Altered ATP7A expression and other compensatory responses in a murine model of Menkes disease.

Abstract

Mutations in the copper-transporter ATP7A lead to severe neurodegeneration in the mottled brindled hemizygous male (MoBr/y) mouse and human patients with Menkes disease. Our earlier studies demonstrated cell-type- and -stage-specific changes in ATP7A protein expression during postnatal neurodevelopment. Here we examined copper and cuproenzyme levels in MoBr/y mice to search for compensatory responses. While all MoBr/y neocortical subcellular fractions had decreased copper levels, the greatest decrease (8-fold) was observed in cytosol. Immunostaining for ATP7A revealed decreased levels in MoBr/y hippocampal pyramidal and cerebellar Purkinje neurons. In contrast, an upregulation of ATP7A protein occurred in MoBr/y endothelial cells, perhaps to compensate for a lack of copper in the neuropil. MoBr/y astrocytes and microglia increased their physical association with the blood-brain barrier. No alterations in ATP7A levels were observed in ependymal cells, arguing for specificity in the alteration observed at the blood-brain barrier. The decreased expression of ATP7A protein in MoBr/y Purkinje cells was associated with impaired synaptogenesis and dramatic cytoskeletal dysfunction. Immunoblotting failed to reveal any compensatory increase in levels of ATP7B. While total levels of several cuproenzymes (peptide-amidating monooxygenase, SOD1, and SOD3) were unaltered in the MoBr/y brain, levels of amidated cholecystokinin (CCK8) and amidated pituitary adenylate cyclase-activating polypeptide (PACAP38) were reduced in a tissue-specific fashion. The compensatory changes observed in the neurovascular unit provide insight into the success of copper injections within a defined neurodevelopmental period.

• Authors: Mark J Niciu, Xin-Ming Ma, Rajaâ El Meskini, Joel S Pachter, Richard E Mains, Betty A Eipper
• Journal: Neurobiology of disease (Neurobiol Dis) Vol. 27 Issue 3 Pg. 278-91 (Sep 2007) ISSN: 0969-9961 [Print] United States
• PMID: 17588765 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Atp7a protein, mouse
• Cation Transport Proteins
• Copper
• Adenosine Triphosphatases
• Copper-Transporting ATPases

Topics

• Adenosine Triphosphatases (metabolism)
• Animals
• Blood-Brain Barrier (metabolism)
• Brain (blood supply, metabolism, pathology)
• Cation Transport Proteins (metabolism)
• Copper (metabolism)
• Copper-Transporting ATPases
• Cytosol (metabolism)
• Disease Models, Animal
• Endothelium, Vascular (metabolism)
• Immunoblotting
• Immunohistochemistry
• Menkes Kinky Hair Syndrome (metabolism)
• Mice
• Mice, Neurologic Mutants
• Neurons (metabolism, pathology)