Is Menkes syndrome a copper storage disorder?

Decreased Expression of the Slc31a1 Gene and Cytoplasmic Relocalization of Membrane CTR1 Protein in Renal Epithelial Cells: A Potent Protective Mechanism against Copper Nephrotoxicity in a Mouse Model of Menkes Disease

Kidneys play an especial role in copper redistribution in the organism. The epithelial cells of proximal tubules perform the functions of both copper uptake from the primary urine and release to the blood. These cells are equipped on their apical and basal membrane with copper transporters CTR1 and ATP7A. Mosaic mutant mice displaying a functional dysfunction of ATP7A are an established model of Menkes disease. These mice exhibit systemic copper deficiency despite renal copper overload, enhanced by copper therapy, which is indispensable for their life span extension. The aim of this study was to analyze the expression of Slc31a1 and Slc31a2 genes (encoding CTR1/CTR2 proteins) and the cellular localization of the CTR1 protein in suckling, young and adult mosaic mutants. Our results indicate that in the kidney of both intact and copper-injected 14-day-old mutants showing high renal copper content, CTR1 mRNA level is not up-regulated compared to wild-type mice given a copper injection. The expression of the Slc31a1 gene in 45-day-old mice is even reduced compared with intact wild-type animals. In suckling and young copper-injected mutants, the CTR1 protein is relocalized from the apical membrane to the cytoplasm of epithelial cells of proximal tubules, the process which prevents copper transport from the primary urine and, thus, protects cells against copper toxicity.

Chelating principles in Menkes and Wilson diseases: Choosing the right compounds in the right combinations at the right time

Dysregulation of copper homeostasis in humans is primarily found in two genetic diseases of copper transport, Menkes and Wilson diseases, which show symptoms of copper deficiency or overload, respectively. However, both diseases are copper storage disorders despite completely opposite clinical pictures. Clinically, Menkes disease is characterized by copper deficiency secondary to poor loading of copper-requiring enzymes although sufficient body copper. Copper accumulates in non-hepatic tissues, but is deficient in blood, liver, and brain. In contrast, Wilson disease is characterized by symptoms of copper toxicity secondary to accumulation of copper in several organs most notably brain and liver, and a saturated blood copper pool. It is a challenge to correct copper dyshomeostasis in either disease though copper depletion in Menkes disease is most challenging. Both diseases are caused by defective copper export from distinct cells, and we seek to give new angles and guidelines to improve treatment of these two complementary diseases. Therapy of Menkes disease with copper-histidine, thiocarbamate, nitrilotriacetate or lipoic acid is discussed. In Wilson disease combination of a hydrophilic chelator e.g. trientine or dimercaptosuccinate with a brain shuttle e.g. thiomolybdate or lipoate, is discussed. New chelating principles for copper removal or delivery are outlined.

Low-temperature (180 K) crystal structure, electron paramagnetic resonance spectroscopy, and propitious anticonvulsant activities of CuII2(aspirinate)4(DMF)2 and other CuII2(aspirinate)4 chelates

The purpose of this research was to characterize by X-ray crystallography the ternary dimethylformamide (DMF) Cu(II) complex of acetylsalicylic acid (aspirin), in an effort to compare the structure-activity relationships for the anticonvulsant activity of this and other Cu(II)aspirinate chelates. The ternary DMF Cu(II) complex of aspirin was synthesized and crystals grown from a DMF solution were characterized by single crystal X-ray diffraction. This crystalline material was analyzed for anticonvulsant activity in the Maximal Electroshock (MES) Grand Mal and subcutaneous Metrazol (scMET) Petit Mal models of seizure used to detect anticonvulsant activity. The ternary DMF complex was found to be a monomolecular binuclear complex, tetrakis-mu-(acetylsalicylato)bis(dimethylformamido)dicopper(II) [Cu(II)(2)(aspirinate)(4)(DMF)(2)] with the following parameters: monoclinic, space group P2(1)/n, a=12.259 (1), b=10.228 (1), c=16.987 (1) A, beta=92.07 (1) degrees; V=2128.5 (3) A(3); Z=2. The structure was determined at 180 K from 2903 unique reflections (I>1sigma(I)) to the final values of R=0.030 and wR=0.033 using F. This binuclear complex contains four acetylsalicylate bridging ligands which are related to each other in a two by two symmetry center. The four nearest O atoms around each Cu atom form a closely square planar arrangement with the square pyramidal coordination completed by the dimethylformamide oxygen atom occupying an apical position at a distance of 2.154 (1) A. Each Cu atom is displaced towards the DMF ligand by 0.187 A from the plane of the four O atoms. Electron paramagnetic resonance (EPR) spectra of [Cu(II)(2)(aspirinate)(4)(DMF)(2)] crystals show a strong antiferromagnetic coupling of the copper atoms, similar to that observed with other binuclear copper(II)salicylate compounds. Studies used to detect anticonvulsant activity revealed that [Cu(II)(2)(aspirinate)(4)(DMF)(2)] was an effective anticonvulsant in the MES model of seizure but ineffective against scMET-induced seizures. The monomolecular ternary binuclear [Cu(II)(2)(aspirinate)(4)(DMF)(2)] complex is more effective in inhibiting MES-induced seizures than other binuclear or mononuclear Cu(II) chelates of aspirin including: binuclear polymeric [Cu(II)(2)(aspirinate)(4)], [Cu(II)(2)(aspirinate)(4)(H(2)O)], which is anticipated to be less polymeric, and monomolecular ternary [Cu(II)(2)(aspirinate)(4)(DMSO)(2)] and [Cu(II)(aspirinate)(2)(Pyr)(2)]. These and other chelates appear to be more effective in the scMET model of seizure than [Cu(II)(2)(aspirinate)(4)(DMF)(2)]. These structure-activity relationships support the potential efficacy of Cu chelates of aspirin in treating epilepsies.

Copper-metallothionein in the kidney of macular mice: a model for Menkes disease

Menkes disease is an X-linked disorder of copper metabolism. Excess amounts of copper in the kidney of Macular mice, a model for this disease, were found as copper-metallothionein (Cu-MT) from kidney of the mice. Histochemical studies of Cu-MT based on its autofluorescent emission properties showed that the protein was predominant in the proximal convoluted tubule (PCT) cells of the cortex. PCT cells are known to be the primary site of the nephrotoxicity caused by heavy metals. MT mRNA was also observed in the cortex, indicating that the protein was biosynthesized in this region. On the basis of these results, we suggest that biosynthesis and degradation of Cu-MT occur repeatedly in the PCT cells of the cortex. We also compared the histochemical localization of Cu-MT in Macular mice and Long-Evans cinnamon rats, a model for Wilson's disease. The significance of this comparison is discussed.

Menkes disease: recent advances and new aspects

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Menkes disease: recent advances and new insights into copper metabolism

Copper is a trace element necessary for the normal function of several important enzymes but copper homeostasis is still poorly understood. In recent years remarkable progress has been made in this field following the isolation of the gene defective in Menkes disease. Menkes disease and occipital horn syndrome are X-linked recessive disorders, demonstrating the vital importance of copper, which is also highly toxic in excessive amounts. Its destructive effects are reflected in the autosomal recessive Wilson's disease. Progressive neurodegeneration and connective tissue disturbances are the main manifestations of Menkes disease. Although many patients present a severe clinical course, variable forms can be distinguished, and the occipital horn syndrome has been suggested to be a mild allelic form. The Menkes locus is mapped to Xq13.3 and the gene defective in Menkes disease has been isolated by positional cloning. The gene is predicted to encode an energy-dependent copper-binding protein, the first intracellular copper transporter described in eukaryotes. Isolation of the gene and subsequent characterization of the exon-intron organization now enables the establishment of DNA-based diagnostic methods. Furthermore, identification of the Menkes disease gene led to other important findings, such as isolation of its mouse homologue, confirming the allelic relationship between Menkes disease and occipital horn syndrome, and isolation of the defective genes in Wilson's disease and its rat homologue.

Metallothionein expression in placental tissue in Menkes' disease. An immunohistochemical study

Menkes' disease is a recessive X-linked disturbance of copper metabolism, resulting in accumulation of copper in several extra-hepatic tissues including the placenta. Metallothionein (MT) is a low-molecular weight protein with a high affinity for group II metal ions, such as copper. Its synthesis is induced by the presence of the ions. The aim of this study was to investigate the pattern of the MT immunoreactivity in placental tissue obtained from women at-risk of Menkes' disease in order to examine whether the MT occurrence and distribution may reflect the copper content. Placental tissue from six women with a family history of Menkes' disease, from 4 women without a family history, and from 2 hydatiform moles was studied. Positive MT immunostaining was found to be independent of the length of fixation, whether the tissue samples were fixed in 4% buffered formaldehyde or Bouin's fixative. The avidin-biotin-complex (ABC)-technique was used. The copper content was measured by neutron activation analysis (NAA). In all placental tissue sections positive MT immunostaining appeared only in the trophoblast and only in proliferating cells. In placental tissue sections obtained from foetuses and children affected by Menkes' disease an additional MT immunostaining appeared in the Hofbauer cells of the chorionic villi. This staining was associated with an increased content of copper as measured by NAA. We conclude that the immunohistochemical demonstration of MT reflects the copper content and may be useful in pre- and postnatal diagnosis of Menkes' disease.

Menkes disease: an X-linked neurological disorder of the copper metabolism

Menkes disease is an X-linked, recessive disturbance of copper metabolism associated with a progressive clinical course and abnormal hair. The disease is dominated by neurological symptoms combined with connective tissue manifestations, most of which can be explained by the lack of important copper enzymes. Despite excessive accumulation of the metal in various tissues, a functional copper deficiency is evident, probably caused by a defective intracellular copper transport protein of unknown nature. The molecular basis of the copper disturbance has proven difficult to define and will most likely have to await cloning of the gene. The chromosomal region of interest has now been narrowed down to a sub-band on the long arm of the chromosome (Xq13.3), and positional cloning is in progress in a number of laboratories including our own. Identification of the Menkes gene will be of importance for our understanding of the cellular handling of copper and other trace elements.

Muscle cell cultures in Menkes' disease: copper accumulation in myotubes

We present 64Cu uptake studies in cultured muscle cells from a one-year-old patient with Menkes' disease. The cultured muscle cells from the patient showed a five-fold higher 64Cu uptake than control muscle cells. Copper uptake in muscle cells was of the same magnitude as that found in fibroblasts from the patient and also from other Menkes' patients. The copper content of a muscle biopsy from the patient was twice that of a control biopsy. The enhanced uptake is probably copper specific, since zinc uptake was unaltered in both muscle cells and fibroblasts from the patient. Cytochrome c oxidase in the muscle of the patient was reduced to one-third of the value for controls, which is in agreement with the hypothesis that in Menkes' disease copper accumulates in a biologically non-active form. However, in cultured muscle cells and fibroblasts from the patient the cytochrome c oxidase activity was in the normal range, probably because of the relatively large amount of copper already available in the culture medium.

Roles of copper in bone maintenance and healing

This review is intended to focus attention on the importance of essential metallo-element metabolism, particularly copper metabolism, as an important component of normal bone metabolism in maintenance and repair. Literature published since Rademacher's early (1) astute observation that copper supplementation increases the rate of bone healing documents and explains key roles of copper-dependent processes required for maintenance and repair of this tissue. State of the art approaches to treatment of bone diseases including lengthening of bone and repair of fractures, can be improved by paying closer attention to the roles of copper and other essential metallo-elements required for optimal treatment.

Copper-measurement in a muscle-biopsy. A possible method for postmortem diagnosis of Menkes disease

A 5-month-old boy showed severe delay in mental and motor development. His hair was normal. He died at 18 months from bronchopneumonia. Autopsy of the brain revealed meningo-cerebral angiodysplasia with tortuous vessels at the surface of the brain. This raised a suspicion of Menkes disease. A muscle-biopsy, the only remaining tissue from the patient, showed an increased copper-content, thus corroborating the suspicion of Menkes disease. Copper-uptake studies on 2 independent repeatedly tested fibroblast-cultures from the mother gave normal values in 4 and elevated levels in three tests. Such a pattern is often seen in carriers of Menkes disease. Furthermore one of the test values was above the critical limit. Just one value above this limit for females from families with Menkes disease will unequivocally classify a woman as a carrier irregardless of her genetic risk. This is to our knowledge the first time copper-measurements in tissues have been used to establish a post-mortem diagnosis of Menkes disease.

Trace elements in human body fluids and tissues

Published figures for trace element concentrations in body fluids and tissues of apparently healthy subjects are widely divergent. For a considerable time, the apparent disparities were readily ascribed to biological sources of variation such as age, sex, dietary habits, physiological conditions, environmental exposure, geographical circumstances, or similar influences. Growing evidence, however, suggests that this interpretation may be seriously questioned in numerous instances. First, values obtained in reference materials leave no doubt that some previous studies must have been subject to gross analytical inaccuracies. Second, it has now been thoroughly documented that inadequate sample collection and manipulation may drastically distort the intrinsic trace element content of biological matrices. This review scrutinizes data reported by a number of investigators. In an effort to settle the currently flourishing confusion, critically selected reference values are set forth for trace element levels in human blood plasma or serum, packed blood cells, urine, lung, liver, kidney, and skeletal muscle tissue.

The failure of parenteral copper therapy in Menkes Kinky Hair syndrome

In the untreated infant with Menkes Kinky Hair Syndrome, copper concentrations in brain and liver are deficient, while excessive copper accumulates in other tissues. The observed serum ceruloplasmin response after parenteral copper administration is suggestive of an impairment in the incorporation of copper into this metalloprotein. These findings, together with increased urinary copper excretion and the absence of clinical improvement, are compatible with a generalized defect in copper metabolism, transport or storage. The excessive accumulation of copper in many tissues illustrates the potential danger of parenteral copper therapy.

In vitro assessment of the toxicity of metal compounds : IV. Disposition of metals in cells: Interactions with membranes, glutathione, metallothionein, and DNA

This review has focused on several parameters related to the delivery of carcinogenic metal compounds to the cell nucleus as a basis for understanding the intermediates formed between metals and cellular components and the effect of these intermediates on DNA structure and function. Emphasis has been placed on metal interactions at the cellular membrane, including lipid peroxidation, metal interactions with glutathione and their relation to membrane injury, and metal effects on the membrane bound enzyme, Na(+)/K(+) ATPase. Metal binding to metallothionein is also considered, particularly as related to transport and utilization of metal ions and to genetic defects in these processes exemplified in Menkes disease. The ability of cadmium to induce the synthesis of metallothionein more strongly than zinc is also discussed in relation to other toxic and carcinogenic metals. The effects of metal ions on purified DNA and RNA polymerase systems are presented with some of the recent studies using biological ligand-metal complexes. This review points out the importance of considering how metals affect in vitro systems when presented as ionic forms or complexed to relevant biological ligands.

Congenital copper deficiency: copper therapy and dopamine-beta-hydroxylase activity in the mottled (brindled) mouse

The mottled (Mo) mouse is an animal model of the human congenital copper (Cu) deficiency disorder, Menkes' kinky hair syndrome. Intraperitoneal Cu chloride injections have been shown to produce clinical and morphological improvements in this mutant mouse. Cu injections (10 micrograms/g) on postnatal days 7 and 10 are shown to increase endogenous activity of the Cu-dependent enzyme dopamine-beta-hydroxylase in the brains of Mo mice. The present study provides insight into the long-term neurochemical changes resulting from a possible treatment regimen for Menkes' kinky hair syndrome.

Menkes' X-linked disease: prenatal diagnosis and carrier detection

Increased 64Cu uptake into cultured cells is a biochemical marker for mutant cells in Menkes' disease (McKusick 30940). Using this marker selective prenatal diagnosis has been carried out in more than 80 at-risk pregnancies. The 64Cu uptake into cultures from affected male fetuses is however, negatively correlated to the fetal age at amniocentesis. After the 18th week of gestation the risk of false negatives is significant. Using copper uptake into uncloned cultures, a number of obligate and possible carriers showed significantly increased values, but the range of values of obligate carriers considerably overlapped those of the normal controls. All values of normal controls were within a limited range and values above the upper limit in females at risk must, therefore, be caused by mutant cells and establish the carrier diagnosis. However, the extreme skewing of the distribution towards normal values in obligate carriers indicates a strong selection against the mutant cell type and this will hamper the detection of all female carriers in risk families. C-banding heteromorphism of the X-chromosome provides a supplementary carrier detection method. Linkage analysis in five Danish families demonstrated a close physical relationship between the gene for Menkes' disease and the centromere region. By comparative gene mapping (mouse/man) the most likely localization of the gene for Menkes' disease can be suggested to be in band q13 on the long arm of the human X-chromosome. This regional assignment facilitates the choice of appropriate X-specific DNA probes in search for linkage at the DNA level.

Cytochrome c oxidase deficiency in Menkes kinky hair disease

In a 4-year-old male with Menkes kinky hair disease (MKHD) treated with copper supplement therapy, reduced cytochrome a + a3 contents in liver was demonstrated to be 0.029 against 0.128 nmol/mg protein in the control. Cytochrome c oxidase activities in brain, liver, skeletal muscle, and heart were 47, 22, 54 and 59% of the control, respectively. The copper contents in brain and liver were decreased. In spite of increased serum levels of copper and ceruloplasmin, the decreased cytochrome c oxidase activities in various organs were not corrected by copper supplement therapy. A search for a therapeutic method which can normalize copper enzymes in brain and liver, would seem to be a prerequisite for the treatment of MKHD.

The effect of copper supplementation on the concentration of copper in the brain of the brindled mouse

The brindled mutant mouse is a useful model to study Menkes kinky-hair syndrome. The metabolic dysfunctions in both human and rodent are related to insufficient levels of bioavailable copper. Recently, copper supplementation therapy has been able both to prevent the appearance of various neuropathological changes and to prolong the life of these mutant mice. The optimum conditions for supplementation have been shown to be two intraperitoneal injections on postnatal days 7 and 10. The present study reports on the brain copper concentrations before, during and after the intraperitoneal copper therapy. The results demonstrate that postnatal days 7 and 10 correspond to two important epochs in copper homoeostasis. The supplementation therapy seems to provide sufficient bioavailable copper to respond to the needs of the animal at these crucial time points. The results are discussed in terms of their importance to the human copper disorder.

Menkes X-linked disease: prenatal diagnosis of hemizygous males and heterozygous females

Menkes X-linked disease, a copper disturbance syndrome, is detectable in cell cultures. Prenatal findings in two at-risk foetuses suggested that prenatal diagnosis was also feasible. In this study, we report substantial evidence that therapeutic abortion can be limited to hemizygous males. Forty-two at-risk pregnancies from 21 European families and 1 Canadian family were monitored with 64Cu-uptake into cultured amniotic fluid cells. In 10 pregnancies with a male karyotype an affected foetus was predicted on the basis of the copper studies. The pregnancies were terminated and the diagnosis was in each case confirmed by a markedly increased placenta copper content. Fourteen male foetuses were predicted to be unaffected and none of them has developed signs of Menkes disease after birth. In 6 of these cases the diagnosis was checked in the newborn boy by placenta copper measurements, and they all had copper concentrations within normal limits. Eighteen pregnancies with a female karyotype were also studied, 9 females could be identified as carriers on the basis of the tissue culture studies or raised placenta copper values.

Synthesis of a metallothionein-like protein in cultured human skin fibroblasts: relation to abnormal copper distribution in Menkes' disease

A metallothionein-like protein (MTP) is synthesized in normal diploid human skin fibroblasts cultured in Zn- or Cu-supplemented medium. Synthesis of MTP is not detected in cells cultured without metal supplementation of complete tissue-culture medium. Cultured fibroblasts from patients with Menkes' disease accumulate excess Cu which chromatographs both with high-molecular-weight protein(s) and with a Cu-MTP. Under normal culture conditions, the Menkes' MTP incorporates [35S]-cystine, but not appreciable amounts of 65Zn. However, Menkes fibroblasts retain the ability to incorporate 65Zn into MTP in response to Zn supplementation of the medium. The results do not support the idea that Menkes' disease results from a failure of Cu to bind to MTP, but rather that an elevated intracellular Cu concentration in Menkes' disease fibroblasts leads to association of excess Cu with high-molecular-weight protein, stimulating synthesis of a Cu-binding MTP.

Studies of the copper-binding proteins in Menkes and normal cultured skin fibroblast lysates

Proteins of approximately 10,000 daltons (presumably metallothionein) and greater than 75,000 daltons bound 64Cu when this metal was added to fibroblast lysates. Treatment with either 2-mercaptoethanol or the disodium salt of ethylenediamine tetraacetic acid demonstrated that the high molecular weight copper-binding proteins in lysates prepared from both normal and Menkes fibroblasts exhibited a relatively low affinity for copper compared to the 10,000 dalton protein(s). No difference was detected in the affinity of the low molecular weight protein(s) of normal and Menkes fibroblast lysates for copper. The amount of 64Cu bound to the 10,000 dalton protein(s), however, was approximately two to three times greater in lysates prepared from Menkes fibroblasts than from normal fibroblasts. Mixing experiments indicated that the increased binding of 64Cu to the 10,000 dalton protein(s) in lysates of Menkes fibroblasts did not result from the deficiency of a factor that effects the cleavage of copper from this protein(s), from the presence of a soluble inhibitor, or from the lack of an activator. In addition, the use of lysates, rather than whole cells, demonstrated that the observed differences in copper binding between the normal and the Menkes fibroblasts were not caused by an abnormality in the membrane transport of copper in the mutant cells. Thus the findings suggest that the increased accumulation and the reduced efflux of copper previously observed in cultured Menkes fibroblasts result either from an increased amount of the 10,000 dalton copper-binding protein(s) or from an increased capacity of this molecule(s) for copper.

Menkes X linked disease: two clonal cell populations in heterozygotes

The 64Cu incorporation into fibroblast clones obtained from three obligate and three suspected Menkes disease heterozygotes was studied. For each obligate heterozygote, two clonal cell populations were observed, one with a Menkes phenotype and one with a normal phenotype, as predicted by the Lyon hypothesis. The cloning results suggested a heterozygous state in two of the suspected carriers. The theoretical and practical limitation of the cloning method for identification of carriers of X linked diseases are discussed.

Menkes X linked disease: heterozygous phenotype in uncloned fibroblast cultures

The 64Cu incorporation into uncloned fibroblast cultures from 16 Menkes disease mothers and 19 first and second degree female relatives was examined. The mean incorporation for the Menkes disease mothers (36.2 +/- 3.6 SEM) differed significantly from that of 25 normal subjects (21.7 +/- 0.9 SEM) suggesting the presence of a significant proportion of mutant cells. In addition, the results suggested a heterozygous state in a number of the female relatives. Uncloned fibroblast cultures from four Menkes disease heterozygotes showed increasingly abnormal copper uptake values after repeated freezing procedures. Manipulation of tissue cultures may help to identify a number of female carriers.

Menkes syndrome: subcellular distribution of copper determined by an ultrastructural histochemical technique

Several cell types from male infants with Menkes disease accumulate increased amounts of copper. Ultrastructural localization of copper by a histologic staining technique and X-ray microanalysis is established the subcellular distribution of the metal. In Menkes patients, copper was heavily concentrated on the brush border of intestinal epithelium as well as on the plasma membrane of cultured fibroblasts. The transport defect seems to be caused by a decreased transport of copper across plasma membrane, which mainly affects the influx mechanism.