Zinc in the retinal pigment epithelium and choriocapillaris interface.
Doctoral thesis, UCL (University College London).
The highest concentration of zinc in human tissues is found in the retinal pigment epithelium (RPE)-choroid complex. Despite the association of zinc deficiency with age-related macular degeneration (AMD) and the widespread use of zinc supplementation to slow the progression of AMD, very little is known about how zinc affects the RPE and the choroid. Molecular and cell biology techniques were used to uncover how changes in zinc levels could play a role in regulating the RPE-choroid complex. First, QRT-PCR was used to assess the expressions of all 24 known zinc transporters in cadaveric human RPE, cultured RPE cells and cells isolated from other parts of the retina, ZIP12 was identified as a potentially important transporter to regulate zinc levels at the RPE-choroid interface. As there is very little published about ZIP12, bioinformatics and data mining were used to understand how this protein might function. Confirmation of these predictions was achieved through the cloning and expression of V5-tagged ZIP12 protein in different cell lines. Based on these experiments, we concluded that ZIP12 is a plasma membrane transporter that mediates zinc influx. In parallel, we tested the hypothesis that extracellular zinc levels in Bruch’s membrane might be involved in regulating both the RPE as well as the fenestrated choroidal capillaries using cultures of ARPE19 and bEND5 cells respectively. The presence of extracellular zinc in the growth media affected the characteristics of ARPE19 cells as well as fenestrae formation in bEND5 cells. In summary, the range of zinc transporter at the RPE-choroid interface was defined and properties of one particular transporter, ZIP12 which may have a specific role at this site, were elucidated. Using cellular systems some of the effects of zinc on the RPE-choroid complex were investigated. Future studies are required to elucidate the role of zinc in the AMD pathogenesis.
|Title:||Zinc in the retinal pigment epithelium and choriocapillaris interface|
|Open access status:||An open access version is available from UCL Discovery|
|Additional information:||Copyright restricted material has been removed from the e-thesis|
|UCL classification:||UCL > School of Life and Medical Sciences > Faculty of Brain Sciences > Institute of Ophthalmology > Institute of Ophthalmology - Ocular Biology|
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