The significance of the Hypoxia-Inducible Factor-3alpha locus; the generation and characterization of a null murine model.

摘要

Over a decade has elapsed since our lab reported a third mammalian Hypoxia-Inducible Factor locus, HIF-3alpha. This locus is shown to encode a member of the basic Helix-Loop-Helix Per-Arnt-Sim superfamily of mammalian transcription factors that drives hypoxia responsive genes. The existing literature is sparse as it relates to this locus, messages, and proteins. Common literature searches return only 38 total articles. Of these 38 articles, only 8 articles concern Hif-3alpha directly. The current mammalian genome assemblies show that three distinct HIF-alpha loci exist in mouse and human. The most well studied HIF subunits include HIF-1alpha, HIF-2alpha and the aryl hydrocarbon receptor nuclear translocator. The goal of this thesis was to provide an experimental framework to aid in assessing the biological significance of the Hypoxia-Inducible Factor-3alpha locus.;Within the first chapter we provide a literature review discussing the recent scientific advances pertaining to the mammalian Per-Arnt-Sim (PAS) superfamily of proteins. In the second chapter, we investigate the molecular regulation of the Hif-3alpha locus. Through our experiments we have found that the locus encodes for multiple transcripts that are inducible under low oxygen conditions. In chapter three we discuss our rationale for generating a conditional allele for Hif-3alpha and we provide the preliminary characterization of our knock-out mouse. Our conclusions within this chapter center on the partial perinatal lethality of the murine null at the Hif-3alpha locus. Using the expression information garnered in chapter two as a guide we detected pathology in the lung and placenta in the mutant model. Further, we define a biological role for Hif-3alpha in the tissues at the oxygen/tissue interface. In the fourth chapter we investigate the role of Hif-3alpha in a hypoxia gene regulation. We used a well studied hypoxia regulated gene, Erythropoietin. We found that Hif-3alpha does not regulate Erythropoietin in the kidney, but we did find it to regulate Neurophilin and Glucose Transporter 4 in the lung.