Current Search: Cyclic GMP-Dependent Protein Kinases (x)
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- Title
- cGMP/PKG-regulated mechanisms of protection from low oxygen and oxidative stress.
- Creator
- Mahneva, Olena, Milton, Sarah L., Dawson-Scully, Ken, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
- Abstract/Description
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Stroke is one of the leading causes of human death in the United States. The debilitating effects of an ischemic stroke are due to the fact that mammalian neurons are highly susceptible to hypoxia and subsequent oxygen reperfusion. From studies in Drosophila melanogaster, cGMP-dependent Protein Kinase (PKG) enzyme is thought to affect anoxia tolerance by modifying the electrical current through potassium ion channels. In this research, two animal models were employed: Drosophila melanogaster...
Show moreStroke is one of the leading causes of human death in the United States. The debilitating effects of an ischemic stroke are due to the fact that mammalian neurons are highly susceptible to hypoxia and subsequent oxygen reperfusion. From studies in Drosophila melanogaster, cGMP-dependent Protein Kinase (PKG) enzyme is thought to affect anoxia tolerance by modifying the electrical current through potassium ion channels. In this research, two animal models were employed: Drosophila melanogaster and mammalian neurons exposed to stroke-like conditions. First, in vivo studies using Drosophila were performed to further our knowledge about the differences between the naturally occurring variants of the Drosophila foraging gene, which shows different protein levels of PKG. Mitochondrial density and metabolic activity between two fly genotypes exposed to anoxia and reoxygenation were compared. It was found that flies with less enzyme potentially showed mitochondrial biogenesis and higher metabolic rates upon reoxygenation. Next, in vivo studies where PKG enzyme was activated pharmacologically were performed; it was found that the activation of the cGMP/PKG pathway led to neuroprotection upon anoxia and reoxygenation. Furthermore, this model was translated into the in vitro model using Drosophila cells. Instead of anoxia and reoxygenation, hypoxia mimetics and hydrogen peroxide were used to induce cellular injury. After showing the cGMP/PKG pathway activation-induced cell protection, the potential downstream targets of the molecular signaling as well as underlying biochemical changes were assessed. It was found that mitochondrial potassium ion channels were involved in the protective signaling and the signaling modulated metabolic function. Furthermore, it was found that acidosis protected Drosophila cells from cell death, metabolic disruption, and oxidative stress. Finally, this research was translated to a mammalian in vitro model of neuronal damage upon stroke-like conditions; there, it was demonstrated that the cGMP/PKG pathway activation in rat primary cortical neurons and human cortical neurons was protective from low oxygen and acute oxidative stress. The results of this study lead to a better understanding of molecular mechanisms taking place during low oxygen and oxidative stresses. Consequently, this knowledge may be used to identify potential therapeutic targets and treatments that may prevent detrimental neurological effects of an ischemic stroke in humans.
Show less - Date Issued
- 2018
- PURL
- http://purl.flvc.org/fau/fd/FA00013013
- Subject Headings
- Stroke, Cyclic GMP-Dependent Protein Kinases, Oxidative Stress
- Format
- Document (PDF)
- Title
- Neuroprotection during acute hyperthermic stress: Role of the PKG pathway in neurons and glia in the protection of neural function in Drosophila melanogaster.
- Creator
- Krill, Jennifer L., Dawson-Scully, Ken, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
- Abstract/Description
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The human brain functions within a narrow range of temperatures and variations outside of this range incur cellular damage and death and, ultimately, death of the organism. Other organisms, like the poikilotherm Drosophila melanogaster, have adapted mechanisms to maintain brain function over wide ranges in temperature and, if exposed to high temperatures where brain function is no longer supported, these animals enter a protective coma to promote survival of the organism once the acute...
Show moreThe human brain functions within a narrow range of temperatures and variations outside of this range incur cellular damage and death and, ultimately, death of the organism. Other organisms, like the poikilotherm Drosophila melanogaster, have adapted mechanisms to maintain brain function over wide ranges in temperature and, if exposed to high temperatures where brain function is no longer supported, these animals enter a protective coma to promote survival of the organism once the acute temperature stress is alleviated. This research characterized the role of different neuronal cell types, including glia, in the protection of brain function during acute hyperthermia, specifically looking at two protective pathways: the heat shock protein (HSP) pathway and the cGMP-dependent protein kinase G (PKG) pathway. Whole animal behavioral assays were used in combination with tissue-specific genetic manipulation of protective pathways to determine the specific cell types sufficient to confer protection of neuronal function during acute hyperthermia. Using the neuromuscular junction (NMJ) preparation, calcium imaging techniques were combined with pharmacological and genetic manipulations to test the hypothesis that alterations in ion channel conductance via endogenous mechanisms regulating the cellular response to high temperature stress alter neuronal function. Expression of foraging RNAi to inhibit PKG expression in neurons or glia demonstrated protection of function during acute hyperthermia measured behaviorally through the extension of locomotor function. This extension of function with the tissue-specific inhibition of PKG was also confirmed at the cellular level using the genetically encoded calcium indicator (GECI), GCaMP3, to image calcium dynamics at the NMJ, where preparations expressing foraging RNAi could continue to elicit changes in calcium dynamics in response to stimulation. Over the course of this study, the mechanism underlying a novel glial calcium wave in the peripheral nervous system was characterized in order to elucidate glia’s role in the protection of neuronal function during acute hyperthermia.
Show less - Date Issued
- 2018
- PURL
- http://purl.flvc.org/fau/fd/FA00013026
- Subject Headings
- Cyclic GMP-Dependent Protein Kinases, Neuroprotection, Hyperthermia, Heat shock proteins, Drosophila melanogaster
- Format
- Document (PDF)
- Title
- Functional Stress Resistance: The Role of Protein Kinase G in Modulating Neuronal Excitability in Caenorhabditis Elegans and Drosophila Melanogaster.
- Creator
- Kelly, Stephanie Suzanne, Dawson-Scully, Ken, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
- Abstract/Description
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Diseases such as epilepsy, pain, and neurodegenerative disorders are associated with changes in neuronal dysfunction due to an imbalance of excitation and inhibition. This work details a novel electroconvulsive seizure assay for C. elegans using the well characterized cholinergic and GABAergic excitation and inhibition of the body wall muscles and the resulting locomotion patterns to better understand neuronal excitability. The time to recover normal locomotion from an electroconvulsive...
Show moreDiseases such as epilepsy, pain, and neurodegenerative disorders are associated with changes in neuronal dysfunction due to an imbalance of excitation and inhibition. This work details a novel electroconvulsive seizure assay for C. elegans using the well characterized cholinergic and GABAergic excitation and inhibition of the body wall muscles and the resulting locomotion patterns to better understand neuronal excitability. The time to recover normal locomotion from an electroconvulsive seizure could be modulated by increasing and decreasing inhibition. GABAergic deficits and a chemical proconvulsant resulted in an increased recovery time while anti-epileptic drugs decreased seizure duration. Successful modulation of excitation and inhibition in the new assay led to the investigation of a cGMP-dependent protein kinase (PKG) which modulates potassium (K+) channels, affecting neuronal excitability, and determined that increasing PKG activity decreases the time to recovery from an electroconvulsive seizure. The new assay was used as a forward genetic screening tool using C. elegans and several potential genes that affect seizure susceptibility were found to take longer to recover from a seizure. A naturally occurring polymorphism for PKG in D. melanogaster confirmed that both genetic and pharmacological manipulation of PKG influences seizure duration. PKG has been implicated in stress tolerance, which can be affected by changes in neuronal excitability associated with aging, so stress tolerance and locomotor behavior in senescent flies was investigated. For the first time, PKG has been implicated in aging phenotypes with high levels of PKG resulting in reduced locomotion and lifespan in senescent flies. The results suggest a potential new role for PKG in seizure susceptibility and aging.
Show less - Date Issued
- 2019
- PURL
- http://purl.flvc.org/fau/fd/FA00013225
- Subject Headings
- Caenorhabditis elegans, Drosophila melanogaster, Cyclic GMP-Dependent Protein Kinases, Seizures
- Format
- Document (PDF)