Mouse models (that develop or can be stimulated to develop lymphomas) are used to examine cancer-related processes. Mouse models can be effective tools used to identify new, early, and pre-malignant markers of lymphomas. Signal Transducer and Activator of Transcription (STAT) 6 is a transcription factor activated through the Jak-Stat pathway. Transgenic mice expressing a constantly activated Stat6 (Stat6VT) were previously generated and characterized to have altered lymphocyte homeostasis. Some of these Stat6VT mice developed a lymphoproliferative disorder (LPD). LPD, including lymphomas, develops when lymphocytes are overproduced or act abnormally. These Stat6VT mice may serve as a model for examining lymphoma development. In order to characterize the altered lymphocytes and determine if LPD observed in the Stat6VT mice is characteristic of lymphoma, RT-PCR analysis and Western analysis were done to examine if the presence of Stat6VT alters the expression of the cell cycle genes Gfi-1 and Gfi-1b and if these genes differ in LPD Stat6VT verses control mice. / Department of Biology

Stat6 is a protein that activates the transcription of IL-4-stimulated genes. Amino acids critical for Stat6 function were examined in a mutational analysis of the Src homology (SH2) domain of the Stat6 protein. One mutation, substitution of two Alanines for Valine and Threonine in the N-terminal portion of the SH2 domain, produced a constitutively active form of the molecule that did not require IL-4 for activation. This mutant was named Stat6VT. Mice expressing Stat6VT in lymphocytes were generated, and it was found that approximately 10% of the population of Stat6VT mice, a lympho-proliferative disorder (LPD) occurred. In this study, we are examining genes that have a possible role in the development of this proliferative condition. Specifically, we examined the expression levels of Tiam1, Tacstdl, and Gfi-1 and Gfi-1B (genes known to regulate cellular proliferation and survival) in wildtype, normal Stat6VT and Stat6VT/LPD splenocytes by RT-PCR. Tiam1 results were inconclusive, and Tacstdl was not expressed at levels different from those seen in controls. Interestingly, Gfi-1 B, the homolog of Gfi-1, was expressed at increased levels in a specific subpopulation of cells from Stat6VT/LPD mice. Taken together, these data suggest that in cells expressing a constitutively active Stat6, increased expression of Gfi-1B may play a role in the mechanism of lymphoma development. / Department of Biology

GLK1 and GLK2 transcription factors have been suggested to be involved in the regulation of chloroplast development, organic nitrogen signaling, disease resistance and circadian rhythmicity (Waters et al. 2009; Gutiérrez et al. 2008; Savitch et al. 2007; Sprott et al. 2010). This implies that multiple factors may play roles in regulation of GLK genes. In the present study, transcriptional regulation of GLK1 and GLK2 in Arabidopsis by various endogenous and environmental stimuli was investigated with the objective of elucidating the primary signalling pathway affecting expression of these two genes. Collectively, results of GLK1 and GLK2 expression in response to the experimental treatments of Arabidopsis point to the regulation of the two genes by changes in photosynthetic metabolism and reactive oxygen species (ROS) levels, and by organic nitrogen signalling. Changes in ROS levels and organic nitrogen signalling may also affect the two genes indirectly by interfering with or altering photosynthetic metabolism.

I present a method that regroups cis-regulatory modules by shared sequences motifs. The goal of this approach is to search for clusters of modules that may share some function, using only sequence similarity. The proposed similarity measure is based on a variable-order Markov model likelihood scoring of sequences. I also introduce an extension of the variable-order Markov model which could better perform the required task. Results. I show that my method may recover subsets of sequences sharing a pattern in a set of generated sequences. I found that the proposed approach is successful in finding groups of modules that shared a type of transcription factor binding site.

Non-steroidal anti-inflammatory drugs (NSAIDs) and their NO derivatives (NO-NSAIDs), and synthetic analogs are highly effective as anticancer agents that exhibit relatively low toxicity compared to most clinically used drugs. However, the mechanisms of action for NSAIDs and NO-NSAIDs are not well defined and this has restricted their clinical applications and applications for combined therapies. Earlier studies from our laboratory reported that specificity protein (Sp) transcription factors (Sp1, Sp3 and Sp4) are overexpressed in several types of human cancers including colon cancer and many Sp-regulated genes are pro-oncogenic and individual targets for cancer chemotherapy. Based on published results showing that NSAIDs downregulate several putative Sp-regulated genes, we hypothesized that the anticancer properties of NSAIDs may be due, in part, to downregulation of Sp transcription factors. NSAIDs including aspirin and tolfenamic acid (TA) and nitro derivatives of NSAIDs such as GT-094 have been investigated in colon cancer cells and in vivo xenograft models. Aspirin and TA induced apoptosis and decreased colon cancer cell growth and tumor growth in vivo and downregulated genes associated with cell growth, survival, and angiogenesis. Previous RNA interference studies in this laboratory have shown that many of these genes are regulated, in part, by Sp transcription factors Sp1, Sp3 and Sp4 that are overexpressed in colon and other cancer cell lines. Not surprisingly, these NSAIDs also decreased Sp1, Sp3 and Sp4 proteins and Sp-regulated gene products in colon cancer cells and this was due to caspase-dependent proteolysis of Sp1, Sp3 and Sp4 proteins. Aspirin-induced activation of caspases and degradation of Sp1, Sp3 and Sp4 was due to sequestration of zinc and could be reversed by addition of zinc sulphate, whereas TA mediated induction of caspases was independent of zinc ions and is currently being investigated. GT-094 is a novel NO chimera-containing NSAID, which also inhibited colon cancer cell proliferation and induced apoptosis; these effects were accompanied by decreased mitochondrial membrane potential (MMP) and induction of reactive oxygen species (ROS), and were reversed after cotreatment with the antioxidant glutathione. GT-094 also downregulated Sp and Sp-dependent gene products and was due to decreased expression of microRNA-27a (miR-27a) and induction of ZBTB10, an Sp transcriptional repressor that is regulated by miR-27a in colon cancer cells. Moreover, the effects of GT-094 on Sp1, Sp3, Sp4, miR-27a and ZBTB10 were also inhibited by glutathione suggesting that the anticancer activity of GT-094 in colon cancer cells is due, in part, to ROS-dependent disruption of miR-27a:ZBTB10. The importance of ROS induction in targeting Sp transcription factors was also confirmed using pro-oxidants such as ascorbic acid, hydrogen peroxide and t-butyl hydroperoxide and similar results have been observed in collaborative studies with other ROS inducers in colon cancer cells. Many cancer cell lines and tumors exhibit addiction to non-oncogenes such as Sp1, Sp3 and Sp4 for maintaining the oncogenic phenotype and future research will focus on the mechanisms of ROS-mediated targeting of Sp transcription factors which represents a novel approach for cancer chemotherapy.

Thesis (Ph. D.)--University of Alabama at Birmingham, 2007. / Title from first page of PDF file (viewed Feb. 7, 2008). Includes bibliographical references (p. 50-57).

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 133-173).

Thesis (M.S.)--Duquesne University, 2007. / Title from document title page. Abstract included in electronic submission form. Includes bibliographical references (p. 76-80) and index.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.