Deciphering the Structures and Mechanisms of Metalloproteins Involved in Human Iron Homeostasis - Project Summary Iron (Fe) is a redox-reactive metal that is essential for several critical physiological functions in the human body. It plays an integral role in oxygen transport, DNA repair and synthesis, mitochondrial energy production, the formation of myelin, the generation and metabolism of neurotransmitters, and the regulation of immune response and defense mechanisms. The body needs to strictly maintain Fe levels as both deficiencies and excess can result in severe health complications. A notable illustration of the consequences of Fe imbalance is ferroptosis, an Fe-dependent form of programmed cell death that has become a focal point in cancer therapy. Furthermore, Fe is acknowledged as a pivotal element in the progression of neurodegenerative diseases. Its accumulation has been consistently observed in the parietal cortex, motor cortex, and hippocampus of brains impacted by such disorders. Significant strides have been made in understanding the overall procedure of human Fe homeostasis, and the principal components involved are relatively well-understood. However, the specific molecular mechanisms governing Fe homeostasis remain obscure. This project will employ a multidisciplinary approach to unravel the structures and mechanisms of metalloproteins integral to human Fe homeostasis from the following perspectives: 1) Deciphering Fe transport through the membrane - Key components of the cellular Fe-regulation system include the only known Fe exporter ferroportin (Fpn) and an extracellular ferroxidase ceruloplasmin (Cp). Perturbation of the regulation is likely the direct cause of Fe accumulation in cells. This work will study the synergistic effects between Fpn and Cp structurally and spectroscopically and clarify the perturbation process; 2) Probing the interactome and transcriptome of iron regulatory proteins (IRPs) via proximity labelling – IRPs are intracellular proteins that detect Fe concentrations and modulate the expression/translation of Fe homeostasis-associated genes post-transcriptionally to maintain cellular iron balance. This project will leverage proximity labeling to discern the interactome and transcriptome of IRP; 3) Exploring the function of amyloid precursor protein (APP) - Amyloid plaques, aggregates of Aβ peptides, are pathological hallmarks of Alzheimer's disease, originating from APP through secretase cleavage. However, the biological role of APP remains enigmatic. Notably, APP mRNA contains an iron response element (IRE) in the 5'-UTR, hinting at a potential role in iron homeostasis as a ferroxidase, though definitive experimental evidence is still pending. This portion of the project will investigate the biological functions of APP in relation to iron homeostasis. In summary, the envisaged research is set to yield insights at the molecular level into Fe homeostasis. This is foundational not just for acquiring an understanding of pivotal physiological functions, but it also paves the way for pioneering therapeutic strategies. Such innovations have the potential to address a myriad of diseases, ranging from cancer to neurodegenerative conditions.
