Prentice, Howard

Alzheimer’s disease (AD) is one of the most common neurodegenerative diseases affecting an estimated 20 million worldwide. The primary pathology of AD is the progressive loss of basal forebrain cholinergic neurons, which is responsible for the cognitive decline experienced by AD patients. The mechanisms underlying this selective vulnerability have not been fully elucidated. Furthermore, oxidative stress is a key factor behind the pathology of AD leading to this neuronal loss. The current literature suggests that there are limited in-vitro models available to accurately simulate the hallmark symptoms of Alzheimer's disease (AD). The SH-SY5Y cell line has been used extensively to study neuronal stress responses but the undifferentiated cell type has been predominantly used. Undifferentiated SH-SY5Y versus differentiated SH-SY5Y have been shown to have different interaction, expression and localization with AD hallmark, amyloid-b -42. This project sought to use differentiated cholinergic cells from the line SH-SY5Y to further isolate and elucidate, in-vitro, the mechanisms behind the oxidative stress response, a key stressor in the pathology of AD. Building upon previous studies, a protocol to differentiate SH-SY5Y cells with retinoic acid (RA) and neurotrophin (BDNF) to mature neurons of the cholinergic phenotype was optimized and implemented. The results showed successful differentiation into the cholinergic phenotype as evidenced via immunofluorescence imaging of choline acetyl transferase (ChAT) expression and mature neurite morphology. To simulate oxidative stress, we exposed both undifferentiated and differentiated SH-SY5Y cells to hypoxic conditions. Results indicated a stress response to mild hypoxic conditions with higher sensitivity in cholinergic differentiated SH-SY5Y. Understanding these hallmark mechanisms behind oxidative stress is crucial to developing mechanism-based therapeutics for AD.

Alzheimer’s disease is a neurodegenerative disease that causes cognitive dysfunction and leads to progressive memory loss and behavioral impairment. About 60% to 80% of dementia cases are attributed to Alzheimer’s disease and currently afflict about 50 million people worldwide. Although it primarily affects people over the age of 65, a person’s risk for developing Alzheimer’s disease earlier can depend on factors such as a family history (genetic inheritance) or experiencing an ischemic stroke event. Current treatments for Alzheimer’s disease include behavioral therapy and drug treatment that can lessen the severity of symptoms but cannot stop progression indefinitely. Sulindac is a non-steroidal anti-inflammatory drug that, by a mechanism independent of its anti-inflammatory properties, has shown to express a preconditioning response to protect from oxidative damage. Granulocyte colony stimulating factor is a hematopoietic glycoprotein that can stimulate the production of granulocytes and stem cells that has proven to provide neuroprotection in models of ischemic stroke via mechanisms including anti-apoptosis and anti-inflammation. In this in vitro study, the potential neuroprotective effects of Sulindac is measured against the effects of oxidative stress when subjected to hypoxia and reperfusion. Regarding un-transfected SHSY-5Y cells, hypoxia was demonstrated to lower cell viability starting at a period of 12 hours. It was found that a low concentration of Sulindac (200 uM) was effective in protecting SHSY-5Y cells against oxidative stress and overall lowering the rate of cell death in the event of hypoxic and reperfusion injury. When SHSY-5Y cells were transfected with Swedish APP mutation, cell viability was also markedly decreased in hypoxic conditions. However when treated with a concentration of 600 uM of Sulindac, cell viability levels were near matched with its normoxic counterparts

Ischemic stroke is defined as a blockage or reduced flow of blood to select areas of brain tissue due to either plaque formation or buildup of blood clots in the small blood vessels. A characteristic of sickle cell anemic patients is the potential for them to experience a similar type of blockage due to the sticky nature of the sickled red blood cells as well as defective oxygen delivery to the brain. Because of this similarity, sickle cell anemia may represent a good animal research model for therapeutic intervention based on stroke models. In recent studies, Granulocyte-Colony Stimulating Factor (GCSF), has been shown to exhibit a robust range of neuroprotective properties against neurological disorders including ischemic stroke through preservation of the endoplasmic reticulum (ER) by modulating various ER stress pathways. Through cognitive deficit analysis in the form of behavioral and locomotor experiments in addition to in situ biomarker analysis by way of western blotting and immunohistochemistry, we found that G-CSF gene therapy exhibited neurogenic and neuroprotective effects in ischemic mouse models and could possibly serve as a good therapy for other diseases that share similar pathology to stroke.

Both proliferative diabetic retinopathy and exudative age-related macular degeneration are major causes of blindness which are caused by growth of defective, leaky and tortuous blood vessels in the retina. Hypoxia is implicated in triggering both of these diseases and results in induction of HIF-1alpha transcription factor in addition to the angiogenic factor VEGF. Müller cells are the major glial cell in the retina and they contribute to neovascularization in hypoxic regions of the retina through eliciting secretion of growth factors, cytokines and angiogenic factors. As Müller cells span the breadth of the retina they can secrete angiostatic factors as well as neuroprotective trophic factors, the Müller cell is a valuable cell type for targeting by potential new gene therapies. The current investigation tests the hypoxia responsiveness of an AAV vector containing a hybrid hypoxia response element together with a GFAP promoter, and this vector encodes the angiostatic protein decorin, a well characterized multi-receptor tyrosine kinase inhibitor. Decorin may have advantages over other key angiostatic factors such as endostatin or angiostatin by virtue of its multiple anti-angiogenic signaling modalities. We employed Q-RT-PCR to evaluate the cell specificity and hypoxia responsiveness of an AAV-Vector termed AAV-REG-Decorin containing a hybrid HRE and GFAP promoter driving expression of the decorin transgene. The vector also contains a silencer element between the HRE and the GFAP domains to enable low basal expression in normoxia as well as high level inducibility in hypoxia. AAV-REGDecorin was found to elicit high level expression of decorin mRNA in hypoxia with greater than 9 – fold induction of the transgene in hypoxic conditions in astrocytes by comparison to normoxic astrocytes. AAV-REG-Decorin showed low levels of transgene expression by comparison to the positive control vector AAV-CMV -decorin containing the ubiquitously active CMV-promoter. The expression levels of decorin mRNA from AAV-REG-Decorin and from AAV-GFAP-Decorin were low in the PC12 neuronal cell model and in the ARPE19 line of retinal pigment epithelial cells with respect to those of AAV-CMV-decorin and no induction of Decorin mRNA was found with AAV-REGDecorin in these two control cell lines. Our novel gene therapy vector will serve as a platform for testing efficacy in rodent disease models (OIR and laser induced choroidal neovascularization) for assessment of the benefits of tightly regulated antiangiogenic gene therapy eliciting decorin transgene expression, both in terms of timing and the cellular source of production, during the progression of the retinal pathophysiology.

FAU's Office of Undergraduate Research and Inquiry hosts an annual symposium where students engaged in undergraduate research may present their findings either through a poster presentation or an oral presentation.

The excess generation of Reactive oxygen species (ROS) can damage
cell components and disrupt cellular functions. Methionine in proteins is easily
oxidized by ROS and converted to methionine sulfoxide. The enzyme peptide
Methionine Sulfoxide Reductase reduces methionine sulfoxide back to methionine.
We report here that MsrA over expression in rat cardiac myocytes prevents damage
from ROS and increases cell viability after hypoxic/reoxygenation events. The nonsteroidal
anti-inflamatory drug (NSAID) sulindac contains a methyl sulfoxide moiety
that can scavenge ROS. Sulindac can be reduced by MsrA and contribute as an
antioxidant in the cell. Our results demonstrate that 1 OOuM sulindac can reduce cell
death in rat cardiac myocytes during hypoxia/reoxygenation, and
ischemia/reperfusion in Langendorf[ perfusions. The BNIP proteins are pro-apoptotic
members of the Bcl-2 family of apoptosis regulating proteins. Hypoxia/acidosis
stabilizes BNIP-3 and increases its association with the mitochondria, causing the
release of cytochrome C and cell death. We report the retrograde perfusion
Langendorffmodel is inconclusive in mouse hearts.

Taurine, an endogenous ammo acid and neuromodulator, has been found to be
neuroprotective against numerous forms of neurotoxicity including glutamate-induced
excitotoxicity. Previously we have shown that taurine inhibits glutamate-induced
calcium influx through VGCCs and NMDA receptors. Although the neuroprotective
effects of taurine against excitotoxicity have been attributed to its intracellular Ca2+
regulatory functions, the complete mechanism underling taurine neuroprotection has
remained unclear. Using primary rat cortical neuronal cell cultures, we have determined
key cytosolic components to the mechanism of taurine neuroprotection. In this study we
have found that taurine inhibits excitotoxicity by suppressing glutamate-induced
elevations in [Ca2+]i, preventing calpain activation, and inhibiting reductions in Bel-
2:Bax ratios and consequently activation of the intrinsic pathway.