Date of Award

8-2014

Level of Access

Open-Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biomedical Sciences

Advisor

James Coffman

Second Committee Member

Carol Bult

Third Committee Member

Thomas Gridley

Abstract

Proper execution of animal development requires that it be integrated with cell division. In part, this is made possible due to cell cycle regulatory genes becoming dependent upon developmental signaling pathways that regulate their transcription. Cyclin D genes are important bridges linking the regulation of the cell cycle to development because these genes regulate the cell cycle, growth and differentiation in response to intercellular signaling. In this dissertation, a cis-regulatory analysis of a cyclin D gene, Sp-CycD, in the sea urchin, Strongylocentrotus purpuratus, is presented. While the promoters of vertebrate cyclin D genes have been analyzed, the cis-regulatory sequences across an entire cyclin D locus that regulate its expression pattern have not.

From conducting the cis-regulatory analysis of Sp-CycD, regulatory regions located within six defined regions were identified. Two of these regions were found upstream of the start of transcription, but the remaining regions were found within introns. Regarding their activity patterns, two intronic regions were most strongly active at the time of induction of Sp-CycD expression, implying they contributed to this induction. The activity patterns of other regions indicated that each could have distinct roles, including controlling and maintaining Sp-CycD expression as it becomes spatially restricted during and after gastrulation.

The sequences of the regulatory regions were analyzed. In three regions subregions containing the cis-regulatory modules responsible for activity were found, and in two other regions, sequences that lacked activating regulatory activity were found, allowing the identities of active regulatory sequences to be inferred. The sequences of each region were further analyzed for bearing significantly represented potential binding sites for transcription factors expressed in developmental lineages of the embryo where Sp-CycD is expressed. The transcription factors included those that act downstream of Wnt-beta catenin and Delta-Notch signaling pathways that induce the development of the endoderm and mesoderm; and those expressed within the Gene Regulatory Networks that contribute to the development of these lineages. From this, testable linkages between these binding sites and transcription factors that could regulate the expression of Sp-CycD as development progresses were identified, providing the foundation for future work.

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