Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.16.3.1 (ceruloplasmin)
5,074 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Wilson disease (WND), an autosomal recessive disorder of copper transport with a broad range of genotypic and phenotypic characteristics, results from mutations in the ATP7B gene. ATP7B encodes a copper transporting P-type ATPase involved in the transport of copper into the plasma protein ceruloplasmin, and for excretion of copper from the liver. Defects in ATP7B lead to copper storage in liver, brain and kidney. Mutation analysis was carried out on 300 WND patients of various origins, and new mutations not previously reported were identified: European white (p.L217X, c.918_931, c.1073delG, c.3082_3085delAAGAinsCG, p.V536A, p.S657R, p.A971V, p.T974M, p.Q1004P, p.D1164N, p.E1173G, p.I1230V, p.M1359I, c.2355+4A>G), Sephardic Jewish (p.Q286X), Filipino (p.G1149A), Lebanese (p.R1228T), Japanese (p.D1267V) and Taiwanese (p.A1328T). All but one missense variant have strong evidence for classification as disease-causing mutations. In the patients reported here, we also identified 20 nucleotide substitutions, six not previously reported, which cause silent amino acid changes or intronic changes. Documentation and characterization of all variants is essential for accurate DNA diagnosis in WND because of the wide range of clinical and biochemical variability.
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PMID:New mutations in the Wilson disease gene, ATP7B: implications for molecular testing. 1837 11

Both copper transporting ATPases, ATP7A and ATP7B, are expressed in mammary epithelial cells but their role in copper delivery to milk has not been clarified. We investigated the role of ATP7A in delivery of copper to milk using transgenic mice that over-express human ATP7A. In mammary gland of transgenic mice, human ATP7A protein was 10- to 20-fold higher than in control mice, and was localized to the basolateral membrane of mammary epithelial cells in lactating mice. The copper concentration in the mammary gland of transgenic dams and stomach contents of transgenic pups was significantly reduced compared to non-transgenic mice. The mRNA levels of endogenous Atp7a, Atp7b, and Ctr1 copper transporters in the mammary gland were not altered by the expression of the ATP7A transgene, and the protein levels of Atp7b and ceruloplasmin were similar in transgenic and non-transgenic mice. These data suggest that ATP7A plays a role in removing excess copper from the mammary epithelial cells rather than supplying copper to milk.
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PMID:Copper transport during lactation in transgenic mice expressing the human ATP7A protein. 1851 74

Wilson's disease is an autosomal recessive disorder of copper metabolism. The culprit gene is ATP7B. The worldwide prevalence is about 1 in 30,000, which may vary by population. Higher prevalence rates were reported using more sensitive screening techniques and pilot population screening. Typical presentations include neuropsychiatric and hepatic dysfunction, whereas atypical presentations are protean. Diagnosis relies on a high clinical suspicion, typical neurological symptoms, presence of Kayser-Fleischer rings, and reduced serum ceruloplasmin concentration. The conventional value of < 0.20 g/l is not a universal diagnostic value. Age of the subjects and analytical variations should be considered when interpreting these levels. Patients with inconclusive findings require further investigations such as 24 h urinary free-copper excretion, penicillamine challenge test, liver copper measurement, and detection of gene mutations. Direct molecular diagnosis remains the most decisive tool. Other tests such as non-ceruloplasmin-bound copper are unreliable. Potential pitfalls and limitations of these diagnostic markers are critically reviewed in this paper. The mainstays of therapy are trientine, penicillamine, and/or zinc. Liver transplantation is lifesaving for those with advanced disease. Ceruloplasmin oxidase activity and serum free-copper concentration should be monitored in patients on long-term de-coppering therapy to prevent iatrogenic copper deficiency.
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PMID:Diagnosis of Wilson's disease: a comprehensive review. 1856 52

Wilson disease is an inherited disorder of human copper metabolism, characterized by gradual accumulation of copper in tissues, predominantly liver and brain. The gene defect lies in the Wilson disease protein ATP7B, a copper transporting ATPase highly active in hepatocytes. In the liver, ATP7B is essential for excretion of excess copper into the bile and for copper loading of ceruloplasmin in the Golgi apparatus. The extrahepatic role of ATP7B is not yet completely understood. We analysed the intestinal expression of ATP7B in mice using RT-PCR, Western blot and indirect immunofluorescence. We found abundant expression of ATP7B in stomach and small intestine, but not in colon. Using confocal microscopy we demonstrate a Golgi localization of ATP7B in enterocytes. In response to elevated copper, the Wilson disease protein shows an intracellular trafficking pattern in the intestinal polarized cell line CaCo-2, moving away from the Golgi apparatus to dispersed vesicles. This suggests a role for intestinal ATP7B in sequestration of copper in intracellular vesicles for maintenance of copper homeostasis in the enterocyte. In conclusion, the expression of ATP7B in the small intestine might represent an additional regulatory mechanism to fine-tune intestinal copper absorption.
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PMID:Localization of the Wilson disease protein in murine intestine. 1867 1

Copper is a redox active metal that is essential for biological function. Copper is potentially toxic; thus, its homeostasis is carefully regulated through a system of protein transporters. Copper is taken up across the lumen surface of the small intestinal microvilli as cuprous ion by Ctr1. Cupric ion may also be taken up, but those processes are less well understood. Within the cell, intestinal as well as others, copper is escorted to specific compartments by metallochaperones. One, CCS, donates copper to superoxide dismutase. Another, COX17, delivers copper to additional chaperones within the mitochondria for synthesis of cytochrome c oxidase. A third chaperone, Atox1, delivers copper to the secretory pathway by docking with 2 P-type ATPases. One, ATP7A, is the protein nonfunctional in Menkes disease. This protein is required for cuproenzyme biosynthesis, and in the enterocyte it is required for copper efflux to portal blood. The second, ATP7B, predominantly expressed in liver, is required for copper metallation of ceruloplasmin and biliary copper excretion. Mutations in ATP7B lead to Wilson disease. Additional intracellular hepatic copper-binding proteins COMMD1 (copper metabolism MURR1 domain) and XIAP (X-linked inhibitor of apoptosis protein) may also be required for excretion. Other proteins involved in copper homeostasis may include metallothionein and amyloid precursor protein. Plasma protein transport of copper from the intestine to liver and in systemic circulation probably includes both albumin and alpha2-macroglobulin. Changes in the expression of copper "transporters" may be useful to monitor copper status of humans, provided a suitable cell type can be sampled.
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PMID:Role of copper transporters in copper homeostasis. 1877 2

Stable-isotope studies in human infants and adults have shown that copper homeostasis occurs, but the contribution of the small intestine to this regulation is still not well understood. Copper first needs to be reduced to the cuprous form, most likely by Steap proteins on the apical membrane. Copper is subsequently absorbed by Ctr1 and then transferred in the enterocyte by the chaperone Atox1 to reach ATP7A for export from the cell. The role of ATP7B, shown to be present in the small intestine, is still poorly understood. In situations of high copper exposure, Ctr1 is endocytosed, metallothionein is induced, and ATP7A moves to a more basolateral localization. However, the ontogeny of regulation of copper homeostasis has received little attention. In rat pups, tissue copper and total-body (67)Cu retention decrease throughout postnatal development, whereas liver (67)Cu retention, serum copper, and ceruloplasmin activity increase. Total (67)Cu absorption decreases and intestinal (67)Cu retention increases with increased copper intake. During early infancy (day 10), copper supplementation increases intestinal copper and metallothionein gene expression, and Ctr1 protein levels increase, whereas Atp7A and Atp7B are unaffected. However, during late infancy (day 20), intestinal copper concentrations are unaffected by supplementation, but Ctr1, ATP7A, and Atp7B protein levels are higher than in controls. Thus, maturation of small intestine copper transport occurs through increased abundance and altered localization of Ctr1, Atp7A, and Atp7B. The mechanisms behind this maturation, including both transcriptional and posttranscriptional regulation, require further studies.
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PMID:Intestinal regulation of copper homeostasis: a developmental perspective. 1877 6

Wilson's disease is an infrequent, autosomic recessive pathology, resulting from a loss of function of an adenosine triphosphatase (ATP7B or WDNP), secondarily to a change (more than 60 are described currently), insertion or deletion of the ATP7B gene located on the chromosome 13q14.3-q21.1, which involves a reduction or an absence of the transport of copper in the bile and its accumulation in the body, notably the brain. Wilson's disease is transmitted by an autosomic recessive gene located on the long arm of chromosome 13. The prevalence of the heterozygote is evaluated at 1/90 and the homozygote at 1/30,000. Consanguinity, frequent in the socially geographically isolated populations, increases the prevalence of the disease. The toxic quantities of copper, which accumulate in the liver since early childhood and perhaps before, remain concentrated in the body for years. Hence, cytological and histological modifications can be detected in the biopsies, before the appearance of clinical or biological symptoms of hepatic damage. The accumulation of copper in the liver is due to a defect in the biliary excretion of metal and is accompanied invariably by a deficit in ceruloplasmin; protein synthesized from a transferred ATP7B gene, which causes retention of the copper ions in the liver. The detectable cellular anomalies are of two types: hepatic lesions resulting in acute hepatic insufficiency, acute hepatitis and finally advanced cirrhosis and lesions of the central nervous system responsible for the neurological and psychiatric disorders. In approximately 40-50% of the patients, the first manifestation of Wilson's disease affects the central nervous system. Although copper diffuses in the liver towards the blood and then towards other tissues, it has disastrous consequences only in the brain. It can therefore cause either a progressive neurological disease, or psychiatric disorders. Wilson's disease begins in the form of a hepatic, neurological, or psychiatric disease in at least 90% of the patients. In some rare cases, the first manifestations of the disease can be psychiatric which, according to the literature, accounts for only 10% of the cases. The disease can be revealed by isolated behavioral problems, an irrational syndrome, a schizophrenic syndrome, or a manic-depressive syndrome. Damage to the central nervous system can be more severe, thus, several differential diagnoses have been discussed: a psychotic disorder of late appearance; a depressive state; a mental confusion disorder. The clinical syndrome is complex. Indeed, it is the polymorphism, which dominates in the description of the psychiatric demonstrations of the disease. This can lead to prejudicial diagnostic wandering, particularly since heavy sedative treatment may be required to suppress behavioral problems. Clinically, Wilson's disease generally appears between the age of 10 and 20. It rarely remains masked until after the age of 40. The first manifestations are hepatic (40% of the cases), neurological (35%) or psychiatric (10%). The inaugural disorder can finally take on a haematological, renal, or mixed form in approximately 15% of the cases. We have detailed the principal clinical elements. In approximately 40-50% of the patients, the first manifestation of the disease affects the central nervous system, where it can cause either a progressive neurological disease, or psychiatric disorders. The ophthalmologic disorder is dominated by Kayser-Fleischer's ring, representing a green or bronze colored ring on the periphery of the cornea. It occupies the higher pole of the cornea, then the lower pole, and extends to the whole circumference. It is generally only visible under examination with a slit lamp. It disappears on average within 3-5 years following copper chelating therapy. Kayser-Fleischer's ring has been described other than in Wilson's disease, in exceptional cases of prolonged cholestasis. On haematological level, the hyperhaemolysis is due to the toxicity of the ionic copper, released massively in the plasma by hepatocellular necrosis. The other manifestations can be found in the following organs: renal, osteoarticular, cardiac, endocrine, cutaneous, and in the teguments. Until 1952, the diagnosis was evoked only on clinical symptomatology. It can henceforth be marked unambiguous, even in the absence of any symptom, by the description of a ceruloplasmin plasma concentration of less than 200 ml/l, and of a Kayser-Fleischer's ring. Hepatic copper on sample is constantly increased during the disease (from 3 to 25 micromol/g of dry weight). On the other hand, the absence of a reduction in the plasma ceruloplasmin does not make it possible to exclude the diagnosis. Conversely, a reduction in ceruloplasmin can exist other than in Wilson's disease (nephritic syndrome, malabsorption syndrome, or severe hepatic insufficiency). Kayser-Fleischer's ring is quasiconstant among patients with neuropsychiatric demonstrations (thus, its absence represents a very strong argument against the diagnosis). It can on the other hand be lacking during hepatic forms, and in this case, its absence is not an argument against the diagnosis. Magnetic resonance imaging can reveal abnormal signals of the grey cores. A genetic study is conducted by liaison analysis in the event of a family history of the disease. When it is not treated, Wilson's disease induces lesions of the tissues, the outcome of which is always fatal. Treatment relies on the regulation of copper chelation, which improves the prognosis, and zinc, which captures the copper in a nontoxic form. The severe psychiatric disorders observed during Wilson's disease may require tranquilizers, but care should be taken because of potential neurological or hepatic side effects. Lithium seems an interesting treatment and remains theoretically indicated, taking into account the scarcity of the extrapyramidal symptoms and the hepatic dysfunction among patients at the stage of cirrhosis, since it is not metabolized in the liver. Although rare, it is important to approach Wilson's disease in psychiatry because the psychiatric manifestations can precede the somatic disorders and help to pose the diagnosis. We stress the importance of the early diagnosis of the pathology, the outcome of which is fatal in the absence of specific treatment.
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PMID:[The onset of psychiatric disorders and Wilson's disease]. 1878 84

Wilson disease is a genetic disorder of copper metabolism. Impaired biliary excretion results in a gradual accumulation of copper, which leads to severe disease. The specific gene defect lies in the Wilson disease protein, ATP7B, a copper-transporting ATPase that is highly active in hepatocytes. The two major functions of ATP7B in the liver are the copper loading of ceruloplasmin in the Golgi apparatus, and the excretion of excess copper into the bile. In response to elevated copper levels, ATP7B shows a unique intracellular trafficking pattern that is required for copper excretion from the Golgi apparatus into dispersed vesicles. We analyzed the translocation of ATP7B by both confocal microscopy and RNA interference, testing current models that suggest the involvement of Murr1/COMMD1 and Rab7 in this pathway. We found that although the ATP7B translocation is conserved among nonhepatic cell lines, there is no co-localization with Murr1/COMMD1 or the Rab marker proteins of the endolysosomal system. Consistent with this finding, the translocation of ATP7B was not impaired by the depletion of either Murr1/COMMD1 or Rab7, or by a dominant-negative Rab7 mutant. In conclusion, our data suggest that the translocation of ATP7B takes place independently of Rab7-regulated endosomal traffic events. Murr1/COMMD1 plays a role in a later step of the copper excretion pathway but is not involved in the translocation of the Wilson disease protein.
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PMID:Copper-induced translocation of the Wilson disease protein ATP7B independent of Murr1/COMMD1 and Rab7. 1897

Wilson disease is a genetic disorder characterized by the accumulation of copper in the body by defective biliary copper excretion. Wilson disease gene product (ATP7B) functions in copper incorporation to ceruloplasmin (Cp) and biliary copper excretion. However, copper metabolism in hepatocytes has been still unclear. Niemann-Pick disease type C (NPC) is a lipid storage disorder and the most commonly mutated gene is NPC1 and its gene product NPC1 is a late endosome protein and regulates intracellular vesicle traffic. In the present study, we induced NPC phenotype and examined the localization of ATP7B and secretion of holo-Cp, a copper-binding mature form of Cp. The vesicle traffic was modulated using U18666A, which induces NPC phenotype, and knock down of NPC1 by RNA interference. ATP7B colocalized with the late endosome markers, but not with the trans-Golgi network markers. U18666A and NPC1 knock down decreased holo-Cp secretion to culture medium, but did not affect the secretion of other secretory proteins. Copper accumulated in the cells after the treatment with U18666A. These findings suggest that ATP7B localizes in the late endosomes and that copper in the late endosomes is transported to the secretory compartment via NPC1-dependent pathway and incorporated into apo-Cp to form holo-Cp.
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PMID:Niemann-Pick C1 protein transports copper to the secretory compartment from late endosomes where ATP7B resides. 1900 72

The mechanism of copper (Cu) transport into the brain is unclear. This study evaluated the main species and route of Cu transport into the brain using in situ brain perfusion technique, and assessed the levels of mRNA encoding Cu transporters using real time RT-PCR. Free (64)Cu uptake in rat choroid plexus (CP), where the blood-cerebrospinal fluid barrier (BCB) is primarily located, is about 50 and 1000 times higher than (64)Cu-albumin and (64)Cu-ceruloplasmin uptake, respectively. The unidirectional transport rate constants (K(in)) for Cu in the CP and brain capillaries of the blood-brain barrier (BBB) were 1034 and 319 microl/s/g, respectively, while K(in) in CSF and capillary-depleted parenchyma were much reduced, 0.8 and 112 microl/s/g, respectively. The K(in) in cerebellum was significantly lower than that in hippocampus. The mRNAs encoding Cu transporter-1 (Ctr1) and ATP7A were higher in the CP than those in brain capillaries and parenchyma, whereas ATP7B mRNA was higher in brain capillaries than those in the CP and brain parenchyma. Taken together, these data suggest that the expression of Cu transporters is higher in brain barriers than in brain parenchyma; the Cu transport into the brain is mainly achieved through the BBB as a free Cu ion and the BCB may serve as a main regulatory site of Cu in the CSF.
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PMID:Copper transport to the brain by the blood-brain barrier and blood-CSF barrier. 1901 16


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