Date of Award
Doctor of Philosophy
Genetics, Development and Cell Biology
Jeffrey M. Trimarchi
The mechanisms which govern cell fate acquisition in the central nervous system (CNS) are of immense interest to researchers from a variety of fields. The progression from progenitor cell to mature neuron requires both extrinsic and intrinsic factors working in concert to produce functional, distinct cell types. Further, the factors which maintain these distinct cell types in the adult will provide information regarding the specific functionalities of individual cells and will facilitate studies of transgenic animals. To identify those molecules which aid in the development of neurons and the maintenance of their unique subtypes, we employed single cell transcriptomics in the vertebrate retina. Through examination of the developing chick retina, we uncovered several factors involved in retinal ganglion cell (RGC) genesis, some of which were conserved between this organism and previous studies performed in the mouse, producing a core set of RGC-crucial genes. We also demonstrated the novel occurrence of multilineage priming of developing neurons in the chick CNS, providing insight into the mechanisms of neurogenesis. The observed transcriptomic heterogeneity of RGCs during development led us to pursue the identification of factors which are specifically expressed in RGC subtypes. This population of neurons is comprised of more than 30 functionally and morphologically distinct cells, many of which lack in-depth knowledge of their light-related responses and circuitry. We employed electrophysiology and transcriptomic profiling of single neurons from the adult mouse retina to uncover genes expressed in various subsets of these cells and have uncovered an ion channel subunit gene as a potential marker of a distinct RGC subtype through this analysis. Furthermore, we employed RNA-Sequencing technology to examine the transcriptomes of a specific subset of RGCs, which are intrinsically photosensitive, and successfully identified several genes which were expressed differentially between these neurons, including the novel localization of a troponin molecule to one of these subtypes. The work presented here demonstrates the complexity of retinogenesis across vertebrate organisms and the subtype markers identified will facilitate future studies of RGC subtype circuitry and functionality.
Lauren Ann Laboissonniere
Laboissonniere, Lauren Ann, "The identification of developmental mechanisms and signatures of mature retinal neurons through single cell transcriptomics" (2018). Graduate Theses and Dissertations. 17234.