Investigating the Effects of Inositol Depletion Using a Simple Eukaryotic Organism Dictyostelium discoideum.

Anna Frej

Research output: ThesisDoctoral Thesis

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Inositol, produced in vivo by the biosynthetic enzyme inositol-3-phosphate synthase (Ino1), is an essential component of inositol phosphates and phosphoinositides that are involved in important cell signalling pathways. Dysregulation of inositol signalling has been implicated in various diseases, including bipolar disorder, Alzheimer’s disease, and diabetes. Research relating to inositol regulation in cells has primarily focused on the molecular and cellular effects of inositol depletion without considering the effects of altered Ino1 levels. This PhD study employed a simple eukaryote, Dictyostelium discoideum, to investigate the distinct effects of the loss of Ino1 and inositol depletion. Ablation of ino1 in this model produced an inositol auxotrophy phenotype and affected development, with the former being only partially restored by an exogenous inositol supply. The removal of exogenous inositol from the ino1- mutant resulted in a 56% decrease in intracellular inositol levels within 12 hours, a reduction in cytokinesis and substrate adhesion, and an accumulation of autophagosomes. Inositol depletion also triggered a decrease in phosphoinositide levels. Intriguingly, the absence of the Ino1 protein and inositol depletion cause distinct metabolic changes, with the greatest changes seen following Ino1 loss. These data suggest a role for the Ino1 protein beyond inositol biosynthesis. To investigate this role, an immunoprecipitation approach was used, where an Ino1 binding partner, Q54IX5, was identified. Q54IX5 is likely to function as a macromolecular adaptor protein. Thus, this study has identified distinct cellular and metabolic effects for both inositol depletion and loss of Ino1, with implications for our understanding of human diseases.
Original languageEnglish
Awarding Institution
  • Royal Holloway, University of London
  • Williams, Robin, Supervisor
  • Devoto, Alessandra, Advisor
  • Churchill, Grant, Supervisor, External person
Thesis sponsors
Award date24 May 2016
Publication statusUnpublished - 2016


  • Dictyostelium discoideum
  • inositol
  • inositol depletion
  • inositol phosphate signalling
  • Inositol Phosphates
  • inositol phosphate synthase
  • Ino1
  • metabolic profiling
  • Phosphoinositol
  • knock-out
  • inositol auxotrophy
  • Bipolar Disorder
  • Alzheimer's disease
  • cytokinesis
  • autophagy
  • chemotaxis
  • Development
  • SEL1

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