{"id":{"repo_id":"buffalo","oai_identifier":"oai:ubir.buffalo.edu:10477/78443"},"canonical_url":"https://search.dev.ndltd.org/etd/buffalo/oai:ubir.buffalo.edu:10477/78443","repository":{"repo_id":"buffalo","name":"Buffalo","base_url":"https://ubir.buffalo.edu/oai/request"},"display":{"title":"Mechanistic insights to the Ca2+-dependent inactivation of NMDA receptors by Calmodulin","abstract":"Ph.D.","abstract_html":"Ph.D.","abstract_has_math":false,"creators":["Iacobucci, Gary; 0000-0001-7596-8380"],"institution":"State University of New York at Buffalo","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Popescu, Gabriela K.","Biochemistry"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2018,"date_issued":"2018-10-25T14:19:16Z","date_published":"2018-10-25T14:19:16Z","updated_at":"2026-07-27T19:05:09Z","subjects":["biophysics","neurosciences","physiology"],"languages":["eng"],"rights":["Users of works found in University at Buffalo Institutional Repository (UBIR) are responsible for identifying and contacting the copyright owner for permission to reuse. University at Buffalo Libraries do not manage rights for copyright-protected works and cannot assist with permissions.","Copyright retained by author."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/10477/78443","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Popescu, Gabriela K.","Biochemistry"]},{"key":"dc:creator","label":"Author","values":["Iacobucci, Gary; 0000-0001-7596-8380"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2018-10-25T14:19:16Z","2018","2018-07-31 00:31:08"]},{"key":"dc:publisher","label":"Institution","values":["State University of New York at Buffalo"]},{"key":"dc:type","label":"Dc Type","values":["Text","Dissertation"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["biophysics","neurosciences","physiology"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Users of works found in University at Buffalo Institutional Repository (UBIR) are responsible for identifying and contacting the copyright owner for permission to reuse. University at Buffalo Libraries do not manage rights for copyright-protected works and cannot assist with permissions.","Copyright retained by author."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/10477/78443"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Ph.D.","Calcium has evolved to be a ubiquitous second messenger that regulates many diverse and often opposing physiological processes in eukaryotic cells. In the central nervous system, NMDA receptors are glutamate and glycine-gated ion channels that mediate large Ca2+ influx during excitatory synaptic transmission. The Ca2+ load through NMDA receptors is responsible for both synaptic plasticity, learning and memory as well as excitotoxicity during aberrant synaptic transmission. To curb excessive Ca2+ influx and fine tune the synaptic current, NMDA receptors employ calmodulin as an endogenous sensor of intracellular Ca2+ that also directly inhibits channel function. In this dissertation, I outline my empirical results that garner new insights into the mechanism of calmodulin-dependent regulation of NMDA receptors. Combining precise whole-cell measurements of calmodulin-dependent inactivation of receptor currents with mathematical modeling of Ca2+ signaling and calmodulin/channel interactions, I found that under specific conditions, the degree of inactivation can be explained by a model where calmodulin primes resting channels for inactivation in the absence of Ca2+. Given the close spatiotemporal coupling of Ca2+ sensing by calmodulin to channel activity, I investigated whether the Ca2+ influx through individual channels was sufficient to engage calmodulin-dependent inactivation of neighboring channels. Using cellattached patch clamp, I determined whether NMDA receptors in multi-channel patches gated cooperatively in a Ca2+/calmodulin-dependent manner. I found that the negative cooperativity exhibited by channels could be augmented by scaffold protein, PSD-95. Lastly, I examined the apparent insensitivity of GluN2B-containing channels to calmodulin. I found that GluN2B channels rapidly inactivate when exposed to tonic Ca2+ dialysis into the cell. To reconcile this discrepancy with the literature, I used patch clamp fluorometry to measure the kinetic mechanism of inactivation while manipulating intracellular Ca2+ levels. I found that both GluN2A and GluN2B channels inactivate by a common mechanism by which perturbations in their activation pathways lead to increased occupancies of desensitized states. The differential subtype kinetics of the active channel explains the subunit-specific manifestation of calmodulin-dependent inactivation. Overall, these findings highlight the nuances of Ca2+ regulation of NMDA receptors and provide new insight into their function in both Ca2+-dependent physiological processes and pathologies."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Mechanistic insights to the Ca2+-dependent inactivation of NMDA receptors by Calmodulin"]}]}],"canonical_facts":{"dc:contributor":["Popescu, Gabriela K.","Biochemistry"],"dc:creator":["Iacobucci, Gary; 0000-0001-7596-8380"],"dc:date":["2018-10-25T14:19:16Z","2018","2018-07-31 00:31:08"],"dc:description":["Ph.D.","Calcium has evolved to be a ubiquitous second messenger that regulates many diverse and often opposing physiological processes in eukaryotic cells. In the central nervous system, NMDA receptors are glutamate and glycine-gated ion channels that mediate large Ca2+ influx during excitatory synaptic transmission. The Ca2+ load through NMDA receptors is responsible for both synaptic plasticity, learning and memory as well as excitotoxicity during aberrant synaptic transmission. To curb excessive Ca2+ influx and fine tune the synaptic current, NMDA receptors employ calmodulin as an endogenous sensor of intracellular Ca2+ that also directly inhibits channel function. In this dissertation, I outline my empirical results that garner new insights into the mechanism of calmodulin-dependent regulation of NMDA receptors. Combining precise whole-cell measurements of calmodulin-dependent inactivation of receptor currents with mathematical modeling of Ca2+ signaling and calmodulin/channel interactions, I found that under specific conditions, the degree of inactivation can be explained by a model where calmodulin primes resting channels for inactivation in the absence of Ca2+. Given the close spatiotemporal coupling of Ca2+ sensing by calmodulin to channel activity, I investigated whether the Ca2+ influx through individual channels was sufficient to engage calmodulin-dependent inactivation of neighboring channels. Using cellattached patch clamp, I determined whether NMDA receptors in multi-channel patches gated cooperatively in a Ca2+/calmodulin-dependent manner. I found that the negative cooperativity exhibited by channels could be augmented by scaffold protein, PSD-95. Lastly, I examined the apparent insensitivity of GluN2B-containing channels to calmodulin. I found that GluN2B channels rapidly inactivate when exposed to tonic Ca2+ dialysis into the cell. To reconcile this discrepancy with the literature, I used patch clamp fluorometry to measure the kinetic mechanism of inactivation while manipulating intracellular Ca2+ levels. I found that both GluN2A and GluN2B channels inactivate by a common mechanism by which perturbations in their activation pathways lead to increased occupancies of desensitized states. The differential subtype kinetics of the active channel explains the subunit-specific manifestation of calmodulin-dependent inactivation. Overall, these findings highlight the nuances of Ca2+ regulation of NMDA receptors and provide new insight into their function in both Ca2+-dependent physiological processes and pathologies."],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/10477/78443"],"dc:language":["eng"],"dc:publisher":["State University of New York at Buffalo"],"dc:rights":["Users of works found in University at Buffalo Institutional Repository (UBIR) are responsible for identifying and contacting the copyright owner for permission to reuse. University at Buffalo Libraries do not manage rights for copyright-protected works and cannot assist with permissions.","Copyright retained by author."],"dc:subject":["biophysics","neurosciences","physiology"],"dc:title":["Mechanistic insights to the Ca2+-dependent inactivation of NMDA receptors by Calmodulin"],"dc:type":["Text","Dissertation"]},"updated_at":"2026-07-27T19:05:09Z"}