Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.779464
Title: Exploring the mechanisms that regulate CaV2.2 trafficking and function
Author: Meyer, James Frederick Otto
ISNI:       0000 0004 7965 1606
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2019
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Abstract:
N-type calcium channels (CaV2.2) are pseudotetrameric voltage-gated calcium channels (VGCCs) predominantly expressed at the presynaptic terminals in the peripheral and central nervous system. CaV2.2 channels are highly calcium selective and play a crucial role in neurotransmitter release, coupling extracellular calcium entry to neurotransmitter exocytosis. The activity of CaV2.2 has multiple forms of regulation including: post-translational modifications (PMTs), proteolytic degradation and subcellular localisation. In addition, the behaviour of VGCCs is modulated by their auxiliary α2δ and β subunits. In this study, I first examine the role of proteolytic α2δ processing on CaV2.2. I find that unprocessed α2δ subunits, while unable to enhance whole-cell CaV2.2 currents, retain the ability to promote cell-surface expression of CaV2.2 in cell lines. Subsequent restoration of α2δ processing did not influence the protein expression of α2δ or of coexpressed CaV2.2. Thereafter, I examined the properties of CaV2.2 mutants featuring substitutions of crucial P-loop glutamate residues within the selectivity filter. I find that mutation of these glutamate residues renders these channels deficient in trafficking both in non-neuronal cell lines and primary neuronal cultures. These data are pertinent given the use of P-loop CaV mutants as dominant negative channels in previous studies. Finally, I compare the influence of α2δ-1, α2δ-2 and α2δ-3 subtypes on the cell-surface and total expression of CaV2.2. Both cell-surface and total expression of CaV2.2 was found to be enhanced by all three subtypes albeit to differing degrees. Further investigation reveals that α2δ-1 and α2δ-2 promote the net forward trafficking of CaV2.2 through Rab11a-dependent recycling. CaV2.2 does not appear to participate in Rab11a-dependent recycling when expressed in the absence of α2δ or with α2δ-3. This study reveals differential regulation of CaV2.2 channels among α2δ subtypes through targeted endosomal trafficking.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.779464  DOI: Not available
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