Copper is an essential nutrient required in many cellular processes. It is a co-factor in anti-oxidant defense by superoxide dismutase, in neurotransmitter biosynthesis, in collagen production and in many other important biotransformations. Adequate copper is essential for human health, but elevated levels of copper are toxic. Sophisticated mechanisms have evolved to regulate the absorbtion and excretion of dietary copper and provide the important homeostasis of cellular and organismal copper. The major protein responsible for the high affinity uptake of copper into human cells is hCTRl The protein consists of 190 aminoacid residues and the PI of this application has, during the previous funding period characterized the membrane topology of hCTRl and shown that it is composed of three transmembrane segments separating an extracellular amino-terminus and an intracellular carboxy-terminus. Structure-function studies utilizing copper transport measurements and mutagenesis in insect cells suggested a pore-like mechanism for transport that has found support in the structural studies from the lab of another member of this program (Dr V Linger), these studies will be extended in mammalian cells. The present application extends a series of findings made in the Pi's lab during the previous funding period, and utilizes methods developed to study hCTRl in mammalian cells and epithelia. The PI has demonstrated that hCTRl is post-translationally modified with Olinked (as well as the more familiar N-linked) sugars. The O-linked modification protects hCTRl against a specific cellular proteolytic cleavage. The mechanisms involved in this specific cleavage and their role in the cell physiology of hCTRl will be characterized. In addition, it has been demonstrated that endogenous hCTRl is present at the basolateral surface of intestinal and renal epithelial cells and intestinal tissue. Thus an hCTR1-independent process is involved in the first step of copper acquisition from the diet. The proposed studies will identify and characterize this pathway as well as investigate the regulation of copper uptake in a number of cells. The roles of a second copper transporter, hCTR2, will also be explored. The experiments will provide essential information about how cells acquire their necessary copper.

Public Health Relevance

The absorption of appropriate amounts of dietary copper is essential for normal growth and brain function, while too much is toxic. Copper has been shown to play a role in several important neurodegenerative and genetic diseases. This work will shed light on how the body takes up copper and how it regulates the levels.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Program Projects (P01)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-CB-L)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Johns Hopkins University
United States
Zip Code
Malinouski, Mikalai; Hasan, Nesrin M; Zhang, Yan et al. (2014) Genome-wide RNAi ionomics screen reveals new genes and regulation of human trace element metabolism. Nat Commun 5:3301
Braiterman, Lelita T; Murthy, Amrutha; Jayakanthan, Samuel et al. (2014) Distinct phenotype of a Wilson disease mutation reveals a novel trafficking determinant in the copper transporter ATP7B. Proc Natl Acad Sci U S A 111:E1364-73
Nyasae, Lydia K; Schell, Michael J; Hubbard, Ann L (2014) Copper directs ATP7B to the apical domain of hepatic cells via basolateral endosomes. Traffic 15:1344-65
Lutsenko, Svetlana (2014) Modifying factors and phenotypic diversity in Wilson's disease. Ann N Y Acad Sci 1315:56-63
Maryon, Edward B; Molloy, Shannon A; Kaplan, Jack H (2013) Cellular glutathione plays a key role in copper uptake mediated by human copper transporter 1. Am J Physiol Cell Physiol 304:C768-79
Maryon, Edward B; Molloy, Shannon A; Ivy, Kristin et al. (2013) Rate and regulation of copper transport by human copper transporter 1 (hCTR1). J Biol Chem 288:18035-46
Ivy, Kristin D; Kaplan, Jack H (2013) A re-evaluation of the role of hCTR1, the human high-affinity copper transporter, in platinum-drug entry into human cells. Mol Pharmacol 83:1237-46
Flores, Adrian G; Unger, Vinzenz M (2013) Atox1 contains positive residues that mediate membrane association and aid subsequent copper loading. J Membr Biol 246:903-13
Barry, Amanda N; Otoikhian, Adenike; Bhatt, Sujata et al. (2011) The lumenal loop Met672-Pro707 of copper-transporting ATPase ATP7A binds metals and facilitates copper release from the intramembrane sites. J Biol Chem 286:26585-94
Braiterman, L; Nyasae, L; Leves, F et al. (2011) Critical roles for the COOH terminus of the Cu-ATPase ATP7B in protein stability, trans-Golgi network retention, copper sensing, and retrograde trafficking. Am J Physiol Gastrointest Liver Physiol 301:G69-81

Showing the most recent 10 out of 48 publications