Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0022716 (Menkes)
 1,057 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Menkes disease gene encodes a P-type transmembrane ATPase (ATP7A) that translocates cytosolic copper ions across intracellular membranes of compartments along the secretory pathway. ATP7A moves from the trans-Golgi network (TGN) to the cell surface in response to exogenously added copper ions and recycles back to the TGN upon copper removal. The protein contains a C-terminal di-leucine motif necessary for internalization from the cell surface. In this study we show that ATP7A is internalized by a novel pathway that is independent of clathrin-mediated endocytosis. Expression of dominant-negative mutants of the dynamin-I, dynamin-II and Eps15 proteins that block clathrin-dependent endocytosis of the transferrin receptor do not inhibit internalization of endogenous ATP7A, or an ATP7A reporter molecule (CD8-MCF1). Similarly, inhibitors of caveolae-mediated uptake do not affect ATP7A internalization whilst preventing uptake of PODIPY-ganglioside GM(1), a caveolae marker. In contrast, expression of a constitutively active mutant of the Rac1 GTPase inhibits plasma membrane internalization of both the ATP7A and transferrin receptor transmembrane proteins. These findings define a novel route required for ATP7A internalization and delivery to endosomes.
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PMID:The Menkes disease ATPase (ATP7A) is internalized via a Rac1-regulated, clathrin- and caveolae-independent pathway. 1281 80

The human X-linked recessive copper deficiency disorder, Menkes disease, is caused by mutations in the ATP7A (MNK) gene, which encodes a transmembrane copper-transporting P-type ATPase (MNK). The MNK protein is localised to the Golgi apparatus and relocalises to the plasma membrane when copper levels are elevated. Previous studies have identified a C-terminal di-leucine endocytic motif (L1487L1488) in MNK, thought to direct it into the clathrin-mediated endocytic pathway. To determine whether MNK is internalised via clathrin-dependent endocytosis, this pathway was blocked in MNK-overexpressing HeLa cells by the transient expression of dominant negative dynamin and Eps15 mutants. MNK internalisation was not inhibited in such cells. MNK internalisation was inhibited in cells treated with hypertonic sucrose that not only blocked clathrin-mediated endocytosis but also fluid-phase endocytosis. These studies, together with earlier studies on the requirement for L1487L1488, suggest that MNK can utilise both clathrin-dependent and clathrin-independent endocytosis in HeLa cells.
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PMID:Studies on endocytic mechanisms of the Menkes copper-translocating P-type ATPase (ATP7A; MNK). Endocytosis of the Menkes protein. 1497 65

Extracellular and intracellular copper and zinc regulate synaptic activity and plasticity, which may impact brain functionality and human behavior. We have found that a metal coordinating molecule, Neocuproine, transiently increases free intracellular copper and zinc levels (i.e., min) in hippocampal neurons as monitored by Phen Green and FluoZin-3 fluorescence, respectively. The changes in free intracellular zinc induced by Neocuproine were abolished by the presence of a non-permeant copper chelator, Bathocuproine (BC), indicating that copper influx is needed for the action of Neocuproine on intracellular Zn levels. Moreover, Neocuproine decreased the mRNA levels of Synapsin and Dynamin, and did not affect the expression of Bassoon, tubulin or superoxide dismutase (SOD). Western blot analysis showed that protein levels of synapsin and dynamin were also down regulated in the presence of Neocuproine and that these changes were accompanied by a decrease in calcium transients and neuronal activity. Furthermore, Neocuproine decreased the number of active neurons, effect that was blocked by the presence of BC, indicating that copper influx is needed for the action of Neocuproine. We finally show that Neocuproine blocks the epileptiform-like activity induced by bicuculline in hippocampal neurons. Collectively, our data indicates that presynaptic protein configuration and function of primary hippocampal neurons is sensitive to transient changes in transition metal homeostasis. Therefore, small molecules able to coordinate transition metals and penetrate the blood-brain barrier might modify neurotransmission at the Central Nervous System (CNS). This might be useful to establish therapeutic approaches to control the neuronal hyperexcitabiltity observed in brain conditions that are associated to copper dyshomeotasis such as Alzheimer's and Menkes diseases. Our work also opens a new avenue to find novel and effective antiepilepsy drugs based in metal coordinating molecules.
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PMID:Copper-uptake is critical for the down regulation of synapsin and dynamin induced by neocuproine: modulation of synaptic activity in hippocampal neurons. 2552 Jun 55