Copper is an essential nutrient. However, despite its importance to human nutrition, little is known about the mechanisms regulating copper homeostasis in mammalian cells. Copper is required by several important enzymes, however, it is also toxic when present in excess concentrations. Thus, copper homeostasis mechanisms must supply sufficient copper to meet cellular needs, while preventing the over-accumulation of this nutrient. Copper uptake in mammalian cells occurs via the membrane-spanning protein, hCtr1. Currently, we have limited knowledge of whether hCtr1-mediated copper uptake is regulated in response to varying copper availability. In contrast, we have a more extensive knowledge of how copper export is regulated in mammalian cells. Two copper ATPases, ATP7A and ATP7B, which are normally located in the trans-Golgi network, are stimulated to relocate to cytoplasmic vesicles or the plasma membrane by elevated copper to facilitate copper efflux from the cytoplasm. In our preliminary studies, we show that the location of the hCtr1 protein is regulated by copper concentrations. Elevated copper stimulates the rapid endocytosis of hCtr1 from the plasma membrane, and this is associated with degradation of the transporter. We hypothesize that this process is likely to be the principle means by which high affinity copper uptake is regulated in mammalian cells. However, the underlying molecular mechanisms and signals involved have not yet been defined. Our long-term goal is to understand the molecular basis for regulating hCtr1-dependent copper uptake. To achieve this overall goal, we propose the following specific aims: 1.To define the intracellular pathway for copper-stimulated endocytosis and degradation of hCtr1. 2. To identify amino acids within hCtr1 important for copper uptake, copper-induced endocytosis and degradation. 3. To assess whether the localization, endocytosis and degradation of hCtr1 is responsive to intracellular copper levels. 4. To determine whether the hCtr1 protein undergoes copper-stimulated endocytosis and degradation in a range of cell types. Our research will contribute greatly to understanding how cells sense and respond to changes in copper availability. The implication of copper in Alzheimer's disease, prion diseases, and several genetic disorders, suggests the study of hCtr1 may have far-reaching implications for the improvement of human health.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Research Project (R01)
Project #
Application #
Study Section
Nutrition Study Section (NTN)
Program Officer
May, Michael K
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Missouri-Columbia
Schools of Arts and Sciences
United States
Zip Code
Ladomersky, Erik; Petris, Michael J (2015) Copper tolerance and virulence in bacteria. Metallomics 7:957-64
White, Carine; Lee, Jaekwon; Kambe, Taiho et al. (2009) A role for the ATP7A copper-transporting ATPase in macrophage bactericidal activity. J Biol Chem 284:33949-56
White, Carine; Kambe, Taiho; Fulcher, Yan G et al. (2009) Copper transport into the secretory pathway is regulated by oxygen in macrophages. J Cell Sci 122:1315-21
Mao, Xiaoqing; Kim, Byung-Eun; Wang, Fudi et al. (2007) A histidine-rich cluster mediates the ubiquitination and degradation of the human zinc transporter, hZIP4, and protects against zinc cytotoxicity. J Biol Chem 282:6992-7000
Guo, Yan; Smith, Kathryn; Lee, Jaekwon et al. (2004) Identification of methionine-rich clusters that regulate copper-stimulated endocytosis of the human Ctr1 copper transporter. J Biol Chem 279:17428-33
Guo, Yan; Smith, Kathryn; Petris, Michael J (2004) Cisplatin stabilizes a multimeric complex of the human Ctr1 copper transporter: requirement for the extracellular methionine-rich clusters. J Biol Chem 279:46393-9