Levels of plasma ceruloplasmin protein are markedly lower following dietary copper deficiency in rodents.
Ceruloplasmin (Cp) is a multicopper oxidase and the most abundant copper binding protein in vertebrate plasma. Loss of function mutations in humans or experimental deletion in mice result in iron overload consistent with a putative ferroxidase function. Prior work suggested plasma may contain multiple ferroxidases. Studies were conducted in Holtzman rats (Rattusnorvegicus), albino mice (Mus musculus), Cp-/- mice, and adult humans (Homo sapiens) to investigate the copper-iron interaction. Dietary copper-deficient (CuD) rats and mice were produced using a modified AIN-76A diet. Results confirmed that o-dianisidine is a better substrate than paraphenylene diamine (PPD) for assessing diamine oxidase activity of Cp. Plasma from CuD rat dams and pups, and CuD and Cp-/- mice contained no detectable Cp diamine oxidase activity. Importantly, no ferroxidase activity was detectable for CuD rats, mice, or Cp-/- mice compared to robust activity for copper-adequate (CuA) rodent controls using western membrane assay. Immunoblot protocols detected major reductions (60-90%) in Cp protein in plasma of CuD rodents but no alteration in liver mRNA levels by qRT-PCR. Data are consistent with apo-Cp being less stable than holo-Cp. Further research is needed to explain normal plasma iron in CuD mice. Reduction in Cp is a sensitive biomarker for copper deficiency.
Broderius
Margaret
M
Department of Biochemistry and Molecular Biology, University of Minnesota Medical School Duluth, USA.
Mostad
Elise
E
Wendroth
Krista
K
Prohaska
Joseph R
JR
D006631:Amine Oxidase (Copper-Containing) / Q000097:blood; D000821:Animal Feed / Q000592:standards; D000818:Animals; D002570:Ceruloplasmin / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D003300:Copper / Q000172:deficiency* / Q000378:metabolism; D003677:Deficiency Diseases / Q000097:blood*; D004195:Disease Models, Animal; D005260:Female; D005526:Food, Formulated; D015870:Gene Expression; D006801:Humans; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013045:Species Specificity
D012333:RNA, Messenger; D003300:Copper; D002570:Ceruloplasmin; D006631:Amine Oxidase (Copper-Containing)