β Scribed by P Ferenci; T C Gilliam; J D Gitlin; S Packman; M L Schilsky; R J Sokol; I Sternlieb
No coin nor oath required. For personal study only.
The opening session, entitled ''Biochemistry and animal In a study of conditionally immortalized liver cell lines models'' was devoted to several aspects of the transport, mederived from LEC rat primary hepatocytes, M. Schilsky, New tabolism, excretion, and toxicity of copper. Various rodent York, NY, showed that copper transport was affected by the models harboring mutations which alter copper metabolism, state of cellular proliferation. Cells treated with a temperaspecifically the Long-Evans Cinnamon (LEC) rat, the Groture-sensitive SV40 T-antigen doubled in about 24 hours at ningen-Yellow (GY) rat, or the toxic milk mouse, came in permissive temperatures, but division and more differentihandy for the study of gene expressions. ated hepatic functions were reduced at temperatures above Dijkstra et al. (Groningen and Delft, The Netherlands) 37ΠC. Yet their copper contents were increased compared studied several parameters of hepatocellular copper transwith controls. Vanadate did not inhibit the cellular uptake port in normal Wistar and mutant Groningen Yellow rats. of radiocopper, indicating the existence of ATP-independent The latter display a defective canalicular adenosine triphoscopper transport. phate (ATP)-dependent glutathione (GSH) conjugate transport caused by the absence of the MOAT transporter (canalic-
STUDIES ON THE LEC RAT AND OTHER MODELS OF ular multispecific organic anion transporter). Vesicles
enriched in canalicular plasma membranes obtained from the livers of Groningen-Yellow rats showed ATP-dependent M. Suzuki (Toho University, Tokyo, Japan) summarized copper transport which conformed to Michaelis-Menten kidata regarding copper metabolism in LEC rats, the best aninetics (Km 8.6 mmol/L and Vmax 6.9 nmol/min/mg protein). A mal model for WD. This mutation is characterized by a defi- comparison of 64 copper uptake by basolateral and canalicular ciency of oxidase active ceruloplasmin in the serum, marked membrane vesicles showed less isotope in the former, indicatincreases in hepatic copper concentration, and reduced biliing that the rat hepatocellular plasma membrane accomoary copper excretion. 2 Steady state levels of ceruloplasmin, dates ATP-dependent copper transporters in both domains. messenger RNA (mRNA) in the livers of LEC rats and in Similar results were observed when measurements of 64 copcontrol Long-Evans Agouti rats were similar, as were the per transport were made using vesicles obtained from human amounts of newly synthesized ceruloplasmin peptide. Belivers. Unfortunately the lack of a satisfactory antibody to cause transcription and translation of ceruloplasmin mRNA the Wilson's disease (WD) gene product (ATP7B) is delaying seem to proceed normally, the data suggest a defect in the the cellular localization, thereby leaving the canalicular incorporation of copper into the apoprotein. membrane, the lysosomes, and the endoplasmic reticulum as Using Northern blot analysis, Yamaguchi et al. (St. Louis, the most likely candidate sites.
MO and Tokyo, Japan) detected an abundance of the WD The same Dutch group found that orally ingested and intragene homologue mRNA in the livers of controls, but not in venously administered copper were processed differently by those of LEC rats, in accord with earlier reports of tissue hepatocytes. Dietary copper proceeded in part via a GSHspecific expression of the WD gene in humans. This finding is consistent with the results of Wu et al. who defined the LEC rat mutation as a deletion of a major portion of the encoding WD gene ATP7B.
π SIMILAR VOLUMES
The aim of this meeting will be the confrontation of the present status of our knowledge about the theoretical and experimental aspects of the problem. Emphasis will be placed on the possibilities of the quantummechanical computations in this field. The collaboration of theoreticians and experimenta