The androgen receptor (AR) is a ligand-activated transcription factor and a member of the nuclear receptor superfamily. Mutations in the androgen receptor are associated with androgen insensitivity syndrome (AIS), and a neurodegenerative disease, spinal bulbar muscular atrophy (SBMA). Most of the mutations causing AIS are loss-of-function missense mutations whereas SBMA is caused by a gain-of-function polyglutamine expansion in the N-terminal domain of the protein. Characterization of AR mutations has led to a better understanding of structure-function relationships of the AR and serves as a prototype for steroid receptors mechanisms of action. / In the first paper, we examine the role of an AR mutation in causing mild androgen insensitivity syndrome. We found that this mutation conferred reduced transactivation by AR through impaired interactions with the AR coactivator, TIF2, and impaired homodimerization. / In the second paper, we investigate the role of the AR polyGln expansion mutation in SBMA pathogenesis. Recent evidence has implicated proteolytic degradation of polyGln-expanded proteins and their subsequent intracellular aggregation in polyGn-expanded disease pathogenesis. We examined the role and composition of aggregates using fluorescently-tagged AR and found that proteolysis need not be a prerequisite for aggregation and that aggregation is not necessary for poly-Gln-induced cellular toxicity. / Finally, we characterize the novel heterodimerization of AR and ERalpha. We determined that this direct interaction has functional implications for the transactivational properties of both receptors.

When viewing a face, healthy individuals tend to fixate on upper regions, particularly the eyes, which provide important configural information about the spatial layout of the face. In contrast, individuals with face blindness (prosopagnosia) rely more on local features – particularly the mouth. Presented here is an examination of face perception deficits in individuals with Posterior Cortical Atrophy (PCA). PCA is a rare progressive neurodegenerative disorder that is characterized by atrophy in occipito-parietal and occipito-temporal areas. PCA primarily affects higher visual processing, while memory, reasoning, and insight remain relatively intact. Common among individuals with PCA is simultanagnosia, an inability to perceive more than one object or detail simultaneously. One might consider simultanagnosia the most extreme form of a feature-based approach. In a series of investigations, individuals with PCA and their healthy control participants completed a same/different discrimination task in which images of faces were presented as cue-target pairs. Eye-tracking equipment (Experiment 1) and the newly developed Viewing window paradigm (Experiment 2) were used to investigate scanning patterns when faces were presented in full view, and through a restricted viewing aperture, respectively. In contrast to previous prosopagnosia research, individuals with PCA each produced unique scan paths that focused on one aspect of the face. Individuals with PCA tended to focus on areas of high-contrast but many of these areas were not diagnostically useful, suggesting that they were having difficulty processing the face even at a featural level. These results suggest a role of simultanagnosia in the scan patterns of PCA patients that is not reflective of ‘typical’ prosopagnosia, and instead points to simultanagnosia, sometimes matched with basic perceptual impairments, as a significant contributor to the face perception deficits seen in PCA.

The disruption of the survival motor neuron (SMN1) gene leads to the children’s genetic disease spinal muscular atrophy (SMA). SMA is characterized by the degeneration of α-motor neurons and skeletal muscle atrophy. Although SMA is primarily considered a motor neuron disease, the involvement of muscle in its pathophysiology has not been ruled out. To gain a better understanding of the involvement of skeletal muscle pathophysiology in SMA, we have developed three aims: to identify cell-specific Smn-interacting proteins, to characterize postnatal skeletal muscle development in mouse models of SMA, and to assess the functional capacity of muscles from SMA model mice. We have used tandem affinity purification to discover Smn interacting partners in disease relevant cell types. We have identified novel cell-specific Smn interacting proteins of which we have validated myosin regulatory light chain as a muscle-specific Smn associated protein in vivo. We have taken advantage of two different mouse models of SMA, the severe Smn-/-;SMN2 mouse and the less severe Smn2B/- mouse, to study the postnatal development of skeletal muscle. Primary myoblasts from Smn2B/- mice demonstrate delayed myotube fusion and aberrant expression of the myogenic program. In addition, the expression of myogenic proteins was delayed in muscles from severe Smn-/-;SMN2 and less severe Smn2B/- SMA model mice. Muscle denervation and degeneration, however, are not the cause of the aberrant myogenic program. At the functional level, we demonstrate a significant decrease in force production in pre-symptomatic Smn-/-;SMN2 and Smn2B/- mice indicating that muscle weakness is an early event in these mice. Immunoblot analyses from hindlimb skeletal muscle samples revealed aberrant levels of developmentally regulated proteins important for muscle function, which may impact muscle force production in skeletal muscle of SMA model mice. The present study demonstrates early and profound intrinsic muscle weakness and aberrant expression of muscle proteins in mouse models of SMA, thus demonstrating how muscle defects can contribute to the disease phenotype independently of and in addition to that caused by motor neuron pathology.

Spinal muscular atrophy (SMA) is the most commonly inherited neurodegenerative disease that leads to infant mortality worldwide. There are no known cures for SMA, but small increase in protein levels of SMN can be beneficial. We have developed adenoviral (Ad) vectors that express a human transgene of SMN and have tested their safety in vitro. We have demonstrated that these viruses can effectively express the transgene following cell entry and that the levels are relative to the virus dose. The viruses do not appear to impact the health and function of the cells, and are capable of increasing the number of Gems. We also attempted to change the tropism of the viruses through fiber protein modifications in order to target muscles and motor neurons. Our results suggest that a therapy based on an Ad-SMN fiber-modified vector may ultimately be successful in treating patients of SMA.

The autosomal recessive disorder spinal muscular atrophy (SMA) causes motor neuron degeneration and muscle wasting, progressing to paralysis and death in severe cases. The disease is caused by deficiency of survival motor neuron protein (SMN) due to deletion or mutation of the SMN1 gene. We seek to develop a protein-based therapy for SMA using an adenoviral vector which encodes a secretable form of SMN fused to a protein transduction domain (PTD) derived from the trans-acting activator of transcription (TAT) from HIV. We generated secretable GFP proteins using transient transfection in mammalian cells and determined that the secretory peptide was inefficient when paired with the native PTD. We generated TAT-GFP proteins in bacteria and observed that the variant TAT3 most reliably tranduced cells in vitro. We did not observe uptake of the therapeutic protein following infection with an adenoviral vector and subsequent secretion of the protein from infected cells.

When viewing a face, healthy individuals tend to fixate on upper regions, particularly the eyes, which provide important configural information about the spatial layout of the face. In contrast, individuals with face blindness (prosopagnosia) rely more on local features – particularly the mouth. Presented here is an examination of face perception deficits in individuals with Posterior Cortical Atrophy (PCA). PCA is a rare progressive neurodegenerative disorder that is characterized by atrophy in occipito-parietal and occipito-temporal areas. PCA primarily affects higher visual processing, while memory, reasoning, and insight remain relatively intact. Common among individuals with PCA is simultanagnosia, an inability to perceive more than one object or detail simultaneously. One might consider simultanagnosia the most extreme form of a feature-based approach. In a series of investigations, individuals with PCA and their healthy control participants completed a same/different discrimination task in which images of faces were presented as cue-target pairs. Eye-tracking equipment (Experiment 1) and the newly developed Viewing window paradigm (Experiment 2) were used to investigate scanning patterns when faces were presented in full view, and through a restricted viewing aperture, respectively. In contrast to previous prosopagnosia research, individuals with PCA each produced unique scan paths that focused on one aspect of the face. Individuals with PCA tended to focus on areas of high-contrast but many of these areas were not diagnostically useful, suggesting that they were having difficulty processing the face even at a featural level. These results suggest a role of simultanagnosia in the scan patterns of PCA patients that is not reflective of ‘typical’ prosopagnosia, and instead points to simultanagnosia, sometimes matched with basic perceptual impairments, as a significant contributor to the face perception deficits seen in PCA.

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Thesis (M.Eng.). / Written for the Dept. of Biomedical Engineering & Montreal Neurological Institute. Title from title page of PDF (viewed 2008.05/13). Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri--Columbia, 1997. / "May 1997." Typescript. Vita. Includes bibliographical references (leaves 81-91). Also available on the Internet.

Thesis (M.S.)--California Polytechnic State University, 2009. / Mode of access: Internet. Title from PDF title page; viewed on January 20, 2009. Major professor: Scott Reaves, Ph.D. "Presented to the faculty of California Polytechnic State University." "In partial fulfillment of the requirement of the degree [of] Master of Science in Agriculture with a specialization in Food Science and Nutrition." "December 2008." Includes bibliographical references (p. 81-90). Also available on microfiche.