The ABCA1 cholesterol transporter associates with one of two distinct dystrophin-based scaffolds in Schwann cells

Department of Physiology and Biophysics, University of Washington, 1959 NE Pacific St, Box 357290, Seattle WA 98195-7290, USA
Glia (Impact Factor: 6.03). 04/2008; 56(6):611-8. DOI: 10.1002/glia.20636
Source: PubMed


Cytoskeletal scaffolding complexes help organize specialized membrane domains with unique functions on the surface of cells. In this study, we define the scaffolding potential of the Schwann cell dystrophin glycoprotein complex (DGC) by establishing the presence of four syntrophin isoforms, (alpha1, beta1, beta2, and gamma2), and one dystrobrevin isoform, (alpha-dystrobrevin-1), in the abaxonal membrane. Furthermore, we demonstrate the existence of two separate DGCs in Schwann cells that divide the abaxonal membrane into spatially distinct domains, the DRP2/periaxin rich plaques and the Cajal bands that contain Dp116, utrophin, alpha-dystrobrevin-1 and four syntrophin isoforms. Finally, we show that the two different DGCs can scaffold unique accessory molecules in distinct areas of the Schwann cell membrane. Specifically, the cholesterol transporter ABCA1, associates with the Dp116/syntrophin complex in Cajal bands and is excluded from the DRP2/periaxin rich plaques.

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Available from: Stan Froehner, Aug 04, 2015
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    • "o extraction with 1% Triton X - 100 and 0 . 1% SDS , and thus must have been tightly associated with the SC IF cy - toskeleton . In fact , this insoluble subcellular fraction was highly enriched in cytoskeletal and cytoskeleton - associated proteins including ITGb4 , actin , vimentin , and DP116 , which are all exclusively located in Cajal bands ( Albrecht et al . , 2008 ; Amici et al . , 2007 ; Cai et al . , 2007 ; Court et al . , 2011 ) . As our biochemical analysis provided evidence for the existence of a plectin – b - DG complex in sciatic nerve , it can be assumed that in Cajal bands plectin anchors b - DG to the vimentin IF cytoskeleton , thereby rendering the DG complex resistant to detergent ext"
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    • "At both locations it partially co-localized with MAP1B. Confirming previous results, we observed that, in the adult, syntrophin was localized at Cajal bands [44]. Teased fibers of wild-type and MAP1B knockout mice did not display consistent differences in syntrophin localization (Fig. 4). "
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    • "In Schwann cells, dystroglycan forms a complex with Dp116, an isoform of dystrophin that is highly expressed in Schwann cells, (Byers et al., 1993; Saito et al., 1999; Imamura et al., 2000) and utrophin (Fabbrizio et al., 1995), a homologue of dystrophin that, like dystrophin, interacts with the actin cytoskeleton (Saito et al., 1999; Imamura et al., 2000). Additional members of the Schwann cell \DGC" include dystrobrevin (Albrecht et al., 2008), syntrophins (Albrecht et al., 2008), and sarcoglyans (Imamura et al., 2000). However, dystroglycan is the key anchor that is necessary to localize most DGC proteins to the Schwann cell abaxonal plasma membrane (Saito et al., 2003). "
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