Localization and functional analyses of the MLC1 protein involved in megalencephalic leukoencephalopathy with subcortical cysts.
Mutations in the MLC1 gene are responsible for one form of the neurological disorder megalencephalic leukoencephalopathy with subcortical cysts (MLC). The disease is a type of vacuolating myelinopathy. The biochemical properties and the function of the MLC1 protein are unknown. To characterize MLC1, we generated polyclonal antibodies. The MLC1 protein was detected in the brain, assembled into higher molecular complexes, as assessed by assembly-dependent trafficking assays. In situ hybridization and immunohistochemistry were used to determine MLC1 localization within the adult mouse brain. MLC1 was expressed in neurons, detected preferentially in particular axonal tracts. This expression pattern correlates with the major phenotype observed in the disease. In addition, it was expressed in some astrocytes, concentrating in Bergmann glia, the astrocyte end-feet membranes adjacent to blood vessels and in astrocyte-astrocyte membrane contact regions. Other neuronal barriers, such as the ependyma and the pia mater, were also positive for MLC1 expression. MLC1 was detected in vivo and in heterologous systems at the plasma membrane. MLC mutations impaired folding, and the defect was corrected in vitro by addition of curcumin, a Ca(2+)-ATPase inhibitor. In summary, this study provides an explanation as to why mutations in MLC1 provoke the disease and points to a possible therapy for some patients.
Teijido
Oscar
O
Department of Biochemistry and Molecular Biology, Josep Samitier 1-5. Barcelona E-08028, Spain.
Martínez
Albert
A
Pusch
Michael
M
Zorzano
Antonio
A
Soriano
Eduardo
E
Del Río
Jose Antonio
JA
Palacín
Manuel
M
Estévez
Raúl
R
D000818:Animals; D001253:Astrocytes / Q000378:metabolism / Q000648:ultrastructure; D001369:Axons / Q000378:metabolism / Q000648:ultrastructure; D015153:Blotting, Western; D002457:Cell Extracts; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D020863:Central Nervous System Cysts / Q000503:physiopathology*; D003474:Curcumin / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004805:Ependyma / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D005434:Flow Cytometry; D006367:HeLa Cells; D020271:Heredodegenerative Disorders, Nervous System / Q000503:physiopathology*; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism*; D051379:Mice; D009154:Mutation; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure; D009865:Oocytes / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010841:Pia Mater / Q000378:metabolism / Q000648:ultrastructure; D014981:Xenopus / Q000378:metabolism
D002457:Cell Extracts; D004791:Enzyme Inhibitors; C425069:MLC1 protein, human; D008565:Membrane Proteins; C498927:Mlc1 protein, mouse; D003474:Curcumin