Functional Proteomics Analysis To Discover And Characterize Oxygen-Dependent Cellular Pathways

Abstract

Oxygen and iron homeostasis are a critical components for the maintenance of cellular biology. These metabolites are essential substrates in cellular metabolism, signaling and bioenergetics, thereby inseparably linked to the normal physiology of all metazoans. To adapt to changes in the microenvironment, cells dynamically modulate hypoxia response pathways. Lack of oxygen reduces the post-translational modification proline hydroxylation and altering key transcription factors such as hypoxia-inducible factor 1alpha and prevents its hydroxyproline-dependent degradation. Stabilized HIF proteins activate the expression of hypoxiaresponse genes to sustain growth under hypoxia condition. The studies herein focus on the hypothesis that post-translational modifications of hydroxylation and phosphorylation are a mechanistic link between oxygen and iron availability and the cellular physiological response. This research has focused on the characterization of oxygen and iron-sensing pathways dependent on proline hydroxylation and phosphorylation. Through a system-wide proteomics survey, I identified Brd4 as a novel proline hydroxylation protein substrate in cancer cells. Specific prolyl hydroxylase activity significantly regulates the Brd4-mediated transcriptional function and strongly induced acute myeloid leukemia cell proliferation and apoptosis. This study integrates molecular biology and quantitative proteomics approaches to discover and characterize cellular oxygen and iron-sensing physiology and reveal novel cellular pathways that may have broad impact in cancer biology and metabolic diseases.