Projects currently pursued in the laboratory of Dr. Svetlana Lutsenko:

1. Structure and Function of Wilson's disease Protein, a copper-transporting P₁-type ATPase ATP7B
   Wilson's disease protein (WNDP) is a large membrane protein that utilizes the energy of ATP-hydrolysis to transport copper from the cytosol through various cell membranes. WNDP belongs to the recently described subfamily of P₁-type ATPases. The structural organization of the P₁-type ATPases is distinct (Lutsenko and Kaplan , 1995) and the functional properties of these transporters are still poorly understood. In order to understand how the Wilson's disease protein works, and how mutations in this protein alter its function, we express and characterize WNDP and its important functional domains. We analyze the structural properties of these proteins using a variety of biochemical and biophysical techniques, their ability to bind physiological ligands, such as copper and ATP, and their role in ligand-dependent protein-protein interactions.

2. Regulation of copper homeostasis through protein trafficking and kinase-mediated phosphorylation
   Copper plays an important role in regulation of its own metabolism. The intracellular concentration of Wilson’s disease protein is copper-dependent. In low copper, WNDP is located in the trans-Golgi network, but when copper is elevated, WNDP traffics to vesicular compartment and then most likely to the plasma membrane. We found that there is a correlation between intracellular localization of WNDP and the level of its phosphorylation by a kinase. To investigate the mechanism of copper-dependent phosphorylation and trafficking we are identifying the phosphorylation sites in WNDP and characterizing the kinase that is involved in WNDP phosphorylation.

3. Metallochaperone Atox1, copper transfer mechanism
   Another important direction in the laboratory is identification and characterization of proteins that regulate WNDP function and membrane targeting. In a cell, the Wilson's disease protein receives copper from a small cytosolic protein, copper-chaperone Atox1. Our current goal is to understand how the chaperone and copper-transporting ATPase find each other in a cell, how copper is transferred from the chaperone to the Wilson's disease protein, and what are the specific molecular consequences of copper transfer.

4. Understanding Wilson’s disease pathology
   Wilson's disease is caused by mutations in copper-transporting ATPase ATP7B. Elevated copper gradually induces a large spectrum of severe abnormalities, including liver fibrosis, neuronal degeneration, and behavioral changes. At present, the molecular events that accompany copper accumulation in tissues are poorly understood. The goal of our studies is to dissect the biochemical basis of pathological changes associated with abnormal accumulation of copper in human cells. To understand these events we are currently identifying the major targets of inborn copper toxicity using the recently developed ATP7B knock-out mouse (an animal model for Wilson's disease (Buiakova et al., 1999) [PDF]), oligonucleotide microarray technology and real-time PCR.

5. Copper homeostasis in the brain (Coming soon)
   Copper binds specifically to a number of proteins with important functions in the brain, including enzymes involved in neurotransmitter biosynthesis, prion protein, and amyloid precursor protein. Defects in copper transport in the brain result in neurological abnormalities and neurodegeneration. To understand how levels of copper are regulated in the brain we study distribution of human copper transporters using fluorescent in situ hybridization with single cell resolution.