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Several dystrophin-glycoprotein complex members are present in crude surface membranes but they are sodium dodecyl sulphate invisible in KCI-washed microsomes from mdx mouse muscle

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Daval S., Rocher C., Cherel Y., Rumeur E.

Cellular and Molecular Biology Letters

2010

tom 15

nr 1

134-152

The dystrophin-glycoprotein complex (DGC) is a large trans-sarcolemmal complex that provides a linkage between the subsarcolemmal cytoskeleton and the extracellular matrix. In skeletal muscle, it consists of the dystroglycan, sarcoglycan and cytoplasmic complexes, with dystrophin forming the core protein. The DGC has been described as being absent or greatly reduced in dystrophin-deficient muscles, and this lack is considered to be involved in the dystrophic phenotype. Such a decrease in the DGC content was observed in dystrophin-deficient muscle from humans with muscular dystrophy and in mice with X-linked muscular dystrophy (mdx mice). These deficits were observed in total muscle homogenates and in partially membrane-purified muscle fractions, the so-called KCl-washed microsomes. Here, we report that most of the proteins of the DGC are actually present at normal levels in the mdx mouse muscle plasma membrane. The proteins are detected in dystrophic animal muscles when the immunoblot assay is performed with crude surface membrane fractions instead of the usually employed KCl-washed microsomes. We propose that these proteins form SDS-insoluble membrane complexes when dystrophin is absent.

Ultrastructure of diaphragm from dystrophic alpha-sarcoglycan-null mice

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Jakubiec-Puka A., Biral D., Krawczyk K., Betto R.

Acta Biochimica Polonica

2005

tom 52

nr 2

α-Sarcoglycan is a 50 kDa single-pass transmembrane glycoprotein exclusively expressed in striated muscle that, together with β-, γ-, and δ-sarcoglycan, forms a sub-complex at the muscle fibre cell membrane. The sarcoglycans are components of the dystrophin-associated glycoprotein (DAG) complex which forms a mechanical link between the intracellular cytoskeleton and extracellular matrix. The DAG complex function is to protect the muscle membrane from the stress of contractile activity and as a structure for the docking of signalling proteins. Genetic defects of DAG components cause muscular dystrophies. A lack or defects of α-sarcoglycan causes the severe type 2D limb girdle muscular dystrophy. α-Sarcoglycan-null (Sgca-null) mice develop progressive muscular dystrophy similar to the human disorder. This animal model was used in the present work for an ultrastructural study of diaphragm muscle. Diaphragm from Sgca-null mouse presents a clear dystrophic phenotype, with necrosis, regeneration, fibre hypertrophy and splitting, excess of collagen and fatty infiltration. Some abnormalities were also observed, such as centrally located nuclei of abnormal shape, fibres containing inclusion bodies within the contractile structure, and fibres with electron-dense material dispersed over almost the entire cell. Additionally, unusual interstitial cells of uncertain identity were detected within muscle fibres. The abnormal ultrastructure of the diaphragm from Sgca-null mice is discussed.

Ograniczanie wyników

1 Acta Biochimica Polonica

1 Cellular and Molecular Biology Letters

1 Betto R.

1 Biral D.

1 Cherel Y.

1 Daval S.

1 Jakubiec-Puka A.

1 Krawczyk K.

1 Rocher C.

1 Rumeur E.

1 2010

1 2005

Wyniki wyszukiwania

Several dystrophin-glycoprotein complex members are present in crude surface membranes but they are sodium dodecyl sulphate invisible in KCI-washed microsomes from mdx mouse muscle

Ultrastructure of diaphragm from dystrophic alpha-sarcoglycan-null mice