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Title: Using Dictyostelium discoideum to develop flavonoid therapeutics for polycystic kidney disease : the role of MATE transporters
Author: Ferrara, Bill Terence
ISNI:       0000 0004 7963 4267
Awarding Body: University of Greenwich
Current Institution: University of Greenwich
Date of Award: 2018
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This project focuses on transport in Dictyostelium discoideum, particularly activity of two novel multidrug and toxin efflux (MATE) transporters. Their role in biological and biomedical implications of flavonoid transport in this model microbe are considered in the light of the evidence for naringenin specifically inhibiting cyst-forming kidney disease. D. discoideum is a valuable model organism for studying both cell biology and processes in human health and disease. Its genome was sequenced some years ago and the amoeba is well studied, but two genes encoding MATE proteins had not previously been studied. Analysis of transcription of the transport genes at different life stages suggested the two MATEs are expressed, with distinct and non-redundant functions. The Ddmate1 transcript was found in highest levels when cells signal to each other and aggregate, whereas Ddmate2 was dominant earlier in the life cycle, when unicellular D. discoideum cells prey on bacteria. Ddmate2 was also highly transcribed after cells have aggregated and differentiated to form a motile, multicellular slug. DdMmate1 is hypothesised to be a toxin efflux transporter in unicellular and developing cells with broad substrate specificity, with increased transcription observed in the presence of all the flavonoids tested, and with ethidium bromide. Ddmate2 response was more complex, with differential increases in transcription to fewer flavonoids, within unicellular stage of life cycle. Selected flavonoids of established therapeutic potential all inhibited cell division in the unicellular life cycle without reducing viability or hindering development and differentiation. A novel method for fluorescence imaging of these compounds was adapted from a method used in plant sciences, enhancing the flavonoid fluorescence emission with conjugated NA. In conjunction with LC-MS, in vivo cellular localisation and differential uptake of flavonoids could then be observed and quantified. Hesperetin and naringenin did not appear to cross the cell membrane, whereas kaempferol, luteolin and quercetin did, with both kaempferol and quercetin being localised to the mitochondria, and some distribution within the cytoplasm.
Supervisor: Thompson, Elinor ; Stevenson, Philip Sponsor: Rosetrees Trust ; University of Greenwich
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QR Microbiology ; RC Internal medicine