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Show SPRING 2013 Kimberly Nguyen Susana Tovar Robert McKnight 174 THE EFFECTS OF MECHANICAL VENTILATION ON INSULIN-LIKE GROWTH FACTOR 1 (IGF-1) PROMOTER ACTIVITY Kimberly Nguyen, Susana Tovar (Robert McKnight) Department of Pediatrics University of Utah One-third of all premature infants that require assisted breathing through mechanical ventilation (MV) develop chronic lung disease (CLD). Mechanically-ventilated lungs are often poorly developed among preterm infants. Lung development is controlled by genetic and epigenetic factors. In the case of MV-induced CLD, there is no known genetic defect. Instead, it is thought that the primary cause is due to disruption in epigenetic regulation of genes. O ne gene critical to lung development is the heavily epigenetically-regulated insulin-like growth factor-1 (IGF-1) gene. For example, it uses multiple promoters, and each promoter generates different m R N A by starting at different sites-transcription start sites (TSS). It has been found that premature infants under artificial ventilation show an overexpression of IGF-1. Such findings indicate that the environment can affect the epigenetic regulation of the IGF-1 gene. Therefore w e wanted to determine whether M V was disrupting the epigenetic regulation of the IGF-1 gene. To investigate this question further, we used a mechanically-ventilated preterm lamb model. In this model, the preterm lamb was treated similarly as a human preterm infant would be. The number of TSS found in the model was greater under M V in comparison to the controls of the study, and it was observed that the different TSSs indicated different usages. Therefore, two different promoter sequences were cloned out to determine if their ability to promote IGF-1 expression would be different. Each promoter was linked to the "firefly" luciferase enzyme and then placed into green monkey kidney cells. The promoter strength was determined by measuring luciferase enzyme activity. However, no difference could be found between the two promoters. |