Date of Award

5-2021

Document Type

Thesis

Degree Name

Master of Science (MS)

College/School

College of Science and Mathematics

Department/Program

Biology

Thesis Sponsor/Dissertation Chair/Project Chair

Carlos Molina

Committee Member

Sandra D. Adams

Committee Member

Lee H. Lee

Abstract

Cell division is a highly regulated, multi-complex system requiring an abundance of proteins working in conjunction with one another. This unity is what ensures proper development of the cell before entering a new phase in the cell cycle. Cells that infringe multiple cycle stages can become malignant, proliferating at an untamable rate. The transcriptional suppressor protein, Inducible cAMP Early Repressor (ICER), is present in some, but not all, cancer cells. ICER functions as a transcriptional repressor of the cAMP Response Element (CRE) gene in aberrant cells which could effectively prevent them from bypassing cell cycle checkpoints and proliferating unchecked. Downstream effects of CRE repression can prevent normal transcription of genes such as cyclin A; coding for a protein that is heavily involved in the S and G2 phases of the cell cycle. ICER has also been shown to have a role in secondary messenger pathways such as β‐adrenoceptor pathways. β‐adrenoceptors are involved in sympathetic regulation among several organ systems including the circulatory and respiratory systems.

Two enhanced green fluorescent protein (EGFP) constructs and Nikon DAPI-FITCTRITC triple band excitation were used to determine the site of ICER-IIγ localization in human melanoma cells, SK-MEL-24. The constructs were designed to have EGFP on either the Nterminus or C-terminus of ICER-IIγ. We sought to establish if EGFP-hindered termini would affect nuclear localization of ICER-IIγ. Data demonstrated that the loci of EGFP tagging had no effect on nuclear localization. Interestingly, when EGFP was bound at the C-terminus, it was observed in the centrosomes of mitotic cells. Moreover, ICER-IIγ presenting cells with free Ntermini were in higher abundance in nuclear cells than those with free C-termini. Our findings suggest that the N-terminus of ICER-IIγ may have a role in mitotic events.

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