Investigation of the Expression, Regulation and Function of Ten Eleven Translocase 3 (TET3) in Neurons

Student thesis: Doctoral ThesisDoctor of Philosophy


5-methylcytosine dioxygenase 3 (TET3) is a member of the Ten-Eleven-Translocation (TET) family of enzymes shown to mediate DNA demethylation by oxidising 5-methylcytosine (5-mC) to 5-hydroxymethylcytosine (5-hmC) and further oxidative intermediates. 5-hmC is a stable DNA modification associated with actively transcribed euchromatin and thus may serve as a mechanism underlying the activation of lineage-specific transcriptional programmes. TET3, specifically, has been proven to be highly expressed in neurons. Nevertheless, the molecular mechanisms which underlie the regulation of TET3 and the role(s) it plays in brain function such as its plasticity are yet to be discovered. Additionally, little is known about TET3 protein isoforms and their potential to be differentially regulated within neurons, tentatively leading to independent specific functions. Here it is demonstrated that mouse neuroblastoma (N2a) cells which were induced to differentiate had differentially expressed TET3 isoform transcripts. Neuro stimulation/inhibition appears to be another factor that can regulate the expression of both variants independently. Additionally, using 5’RACE and bioinformatics tools, mouse TET3 transcripts were shown to comprise multiple transcriptional start sites originating from two distinct promoter regions and potentially transcribing two protein isoforms. Investigating both TET3 promoter regions, positive and negative cis-regulatory regions were identified in transfected N2a and mouse embryonic fibroblast (MEF) cells. Furthermore, GATA2 was found to be a potential negative trans-acting factor for the TET3 Upstream promoter. Moreover, both TET3 isoforms seem to be regulated through epigenetic modifications. Lastly, TET3 was shown to mediate cellular respiration in N2a cells. The mRNA expression of some nuclear and mitochondrial-encoded OxPhos genes and mitochondrial-function-associated genes were observed to be regulated by TET3. ENDOG, an endonuclease associated with mtDNA replication and apoptosis, was identified as a direct target of TET3 demethylation. The identification of the TET3 regulators and the role TET3 plays in respiration will greatly inform our understanding of neuronal regulation.
Date of Award1 Jun 2023
Original languageEnglish
Awarding Institution
  • King's College London
SupervisorAlison Brewer (Supervisor), Clemens Kiecker (Supervisor), Alison Brewer (Supervisor) & Clemens Kiecker (Supervisor)

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