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You searched for +publisher:"University of Vermont" +contributor:("Morielli, Anthony"). Showing records 1 – 2 of 2 total matches.

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University of Vermont

1. Williams, Michael. Secretin-Modulated Potassium Channel Trafficking as a Novel Mechanism for Regulating Cerebellar Synapses.

Degree: PhD, Neuroscience, 2013, University of Vermont

The voltage-gated potassium channel Kv1.2 is a critical modulator of neuronal physiology, including dendritic excitability, action potential propagation, and neurotransmitter release. However, mechanisms by which Kv1.2 may be regulated in the brain are poorly understood. In heterologous expression systems Kv1.2 is regulated by endocytosis of the channel from the plasma membrane, and this trafficking can be modulated by adenylate cyclase (AC). The goal of this dissertation was to determine whether AC modulated endocytic trafficking of endogenous Kv1.2 occurred in the mammalian nervous system. Within the brain, Kv1.2 is expressed at its highest levels in the cerebellar cortex. Specifically, Kv1.2 is expressed in dendrites of Purkinje cells (PC), the sole efferent neurons of the cerebellar cortex; Kv1.2 is also expressed in axon terminals of Basket cells (BC), which make inhibitory synapses to Purkinje cells. The loss of functional Kv1.2 in PC dendrites or BC axon terminals causes profound changes in the neurophysiology of Purkinje cells, and aberrant loss of Kv1.2 produces cerebellar ataxia. Therefore, the cerebellum offers a brain structure where Kv1.2 is abundant and has known and important roles in synaptic physiology. A candidate regulator of Kv1.2 trafficking in cerebellar synapses is the secretin peptide receptor: the receptor is also located in both PC dendrites and BC axon terminals, and ligand binding to the secretin receptor stimulates AC. Although secretin affects cerebellar neurophysiology and cerebellar dependent behavior, the mechanisms are not well resolved. By cell-surface protein biotinylation and subsequent immunoblot quantitation of secretin treated rat cerebellar slice lysates, secretin was found to decrease cell-surface Kv1.2. This effect could be mimicked by stimulating AC with forskolin, and could be occluded by inhibition of the secretin receptor, AC, or protein kinase A. The secretin receptor stimulated loss of surface Kv1.2 was not accompanied by decreased total Kv1.2 protein levels, but did involve enhanced channel endocytosis. Microscopy studies using two novel independent techniques provided evidence that both BC axon terminals and PC dendrites are sites of AC-stimulated Kv1.2 endocytosis. The physiological significance of secretin mediated suppression of Kv1.2 was supported by collaborative studies which found infusions into the cerebellar cortex of either a toxin that inhibits Kv1.2, or of secretin, enhanced eyeblink conditioning, a form of cerebellar dependent learning, in rats. These studies provided the first evidence that Kv1.2 is regulated by endocytic trafficking in the brain. However, to address the role of that trafficking in synaptic physiology requires knowledge about the determinants of Kv1.2’s endocytic potential, and non-destructive assays to measure Kv1.2 endocytosis in neural circuits. This dissertation therefore concludes with preliminary studies that explore an ancient motif regulating Kv1.2 trafficking, and that discuss a novel dual fluorescent fusion protein reporter… Advisors/Committee Members: Morielli, Anthony.

Subjects/Keywords: Peptides; Cerebellum; Memory; Learning; Ion Channels

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Williams, M. (2013). Secretin-Modulated Potassium Channel Trafficking as a Novel Mechanism for Regulating Cerebellar Synapses. (Doctoral Dissertation). University of Vermont. Retrieved from https://scholarworks.uvm.edu/graddis/241

Chicago Manual of Style (16th Edition):

Williams, Michael. “Secretin-Modulated Potassium Channel Trafficking as a Novel Mechanism for Regulating Cerebellar Synapses.” 2013. Doctoral Dissertation, University of Vermont. Accessed October 17, 2019. https://scholarworks.uvm.edu/graddis/241.

MLA Handbook (7th Edition):

Williams, Michael. “Secretin-Modulated Potassium Channel Trafficking as a Novel Mechanism for Regulating Cerebellar Synapses.” 2013. Web. 17 Oct 2019.

Vancouver:

Williams M. Secretin-Modulated Potassium Channel Trafficking as a Novel Mechanism for Regulating Cerebellar Synapses. [Internet] [Doctoral dissertation]. University of Vermont; 2013. [cited 2019 Oct 17]. Available from: https://scholarworks.uvm.edu/graddis/241.

Council of Science Editors:

Williams M. Secretin-Modulated Potassium Channel Trafficking as a Novel Mechanism for Regulating Cerebellar Synapses. [Doctoral Dissertation]. University of Vermont; 2013. Available from: https://scholarworks.uvm.edu/graddis/241


University of Vermont

2. Connors, Emilee. Positive Trafficking Pathways of a Voltage Gated Potassium Channel.

Degree: PhD, Pharmacology, 2009, University of Vermont

ABSTRACT The voltage-gated potassium channel Kv1.2 is a key determinant of cellular excitability in the nervous and cardiovascular systems. In the brain, Kv1.2 is strongly expressed in neurons of the hippocampus, a structure essential for learning and memory, and the cerebellum, a structure essential for motor control and cognition. In the vasculature, Kv1.2 is expressed in smooth muscle cells where it contributes to the regulation of blood flow. Dynamic regulation of Kv1.2 is fundamental to its role in these tissues. Disruption of this regulation can manifest in a range of pathological conditions, including seizure, hypertension and neuropathic pain. Thus, elucidating the mechanisms by which Kv1.2 is regulated addresses fundamental aspects of human physiology and disease. Kv1.2 was the first voltage gated ion channel found to be regulated by tyrosine phosphorylation. The ionic current of Kv1.2 is suppressed following tyrosine phosphorylation by a process involving channel endocytosis. Movement of channel away from the plasma membrane involves many proteins associated with the cytoskeleton, including dynamin, cortactin and RhoA. Because trafficking of Kv1.2 away from the cell surface has emerged as the primary mechanism for its negative regulation, we hypothesized that trafficking of the channel to the cell surface could be a mechanism for positive regulation of the Kv1.2 ionic current. Activation of the cAMP/PKA pathway enhances the ionic current of Kv1.2. We hypothesized that a mechanism for this positive regulation is an increase in the amount of channel protein present at the cell surface. Our data show that cAMP can regulate Kv1.2 surface levels by two opposing trafficking pathways, one PKA-dependent and one PKA-independent. Channel homeostasis is preserved by the dynamic balance between these two pathways. Accordingly, any change in the levels of cAMP causes a net increase in the amount of Kv1.2 present at the cell surface. Specific C-terminal phosphorylation sites of Kv1.2 were identified and shown to have a role in maintaining basal surface channel levels. These findings demonstrate channel trafficking as a mechanism for the positive regulation of the Kv1.2 ionic current. In addition to Kv1.2 trafficking at the plasma membrane, movement of the channel from the biosynthetic pathway to the cell surface is another checkpoint for its regulation. Here we show that the protein arginine methyltransferase 8 (PRMT8) is able to promote the ER exit of Kv1.2, resulting in an increase in Kv1.2 surface expression. PRMT8 not only promoted surface expression of the high mannose glycosylated form of Kv1.2, characteristic of immature, ER-localized channels, but also enhanced Kv1.2 total protein levels, most likely by decreasing the amount of channel protein available for ER-associated degradation (ERAD). These findings highlight biosynthetic trafficking of Kv1.2 as a crucial part of its regulation and identify a novel role for PRMT8, as a regulator of biosynthetic protein trafficking. Advisors/Committee Members: Morielli, Anthony.

Subjects/Keywords: Potassium Channel; Phosphorylation

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Connors, E. (2009). Positive Trafficking Pathways of a Voltage Gated Potassium Channel. (Doctoral Dissertation). University of Vermont. Retrieved from https://scholarworks.uvm.edu/graddis/52

Chicago Manual of Style (16th Edition):

Connors, Emilee. “Positive Trafficking Pathways of a Voltage Gated Potassium Channel.” 2009. Doctoral Dissertation, University of Vermont. Accessed October 17, 2019. https://scholarworks.uvm.edu/graddis/52.

MLA Handbook (7th Edition):

Connors, Emilee. “Positive Trafficking Pathways of a Voltage Gated Potassium Channel.” 2009. Web. 17 Oct 2019.

Vancouver:

Connors E. Positive Trafficking Pathways of a Voltage Gated Potassium Channel. [Internet] [Doctoral dissertation]. University of Vermont; 2009. [cited 2019 Oct 17]. Available from: https://scholarworks.uvm.edu/graddis/52.

Council of Science Editors:

Connors E. Positive Trafficking Pathways of a Voltage Gated Potassium Channel. [Doctoral Dissertation]. University of Vermont; 2009. Available from: https://scholarworks.uvm.edu/graddis/52

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