Abstracts Category : Other

Transcriptomic and Proteomic Characterizations of Goldfish (Carassius auratus) Radial Glia Reveal Complex Regulation by the Neuropeptide Secretoneurin

by Fonte Dillon Da

In the teleost brain, radial glial cells (RGCs) are the main macroglia and are stem- like progenitors that express key steroidogenic enzymes, including the estrogen- synthesizing enzyme, aromatase B (cyp19a1b). As a result, RGCs are integral to neurogenesis and neurosteroidogenesis in the brain, however little is known about the permissive factors and signaling mechanisms that control these functions. The aim of this thesis is to investigate if the secretogranin-derived neuropeptide secretoneurin (SN) can exert regulatory control over goldfish (Carassius auratus) RGCs. Immunohistochemistry revealed a close neuroanatomical relationship between RGCs and soma of SNa- immunoreactive magnocellular and parvocellular neurons in the preoptic nucleus in both goldfish and zebrafish (Danio rerio) models. Both intracerebroventricular injections of SNa into the third brain ventricle and SNa exposures of cultured goldfish RGCs in vitro show that SNa can reduce cyp19a1b expression, thus implicating SNa in the control of neuroestrogen production. RNA-sequencing was used to characterize the in vitro transcriptomic responses elicited by 1000 nM SNa in RGCs. These data revealed that gene networks related to central nervous system function (neurogenesis, glial cell development, synaptic plasticity) and immune function (immune system activation, leukocyte function, macrophage response) were increased by SNa. A dose-response study using quantitative proteomics indicates a low 10 nM dose of SNa increased expression of proteins involved in cell growth, proliferation, and migration whereas higher doses down- regulated proteins involved in these processes, indicating SNa has dose-dependent regulatory effects. Together, through these altered gene and protein networks, this thesis proposes SNa exerts trophic and immunogenic effects in RGCs. These datasets identified a total of 12,180 and 1,363 unique transcripts and proteins, respectively, and demonstrated that RGCs express a diverse receptor and signaling molecule profile. Therefore, RGCs can respond to and synthesize an array of hormones, peptides, cytokines, and growth factors, revealing a multiplicity of new functions critical to neuronal-glial interactions.