Date of Award

1-2012

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 A. Molina

Committee Member

Quinn Vega

Committee Member

Hans Schelvis

Abstract

The Inducible cAMP Early Repressor (ICER) is a dominant transcriptional repressor that binds to cAMP responsive elements (CRE) located in the promoter of a target gene to repress cAMP-mediated gene transcription. The promoter of ICER contains four regulatory CRE sequences, termed cAMP autoregulatory response elements (CAREs) that are highly inducible by cAMP signaling. In a cell, cAMP pathway induces the expression of ICER, however, when ICER protein level increases above normal level, it can repress its own production by binding to these CARE sites located in its promoter region. ICER is normally present in neuroendocrine cells, however, it is not present in tumor cells. In addition, the growths of these tumor cells have been known to be hampered when ICER was reintroduced. Therefore, it is hypothesized that ICER, putative tumor suppressor, manipulation could potentially be used as a new treatment for cancers. Until now, the activity of ICER promoter has been studied in organisms such as rat and mouse; however, human form of ICER promoter has not been characterized yet. Thus, the goal of this research was to characterize the human ICER promoter and to do the comparative studies of the promoter activity in human prostate cancer cells, LNCaP. In order to achieve our goal, the human ICER promoter, composed of four putative CAREs, was analyzed in vitro as well as in LNCaP cells. Our research show that human ICER promoter is composed of three CAREs, namely CAREl, CARE3 and CARE4. Result of our in vivo analysis show that the hICER promoter activity is inducible by cAMP/PKA pathway and repressible by ICER in LNCaP cells. We also show that the induction and repression of ICER promoter activity was specifically due to the presence of three CAREs in hICER promoter. Comparative studies of hICER promoter activity show that CARE1, CARE3 and CARE4 function in a cooperative manner to regulate ICER gene expression in a very fine tune manner.

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