Thesis (Ph.D.)--Indiana University, School of Optometry, 2004. / Title from PDF t.p. (viewed Dec. 2, 2008). Source: Dissertation Abstracts International, Volume: 66-01, Section: B, page: 0050. Chair: Joseph A. Bonanno.

Thesis (Ph.D.)--Indiana University, School of Optometry, 2004. / Title from PDF t.p. (viewed Dec. 2, 2008). Source: Dissertation Abstracts International, Volume: 66-01, Section: B, page: 0050. Chair: Joseph A. Bonanno.

Thesis (Ph.D.)--University of California, San Francisco, 2010. / Source: Dissertation Abstracts International, Volume: 71-02, Section: B, page: . Adviser: Thea D. Tlsty.

Thesis (Ph.D.)--University of California, San Francisco, 2009. / Source: Dissertation Abstracts International, Volume: 70-10, Section: B, page: 6103. Adviser: Jason G. Cyster.

<p> <b>Statement:</b> A global <i>Rbp1</i> knock out (<i> Rbp1-/-</i>) mouse model was used to correlate direct retinoid measurements with vitamin A metabolizing and atRA biosynthesizing enzyme activities, Crbp function and tissue microenvironment for the first time. </p><p> <b>Methods:</b> atRA was quantified by LC-MRM³ and ROL/RE/RAL was quantified by HPLC-UV. Enzyme activities were measured from enzymes present in subcellular fractions isolated from WT and <i>Rbp1-/- </i> tissues. Mouse CrbpI and CrbpIII were purified from transformed <i> Escherichia coli</i> for functional comparative studies. Tissue were formalin fixed for histological examination. Relative gene expression was analyzed using quantitative PCR. </p><p> <b>Results:</b> Reduced atRA was consistently quantified in extrahepatic tissues with elevated ROL/RE. Relative gene expression showed altered expression in retinoid pathway proteins and atRA loss preceded expression changes in some cases. Tissue microenvironments also consistently showed a loss of structure and organization along with accumulation of extracellular matrix and hyperplasia without apparent disease. Functional studies showed that CrbpIII binds retinol with less affinity than CrbpI and does not function equivalently to CrbpI in regulation of atRA biosynthesis. Also, metabolizing enzymes had altered activities in the <i>Rbp1-/-</i> tissues with reduced atRA biosynthesis. </p><p> <b>Conclusions:</b> Loss of CrbpI results in altered regulation of enzyme activity and atRA homeostasis cannot be maintained by other Crbp homologs in extrahepatic tissues. Dysfunctional atRA biosynthesis due to loss of CrbpI results in altered tissue microenvironment characteristic of dietary vitamin A deficiency and precancerous dysfunction associated with cancers that are observed to have silenced CrbpI.</p>

<p> One of the greatest problems in prostate cancer management today is accurate identification of patients who require treatment for aggressive disease versus those with indolent disease who are suitable for observational strategies. Histological appearance of the tumor, called Gleason score in the prostate cancer field, is the most predictive measure currently used. However, recent studies in multiple tumor types have shown that histological appearance does not always reflect the underlying molecular phenotype of the lesion. Therefore, in prostate cancer specifically, assessment of a molecular marker of androgen receptor driven epithelial differentiation may have clinical predicative capabilities. SAM pointed domain-containing Ets transcription factor (SPDEF) is a potential AR target gene that has shown to be necessary and sufficient for epithelial cell differentiation in many tissues. Although generally associated with good prognosis, SPDEF's role in cancer in unclear. This study demonstrates, through retrospective immunohistochemical analysis, the utility of SPDEF as a predictive biomarker for patients that have an extended benefit from androgen deprivation therapy (ADT). Furthermore, dual roles of SPDEF to inhibit the initiation and supporting the progression of castrate recurrent disease through novel androgen receptor expression regulation in castrate conditions are shown. In ADT na&iuml;ve patients, SPDEF did not associate with metastatic disease or an induction of epithelial to mesenchymal transition. However, aggressive tumors tended to be larger, have greater SPDEF variability, and lack vimentin expression; a phenotype that could be explained by a partial EMT. In conclusion, SPDEF may be clinically useful to assess the epithelial phenotype of tumors, and could have utility identifying patients that will respond well to androgen deprivation therapy.</p>

<p> Intercalated discs (ICDs) are cardiac-specific structures located at the longitudinal termini of cardiomyocytes. Classically, the functions assigned to ICDs include mechanical and electrical communications among adjacent cardiomyocytes. More recently, it has been increasingly realized that ICDs also function in signal transduction and regulation of the surface expression of ion channels. Accordingly, defects of ICD components are shown to cause a number of human cardiac diseases and changes of ICDs are associated with cardiomyopathy, arrhythmias, and heart failure. The expansion of our knowledge about the development, function and maintenance of ICDs are promoted by identification, cataloging and characterization of the molecular components of the ICDs. In this thesis, I characterize a family of Xin repeat-containing proteins, which are striated muscle-specific and localized to the ICDs in the cardiomyocytes. This thesis provides novel insights into the mechanism of the formation, maintenance and functions of ICDs. </p><p> Our previous studies showed that the Xin repeat-containing proteins play critical role in cardiac morphogenesis and cardiac function. Knocking down the <i>Xin</i> in chicken embryo collapses the wall of developing heart chambers and leads to abnormal cardiac morphogenesis. In mammals, a pair of paralogous genes, <i>Xin&alpha;</i> and <i>Xin&beta; </i>, exists. Ablation of the mouse <i>Xin&alpha;</i> (<i> mXin&alpha;</i>) does not affect heart development. Instead, the mXin&alpha;-deficient mice show adult late-onset cardiac hypertrophy and cardiomyopathy with conduction defects. The ICD structural defects in mXin&alpha;-null mice occur between 1 and 3 months of age and progressively worsen with aging. The mXin&alpha;-deficient hearts up-regulate mXin&beta;, suggesting a partial compensatory role of mXin&beta;. </p><p> In this thesis, I focus on two questions. First, what are the molecular mechanisms of mXin&alpha;'s functions that account for the observed phenotypes in the mXin&alpha;-deficient hearts? And second, what are the functions of mXin&beta;? Through biochemical methods and electron microscopy, I demonstrated that mXin&alpha; binds and bundles actin filaments. In addition, a direct interaction between mXin&alpha; and the adherens junction protein &beta;-catenin facilitates mXin&alpha;'s interaction with the actin filaments. Based on this in vitro characterization of mXin&alpha;, we proposed that mXin&alpha; may act as a direct link between the adherens junctions and actin cytoskeleton, thus providing an important means to strengthening the intercellular adhesion at the ICDs. To characterize mXin&beta;'s roles, I generated and characterized <i> mXin&beta;</i>-knockout mice. I showed that complete loss of mXin&beta; leads to cardiac morphological defects, diastolic dysfunction and heart failure, which lead to severe growth retardation and early postnatal lethality. I also showed that mXin&beta; might be involved in a number of cell signaling pathways and provide multiple lines of evidence to support mXin&beta;'s roles in the formation of ICDs. </p><p> In summary, this thesis provides novel insights into the specialization of the adherens junctions at the ICDs to withstand the contractile forces, and the molecular mechanisms for the establishment, maintenance and function of ICDs. The knowledge gained from the roles of Xin proteins in cardiac development and function will likely provide new insights for improved therapeutic strategies for human cardiomyopathy, arrhythmias and heart failure.</p>

<p> Ischemic heart disease impacts millions worldwide and can progress to heart failure. Percutaneous coronary intervention (PCI) is first-line therapy for patients presenting with an acute ischemic event or acute coronary syndrome (ACS). However, PCI can also worsen cardiomyocyte death, cardiac dysfunction and adverse remodeling via reperfusion injury, largely an oxidative stress-mediated insult. Novel alternative therapies for ACS have proven elusive, with no new classes of agents in years. We investigated cardiac troponin I-interacting kinase (TNNI3K), a cardiomyocyte-specific kinase, as a potential modulator of ischemia/reperfusion (I/R) injury and chronic left ventricular (LV remodeling). We found TNNI3K enhances production of mitochondrial reactive oxygen species (mROS) and induces mitochondrial dysfunction, thus increasing cardiomyocyte death and I/R injury. Moreover, TNNI3K-mediated injury is largely dependent on p38 MAPK activation. We developed a series of small-molecule TNNI3K inhibitors that reduce mitochondrial-derived superoxide generation, p38 activation, and infarct size when delivered at reperfusion to mimic ACS intervention. Moreover, although TNNI3K inhibition does not modulate the adverse remodeling that occurs after a non-reperfused myocardial infarction (MI), TNNI3K inhibition preserves cardiac function and limits chronic adverse remodeling in a model of MI with reperfusion. Taken together, TNNI3K plays an adverse role in the cardiomyocyte response to I/R, in part by driving mROS production and augmenting p38-mediated cell death specifically via reperfusion injury. Our findings reveal a previously unexplored role for TNNI3K in regulating the oxidative stress response in the heart, and support the potential for TNNI3K as a novel therapeutic target for ACS.</p>

<p> This dissertation examines the role of retinoic acid receptor activation in the post-transcriptional regulation of a fibroblast growth factor binding protein. Previous work showed that all-trans retinoic acid (ATRA) reduces mRNA expression of the angiogenic switch molecule, Fibroblast Growth Factor Binding Protein 1 (FGFBP1 or FGF-BP), independent of an effect on transcription of the FGFBP1 mRNA. I hypothesized that a retinoid-induced microRNA was involved in FGFBP1 mRNA loss. MicroRNAs (miRs) are 19-22 nucleotide (nt) single stranded non-coding RNAs that post-transcriptionally repress mature mRNA function, thereby reducing expression of their target proteins. The current dogma suggests that miRs canonically bind to the 3' untranslated region (UTR) of mRNA through a 7-nt seed-matched site. However, recent data indicate that miRs may also bind the open reading frame (ORF) of mRNAs. In this dissertation, I show that miR-27b-3p and miR-125a-5p are induced by ATRA and target FGFBP1. Overexpression of miR-27b-3p and miR-125a-5p rapidly reduced FGFBP1 mRNA levels through a target site in the open reading frame of the FGFBP1 mRNA. Both microRNAs showed specificity for regions within the ORF of FGFBP1, suggesting that these microRNAs may also be involved in inhibiting translation of the FGFBP1 protein. Next generation sequencing data from The Cancer Genome Atlas shows that loss of these microRNAs is characteristic of several epithelial cancers, including head and neck, lung, and cervical squamous cell carcinomas, suggesting a tumor suppressor role for miRs 27a-3p and 125a-5p. In total, these data suggest an important regulatory role for miRs 27b-3p and 125a-5p in the oncogenesis of squamous cell carcinomas, through modulation of FGFBP1 expression.</p>

Thesis (Ph.D.)--University of California, San Francisco, 2005. / Source: Dissertation Abstracts International, Volume: 66-12, Section: B, page: 6537. Adviser: Frank McCormick.