Exploring the Cellular and Molecular Mechanisms Driving Connexin-36 Electrical Plasticity and the Functional Consequences of its Loss on the Sensorimotor Behaviors of Zebrafish (Danio Rerio)

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dc.contributor.advisorZoidl, Georg R.
dc.contributor.authorBrown, Cherie Alicia
dc.date.accessioned2022-12-14T16:34:39Z
dc.date.available2022-12-14T16:34:39Z
dc.date.copyright2022-08-03
dc.date.issued2022-12-14
dc.date.updated2022-12-14T16:34:39Z
dc.degree.disciplineBiology
dc.degree.levelDoctoral
dc.degree.namePhD - Doctor of Philosophy
dc.description.abstractIn mammals, connexin-36 (Cx36) is the major component of electrical synapses, also found alongside chemical synapses throughout the brain. An equivalent form of long-term potentiation (LTP) exclusively at Cx36 electrical synapses, termed the run-up, has been previously identified; however, the mechanism and molecular machinery involved remains elusive. We hypothesized an LTP-like mechanism was involved at Cx36 electrical synapses, potentiating the run-up. To address this, we investigated the tubulin-dependent delivery of Cx36 connexons to the plasma membrane in Neuro2a cells. A putative Cx36-tubulin binding motif was elucidated via sequence alignment, and the direct binding of tubulin with the C-terminal tail of Cx36 was confirmed via BioID. TIRF and FRAP microscopy techniques established that Cx36 is transported from the trans-Golgi network to the plasma membrane via interactions with the tubulin-cytoskeleton. Manipulating the Cx36-tubulin interaction via mutations and pharmacological inhibition reduced Cx36 trafficking to the gap junction plaque and inhibited run-up. While we identified tubulin as a driving force in achieving Cx36 run-up, we found that its transport occurred independently of CaM-CaMKII activity. Despite the similarities in machinery used between chemical and electrical synapses, the functional consequence of Cx36 asymmetry at homotypic aggregates had yet to be addressed. Next, we investigated the role of Cx36 in sensorimotor circuitry in zebrafish (Danio rerio), where the teleost orthologs are expressed distinctly. Here, we targeted the gjd2b gene since its corresponding ortholog, Cx35b, is expressed presynaptically. Based on current literature, we hypothesized that complex alterations to neuronal circuitry via Cx35b knock-out (KO) would affect vision, sensorimotor gating, and plasticity-dependent cognitive processing. We found that Cx35b expression coincides with photoreceptor cell specificity and expression in the inner plexiform layer. Cx35b KO resulted in developmental deviances, cranial defects, visual ambiguities (discrimination of light stimulus brightness, arrangement, and temporal properties), and increased levels of anxiety; however, KO did not impair non-associative learning and memory. Genetically, loss of the gjd2b gene resulted in changes primarily in connexin, dopaminergic, and immediate early gene regulation. Taken together, we concluded that Cx36 shares molecular machinery with chemical synapses to rectify neuronal communication, and this molecular asymmetry is critical in driving behavioral outcomes.
dc.identifier.urihttp://hdl.handle.net/10315/40710
dc.languageen
dc.rightsAuthor owns copyright, except where explicitly noted. Please contact the author directly with licensing requests.
dc.subjectBiology
dc.subjectNeurosciences
dc.subjectCellular biology
dc.subject.keywordsCellular and molecular biology
dc.subject.keywordsNeuroscience
dc.subject.keywordsGap junction
dc.subject.keywordsElectrical synapses
dc.subject.keywordsConnexin 36
dc.subject.keywordsConnexin 35b
dc.subject.keywordsTubulin
dc.subject.keywordsZebrafish
dc.subject.keywordsBehavior
dc.subject.keywordsVision
dc.titleExploring the Cellular and Molecular Mechanisms Driving Connexin-36 Electrical Plasticity and the Functional Consequences of its Loss on the Sensorimotor Behaviors of Zebrafish (Danio Rerio)
dc.typeElectronic Thesis or Dissertation

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