DOI

10.17077/etd.4ouz-bp06

Document Type

Dissertation

Date of Degree

Fall 2018

Degree Name

PhD (Doctor of Philosophy)

Degree In

Neuroscience

First Advisor

Usachev, Yuriy

First Committee Member

Taylor, Eric B

Second Committee Member

Strack, Stefan

Third Committee Member

Lee, Amy

Fourth Committee Member

Song, Long-Sheng

Abstract

During neuronal activity mitochondria alter cytosolic Ca2+ signaling by buffering then releasing Ca2+ in the cytosol. This calcium transport by mitochondria affects the amplitude, duration, and spacial profile of the Ca2+ signal in the cytosol of neurons. This buffering by mitochondria has been shown to affect a variety of neuronal functions including: neurotransmission, gene expression, cell excitability, and cell death. Recently, researchers discovered that the protein CCDC109A (mitochondrial Ca2+ uniporter) was the protein responsible for mitochondrial Ca2+ uptake. Using a genetic knockout (KO) mouse model for the mitochondrial Ca2+ uniporter (MCU) my research investigated the role of MCU in neuronal function. In cultured central and peripheral neurons, MCU-KO significantly reduced mitochondrial Ca2+ uptake while significantly increasing the amplitude of the cytosolic Ca2+ signal amplitude. Behaviorally, MCU-KO mice show a small but significant impairment in memory tasks: fear conditioning and Barnes maze. Using a maximal electroshock seizure threshold model of in vivo seizure activity my research found that MCU-KO significantly increases the threshold for maximal seizure activity in mice and significantly reduces seizure severity. In addition to mitochondrial Ca2+ uptake, my research also investigated the mechanisms involved in mitochondrial Ca2+ extrusion. The protein SLC8B1 (SLC24A6, NCLX) is the putative transporter responsible for the Na+/Ca2+ exchange, mitochondrial calcium extrusion. Using genetic NCLX-KO mice, our research found that in neurons NCLX contributes to cytosolic Ca2+ extrusion, but does seem to directly affect mitochondrial Ca2+ extrusion.

Keywords

calcium, mitochondria, mitochondrial calcium uniporter, NCLX, neuron

Pages

xiii, 177 pages

Bibliography

Includes bibliographical references (pages 160-177).

Copyright

Copyright © 2018 Jacob Eugene Rysted

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