DIPARTIMENTO DI MEDICINA MOLECOLARE E BIOTECNOLOGIE MEDICHE
The aim of the research
Wilson disease (WD) is an autosomal recessive Copper (Cu) toxicosis associated with Cu accumulation in the liver.
This build-up of Cu causes death of the hepatocytes, the release of Cu, and its accumulation in extra-hepatic tissues, including the central nervous system. When untreated, death can result from liver failure. The gene defective in WD encodes ATP7B, a Cu-transporting protein primarily expressed in the liver. ATP7B changes intracellular localization in response to Cu levels. Under normal Cu levels, ATP7B resides within the trans-Golgi network (TGN), where it pumps Cu into the TGN lumen for incorporation into newly synthesized cuproenzymes, ferroxidase and ceruloplasmin. On increased Cu levels, ATP7B redistributes to the surface of the bile canaliculi of the cells and participate in the physiological Cu excretion into the biliary flow. The most frequent ATP7B mutation, H1069Q (40%-75% in the white population), results in a transporter protein with residual Cu transfer activity but accumulated in the endoplasmic reticulum (ER) and impaired in the Cu-dependent trafficking from the TGN. The mutation alters the structure of the protein resulting in a limited misfolding, and eventually the mutant ATP7B is not exported from the ER to the TGN. Thus, an apparently limited misfolding of ATP7B-H1069Q causes this form of WD. We have recently found that the protein chaperone CRYAB rescues folding, transport to the TGN and response to Cu overload of ATP7B-H1069Q in cultured cells. In this project, we will attempt to reproduce these results with small peptides derived from CRYAB and/or ATP7B and to validate them in in hepatocytes obtained differentiating staminal cells generated from fibroblasts of patients homozygous for the H1069Q mutation. The identified peptides would have a potential strong pharmaceutical interest, being suited to be developed to obtain a druggable molecule to specifically target hepathocytes harboring the H1069Q mutation.