Ca2+ Signaling in the Near Plasma Membrane Microdomain of Non-Excitable Cells
dc.contributor.advisor | Bezprozvanny, Ilya | en |
dc.creator | Yao, Jian | en |
dc.date.accessioned | 2011-02-01T19:37:03Z | |
dc.date.available | 2011-02-01T19:37:03Z | |
dc.date.issued | 2011-02-01 | |
dc.description.abstract | Calcium is the most versatile second messenger and plays fundamental roles in orchestrating enzyme secretion in exocrine acinar cells. Previous studies in excitable cells demonstrated the existence of high Ca2+ microdomains. The major function of such microdomains is to create high local calcium concentration to activate various calcium-dependent signaling events. However, in non-excitable cells, direct evidence of such microdomains is absent. The goal of my study is to characterize the properties of high Ca2+ microdomains in acinar cells and explore its physiological relevance in the context of the secretory functions. By combining Total Internal Reflection Fluorescence Microscopy (TIRFM) technique and wide-field fluorescence imaging, I was able to quantify and compare changes in the concentration of free Ca2+ in the near membrane microdomains (?[Ca2+]PM) and in the bulk cytosol (?[Ca2+]Cyto). ?[Ca2+]PM is about 3-fold larger than ?[Ca2+]Cyto under maximal agonist stimulation, while resting [Ca2+]PM and [Ca2+]Cyto shows no difference. Near membrane microdomains also showed greater Ca2+ influx following store depletion induced either by activating surface receptor or by inhibiting SERCA pump. In response to physiological strength of stimulation, Ca2+ oscillation in the two compartments showed significantly different dynamics. The activation mechanisms of the Ca2+-induced Ca2+ release (CICR) are well established in cardiac and skeletal muscles and involves high Ca2+ microdomains. My study was the first to demonstrate the presence of CICR in the parotid acinar cell. In these cells, minimal activation of Ca2+ influx by partially depleting the stores, either by directly activating the cell surface receptor or by inhibiting SERCA, leads to an explosive release of Ca2+ from the majority of the stores, mediated presumably by RyR away from microdomains. The last part of my study is on the effects of chronic ER stress on Ca2+ signaling. The study suggests that ER stress induced by PERK mutation impeded both the efficiency and fidelity of Ca2+ signaling. My work validates the existence of near plasma membrane microdomains in non-excitable exocrine cells. The fact that [Ca2+]PM and [Ca2+]Cyto differ in many ways suggests that microdomains is the central signaling platform in these cells. | en |
dc.identifier.oclc | 719450260 | |
dc.identifier.uri | https://hdl.handle.net/2152.5/864 | |
dc.language.iso | en | en |
dc.subject | Calcium | en |
dc.subject | Calcium Channels | en |
dc.subject | Parotid Gland | en |
dc.title | Ca2+ Signaling in the Near Plasma Membrane Microdomain of Non-Excitable Cells | en |
dc.type | Thesis | en |
thesis.date.available | 2013-01-26 | |
thesis.degree.department | Graduate School of Biomedical Sciences | en |
thesis.degree.discipline | Integrative Biology | en |
thesis.degree.grantor | UT Southwestern Medical Center | en |
thesis.degree.level | Doctoral | en |
thesis.degree.name | Doctor of Philosophy | en |
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