Mechanisms regulating lens fiber cell elongation
Date
2018
Authors
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Publisher
University of Delaware
Abstract
How changes in cell shape are driven by events at the molecular and cellular levels is an ongoing area of investigation for developmental biologists. Lens epithelial cells differentiate into lens fiber cells and undergo a significant cell shape change during this process. Understanding how these cell shape changes occur could allow for a deeper understanding of similar processes in other tissues. Further, disorders of eye and lens development such as congenital cataracts and microphthalmia, which are the major causes of visual disability in children, can in some cases be caused by misregulation of cell shape. The cell fate decision between lens epithelial and fiber cell requires the transcription factor, Prox1, a global regulator of lens fiber preferred gene expression. RNAseq identified numerous cytoskeletal associated proteins mediating fiber cell elongation. Kinesin 1a (Kif1a), microtubule associated end binding protein RP/EB (Mapre3) and tubulin-β6 (Tubb6) are three genes differentially expressed in Prox1 null lenses that were prioritized for further study as possible regulators of lens fiber cell elongation based on their evolutionary conservation, lens preferred expression, and the availability of antibodies. While the expression of Kif1a, Mapre3, and Tubb6 have been characterized in mice, this thesis sought to use an alternative model to study their function due to the high cost of using mice. Xenopus tropicalis is a low-cost amphibian system for genetic and developmental biology research. Immunofluorescence for the established lens fiber marker, aquaporin0 (Aqp0) and histological staining methods confirmed lens fiber elongation occurs between stages 32/34 and 35/36. Therefore, the function of these three cytoskeletal associated genes were characterized using X. tropicalis. Morpholino-driven knockdowns of these genes offers insight into these genes’ role in the elongation process. Preliminarily, Kif1a knockdown produced an embryonic lethal phenotype before lens development occurred. Mapre3 knockdown resulted in an ocular pigmentation defect. Lastly, Tubb6 knockdown resulted in microphthalmia and reduced expression of the fiber cell marker, Aquaporin 0. Therefore, Tubb6 and Mapre3 may be essential for lens and/or eye morphogenesis. The future of this project will expand the preliminary data provided at the conclusion of this study to elucidate the function of these cytoskeletal associated genes in the regulation of lens fiber elongation.
Description
Keywords
Biological sciences, Health and environmental sciences, Elongation, Kif1a, Lens fiber cell, Mapre3, Tubb6