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Vanderbilt University
1.
Armour, Eric Andrew.
Dysregulated mTOR signaling and tissue-specific phenotypes in Tuberous Sclerosis Complex.
Degree: PhD, Cell and Developmental Biology, 2013, Vanderbilt University
URL: http://hdl.handle.net/1803/14546 
► Tuberous Sclerosis Complex (TSC) is a multi-organ hamartomatous disease caused by loss of function mutations in either the TSC1 or TSC2 genes. Despite involvement of…
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▼ Tuberous Sclerosis Complex (TSC) is a multi-organ hamartomatous disease caused by loss of function mutations in either the TSC1 or TSC2 genes. Despite involvement of multiple organs such as the kidneys, lungs, and skin, neurological aspects are usually the most severe due to a very high prevalence of cognitive impairment, autism and epilepsy. The protein products of TSC1 and TSC2, hamartin and tuberin respectively, regulate the mTOR kinase signaling pathway. Current models of TSC propose that hamartoma formation is secondary to a loss of heterozygosity at either the TSC1 or TSC2 loci, and subsequent hyperactivation of mTOR Complex 1 (mTORC1). In this dissertation I explore the underlying mechanisms of organ specific pathogenesis in TSC.
In the first half of my dissertation, I demonstrate that loss of Tsc1 in the distal convoluted tubule of the kidney results in cystogenesis. Cyst formation in these kidneys is due to a mTORC1 but not mTORC2 dependent process. I then show that cystic changes in these kidneys may be due to ciliary defects.
While a loss of heterozygosity has clearly been reported in the kidney and other organ system, second hit mutations in neural lesions have only rarely been identified. Thus, to begin to define the role of the heterozygosity of TSC1 or TSC2 during the pathogenesis of TSC in the brain, we generated induced pluripotent stem cells (iPSC) from patients with TSC. Deep sequencing of these patents revealed that all of our patient derived lines are heterozygous for TSC2 mutations. I then provide evidence that these heterozygous iPSCs are abnormal with increased cell survival and enhanced maintenance of pluripotency. These changes may be due to slight changes in mTORC1 signaling.
The work presented in this dissertation increases our understanding of the tissue specific phenotypes and underlying mechanisms of TSC pathogenesis. This research may lead to the identification of new therapeutic targets for TSC and associated comorbidities.
Advisors/Committee Members: Alfred L. George (committee member), Maureen A. Gannon (committee member), Wenbiao Chen (committee member), Kevin C. Ess (committee member), Chin Chiang (Committee Chair).
Subjects/Keywords: TSC; pluripotency; Tuberous Sclerosis; cilia; cystogenesis; mTOR
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APA (6th Edition):
Armour, E. A. (2013). Dysregulated mTOR signaling and tissue-specific phenotypes in Tuberous Sclerosis Complex. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/14546
Chicago Manual of Style (16th Edition):
Armour, Eric Andrew. “Dysregulated mTOR signaling and tissue-specific phenotypes in Tuberous Sclerosis Complex.” 2013. Doctoral Dissertation, Vanderbilt University. Accessed January 15, 2021.
http://hdl.handle.net/1803/14546.
MLA Handbook (7th Edition):
Armour, Eric Andrew. “Dysregulated mTOR signaling and tissue-specific phenotypes in Tuberous Sclerosis Complex.” 2013. Web. 15 Jan 2021.
Vancouver:
Armour EA. Dysregulated mTOR signaling and tissue-specific phenotypes in Tuberous Sclerosis Complex. [Internet] [Doctoral dissertation]. Vanderbilt University; 2013. [cited 2021 Jan 15].
Available from: http://hdl.handle.net/1803/14546.
Council of Science Editors:
Armour EA. Dysregulated mTOR signaling and tissue-specific phenotypes in Tuberous Sclerosis Complex. [Doctoral Dissertation]. Vanderbilt University; 2013. Available from: http://hdl.handle.net/1803/14546
Vanderbilt University
2.
Murphy, Lisa Lynn.
The Physiology and Pathophysiology of a Fetal Splice Variant of the Cardiac Sodium Channel.
Degree: PhD, Pharmacology, 2014, Vanderbilt University
URL: http://hdl.handle.net/1803/11214
► Mutations in SCN5A encoding the cardiac voltage-gated sodium channel (NaV1.5) can result in severe life-threatening cardiac arrhythmias such as long QT syndrome (LQTS). However, the…
(more)
▼ Mutations in SCN5A encoding the cardiac voltage-gated sodium channel (NaV1.5) can result in severe life-threatening cardiac arrhythmias such as long QT syndrome (LQTS). However, the molecular basis for arrhythmia susceptibility in early developmental stages remains unclear. Our lab has shown prominent expression of a fetal-expressed splice variant of the cardiac sodium channel (fetal NaV1.5) in human fetal and infant hearts. We hypothesized that mutations in SCN5A expressed in the fetal NaV1.5 may result in more severe functional effects vs expression in adult NaV1.5. Electrophysiological studies were conducted on heterologously expressed WT or mutant adult or fetal NaV1.5. We compared the functional effects of SCN5A mutations associated with early-onset LQTS with that of a mutation associated with typical onset LQTS (delKPQ) expressed in the context of fetal NaV1.5. We have shown that early onset LQT3 mutations exhibit equal or more severe functional consequences such as persistent sodium current (INa) in the fetal NaV1.5 vs expression in the adult NaV1.5. Typical onset mutation, delKPQ, demonstrated an attenuated gain of function in fetal NaV1.5. In addition to these findings, we elucidated the molecular mechanism of calmodulin (CaM) mutations associated with neonatal LQTS on NaV1.5. We hypothesized that mutant CaM would evoke an increased persistent INa associated with LQTS. Electrophysiological studies were conducted on WT adult or fetal NaV1.5 co-expressed with WT or mutant calmodulin. We observed that CaM-D130G co-expressed with fetal NaV1.5 exhibits a significantly greater persistent INa vs co-expression with WT CaM. This increase in persistent INa was not observed for CaM-D130G co-expressed with the canonical NaV1.5 and required the presence of high calcium. We also show that CaM mutations caused slowing of calcium-dependent inactivation of
L-type calcium channels. We conclude that developmentally regulated alternative splicing of SCN5A contributes to the genetic risk for prenatal life-threatening cardiac arrhythmias. We also conclude that the voltage-gated cardiac sodium channel is not consistently involved in the molecular mechanism of LQTS associated with mutations in calmodulin.
Advisors/Committee Members: Alfred L. George Jr., MD (committee member), Katherine T. Murray, MD (committee member), Dan M. Roden, MD (committee member), Jennifer A. Kearney, PhD (committee member), Ronald B. Emeson, PhD (Committee Chair).
Subjects/Keywords: sodium channel; long QT syndrome; arrhythmias; ion channels
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APA (6th Edition):
Murphy, L. L. (2014). The Physiology and Pathophysiology of a Fetal Splice Variant of the Cardiac Sodium Channel. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/11214
Chicago Manual of Style (16th Edition):
Murphy, Lisa Lynn. “The Physiology and Pathophysiology of a Fetal Splice Variant of the Cardiac Sodium Channel.” 2014. Doctoral Dissertation, Vanderbilt University. Accessed January 15, 2021.
http://hdl.handle.net/1803/11214.
MLA Handbook (7th Edition):
Murphy, Lisa Lynn. “The Physiology and Pathophysiology of a Fetal Splice Variant of the Cardiac Sodium Channel.” 2014. Web. 15 Jan 2021.
Vancouver:
Murphy LL. The Physiology and Pathophysiology of a Fetal Splice Variant of the Cardiac Sodium Channel. [Internet] [Doctoral dissertation]. Vanderbilt University; 2014. [cited 2021 Jan 15].
Available from: http://hdl.handle.net/1803/11214.
Council of Science Editors:
Murphy LL. The Physiology and Pathophysiology of a Fetal Splice Variant of the Cardiac Sodium Channel. [Doctoral Dissertation]. Vanderbilt University; 2014. Available from: http://hdl.handle.net/1803/11214
Vanderbilt University
3.
Campbell, Courtney Michelle.
Pharmacological Targeting of Gain-of-function KCNQ1 Mutations Predisposing to Atrial Fibrillation.
Degree: PhD, Pharmacology, 2013, Vanderbilt University
URL: http://hdl.handle.net/1803/13258
► Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in adults. The discovery of mutations in familial AF illustrated the contribution of specific genetic…
(more)
▼ Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in adults. The discovery of mutations in familial AF illustrated the contribution of specific genetic factors to AF susceptibility and suggested molecular mechanisms for some heritable forms of this common arrhythmia. This dissertation focused on the first identified causative familial AF mutation (S140G) in the voltage gated potassium channel gene KCNQ1. Because transgenic S140G mouse models were inadequate for reproducing an AF-prone substrate, we first developed methods for high yield isolation, extended culture, and transfection of adult atrial myocytes suitable for electrophysiological experiments. Using a novel serial sampling technique, we were able to achieve reproducible high yields of both ventricular and atrial myocytes. Adenovirus-mediated transduction proved most efficient in rabbit myocyte preparations with high titers and robust expression of transgenes. Using this rabbit adult atrial myocyte model system, we demonstrated that S140G-IKs expressing myocytes had triggered activity at low frequency stimulation and a shorter action potential duration at higher frequency with hyperpolarized resting membrane potential compared to WT-IKs expressing myocytes. We hypothesized that KCNQ1 mutations predisposing to AF encode potassium channels with distinct pharmacological properties that could render them susceptible to selective inhibition. Consistent with our hypothesis, we observed that S140G-IKs exhibits enhanced sensitivity to the IKs-selective blocker, HMR-1556. This enhancement was correlated with the emergence of an additional high affinity state, which was also observed with V141M-IKs, a neighboring gain-of-function AF-associated mutation. Using a concentration that predominantly inhibits the high affinity state, we demonstrated that HMR-1556 effectively suppressed HET-IKs amplitude to a level that was not significantly different from WT-IKs. Further, this drug concentration attenuated the use-dependent accumulation of HET-IKs that occurs during repetitive pulsing. Significantly, we demonstrated that HMR-1556 can mitigate the S140G-IKs induced APD shortening in cultured adult rabbit atrial myocytes without affecting action potentials in myocytes expressing WT-IKs. These findings offer evidence supporting the potential for genotype-specific therapy of familial AF.
Advisors/Committee Members: Katherine T. Murray (committee member), Chee C. Lim (committee member), L. Jackson Roberts, II (committee member), Alfred L. George, Jr (committee member), Dan M. Roden (Committee Chair).
Subjects/Keywords: atrial fibrillation; arrhythmia; personalized medicine; myocytes; cardiac; ion channels; potassium channels; pharmacology
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APA (6th Edition):
Campbell, C. M. (2013). Pharmacological Targeting of Gain-of-function KCNQ1 Mutations Predisposing to Atrial Fibrillation. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/13258
Chicago Manual of Style (16th Edition):
Campbell, Courtney Michelle. “Pharmacological Targeting of Gain-of-function KCNQ1 Mutations Predisposing to Atrial Fibrillation.” 2013. Doctoral Dissertation, Vanderbilt University. Accessed January 15, 2021.
http://hdl.handle.net/1803/13258.
MLA Handbook (7th Edition):
Campbell, Courtney Michelle. “Pharmacological Targeting of Gain-of-function KCNQ1 Mutations Predisposing to Atrial Fibrillation.” 2013. Web. 15 Jan 2021.
Vancouver:
Campbell CM. Pharmacological Targeting of Gain-of-function KCNQ1 Mutations Predisposing to Atrial Fibrillation. [Internet] [Doctoral dissertation]. Vanderbilt University; 2013. [cited 2021 Jan 15].
Available from: http://hdl.handle.net/1803/13258.
Council of Science Editors:
Campbell CM. Pharmacological Targeting of Gain-of-function KCNQ1 Mutations Predisposing to Atrial Fibrillation. [Doctoral Dissertation]. Vanderbilt University; 2013. Available from: http://hdl.handle.net/1803/13258
Vanderbilt University
4.
Ciampa, Erin Julia.
Investigating the function of KCNE4 in cardiac physiology.
Degree: PhD, Pharmacology, 2011, Vanderbilt University
URL: http://hdl.handle.net/1803/10729
► KCNE4 is a potassium channel modulating protein that can dramatically inhibit distinct potassium currents, but we lack a clear understanding its mechanism for doing so…
(more)
▼ KCNE4 is a potassium channel modulating protein that can dramatically inhibit distinct potassium currents, but we lack a clear understanding its mechanism for doing so and its physiologic significance. In this project we sought new understanding of the physiological functions of KCNE4, through identification of its protein interacting partners and assessment of the consequences of Kcne4 knockout in mouse cardiac physiology.
A membrane-based yeast two-hybrid screen identified 20 putative interacting partners of KCNE4. The ‘hit’ with the most obvious potential for functional intersection with KCNE4 was calmodulin (CaM), a known ion channel modulator. We subsequently demonstrated a Ca2+-dependent biochemical interaction between KCNE4 and CaM and that KCNQ1 modulation by KCNE4 is impaired both upon mutation of the CaM-interaction site of KCNE4 and by acutely chelating intracellular calcium to displace CaM from KCNE4. These findings suggest a connection between the mechanism of KCNQ1 inhibition by KCNE4 and the activating effect of CaM on the channel. Whereas we had previously assumed that the inhibition of KCNQ1 by KCNE4 is caused by a direct effect of KCNE4 on the channel, these data introduce the new possibility that KCNE4 inhibits KCNQ1 by disrupting CaM-mediated activation.
Analysis of a Kcne4-null mouse constituted another approach to investigating the physiologic significance of KCNE4. We hypothesized that Kcne4 may be an endogenous negative regulator of repolarizing currents in the cardiac action potential, and that Kcne4-null mice might display shortened repolarization time, with possible implications for arrhythmia susceptibility or excitation-contraction coupling. Electrocardiographic analysis revealed that Kcne4-null mice under isoflurane anesthesia have a shortened QTc interval compared with wild-type littermates. Our hypothesis was also supported by the observation of shortened action potential duration in isolated ventricular myocytes from Kcne4-null mice. Further, echocardiography studies demonstrated that conscious Kcne4-null mice have increased left ventricular internal diameter during diastole and systole and impaired myocardial contractility.
Collectively, these studies suggest KCNE4 may contribute to cardiac physiology as a Ca2+-sensitive modulator of repolarizing currents, with possible downstream effects on excitation-contraction coupling and myocardial contractility.
Advisors/Committee Members: Alfred L. George, Jr (committee member), James R. Goldenring (committee member), Bjorn C. Knollmann (committee member), Christopher B. Brown (committee member), Ronald B. Emeson (Committee Chair).
Subjects/Keywords: electrophysiology; ion channel; KCNE4; calmodulin; cardiac repolarization
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APA (6th Edition):
Ciampa, E. J. (2011). Investigating the function of KCNE4 in cardiac physiology. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/10729
Chicago Manual of Style (16th Edition):
Ciampa, Erin Julia. “Investigating the function of KCNE4 in cardiac physiology.” 2011. Doctoral Dissertation, Vanderbilt University. Accessed January 15, 2021.
http://hdl.handle.net/1803/10729.
MLA Handbook (7th Edition):
Ciampa, Erin Julia. “Investigating the function of KCNE4 in cardiac physiology.” 2011. Web. 15 Jan 2021.
Vancouver:
Ciampa EJ. Investigating the function of KCNE4 in cardiac physiology. [Internet] [Doctoral dissertation]. Vanderbilt University; 2011. [cited 2021 Jan 15].
Available from: http://hdl.handle.net/1803/10729.
Council of Science Editors:
Ciampa EJ. Investigating the function of KCNE4 in cardiac physiology. [Doctoral Dissertation]. Vanderbilt University; 2011. Available from: http://hdl.handle.net/1803/10729
Vanderbilt University
5.
Jorge, Benjamin S.
Genetic Variation in the Voltage-gated Potassium Channel Genes KCNV2 and KCNB1 Contributes to Epilepsy Susceptibility.
Degree: PhD, Neuroscience, 2014, Vanderbilt University
URL: http://hdl.handle.net/1803/14387
► Epilepsy is a common neurological disease characterized by an enduring predisposition to generate seizures. Although multiple factors contribute to epilepsy, the majority of cases are…
(more)
▼ Epilepsy is a common neurological disease characterized by an enduring predisposition to generate seizures. Although multiple factors contribute to epilepsy, the majority of cases are genetic in origin. Variable expressivity is commonly observed in families with inherited mutations in epilepsy-associated genes, suggesting that variation in genetic modifiers may contribute to epilepsy phenotypes. We previously identified the modulatory voltage-gated potassium channel subunit, Kcnv2, as a candidate modifier gene in a transgenic mouse model of epilepsy. This dissertation outlines: the validation of Kcnv2 as a quantitative modifier of epilepsy in mice; the identification of KCNV2 variants in pediatric epilepsy patients; the determination of Kcnv2 regulatory regions; and the identification of mutations in a delayed-rectifier potassium channel gene, KCNB1, in individuals with epileptic encephalopathy. These studies highlight the importance of delayed-rectifier potassium current in governing neuronal excitability and demonstrate the utility of identifying and characterizing genetic modifiers to elucidate mechanisms of pathogenesis.
Advisors/Committee Members: Kevin C. Ess, M.D., Ph.D. (committee member), Jennifer A. Kearney, Ph.D. (committee member), Douglas P. Mortlock, Ph.D. (committee member), Alfred L. George, Jr., M.D. (Committee Chair).
Subjects/Keywords: potassium channel; epileptic encephalopathy; mouse model; genetics; whole-exome sequencing; epilepsy
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APA (6th Edition):
Jorge, B. S. (2014). Genetic Variation in the Voltage-gated Potassium Channel Genes KCNV2 and KCNB1 Contributes to Epilepsy Susceptibility. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/14387
Chicago Manual of Style (16th Edition):
Jorge, Benjamin S. “Genetic Variation in the Voltage-gated Potassium Channel Genes KCNV2 and KCNB1 Contributes to Epilepsy Susceptibility.” 2014. Doctoral Dissertation, Vanderbilt University. Accessed January 15, 2021.
http://hdl.handle.net/1803/14387.
MLA Handbook (7th Edition):
Jorge, Benjamin S. “Genetic Variation in the Voltage-gated Potassium Channel Genes KCNV2 and KCNB1 Contributes to Epilepsy Susceptibility.” 2014. Web. 15 Jan 2021.
Vancouver:
Jorge BS. Genetic Variation in the Voltage-gated Potassium Channel Genes KCNV2 and KCNB1 Contributes to Epilepsy Susceptibility. [Internet] [Doctoral dissertation]. Vanderbilt University; 2014. [cited 2021 Jan 15].
Available from: http://hdl.handle.net/1803/14387.
Council of Science Editors:
Jorge BS. Genetic Variation in the Voltage-gated Potassium Channel Genes KCNV2 and KCNB1 Contributes to Epilepsy Susceptibility. [Doctoral Dissertation]. Vanderbilt University; 2014. Available from: http://hdl.handle.net/1803/14387
Vanderbilt University
6.
Bartlett, Christina Swan.
Role of the prostaglandin E2 receptor EP1 in hypertensive end-organ damage.
Degree: PhD, Pharmacology, 2012, Vanderbilt University
URL: http://hdl.handle.net/1803/14916
► Hypertension is a prevalent disease affecting one in three adults in the United States. Approximately 25 % of the adult population is either not receiving…
(more)
▼ Hypertension is a prevalent disease affecting one in three adults in the United States. Approximately 25 % of the adult population is either not receiving therapy for their hypertension or is unable to control their blood pressure with current therapies, making treatment of hypertension an important public health goal. In blood pressure regulation, PGE2 can act in a pro-hypertensive or anti-hypertensive manner. It has been demonstrated that EP2 and EP4 receptors mediate the vasodepressor actions of PGE2 and EP1 and EP3 receptors mediate the vasopressor actions of PGE2. Additionally, PGE2 and the EP1 receptor have been demonstrated to mediate at least part of the actions of angiotensin II.
I sought to determine the contribution of EP1 and/or EP3 receptors to hypertensive end-organ damage and diabetic nephropathy. In this dissertation, I utilize mice with genetic disruption of EP1 or EP3 receptors and characterize the outcomes of several models of hypertensive organ damage. In the Nphx/DOCA-NaCl/Ang II model of hypertension, I have demonstrated that disruption of EP1 or EP3 can afford substantial protection from end-organ damage and reduce incidence of mortality. The beneficial effects of EP1 disruption, and likely EP3 disruption, appear to be a result of reduction in MAP in this model. The use of another model involving uninephrectomy and Ang II on a 129S6 background suggests the EP1 receptor plays an important role in hypertensive renal disease independent of blood pressure reduction. Furthermore, genetic disruption of EP1 protected eNOS-/- mice from diabetes-induced proteinuria, independent of blood pressure reduction.
In summary, the data presented in this dissertation advances our knowledge of the role of EP1 and EP3 receptors in hypertension and subsequent sequalae and demonstrate a detrimental role of EP1 in this disease. Targeting the EP1 receptor may be a viable pharmaceutical treatment strategy for hypertension and subsequent organ damage.
Advisors/Committee Members: Richard M. Breyer (committee member), Vsevolod V. Gurevich (committee member), Ambra Pozzi (committee member), Alfred L. George, Jr. (committee member), Brian E. Wadzinski (Committee Chair).
Subjects/Keywords: Prostaglandin; Receptor; Hypertension; Diabetes
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APA (6th Edition):
Bartlett, C. S. (2012). Role of the prostaglandin E2 receptor EP1 in hypertensive end-organ damage. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/14916
Chicago Manual of Style (16th Edition):
Bartlett, Christina Swan. “Role of the prostaglandin E2 receptor EP1 in hypertensive end-organ damage.” 2012. Doctoral Dissertation, Vanderbilt University. Accessed January 15, 2021.
http://hdl.handle.net/1803/14916.
MLA Handbook (7th Edition):
Bartlett, Christina Swan. “Role of the prostaglandin E2 receptor EP1 in hypertensive end-organ damage.” 2012. Web. 15 Jan 2021.
Vancouver:
Bartlett CS. Role of the prostaglandin E2 receptor EP1 in hypertensive end-organ damage. [Internet] [Doctoral dissertation]. Vanderbilt University; 2012. [cited 2021 Jan 15].
Available from: http://hdl.handle.net/1803/14916.
Council of Science Editors:
Bartlett CS. Role of the prostaglandin E2 receptor EP1 in hypertensive end-organ damage. [Doctoral Dissertation]. Vanderbilt University; 2012. Available from: http://hdl.handle.net/1803/14916
Vanderbilt University
7.
Huang, Xuan.
Epilepsy-associated mutations in GABRG2: characterization and therapeutic opportunities.
Degree: PhD, Neuroscience, 2014, Vanderbilt University
URL: http://hdl.handle.net/1803/14755
► Epilepsy is a neurological disorder affecting almost one percent of the population, and genetic epilepsy are those caused by a presumed or unknown genetic factor(s).…
(more)
▼ Epilepsy is a neurological disorder affecting almost one percent of the population, and genetic epilepsy are those caused by a presumed or unknown genetic factor(s). Mutations in GABAA receptors, pentameric chloride ion channels mediating fast inhibitory neurotransmission, have been identified in patients and families with epilepsy and found to cause epilepsy in animal models. The majority of synaptic GABAARs are αβγ type receptors composed of two α, two β and one γ2 subunits, and half of these epilepsy-associated GABAAR mutations are located in γ2 subunits encoded by the GABRG2 gene. A better understanding of how different types of epilepsy-associated GABRG2 mutations affect receptor trafficking and channel function, and how these mutations cause epilepsy in mouse models, will facilitate future epilepsy diagnosis as well as treatments. Here we have studied three different types of mutations represented by GABRG2(N79S, R82Q, and P83S), GABRG2(Q40X), and GABRG2(Q390X), in cultured HEK cells or animal models. We found that missense mutations located in receptor interface will disrupt receptor assembly and trafficking, which may be improved by slowing receptor biogenesis. We found that nonsense mutations showing loss of function could be partially rescued using gentamicin-induced stop codon read-through. Finally we showed that gene-target therapy could reverse the seizure phenotype in a mouse model carrying a detrimental mutation with dominant negative effects. To conclude, we have shown different molecular mechanisms are associated with these mutations, and distinct mutation-specific therapy may be potentially developed for future treatments.
Advisors/Committee Members: Richard M. Breyer (committee member), Kevin C. Ess (committee member), Robert L. Macdonald (committee member), Alfred L. George (Committee Chair), Bruce D. Carter (Committee Chair).
Subjects/Keywords: GABA(A) receptors; GABRG2; genetic epilepsy; mutation; therapy
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APA (6th Edition):
Huang, X. (2014). Epilepsy-associated mutations in GABRG2: characterization and therapeutic opportunities. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/14755
Chicago Manual of Style (16th Edition):
Huang, Xuan. “Epilepsy-associated mutations in GABRG2: characterization and therapeutic opportunities.” 2014. Doctoral Dissertation, Vanderbilt University. Accessed January 15, 2021.
http://hdl.handle.net/1803/14755.
MLA Handbook (7th Edition):
Huang, Xuan. “Epilepsy-associated mutations in GABRG2: characterization and therapeutic opportunities.” 2014. Web. 15 Jan 2021.
Vancouver:
Huang X. Epilepsy-associated mutations in GABRG2: characterization and therapeutic opportunities. [Internet] [Doctoral dissertation]. Vanderbilt University; 2014. [cited 2021 Jan 15].
Available from: http://hdl.handle.net/1803/14755.
Council of Science Editors:
Huang X. Epilepsy-associated mutations in GABRG2: characterization and therapeutic opportunities. [Doctoral Dissertation]. Vanderbilt University; 2014. Available from: http://hdl.handle.net/1803/14755
Vanderbilt University
8.
Tang, Xin.
Modulation of GABAA receptor function by PKA and PKC protein phosphorylation.
Degree: PhD, Neuroscience, 2010, Vanderbilt University
URL: http://hdl.handle.net/1803/11843
► We studied the modulation of ¦Á4¦Â3¦Ã2L and ¦Á4¦Â3¦Ä GABAA receptor currents by two protein kinases, PKA and PKC. Although modulation of synaptic ¦Á1¦Â¦Ã2 GABAA receptor…
(more)
▼ We studied the modulation of ¦Á4¦Â3¦Ã2L and ¦Á4¦Â3¦Ä GABAA receptor currents by two protein kinases, PKA and PKC. Although modulation of synaptic ¦Á1¦Â¦Ã2 GABAA receptor isoforms has been studied widely, study of the modulation of peri- and extrasynaptic ¦Á¦Â¦Ä and non-synaptic ¦Á¦Â¦Ã GABAA receptors by protein phosphorylation is lacking. Using patch-clamp recording, we compared the effects of protein phosphorylation of ¦Á4¦Â3¦Ã2L and ¦Á4¦Â3¦Ä GABAA receptors under different levels of activation that included spontaneous openings, tonic currents activated by low GABA concentrations and phasic currents activated by high GABA concentrations. We found that PKA-activation preferentially increased spontaneous ¦Á4¦Â3¦Ä receptor currents by increasing single channel open frequency and decreased GABA-activated steady-state, tonic ¦Á4¦Â3¦Ä currents, but only had small effects on spontaneous and GABA-activated tonic ¦Á4¦Â3¦Ã2L currents, indicating the differential modulation of tonic inhibition mediated by ¦Á4¦Â3¦Ã2L and ¦Á4¦Â3¦Ä GABAA receptors. In contrast, both PKA and PKC had similar effects on desensitization of phasic ¦Á4¦Â3¦Ã2L and ¦Á4¦Â3¦Ä currents, implying a common modulatory mechanism of protein phosphorylation in regulating synaptic current kinetics. Our study suggested that protein phosphorylation had profound effects on different GABAA receptor isoforms, which should also be determined by receptor sub-cellular (synaptic or non-synaptic) localization and by the level of ambient GABA (spontaneous or GABA-activated), thus ensuring precise modulation of specific GABAA receptor properties in specific brain areas.
Advisors/Committee Members: Alfred L. George (committee member), Albert H. Beth (committee member), Robert L. Macdonald (committee member), Roger J. Colbran (Committee Chair).
Subjects/Keywords: PKC; GABAA receptor; phosphorylation; PKA
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APA (6th Edition):
Tang, X. (2010). Modulation of GABAA receptor function by PKA and PKC protein phosphorylation. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/11843
Chicago Manual of Style (16th Edition):
Tang, Xin. “Modulation of GABAA receptor function by PKA and PKC protein phosphorylation.” 2010. Doctoral Dissertation, Vanderbilt University. Accessed January 15, 2021.
http://hdl.handle.net/1803/11843.
MLA Handbook (7th Edition):
Tang, Xin. “Modulation of GABAA receptor function by PKA and PKC protein phosphorylation.” 2010. Web. 15 Jan 2021.
Vancouver:
Tang X. Modulation of GABAA receptor function by PKA and PKC protein phosphorylation. [Internet] [Doctoral dissertation]. Vanderbilt University; 2010. [cited 2021 Jan 15].
Available from: http://hdl.handle.net/1803/11843.
Council of Science Editors:
Tang X. Modulation of GABAA receptor function by PKA and PKC protein phosphorylation. [Doctoral Dissertation]. Vanderbilt University; 2010. Available from: http://hdl.handle.net/1803/11843
Vanderbilt University
9.
Xu, Ming.
Molecular mechanisms of ADAR2 localization and substrate specificity.
Degree: PhD, Pharmacology, 2006, Vanderbilt University
URL: http://hdl.handle.net/1803/11271
► ADAR2-mediated adenosine-to-inosine (A-to-I) RNA editing can affect the coding potential, splicing pattern, stability, and localization of the targeted RNA transcripts. ADAR2 contains two double-stranded RNA…
(more)
▼ ADAR2-mediated adenosine-to-inosine (A-to-I) RNA editing can affect the coding potential, splicing pattern, stability, and localization of the targeted RNA transcripts. ADAR2 contains two double-stranded RNA binding motifs (dsRBM) and a conserved adenosine deaminase domain. To investigate how the dsRBMs of ADAR2 bind to natural substrates, we developed an NMR-based model of the complex formed between the two dsRBMs and an RNA duplex derived from a naturally-occurring ADAR2 substrate. These structural studies demonstrated that dsRBMs recognize specific structural determinants and hence contribute to substrate specificity. In addition, we demonstrated that the dsRBMs of ADAR2 differ in their ability to modulate subnuclear localization and editing activity although their sequences/structures are highly conserved, emphasizing the functional inequality between members of this conserved protein motif family.
Advisors/Committee Members: Randy D. Blakely (committee member), P. Jeffrey Conn (committee member), David W. Piston (committee member), Ronald B. Emeson (committee member), Alfred L. George, Jr. (Committee Chair).
Subjects/Keywords: Double-stranded RNA; dsRNA; specific recognition; nucleolar localization; RNA editing; Adenosine deaminase
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APA (6th Edition):
Xu, M. (2006). Molecular mechanisms of ADAR2 localization and substrate specificity. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/11271
Chicago Manual of Style (16th Edition):
Xu, Ming. “Molecular mechanisms of ADAR2 localization and substrate specificity.” 2006. Doctoral Dissertation, Vanderbilt University. Accessed January 15, 2021.
http://hdl.handle.net/1803/11271.
MLA Handbook (7th Edition):
Xu, Ming. “Molecular mechanisms of ADAR2 localization and substrate specificity.” 2006. Web. 15 Jan 2021.
Vancouver:
Xu M. Molecular mechanisms of ADAR2 localization and substrate specificity. [Internet] [Doctoral dissertation]. Vanderbilt University; 2006. [cited 2021 Jan 15].
Available from: http://hdl.handle.net/1803/11271.
Council of Science Editors:
Xu M. Molecular mechanisms of ADAR2 localization and substrate specificity. [Doctoral Dissertation]. Vanderbilt University; 2006. Available from: http://hdl.handle.net/1803/11271
Vanderbilt University
10.
Misra, Sunita N.
Characterization of Mutant Human Brain Sodium Channels Associated with Familial Epilepsy.
Degree: PhD, Pharmacology, 2008, Vanderbilt University
URL: http://hdl.handle.net/1803/12753
► Investigating genetic forms of epilepsy allows for improved understanding of epilepsy pathophysiology in general. Mutations in voltage-gated sodium channels are a frequent cause of genetic…
(more)
▼ Investigating genetic forms of epilepsy allows for improved understanding of epilepsy pathophysiology in general. Mutations in voltage-gated sodium channels are a frequent cause of genetic forms of epilepsy. First we constructed a computational model of one sodium channel isoform and an epilepsy-associated mutation that refined our knowledge of how sodium channels inactivate. We next utilized a heterologous expression system to biophysically and biochemically characterize epilepsy-associated mutations. We found that aberrant cell surface expression as well as biophysical abnormalities may underlie some epilepsy syndromes. Finally we performed experiments in a transgenic mouse model system of epilepsy to examine the effect of genetic modifiers on sodium channel function. In summary, this research utilized three different model systems to improve our understanding of genetic forms of epilepsy.
Advisors/Committee Members: Robert L. Macdonald (committee member), Vsevolod V. Gurevich (committee member), Alfred L. George, Jr. (committee member), Danny G. Winder (committee member), Gregory Mathews (committee member), P. Jeffrey Conn (Committee Chair).
Subjects/Keywords: Sodium channels – Pathophysiology; electrophysiology; epilepsy; Epilepsy – Genetic aspects; Epilepsy – Molecular aspects
Record Details
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Record Details
Similar Records
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❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Misra, S. N. (2008). Characterization of Mutant Human Brain Sodium Channels Associated with Familial Epilepsy. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/12753
Chicago Manual of Style (16th Edition):
Misra, Sunita N. “Characterization of Mutant Human Brain Sodium Channels Associated with Familial Epilepsy.” 2008. Doctoral Dissertation, Vanderbilt University. Accessed January 15, 2021.
http://hdl.handle.net/1803/12753.
MLA Handbook (7th Edition):
Misra, Sunita N. “Characterization of Mutant Human Brain Sodium Channels Associated with Familial Epilepsy.” 2008. Web. 15 Jan 2021.
Vancouver:
Misra SN. Characterization of Mutant Human Brain Sodium Channels Associated with Familial Epilepsy. [Internet] [Doctoral dissertation]. Vanderbilt University; 2008. [cited 2021 Jan 15].
Available from: http://hdl.handle.net/1803/12753.
Council of Science Editors:
Misra SN. Characterization of Mutant Human Brain Sodium Channels Associated with Familial Epilepsy. [Doctoral Dissertation]. Vanderbilt University; 2008. Available from: http://hdl.handle.net/1803/12753
. 
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