Coxsackievirus B3 (CVB3) is the primary cause of viral myocarditis. The role of cystein-x-cystein (CXC) chemokine ligand 10 (CXCL10, formerly interferon-y-inducible protein 10) in CVB3-induced myocarditis is unknown. To explore the contribution of CXCL10 to CVB3-induced myocarditis, we performed functional analyses using newly generated transgenic mice with cardiac-specific CXCL10 overexpression (Tg) and CXCL10 knock out (KO) mice. The mRNA levels of CXCL10 peaked in the myocardium at day 3 post-infection prior to immune infiltration, suggesting that mainly resident cells of the heart are the sources of CXCL10. Indeed, we showed that CXCL10 can be induced by IFN-y but not by CVB3 infection in cultured cardiomyocytes. Further, a transgenic mouse model with cardiac-specific overexpression of CXCL10 was generated. CXCL10 Tg mice had spontaneous infiltrations of mononuclear cells with limited mRNA upregulation of IFN-y and IL-10, which were not sufficient to cause the impairment of cardiomyocyte or cardiac function. Following CVB3 infection, the viral titre in the mouse hearts inversely correlated with the levels of CXCL10 at day 3 post-infection. Further, the decreased virus titers in the CXCL10 Tg mouse hearts led to reduced cardiac damage indicated by low serum cTnI levels and improved cardiac functional performance and vice versa in the KO mice. This antiviral ability of CXCL10 may be through increased recruitment of natural killer (NK) cells to the heart and increased IFN-y expression early post-infection. At days 7 and day 10 post-infection with massive influx of mononuclear cells, the expression of CXCL10 enhanced the infiltration of CXCR3+ cells, CD4+, and CD8+ T cells as well as their associated inflammatory cytokines. However, the augmented accumulation of these immune cells and associated cytokines did not alter the viral clearance and mouse survival. Our data demonstrate for the first time that CXCL1 0 confers the protection to the heart during the early course of CVB3 infection, which may be primarily attributed to NK cell recruitment to the site of infection. This data suggest that CXCL10 is an important player in the orchestrated action of a group of cytokines and chemokines in combating against the CVB3-induced myocarditis in the early phase of infection.

The mouse node is the structural equivalent of Spemann's Organizer. The transcription factor Foxa2 (HNF3beta) is required for node and notochord specification and its enhancer has been characterized to a 500bp element that drives the expression of a reporter gene to the node and notochord in transgenic embryos. / The aim of the study was to identify sequence elements, within this enhancer, required to drive node/notochord specific-expression. Since, in the Xenopus organizer, Siamois activates organizer-specific gene expression, it was tested whether this factor could activate expression from the Foxa2 node-specific enhancer. Using deletion analysis, the response element was mapped to a 33bp region and it was shown that this element was both necessary and sufficient for reporter gene activation by X-Siamois . Furthermore, it was shown that X-Siamois can bind this DNA element and two sequence motifs required for binding and transactivation by X-Siamois were identified. Preliminary results suggest that the 33bp element, within the 500bp enhancer, is required for the maintenance of expression in the notochord of transgenic mice.

Calreticulin (CRT) is a multifunctional Ca2+ dependent chaperone protein, which is localized to the endoplasmic reticulum and plays many important biological roles. In addition to its critical role in cardiovascular development, CRT has been reported to be important for cell migration, adhesion and apoptosis. A few studies have also suggested different roles for exogenous CRT in angiogenesis and tumor growth however no direct evidence for the role of endogenous CRT in these processes is available. To study the in vivo role of CRT in angiogenesis and vascular development, we generated a transgenic mouse overexpressing CRT under the control of the Tie2 promoter (referred to as Tie2-CRT) which is active in both endothelial cells and hematopoietic stem cells (HSCs). The main phenotype of these mice is an increased incidence of lung tumors. These tumors have been characterized according to their histochemical properties as being adenocarcinoma with a Surfactant Protein-C positive (SP-CPos) and Clara Cell Protein negative (CC10Neg) phenotype suggesting an alveolar origin for these tumors. We observed that during the early stages of tumor formation, the lungs show signs of increased inflammation as evidenced by congestion, reddish discoloration and the accumulation of inflammatory cells. We have also identified that the early stage tumors contain cells that express exogenous CRT and HSC markers including CD133, Sca-1, and c-Kit. As the tumor progresses to a fully developed adenocarcinoma, these cells lose the expression of exogenous CRT and HSCs markers and gain an alveolar type II phenotype (SP-CPos). In vitro evaluation of tumor progression using lung tumor cells from Tie2-CRT mice demonstrated a differentiation dependent expression of HSC markers by tumor cells supporting the hypothesis that HSCs might be the cells of origin for the lung tumors observed in Tie2-CRT mice. In summary, the results from this study provide evidence that lung tumors from the Tie2-CRT mice are non-epithelial in origin and that the undifferentiated population of tumor cells have HSC characteristics. After differentiation, these cells lose their stem cell phenotype and acquire an epithelial phenotype. This study is the first to examine the potential link between CRT and lung cancer development.

Calreticulin (CRT) is a multifunctional Ca2+ dependent chaperone protein, which is localized to the endoplasmic reticulum and plays many important biological roles. In addition to its critical role in cardiovascular development, CRT has been reported to be important for cell migration, adhesion and apoptosis. A few studies have also suggested different roles for exogenous CRT in angiogenesis and tumor growth however no direct evidence for the role of endogenous CRT in these processes is available. To study the in vivo role of CRT in angiogenesis and vascular development, we generated a transgenic mouse overexpressing CRT under the control of the Tie2 promoter (referred to as Tie2-CRT) which is active in both endothelial cells and hematopoietic stem cells (HSCs). The main phenotype of these mice is an increased incidence of lung tumors. These tumors have been characterized according to their histochemical properties as being adenocarcinoma with a Surfactant Protein-C positive (SP-CPos) and Clara Cell Protein negative (CC10Neg) phenotype suggesting an alveolar origin for these tumors. We observed that during the early stages of tumor formation, the lungs show signs of increased inflammation as evidenced by congestion, reddish discoloration and the accumulation of inflammatory cells. We have also identified that the early stage tumors contain cells that express exogenous CRT and HSC markers including CD133, Sca-1, and c-Kit. As the tumor progresses to a fully developed adenocarcinoma, these cells lose the expression of exogenous CRT and HSCs markers and gain an alveolar type II phenotype (SP-CPos). In vitro evaluation of tumor progression using lung tumor cells from Tie2-CRT mice demonstrated a differentiation dependent expression of HSC markers by tumor cells supporting the hypothesis that HSCs might be the cells of origin for the lung tumors observed in Tie2-CRT mice. In summary, the results from this study provide evidence that lung tumors from the Tie2-CRT mice are non-epithelial in origin and that the undifferentiated population of tumor cells have HSC characteristics. After differentiation, these cells lose their stem cell phenotype and acquire an epithelial phenotype. This study is the first to examine the potential link between CRT and lung cancer development.

Coxsackievirus B3 (CVB3) is the primary cause of viral myocarditis. The role of cystein-x-cystein (CXC) chemokine ligand 10 (CXCL10, formerly interferon-y-inducible protein 10) in CVB3-induced myocarditis is unknown. To explore the contribution of CXCL10 to CVB3-induced myocarditis, we performed functional analyses using newly generated transgenic mice with cardiac-specific CXCL10 overexpression (Tg) and CXCL10 knock out (KO) mice. The mRNA levels of CXCL10 peaked in the myocardium at day 3 post-infection prior to immune infiltration, suggesting that mainly resident cells of the heart are the sources of CXCL10. Indeed, we showed that CXCL10 can be induced by IFN-y but not by CVB3 infection in cultured cardiomyocytes. Further, a transgenic mouse model with cardiac-specific overexpression of CXCL10 was generated. CXCL10 Tg mice had spontaneous infiltrations of mononuclear cells with limited mRNA upregulation of IFN-y and IL-10, which were not sufficient to cause the impairment of cardiomyocyte or cardiac function. Following CVB3 infection, the viral titre in the mouse hearts inversely correlated with the levels of CXCL10 at day 3 post-infection. Further, the decreased virus titers in the CXCL10 Tg mouse hearts led to reduced cardiac damage indicated by low serum cTnI levels and improved cardiac functional performance and vice versa in the KO mice. This antiviral ability of CXCL10 may be through increased recruitment of natural killer (NK) cells to the heart and increased IFN-y expression early post-infection. At days 7 and day 10 post-infection with massive influx of mononuclear cells, the expression of CXCL10 enhanced the infiltration of CXCR3+ cells, CD4+, and CD8+ T cells as well as their associated inflammatory cytokines. However, the augmented accumulation of these immune cells and associated cytokines did not alter the viral clearance and mouse survival. Our data demonstrate for the first time that CXCL1 0 confers the protection to the heart during the early course of CVB3 infection, which may be primarily attributed to NK cell recruitment to the site of infection. This data suggest that CXCL10 is an important player in the orchestrated action of a group of cytokines and chemokines in combating against the CVB3-induced myocarditis in the early phase of infection.

Thesis (Ph. D.)--University of Hong Kong, 2007. / Also available online.

Thesis (M. Med. Sc.)--University of Hong Kong, 2007.

Thesis (Ph. D.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

Thesis (M.A.)--George Mason University, 2008. / Vita: p. 68. Thesis director: Jane M. Flinn. Submitted in partial fulfillment of the requirements for the degree of Master of Arts in Psychology. Title from PDF t.p. (viewed June 30, 2008). Includes bibliographical references (p. 62-67). Also issued in print.

Thesis (M. Phil.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 154-162). Also available in print.