Previous studies from our lab have shown that the Activating Protein- 2 (AP-2) transcription factors, AP-2α and AP-2β, are important in retinal development. It was discovered that these are co-expressed in developing horizontal cells and postmitotic amacrine cells. To understand their role in retinogenesis, and the impact of their deletion on the adult retina, a double mutant mouse model was created, AP-2αKI/flox/AP-2β-/flox. The neural retina of the AP-2αKI/flox/AP-2β-/flox mice was examined in the current study using histological, immunofluorescent and electron microscopy (EM) techniques at embryonic, post-natal and adult stages. These double mutants displayed a variety of abnormalities in the inner retina. Loss of AP-2α and AP-2β at E10.5 led to a complete absence of developing and mature horizontal cells. This loss was associated with changes in the outer plexiform layer, which diminished from two to four months of age. There were also defects with photoreceptor ribbons in which triad synapses failed to form, and instead led to rudimentary, spherical-shaped ribbons. There was also significant retraction of photoreceptor axons. Furthermore, this study was able to infer a role of AP-2α and AP-2β as acting upstream of the Onecut-1 protein, which targets Lim1 and Prox1 to direct horizontal cell genesis. Examining amacrine cells of the double mutants shows evidence that AP-2α and AP-2β are involved in the mosaic arrangement pattern of amacrine cell bodies and axons. Previous work on embryonic double mutants displayed clustering of amacrine cells. This study observed abnormalities in the dendrites of the inner plexiform layer, which consists of amacrine cell processes. Taken together, the work presented in this thesis implicates the redundant requirement of both AP-2α and AP-2β in development of horizontal cells and patterning of amacrine cells in the neural retina. / Thesis / Master of Health Sciences (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/16051 |
| Date | 11 1900 |
| Creators | Zaveri, Mizna |
| Contributors | West-Mays, Judith, Medical Sciences |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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