MLC1 trafficking and membrane expression in astrocytes: Role of caveolin-1 and phosphorylation

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• 作者：Angela Lanciotti ; Maria Stefania Brignone ; Serena Camerini ; Barbara Serafini ; Gianfranco Macchia ; Carla Raggi ; Paola Molinari ; Marco Crescenzi ; Marco Musumeci ; Massimo Sargiacomo ; Francesca Aloisi ; Ta
• 关键词：Leukoencephalopathy ; Caveolin-1 ; Astrocytes ; MLC ; Dystrophin glycoprotein complex (DGC) ; Glial cells ; PKC ; PKA ; Endocytosis ; Rafts
• 刊名：Neurobiology of Disease
• 出版年：2010
• 出版时间：March 2010
• 年：2010
• 卷：37
• 期：3
• 页码：581-595
• 全文大小：2287 K

文摘

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare congenital leukodystrophy caused by mutations in the MLC1 gene that encodes a membrane protein of unknown function. In the brain MLC1 protein is mainly expressed in astrocyte end-feet, localizes in lipid rafts and associates with the dystrophin glycoprotein complex (DGC). Using pull-down and co-fractionation assays in cultured human and rat astrocytes, we show here that MLC1 intracellular domains pull-down the DGC proteins syntrophin, dystrobrevin, Kir4.1 and caveolin-1, the structural protein of caveolae, thereby supporting a role for DGC and caveolar structures in MLC1 function. By immunostaining and subcellular fractionation of cultured rat or human astrocytes treated with agents modulating caveolin-mediated trafficking, we demonstrate that MLC1 is also expressed in intracellular vesicles and endoplasmic reticulum and undergoes caveolae/raft-mediated endocytosis. Inhibition of endocytosis, cholesterol lowering and protein kinases A- and C-mediated MLC1 phosphorylation favour the expression of membrane-associated MLC1. Because pathological mutations prevent MLC1 membrane expression, the identification of substances regulating MLC1 intracellular trafficking is potentially relevant for the therapy of MLC.