Role of Tau and NRF2 in oxidative stress responses

Thesis

Diabetic kidney disease (DKD) is a complication of diabetes with significant morbidity and limited therapeutic options. With increasing diabetes prevalence there is an urgent need for better understanding of DKD pathogenesis with the goal of identifying more effective treatments and prevention approaches. Oxidative stress is a known contributor to DKD, but efforts to target this by pharmacological upregulation of the antioxidant transcription factor Nuclear factor-erythroid factor 2-related factor 2 (NRF2) in DKD clinical trials have not led to new therapeutics. This project investigated how oxidative stress influences DKD, with three key objectives and findings:

a) I characterised the effects of oxidative stress in podocytes, finding evidence for a bimodal effect of NRF2, and the identification of new candidate NRF2-regulated genes. Pharmacological induction of NRF2 in the podocytes using NRF2 agonist CDDO-Im or NRF2 activation/inhibition with CRISPR-dCAS9 were assessed for their effect on tBHP-induced stress induction: both a 50% inhibition of NRF2 expression or exposure to 30 nM CDDO-Im for 6 hours were found to be protective.

b) I identified a novel role for the Microtubulin Associated Protein Tau (MAPT) gene in protection against oxidative stress. In immortalised human podocytes, MAPT transcriptomic expression increased with tBHP-induced oxidative stress. In the neuroblastoma cell line SH-SY5Y, which expresses high levels of Tau, Tau KO led to increased oxidative stress, reversible by re-expressing Tau, but not fully rescued by NRF2 upregulation or microtubule stabilisation.

c) I began to develop a more physiological model for the analysis of Tau-associated oxidative stress, by deletion of MAPT in induced pluripotent stem cells (iPSC), and optimisation of my oxidative stress assay in human iPSC-derived kidney organoids.

Authors: Ameyaw, B

• DOI: 10.5287/ora-7qzrekg1a
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English