Hereditary hemochromatosis (HH) is the most common inherited disorder in people of Northern European origin. Iron overload results in damage specific organs leading to cirrhosis of the liver, liver cancer, diabetes, cardiomyopathy, and arthritis. The liver is a major iron-sensing organ in the body. Transferrin is the major iron transport protein in the blood. Mutations in transferrin receptor 2 (TfR2), which is predominantly expressed in hepatocytes and erythrocyte precursors result in HH. Tfr2 forms a complex with HFE, another protein involved in iron homeostasis. Experiments described in this proposal will test the model that the TfR2-HFE complex provides a sensing mechanism to detect iron-loaded Tf and thereby regulates the transcription of hepcidin, a peptide hormone that negatively regulates the efflux of iron out of intestinal cells and macrophages. Alternatively, the TfR2-HFE complex could establish basal levels of hepcidin transcription. Other proteins involved in the complex and in signaling mechanisms will be identified. The long-term goal of this research is to understand how mutations in key proteins disturb the iron balance in the body to reveal the mechanisms by which the body regulates iron-homeostasis.

Public Health Relevance

The uptake of iron into the body is tightly controlled. Too little iron causes anemia and compromised brain development. Complications of too much iron include liver cirrhosis, liver cancer, heart arrythmias, and arthritis. This project seeks to understand how the body senses and regulates iron-uptake.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK072166-10
Application #
9242004
Study Section
Molecular and Cellular Hematology Study Section (MCH)
Program Officer
Roy, Cindy
Project Start
2005-07-01
Project End
2018-03-31
Budget Start
2017-04-01
Budget End
2018-03-31
Support Year
10
Fiscal Year
2017
Total Cost
$353,940
Indirect Cost
$124,109
Name
Oregon Health and Science University
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
096997515
City
Portland
State
OR
Country
United States
Zip Code
97239
Kleven, Mark D; Jue, Shall; Enns, Caroline A (2018) Transferrin Receptors TfR1 and TfR2 Bind Transferrin through Differing Mechanisms. Biochemistry 57:1552-1559
Wahedi, Mastura; Wortham, Aaron M; Kleven, Mark D et al. (2017) Matriptase-2 suppresses hepcidin expression by cleaving multiple components of the hepcidin induction pathway. J Biol Chem 292:18354-18371
Zane, Hannah K; Doh, Julia K; Enns, Caroline A et al. (2017) Versatile Interacting Peptide (VIP) Tags for Labeling Proteins with Bright Chemical Reporters. Chembiochem 18:470-474
Zhao, Ningning; Zhang, An-Sheng; Wortham, Aaron M et al. (2017) The Tumor Suppressor, P53, Decreases the Metal Transporter, ZIP14. Nutrients 9:
Tuschl, Karin; Meyer, Esther; Valdivia, Leonardo E et al. (2016) Mutations in SLC39A14 disrupt manganese homeostasis and cause childhood-onset parkinsonism-dystonia. Nat Commun 7:11601
Zhao, Ningning; Maxson, Julia E; Zhang, Richard H et al. (2016) Neogenin Facilitates the Induction of Hepcidin Expression by Hemojuvelin in the Liver. J Biol Chem 291:12322-35
Zhao, Ningning; Nizzi, Christopher P; Anderson, Sheila A et al. (2015) Low intracellular iron increases the stability of matriptase-2. J Biol Chem 290:4432-46
Chen, Juxing; Enns, Caroline A (2015) CD81 promotes both the degradation of transferrin receptor 2 (TfR2) and the Tfr2-mediated maintenance of hepcidin expression. J Biol Chem 290:7841-50
Worthen, Christal A; Enns, Caroline A (2014) The role of hepatic transferrin receptor 2 in the regulation of iron homeostasis in the body. Front Pharmacol 5:34
Zhao, Ningning; Zhang, An-Sheng; Worthen, Christal et al. (2014) An iron-regulated and glycosylation-dependent proteasomal degradation pathway for the plasma membrane metal transporter ZIP14. Proc Natl Acad Sci U S A 111:9175-80

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