The applicants note that iron is an essential element but that excessive iron accumulation leads to cell and organ dysfunction. Multiple tightly regulated mechanisms exist to meet the cellular need for iron and to remove iron from biological fluids. The applicants plan to continue their approach of using yeast genetics to identify genes involved in iron metabolism. They first plan to study multicopper oxidase-based iron-transport systems. Studies in humans and in yeast have identified the ferroxidase activity of multicopper-based iron-transport systems as responsible for selective high-affinity iron transport across the plasma membrane. The applicants propose to use a combined genetic and biochemical approach to determine the mechanisms of assembly of the active site of multicopper oxidases. Studies in yeast by the applicants have provided evidence that chloride provided by intracellular chloride channels is required to assemble copper on the yeast Fet3p. They now propose to determine how chloride is involved in copper assembly and whether chloride binds to the enzyme. In yeast, the ferroxidase is involved in iron uptake, while in humans ferroxidases are involved in iron export and import. The applicants plan to determine the physical relationship between multicopper oxidases and the direction of iron transport, testing their hypothesis that it is the iron carrier or transporter that determines the direction of iron transport. In addition, the applicants will determine if Hephaestrin, the gene responsible for the phenotype of defective iron transport in the sex-linked anemia (sla) mouse, is a multicopper oxidase. If so, they plan to examine its cellular location and assembly. Iron, as well as other transition metals, is transported across the membrane of the vesicular system (endoplasmic reticulum, Golgi and lysosomes). The function of vesicular metal transport is two-fold: i) to store metals within the vesicular system, thereby removing them from the cytosol; and ii) to assemble metallo-proteins that are either resident or secreted enzymes. Using yeast genetics, the applicants have identified iron and copper-regulated or dependent transport systems in the vesicular apparatus. They now plan to define the function of these transporters, determining whether these transporters are involved in metal storage or metallo-enzyme assembly. They propose genetic approaches to determine if zinc or iron is stored in the vacuole and to identify the responsible transporters. They plan to determine where the lysosomal iron enzyme tartrate-resistant acid phosphatase (TRAP) obtains its iron by expressing this molecule in yeast and, then using selection systems to define iron transporters.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37DK030534-23
Application #
6688334
Study Section
Hematology Subcommittee 2 (HEM)
Program Officer
Badman, David G
Project Start
1982-01-01
Project End
2004-12-31
Budget Start
2004-01-01
Budget End
2004-12-31
Support Year
23
Fiscal Year
2004
Total Cost
$323,441
Indirect Cost
Name
University of Utah
Department
Pathology
Type
Schools of Medicine
DUNS #
009095365
City
Salt Lake City
State
UT
Country
United States
Zip Code
84112
Yien, Yvette Y; Shi, Jiahai; Chen, Caiyong et al. (2018) FAM210B is an erythropoietin target and regulates erythroid heme synthesis by controlling mitochondrial iron import and ferrochelatase activity. J Biol Chem 293:19797-19811
Ward, Diane M; Chen, Opal S; Li, Liangtao et al. (2018) Altered sterol metabolism in budding yeast affects mitochondrial iron-sulfur (Fe-S) cluster synthesis. J Biol Chem 293:10782-10795
Meznarich, Jessica A; Draper, Lauren; Christensen, Robert D et al. (2018) Fetal presentation of congenital dyserythropoietic anemia type 1 with novel compound heterozygous CDAN1 mutations. Blood Cells Mol Dis 71:63-66
Li, Liangtao; Ward, Diane M (2018) Iron toxicity in yeast: transcriptional regulation of the vacuolar iron importer Ccc1. Curr Genet 64:413-416
MacQueen, B C; Christensen, R D; Ward, D M et al. (2017) The iron status at birth of neonates with risk factors for developing iron deficiency: a pilot study. J Perinatol 37:436-440
Yaish, Hassan M; Farrell, Colin P; Christensen, Robert D et al. (2017) Two novel mutations in TMPRSS6 associated with iron-refractory iron deficiency anemia in a mother and child. Blood Cells Mol Dis 65:38-40
Li, Liangtao; Kaplan, Jerry; Ward, Diane M (2017) The glucose sensor Snf1 and the transcription factors Msn2 and Msn4 regulate transcription of the vacuolar iron importer gene CCC1 and iron resistance in yeast. J Biol Chem 292:15577-15586
Li, Liangtao; Miao, Ren; Bertram, Sophie et al. (2012) A role for iron-sulfur clusters in the regulation of transcription factor Yap5-dependent high iron transcriptional responses in yeast. J Biol Chem 287:35709-21
(2012) Retraction notice to: Decoupling ferritin synthesis from free cytosolic iron results in ferritin secretion. Cell Metab 15:927
Lin, Huilan; Li, Liangtao; Jia, Xuan et al. (2011) Genetic and biochemical analysis of high iron toxicity in yeast: iron toxicity is due to the accumulation of cytosolic iron and occurs under both aerobic and anaerobic conditions. J Biol Chem 286:3851-62

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