A mutation in the ATP7B copper transporter causes reduced dopamine beta-hydroxylase and norepinephrine in mouse adrenal.
The copper-transporting ATPases Atp7A and Atp7B play a major role in controlling intracellular copper levels. In addition, they are believed to deliver copper to the copper-requiring proteins destined for the secretory vesicles. One cuproprotein, dopamine beta-hydroxylase (DBH) functions in the biosynthesis of norepinephrine and epinephrine, neurohormones in endocrine and nervous tissue. To evaluate the consequences of loss of Atp7B on the function of DBH, the level of proteins in adrenal gland were compared between normal mice and mice containing a null mutation in the ATP7B gene. The levels of DBH, as well as another vesicular protein, chromogranin A, are reduced in the ATP7B -/- mice. In addition to the lower level of enzyme, the products of DBH catalytic activity, norepinephrine and epinephrine, are also decreased. Although these changes are a consequence of ATP7B gene function, Atp7B mRNA is not normally expressed in the adrenal gland. Instead, Atp7A mRNA is present. The levels of copper and DBH RNA within adrenals of the ATP7B -/- mice are not different from the wild type. The results of these experiments suggest that copper-requiring enzymes are affected by a loss of ATP7B even in tissue not normally expressing this protein. Therefore the multisystemic effects observed in Wilson disease, the human disorder characterized by mutation in ATP7B, may be a secondary consequence of the major accumulation of copper in liver.
Gerbasi
Vincent
V
Department of Biochemistry and Molecular Biology, Oregon Health Sciences University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
Lutsenko
Svetlana
S
Lewis
Elaine J
EJ
D000251:Adenosine Triphosphatases / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism; D000311:Adrenal Glands / Q000201:enzymology / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D027682:Cation Transport Proteins / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism; D000073840:Copper-Transporting ATPases; D017931:DNA Primers; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism*; D004837:Epinephrine / Q000378:metabolism; D005838:Genotype; D006527:Hepatolenticular Degeneration / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D009638:Norepinephrine / Q000378:metabolism*; D012016:Reference Values; D020133:Reverse Transcriptase Polymerase Chain Reaction
D027682:Cation Transport Proteins; D017931:DNA Primers; D004299:Dopamine beta-Hydroxylase; D000251:Adenosine Triphosphatases; C000612464:ATP7B protein, human; D000073840:Copper-Transporting ATPases; D009638:Norepinephrine; D004837:Epinephrine