MOLECULAR AND PHYSIOLOGICAL ROLES OF VON HIPPEL-LINDAU MUTATION AND HYPOXIA INDUCIBLE FACTORS: FINE-TUNED EXPRESSION EFFECTS ON ANGIOGENESIS AND METABOLISM Public Deposited

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  • March 19, 2019
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  • Arreola, Alexandra
    • Affiliation: School of Medicine, Curriculum in Genetics and Molecular Biology
Abstract
  • Renal cell carcinoma (RCC) accounts for approximately 58,000 new cases and over 13,000 deaths annually in the United States, afflicting men and women at a 2:1 ratio. The majority of the cases are linked to inactivation, either by mutation or loss, of the von Hippel-Lindau (VHL) tumor suppressor gene. Somatic mutations of VHL are associated with the sporadic form of RCC. Germ line inactivation of one VHL allele results in VHL disease, a hereditary cancer syndrome. The dominant histological subtype of RCC is clear cell (ccRCC), accounting for 75% of cases and most commonly associated with VHL disease. VHL protein (pVHL) regulates hypoxia inducible factors (HIFs) in an oxygen-dependent manner. HIFs, in turn, are master regulators of various targets such as those important for cell growth, metabolism, and angiogenesis. Genetically engineered mouse models with conditional VHL-independent HIF over-expression were utilized to generate primary neonatal epithelial kidney cultures that can be genetically manipulated <italic>ex vivo</italic> to stably express non-hydroxylated HIF-1&alpha; or HIF-2&alpha; transgenes. HIF-1&alpha; promoted high levels of both glycolysis and oxidative phosphorylation, with relatively indiscriminate use of nutrients. HIF-2&alpha; cells were capable of promoting glucose metabolism, but were not responsive to glutamine sources. Expression of these genes alters the nutrient resource utilization and energy generation strategy in primary kidney cells. To elucidate the molecular effects of pVHL mutation on angiogenesis, we conducted investigations under <italic>in vivo</italic> and <italic>in vitro</italic> settings. Conditional expression of a mutant pVHL with loss of heterozygosity and conditional deletion of pVHL, in newborn mice, resulted in altered migration and branching of developing retina vasculature. Although still partially functional in the regulation of HIFs, pVHL mutation disrupts the normal vascularization capabilities of endothelial cells to a greater extent than pVHL loss. Moderate perturbations of pVHL action can lead to significant and distinct defects in angiogenesis. This dissertation demonstrates the effects that fine tuned pVHL and HIF expression levels can have on key pathways in normal cellular contexts. It is important to understand the role of these genetic and molecular perturbations in a normal state to ultimately understand what goes awry in the formation and progression of the cancer state.
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  • In Copyright
Advisor
  • Magnuson, Terry
  • Rathmell, W. Kimryn
  • Bautch, Victoria
  • Coleman, William
  • Kim, William
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2014
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  • Chapel Hill, NC
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