Mechanisms of Transcriptional Regulation by NFAT and AP-1 Transcriptional Activators

Walters, Ryan David

Graduate Thesis Or Dissertation

Mechanisms of Transcriptional Regulation by NFAT and AP-1 Transcriptional Activators Public Deposited

Analytics

Citations

Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/pk02c9856

Abstract

Transcription of mRNA by RNA Polymerase II (Pol II) is a fundamental step in gene expression. In mammalians, this is a highly regulated process that requires the assembly and coordination of a multitude of nuclear factors that determine the level of transcription of any particular gene. This thesis investigates the mechanisms of transcriptional regulation by NFAT and AP-1 proteins, two families of transcription factors that play pivotal roles in tumorigenesis, proliferation, and the immune response. Using the human interleukin-2 (IL-2) gene as a model system, we characterized the mechanism of transcriptional synergy by NFATc2 and cJun in activated T cells. We propose a model by which cJun homodimers are recruited to the IL-2 promoter as a coactivator of NFATc2, resulting in high levels of transcription. This recruitment is mediated by a unique interaction between the C-terminal activation domain of NFATc2 and the DNA binding domain of a cJun homodimer. Given the distinct role of cJun homodimers in regulating transcription, we aimed to develop DNA aptamers that are capable of distinguishing between cJun homodimers and cJun heterodimers, such as cJun/cFos. SELEX targeting DNA-bound cJun resulted in DNA aptamers that bind cJun homodimers with high affinity and specificity. For the highest affinity aptamer, we characterized the mechanism of binding, its secondary structure, and identified the minimal binding region. We determined that this aptamer effectively inhibits cJun from binding its corresponding DNA recognition element, and in cells we show that the aptamer can inhibit cJun homodimer activated transcription.

Creator