Thesis (Ph. D.)--University of Missouri--Columbia, 1996. / "May 1996." Typescript. Vita. Includes bibliographical references (leaves 131-150). Also available on the Internet.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 6 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 6 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 4 uppsatser.

Thesis (Ph. D.)--University of Missouri--Columbia, 2004. / "July 2004" Typescript. Vita. Includes bibliographical references (l. 123-133). Also issued on the Internet.

Thesis (M.S.) -- University of Texas Southwestern Medical Center at Dallas, 2005. / Embargoed. Vita. Bibliography: 81-88.

Osteocalcin (OC) is a bone specific protein expressed during differentiation and mineralization of the bone extracellular matrix. The Osteocalcin gene is transcriptionally regulated by several basal, hormone- and cytokine-responsive elements. To address the potential role of TGF-β1 regulation and tissue-specific expression of the OC gene, we defined regulatory elements and factors mediating the transcriptional activity of the rat OC (rOC) promoter. TGF-β1 modulates the differentiation of cells of the osteogenic lineage and downregulates the osteoblast-specific expression of OC. By promoter deletion and mutational analyses, a TGF-β1 responsive element at nt -146 to -139 and a contiguous tissue-specific enhancer element at nt -136 to -130 on the rOC promoter were identified. These studies show that Fra-2, a member of the AP-1 family of proteins, binds to the TGF-β1 responsive element and activates basal OC expression. TGF-β1 induced phosphorylation of Fra-2 inhibits this activation, resulting in repression of OC gene transcription. The tissue-specific enhancer element contiguous to the TGF-β1 responsive element contains an AML (Cbfa) binding sequence. This element, designated OC Box II, contributes to 75% of the basal OC promoter activity and forms an osteoblast-specific protein-DNA complex in in-vitro assays. The activation potential of this binding sequence was established by overexpressing AML (Cbfa) transcription activator proteins in osteoblastic as well as in non-osseous cell lines. Interestingly, overexpression not only enhances rOC promoter activity in osteoblasts but also mediates promoter activity in a non-osseous human fibroblastic cell-line. Subsequently, we identified AML-3 (Cbfa1) as the major AML family member present in the osteoblast specific complex and demonstrate that AML-3 (Cbfa1) is expressed predominantly as a 5.4 kb transcript in rat bone tissues. Finally, to establish the functional involvement of AML (Cbfa) transcription factors in osteoblast differentiation, we utilized antisense strategies to demonstrate that blocking expression of all AML (Cbfa) related genes in primary osteoblast cultures significantly decreased several parameters which are linked to differentiation of normal diploid osteoblasts. These results indicate that AML-3 (Cbfa1) is a key transcription factor in bone cells and that the activity of the AML (Cbfa) family of proteins is required for completion of osteoblast differentiation.

Thesis (Ph. D.)--University of Missouri--Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves : 131-150). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri--Columbia, 2004. / Typescript. Vita. Includes bibliographical references (leaves 123-133). Also issued on the Internet.

The following work demonstrates that chromatin regulators play far more pronounced roles in dynamic gene expression than they do in steady-state. Histone modifications have been associated with transcription activity. However, previous analyses of gene expression in mutants affecting histone modifications show limited alteration. I systematically dissected the effects of 83 histone mutants and 119 gene deletion mutants on gene induction/repression in response to diamide stress in yeast. Importantly, I observed far more changes in gene induction/repression than changes in steady-state gene expression. The extensive dynamic gene expression profile of histone mutants and gene deletion mutants also allowed me to identify specific interactions between histone modifications and chromatin modifiers. Furthermore, by combining these functional results with genome-wide mapping of several histone modifications in the same time course, I was able to investigate the correspondence between histone modification occurrence and function. One such observation was the role of Set1-dependent H3K4 methylation in the repression of ribosomal protein genes (RPGs) during multiple stresses. I found that proper repression of RPGs in stress required the presence, but not the specific sequence, of an intron, an element which is almost unique to this gene class in Saccharomyces cerevisiae. This repression may be related to Set1’s role in antisense RNA-mediated gene silencing. Finally, I found a potential role for Set1 in producing or maintaining uncapped mRNAs in cells through a mechanism that does not involved nuclear exoribonucleases. Thus, deletion of Set1 in xrn1Δ suppresses the accumulation of uncapped transcripts observed in xrn1Δ. These findings reveal that Set1, along with other chromatin regulators, plays important roles in dynamic gene expression through diverse mechanisms and thus provides a coherent means of responding to environmental cues.