Iron is an essential trace element, which serves as a cofactor for enzymes involved in multiple metabolic pathways, including synthesis of DNA, ribosome biogenesis, lipid metabolism, and mitochondrial oxidative phosphorylation. In eukaryotes, iron utilization and storage are tightly controlled. Dysregulation of iron homeostasis has been implicated in the development of many human age-related diseases such as type 2 diabetes, cancer, neurodegeneration and cardiovascular disease. However, how iron homeostasis contributes to organismal aging remains unclear. The overarching goal of this proposal is to study the role of Cth1 and Cth2, two mRNA-binding proteins (RBPs) involved in post-transcriptional regulation of iron homeostasis, in lifespan regulation using yeast model. We have recently shown that deletion of CTH1 and CTH2 leads to significant lifespan extension in yeast. We discovered that in response to iron deficiency Cth1 and Cth2 can directly inhibit the translation of several mRNA targets leading to the remodeling of cellular metabolism. By inhibiting synthesis of their target proteins, Cth1 and Cth2 allow the cell to limit iron utilization for non-essential processes leading to rapid loss of the mitochondrial function. Intriguingly, we found that aging in yeast is also accompanied by increased activity of the iron starvation response. Because age-induced loss of vacuolar acidity and decline of the mitochondrial function have been implicated in driving the aging process, we propose that Cth1 and Cth2 might mediate these effects by inhibiting synthesis of mitochondrial iron-containing proteins. To address this hypothesis, we outline three Specific Aims that utilize a multidisciplinary approach combining next-generation sequencing, metabolomics, high-resolution live-cell microscopy, and biochemical approaches. We propose to: 1) identify genes that are translationally regulated in response to iron deficiency; 2) elucidate the consequences of Cth1 and Cth2 deficiency on metabolism and mitochondrial function; 3) investigate the link between age-induced decline in vacuolar acidity, iron starvation response, and genomic instability. Together, successful completion of these studies will improve our understanding of the molecular mechanisms underlying the regulation of iron homeostasis during aging. Given that fungal genes regulated by iron are evolutionarily conserved among eukaryotes, the data collected from S. cerevisiae will have direct implications for understanding human diseases associated with iron dysregulation.

Iron is an essential metal for normal growth and development and defects in iron homeostasis are linked to human diseases. In eukaryotes, iron homeostasis is regulated at the post-transcriptional level by Cth1 and Cth2 mRNA-binding proteins that repress translation of non-essential iron-containing proteins when iron becomes scarce. The experiments outlined in this proposal aim to identify genes that are translationally regulated in response to iron deficiency, characterize metabolic consequences of iron dysregulation, and investigate the role of iron homeostasis genes in lifespan control.