Rett syndrome is a neurological condition that affects primarily girls. Approximately 40% of Rett syndrome cases arise from nonsense mutations. Several studies have shown that certain aminoglycosides can suppress some types of nonsense mutations in a context dependent manner, and allow the generation of a full length protein. It remains mostly unclear whether different nonsense mutations of MECP2 will be responsive to aminoglycoside treatment. In this study I tested whether some nonsense mutations of MECP2 seen clinically in Rett syndrome girls can be partially suppressed by aminoglycoside administration. My results show that aminoglycosides allow different mutant forms of MECP2 to be overcome in transiently transfected HEK-293 cells, but with differing levels of efficiency. Furthermore, I also show that aminoglycosides increased the prevalence of full length MeCP2 protein in a lymphocyte cell line derived from a Rett girl with R255X mutation. This study establishes the “proof of principle” that some nonsense mutations causing Rett syndrome can be suppressed by drμg treatment.

Mindin (Spondin 2) is a highly conserved extracellular matrix protein of the Mindin-F-spondin family and a regulator of host innate immunity. Despite its expression in the heart, its role in cardiac stress response is unknown. The objective of this study was to determine the role of mindin following myocardial infarction (MI). C57/BL6 wild-type (mindin+/+) or mindin knockout (mindin-/-) mice were randomized to permanent left anterior descending (LAD) coronary artery ligation or sham operation. Mindin expression level increased maximally on day 7 post MI, but returned to baseline by day 28. Mindin-/- mice showed reduced mortality, rupture rate, cardiac MMP-9/-2 activities, NF-kB activation, cytokines and macrophage recruitment. We concluded that mindin is a significant contributor to mortality and acute adverse remodeling post MI, partly through its unique attributes of innate immune regulator and inhibitor of angiogenesis. Mindin may function as a potential biomarker or therapeutic target post MI.

Tumour suppressor 73 (Trp73) gene shares structural and functional homology with p53. Trp73 encodes multiple isoforms with opposing effects. The TAp73 isoform is a transcription factor and is classified as a tumour suppressor where as the DNp73 isoform is a putative oncogene. Imbalance of the two opposing isoforms has been reported in human malignancies including ovarian cancer. TAp73 deficiency results in a dramatic increase in the DNp73 isoform, mimicking the altered isoform balance observed in human ovarian cancer. The effects of TAp73 deficiency in mouse OSE cells were assessed. TAp73 deficiency is not sufficient to induce ovarian cancer in mice. However, TAp73 deficiency compromises cellular proliferation in OSE cell lines. Furthermore, expression of p73 isoforms and epithelial markers is altered in TAp73 deficient cell line. Further studies are needed to determine if TAp73 deficiency in conjunction with other molecular alterations can mediate transformation of OSE cells leading to ovarian cancer.

Type 2 diabetes is characterized by insulin resistance and pancreatic β-cell failure. Insulin resistance leads to increased insulin demand, which can lead to increased proinsulin misfolding in the endoplasmic reticulum (ER). The accumulation of the misfolded proteins in the ER can cause ER stress, which can lead to pancreatic β-cell dysfunction. Cells respond to ER stress by the unfolded protein response (UPR), which increases protein folding capacity and causes degradation of misfolded proteins. Using a pancreatic β-cell model of induced misfolded proinsulin expression (proinsulin-C96Y tagged with GFP) we discovered that one of the most highly induced genes was stromal cell-derived factor 2 like 1 (SDF2L1). SDF2L1 is an ER localized soluble protein with an as yet unknown function. In this thesis I examined the potential role of SDF2L1 in pancreatic β-cells in ER stress conditions.

Exposure to hyperoxia has been shown to have detrimental effects on newborn hemodynamics and antioxidant activities in males. These effects are unknown in the newborn female, despite clinical data showing that in children undergoing surgery females have poorer outcomes. This thesis explored whether newborn females respond worse than males to hyperoxia, specifically in hemodynamics and antioxidant activity. Hemodynamic results showed continual decreases in DBP and MAP, increases in HR, decreases in SBP, and increases in PP, which were experienced earlier and to a greater degree in the female. Additionally, reduced antioxidant activity seen in newborns was worse in females in both the heart and skeletal muscle. These results suggest that in response to hyperoxia, newborn females are at a hemodynamic disadvantage when compared to males, which may be a contributing factor for why female children are at a higher risk during surgery or medical management involving hyperoxia.

Short-chain fatty acids (SCFAs) are anaerobic bacterial metabolites. Cystic fibrosis (CF) lung disease is a condition caused by mutations in the cystic fibrosis transmembrane conductange regulator (CFTR) gene and is characterized by persistent lung inflammation and bacterial colonization. We measured the concentrations of SCFAs in sputum of patients with CF and tested the effect of these compounds on bacterial growth. Furthermore we found that SCFAs can influence the inflammatory protein expression and cytokine release in airway epithelial cells. SCFAs differentially alter cytokine release in CF bronchial epithelial cells (CFBE) compared to CFBE expressing wild-type CFTR. We also studied the effect of SCFAs in an acute lung injury model in BALB/cJ mice and found that intratracheally administered SCFAs can affect the inflammatory environment of the airways in vivo. We conclude that SCFAs may be important in the airways and that further investigation is warranted to understand their effects on inflammation and infection.

Blood CORT is commonly used to assess stress in rodents, but sampling can trigger a rapid stress response. This study aims to identify whether faecal CORT metabolites (FCM) can reflect changes in CORT induced by 7-day food restriction (FR) and an ACTH challenge. Blood and 24hr faecal samples were collected at baseline and Day 7 for control (n=8) and FR (n=10) rats. On Day 8, after a baseline blood sample, an ACTH injection was administered and followed by blood and fecal sampling. Results showed increased serum CORT and FCM in response to FR. Increased adrenal sensitivity with FR was illustrated by a greater increase in serum CORT compared to control in response to ACTH. Lastly, although it appeared that ACTH induced an increase in FCM in FR and control, only the latter reached statistical significance. Thus FCM might be better suited for quantifying chronic rather than acute changes in CORT.

Gonadotropin-Releasing Hormone (GnRH), the master regulator of the reproductive axis, is hypothesized to play an essential role in directly sensing changes in energy levels to maintain fertility. There are a number of GnRH cell lines that have been utilized to study reproductive function; however these have been embryonic in origin and clonally derived. To investigate the cellular mechanisms underlying glucose responsiveness in GnRH neurons, we generated a novel GnRH cell line through immortalization, and fluorescent activated cell (FAC)-sorting of hypothalamic primary culture taken from a GnRH-GFP transgenic mouse. The mHypoA-GnRH/GFP neurons express a complement of markers of fully differentiated GnRH neurons. Glucose induces neuronal activation of mHypoA-GnRH/GFP neurons and glucose metabolism initiates an AMP-Protein Kinase (AMPK)-dependent mechanism to exert transcriptional and secretory control of GnRH. These findings support the use of this novel GnRH cell model for defining components involved in cellular and molecular action of glucose in GnRH neurons.

Rett syndrome is a neurological condition that affects primarily girls. Approximately 40% of Rett syndrome cases arise from nonsense mutations. Several studies have shown that certain aminoglycosides can suppress some types of nonsense mutations in a context dependent manner, and allow the generation of a full length protein. It remains mostly unclear whether different nonsense mutations of MECP2 will be responsive to aminoglycoside treatment. In this study I tested whether some nonsense mutations of MECP2 seen clinically in Rett syndrome girls can be partially suppressed by aminoglycoside administration. My results show that aminoglycosides allow different mutant forms of MECP2 to be overcome in transiently transfected HEK-293 cells, but with differing levels of efficiency. Furthermore, I also show that aminoglycosides increased the prevalence of full length MeCP2 protein in a lymphocyte cell line derived from a Rett girl with R255X mutation. This study establishes the “proof of principle” that some nonsense mutations causing Rett syndrome can be suppressed by drμg treatment.

Mindin (Spondin 2) is a highly conserved extracellular matrix protein of the Mindin-F-spondin family and a regulator of host innate immunity. Despite its expression in the heart, its role in cardiac stress response is unknown. The objective of this study was to determine the role of mindin following myocardial infarction (MI). C57/BL6 wild-type (mindin+/+) or mindin knockout (mindin-/-) mice were randomized to permanent left anterior descending (LAD) coronary artery ligation or sham operation. Mindin expression level increased maximally on day 7 post MI, but returned to baseline by day 28. Mindin-/- mice showed reduced mortality, rupture rate, cardiac MMP-9/-2 activities, NF-kB activation, cytokines and macrophage recruitment. We concluded that mindin is a significant contributor to mortality and acute adverse remodeling post MI, partly through its unique attributes of innate immune regulator and inhibitor of angiogenesis. Mindin may function as a potential biomarker or therapeutic target post MI.