Krall, Rebecca
(2020)
A Postsynaptic Mechanism of Zinc Transport Driving Inhibition of NMDA Receptors.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Zinc is an essential element with diverse signaling functions in the central nervous system. Extracellular zinc acts on a variety of receptors to modulate neurotransmission. Notably, zinc binds and inhibits the GluN2A subunit of NMDA receptors (NMDARs) with high affinity. Inside the cell, zinc also triggers diverse signaling cascades, ranging from zinc-induced gene expression to cell death triggered by high concentrations of zinc. To maintain sufficient signaling without tipping the scales towards cell death, a complex system of transporters, metalloproteins, and ion channels regulate the localization and concentration of zinc. The zinc transporter, ZnT3, concentrates the majority of loosely bound ‘labile’ zinc into synaptic vesicles from where it then is released into the cleft in an activity-dependent manner. Current modeling of vesicular zinc assumes that ZnT3-dependent zinc is released and subsequently diffuses across the cleft and this is sufficient to account for its actions on postsynaptic targets, including NMDARs. Interestingly, the transporter ZnT1 is located in the postsynaptic density and binds directly to the GluN2A subunit of NMDARs, suggesting that ZnT1’s transport of zinc out of the cytoplasm into the extracellular space may contribute to NMDAR inhibition. This suggests that ZnT1 and intracellular zinc may critically regulate zinc inhibition of NMDARs through ZnT1’s interaction with GluN2A. To explore this question, we developed a novel peptide that specifically disrupts the interaction between GluN2A and ZnT1. We found that either disrupting ZnT1’s association with GluN2A or chelating intracellular zinc is sufficient to block endogenous inhibition of NMDARs, even in the presence of presynaptic zinc release. ZnT1, in addition to transporting cytosolic zinc, is also upregulated by intracellular zinc through the metal regulatory transcription factor 1. We found that increasing intracellular zinc is sufficient to drive upregulation of ZnT1-GluN2A interactions and subsequent inhibition of NMDARs. Together these data reveal a novel mechanism in which presynaptic release, intracellular zinc, and ZnT1 cooperatively drive inhibition of NMDARs. These findings add complexity to our current understanding of zinc dynamics at the synapses and provide a novel mechanism for modulating zinc and NMDAR signaling.
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Details
| Item Type: |
University of Pittsburgh ETD
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| Status: |
Unpublished |
| Creators/Authors: |
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| ETD Committee: |
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| Date: |
29 December 2020 |
| Date Type: |
Publication |
| Defense Date: |
22 October 2020 |
| Approval Date: |
29 December 2020 |
| Submission Date: |
6 November 2020 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
135 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
School of Medicine > Neurobiology |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Zinc, ZnT1, NMDA Receptors, GluN2A |
| Date Deposited: |
29 Dec 2020 15:57 |
| Last Modified: |
29 Dec 2020 15:57 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/39855 |
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