing insight into the cellular differences that occur in proliferating cells. The basis of the technique involved the dissociation and fluorescent labelling of samples pre-labelled with EdU. These labelled cells were then isolated using FACS and RNA was then extracted for assessment of quality and analysis. The optimisation of each step was required to conserve the cell integrity and RNA quality. An enzyme cocktail that provided a gentle dissociation of neuronal tissue, decreased copper in the EdU labelling reaction, and minimising cell disruption during FACS was developed. Thereby, single proliferating cells and their RNA content was effectively extracted from neural tissues. The RNA extracted from the dividing cells showed significant expression differences of several key RNA products when compared to the non-dividing cells of the same tissue. These techniques provide a powerful tool kit to investigate proliferating cells of neural origin. Their use is not limited to the tissues and applications outlined in this thesis but are translatable to other tissue and biomolecules.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School of Natural SciencesScience, Environment, Engineering and TechnologyFull Tex
Olfactory Stem Cells as Disease Models for Schizophrenia
No full textSchizophrenia is a strongly heritable multifactorial mental disorder that affects 1% of any population, but disease etiology is not yet fully understood. The limitations of using animal models, post-mortem brain studies and difficulty to obtain human brain biopsies have impeded the understanding of this disease from the biological perspective. There is a consensus, based on epidemiology and post-mortem human brains that schizophrenia is a neurodevelopmental disorder, but cellular and molecular mechanisms for this hypothesis are lacking. We have developed a model to address this using human olfactory neurosphere-derived (hONS) ‘stem’ cells, which were obtained non-invasively from human participants, expressed neural stem cell markers and allows comparative analyses of age- and sex-matched cell lines from patients diagnosed with schizophrenia with cell lines from healthy participants. Patient cells from various sources have a common dysregulation to gene pathway networks involved in axonal guidance, cell adhesion, cytoskeletal remodeling, focal adhesion signaling and reelin signaling - all important pathways that regulate cell migration.
A high throughput live cell tracking technique was developed to unbiasly quantify cell motility in vitro. At baseline on uncoated tissue culture plastic (TCP), patient cells moved longer distances than control cells. Patient cells were unable to respond to their microenvironment when increasing concentrations of well-defined ECM proteins were coated on TCP cell culture surfaces. This was despite patient cells expressing the necessary cell surface integrin receptors measured by flow cytometry, which meant they have the capacity to bind and recognize all tested ECM proteins. Patient cells have consistently lower levels of cytoskeletal proteins in filamentous actin (F-actin) and stable microtubules, which became more evident when cultured on ECM proteins. Despite being able to adjust their cell sizes and shapes, patient cells were consistently smaller than control cells. Focal adhesion kinase (FAK) levels were consistently lower in patient cells and they were unable to manufacture enough focal adhesions of the correct sizes upon contact with ECM proteins. These findings highlighted a global deficit to cell migration in schizophrenia that was not limited to just Fibronectin but also on all ECM proteins, which were caused by disease-dependent intracellular deficits in patient cell cytoskeleton and focal adhesions. Reelin is an important brain ECM protein that orchestrates neuronal migration during neurodevelopment and its expression is reduced in post-mortem brain tissues from patients with schizophrenia. In this study, reelin protein levels were also reduced in patient hONS cells compared to control cells. Despite having the capabilities to bind to reelin through expression of key reelin signaling pathway accessory protein Dab1 and reelin-binding receptors ApoER2 and VLDLR, patient cells were unable to respond to extracellular reelin. Patient cells were unable to adjust their movement track lengths when tracked on surfaces coated with full length reelin. Similar to our previous findings on other ECM proteins, patient cells had lower levels of F-actin and stable microtubules, and were consistently smaller in size compared to control cells. Our findings suggested that non-responsive cell migration deficits were caused by defective focal adhesion responses to extracellular reelin. Instead of producing more focal adhesions that were larger in response to reelin, patient cells reduced both the densities and sizes of their focal adhesions at the peripheral region of the cell where lamellipodia forms. This was the first study to demonstrate a biological link between reelin signaling and schizophrenia, with a focus on the effects of reelin on cell migration.
Published computer programs were used in silico to investigate the mechanistic components of cell migration and to further investigate reasons why patient cells were unable to respond to their ECM microenvironment. X-Y displacement coordinates for each individually tracked cell were analyzed by the DiPer and migration phase/cell turning analysis programs to compute cell movement variables in directionality, diffusivity, persistence and idling and turning. At baseline on TCP, patient cells did not move at the correct trajectories, failed to make directional changes, paused less and turned less when tracked for 24 h. When tracked on ECM proteins, it was difficult to pinpoint one explanation to explain our non-responsive cell migration findings as various mechanistic variables played a collective part to potentially give rise to the observed non-responsive cell migration phenotype. One explanation was that patient cells spent more time in persistent movement and were unable to make necessary changes to their directions. Another explanation was the unchanged cell pausing tendencies on Type I Collagen as a plausible explanation for observed non-responsive changes to motility on that ECM protein. The same in silico computational analyses showed that patient cells did not respond to extracellular reelin because they could not reduce the rate at which they changed the straightness of their movement trajectories. Patient cells were also unable to make well-timed changes to the direction of their movement trajectories by being more persistent in one direction for longer. Decreased densities and sizes of focal adhesions in patient cells upon contact with extracellular reelin resulted in patient cells not decreasing their turn angles, but instead made larger uncoordinated turns. The way that control cells responded negatively to extracellular reelin supported the hypothesis in the field that reelin acts as a “stop signal” for actively moving neuronal cells, which was disrupted in patient cells.
In conclusion, this thesis has uncovered a novel non-responsive cell migration phenotype in schizophrenia, which was broadly relevant on different ECM proteins, to suggest consistent defects in how patient cells respond to their surrounding microenvironment. Findings from this thesis also showed that observed cell migration deficits were caused by differences to intracellular components such as cell cytoskeleton and focal adhesions, coupled to previously published findings that FAK, integrin and actin signaling pathways were all dysregulated in schizophrenia. Using an analogy of patient cells as a moving vehicle, our findings showed a global defect to many parts of this faulty “vehicle”, such as defective “ignition” in FAK signaling, uncoordinated “wheels” in the lamellipodia and consistent faults to the “clutch” mechanism in the focal adhesions. All working in concert to cause patient cells to move in a less coordinated fashion and unable to make controlled mechanistic changes to their movement, causing them to ultimately lose their way.School of Environment and ScScience, Environment, Engineering and TechnologyFull Tex
Developing Olfactory Ensheathing Cells for ex vivo Delivery of GDNF
No full textOlfactory ensheathing cells have well described neurotrophic properties and can promote repair of damaged nerves in the central nervous system. Genetically engineering these cells to deliver therapeutic proteins could 'supercharge' their existing abilities to repair damaged nerves and prevent neurodegeneration in disease. The present study used retroviral vectors to engineer human olfactory ensheathing cells to co-express the potent neurotrophin GDNF and reporter genes under a tetracycline-inducible promoter. The goal here was to provide proof of concept for using olfactory ensheathing cells (OECs) for controlled ex vivo delivery of GDNF in preclinical studies. Until now, OECs from the olfactory mucosa have not been examined or developed for this purpose. Here a systematic evaluation of OECs revealed their suitability for developing ex vivo gene therapies.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School of Biomolecular and Physical SciencesScience, Environment, Engineering and TechnologyFull Tex
Investigations of Olfactory Mucosa to Test the Neurodevelopmental Nature of Psychoses
No full textEvidence from various sources suggests that schizophrenia may result from altered brain development. The adult olfactory epithelium provides an available 'window' on neuronal development because new neurons are formed there throughout life. This thesis set out to test the neurodevelopmental hypothesis of psychotic disease. Two cell-based models, skin fibroblast and olfactory mucosa culture, were employed to investigate this hypothesis. In order to first demonstrate the utility of olfactory mucosa culture as a model of neurodevelopment, and to allow the candidate to gain proficiency in the culture of this tissue, an investigation of the mitogenic and differentiating properties of insulin-like growth factor-I within this system was undertaken. Insulin-like growth factor-I has multiple effects within the developing nervous system but its role in neurogenesis in the adult nervous system is less clear. The adult olfactory mucosa is a site of continuing neurogenesis that expresses insulin-like growth factor-I, its receptor, and its binding proteins. The action of insulin-like growth factor-I was assayed in several serum-free culture systems combined with bromodeoxyuridine labelling of proliferating cells and immunochemistry for specific cell types. Once proficiency in olfactory mucosa culture was gained, this model was applied to biopsied olfactory mucosa from schizophrenia and bipolar disorder patients in order to test the developmental parameters of adhesion, cell proliferation, and cell death in a neural tissue. It was previously shown that olfactory cultures from individuals with schizophrenia had increased cell proliferation and attached less frequently than cultures from healthy controls suggesting disrupted neurogenesis. An aim of this study was to replicate those observations in individuals with schizophrenia and and extend them to individuals with bipolar disorder. After completion of the cell and tissue culture assays, microarray analysis of these cell-based models was used to reveal gene expression differences present between patients and healthy controls. Microarray analysis is a complicated technique and the limited amounts of RNA that can be extracted from a single nasal biopsy further compounds this issue. In order to obtain enough material for microarray hybridization RNA samples underwent antisense amplification. Therefore, with the aim of allowing the candidate to gain proficiency in both these techniques prior to microarray analysis of olfactory biopsies from patients with schizophrenia and bipolar disorder, a pilot microarray study of cultured skin fibroblasts from schizophrenia patients and healthy controls was performed. The present findings show that insulin-like growth factor-I and its receptor were expressed by globose basal cells (the neuronal precursor), by neurons and by olfactory ensheathing cells, the special glia of the olfactory nerve. Insulin-like growth factor-I reduced the numbers of proliferating neuronal precursors, induced their differentiation into neurons, and promoted morphological differentiation of neurons. In contrast, this growth factor was mitogenic for olfactory ensheathing cells. The evidence suggests that insulin-like growth factor-I is an autocrine/paracrine signal that induces neuronal precursors to differentiate into olfactory sensory neurons and induces olfactory ensheathing cells to proliferate and that olfactory mucosa culture is valuable in modelling neurodevelopmental processes. When the olfactory musoca culture model was applied to patients with psychosis, a two-fold increase in proliferation of neural cells was found in schizophrenia compared to controls and bipolars. In bipolar cultures there was a 3-fold increase in cell death compared to controls and schizophrenia. Microarray analysis of cultured skin fibroblasts revealed differential expression of over 1000 genes between patients and controls. Inspection of the significant data showed alterations to gene expression between groups in the cell cycle, oxidative phosphorylation, TCA cycle and oxidative stress pathways. Gene expression in each of these pathways was predominately decreased in schizophrenia. Quantitative PCR analysis of selected differentially expressed genes involved with cell cycle regulation validated the increased expression of vitamin D receptor, and decreased expression of proliferating cell nuclear antigen and DEAD (Asp-GIu-Ala-Asp) box polypeptide 5 in skin fibroblasts from patients with schizophrenia. Microarray analysis of biopsied olfactory mucosa showed 146 and 139 differentially expressed genes in schizophrenia and bipolar disorder respectively, compared to controls. Consistent with increased mitosis in schizophrenia biopsy cultures three genes that function to positively influence cell cycle had increased expression. In the bipolar disorder group a dysregulation of the phosphatidylinositolsignalling pathway was seen; five genes that either directly function within or interact with this pathway had decreased expression. There is speculation that the therapeutic effect of psychotropic drugs acting upon this pathway in bipolar disorder involves reduction of neuronal cell death. Increased mitosis of neural cells has now been observed in two separate groups of schizophrenic patients indicating a robust finding. The use of fibroblast and olfactory mucosal tissue can be used to study biological and genetic aspects of neurodevelopment in living humans both with and without psychotic disease. Biopsied olfactory mucosa provides benefits over the use of autopsied material for study of psychotic disease because post-mortem duration and agonal factors that lead to tissue, protein and nucleic acid degradation are not an issue. This study provides evidence for a neurodevelopmental aetiology of schizophrenia and bipolar disorder acting at the level of cell cycle control. Subtle changes in the timing of cell cycle regulation could account for the brain pathologies observed in these diseases. Olfactory mucosa culture is a valuable model of neurodevelopmental processes.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School of Biomolecular and Biomedical SciencesFull Tex
Investigations of Olfactory Stem Cells in Schizophrenia
No full textSchizophrenia is a severely debilitating psychiatric disorder with a complex aetiology where aberrant expression of multiple genes, concurrent with neurodevelopmental events, is believed to lead to the disorder. The ability to biopsy and culture olfactory neuroepithelium from patients with schizophrenia may provide a window into the processes underlying the altered brain development and function in the disorder. It has been established that neurogenesis, the formation of new neurons, occurs throughout life. There are several lines of evidence suggesting adult neurogenesis may be affected in schizophrenia. The functional relevance of neurogenesis in the adult mammalian brain remains unknown, however a disruption of neurogenesis during early development is consistent with the neurodevelopmental hypothesis of schizophrenia. The presence of a neural stem cell has been established in the olfactory neuroepithelium, which can give rise to various neural populations, providing a valuable source for studying various aspects of neurogenesis. The aim of this study was to investigate the utility of olfactory stem cell lines in studying the processes underlying altered brain development and brain functioning in schizophrenia. We also investigated the skin fibroblast cell model, to assess the utility of non-neural cells in studying schizophrenia. A mitochondrial dysfunction and increased oxidative stress have been linked to patients with schizophrenia, and have been proposed to be involved in the pathophysiology of the disorder. We compared gene expression, neural differentiation, mitochondrial function and focal adhesion in cells from patients with schizophrenia and healthy controls. Our results showed significant disruptions of signaling pathways important in adhesion, cell communication and signaling in the olfactory stem cell lines from the patients group, and no significant pathway disrupted in the skin fibroblasts. Though both cell models indicated a focal adhesion dysfunction in schizophrenia, we found that olfactory stem cell lines show signs of a more severe dysregulation when compared to skin fibroblasts, which may reflect the differing structural roles of fibroblasts compared to neural cells. There was also an impaired oxidative stress response in both cell models, and also a mitochondrial dysfunction in the olfactory stem cell lines, phenomena which support the hypothesis that mitochondrial dysfunction and oxidative stress are involved in schizophrenia pathophysiology. Significantly, differences in differentiation between patient and control groups were revealed. Altered neurogenesis in cells from patients with schizophrenia, support our other hypothesis that adult neurosgenesis is involved in schizophrenia pathophysiology. Though the details of adult neurogenesis, focal adhesion, mitochondrial function and oxidative stress remain to be elucidated in schizophrenia, these findings together with their proposed roles in brain function make them relevant to schizophrenia research. While we found that fibroblasts are not informative as a cell model for schizophrenia, we conclude that olfactory stem cell lines are a promising tool for studying neurobiological aspects of schizophrenia.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School of Biomolecular and Physical and Physical SciencesScience, Environment, Engineering and TechnologyFull Tex
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