Functions of Caveolin-1 and Caveolin-3 in muscular dystrophy

Chen, Hung-Chih (2014). Functions of Caveolin-1 and Caveolin-3 in muscular dystrophy. University of Birmingham. Ph.D.

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Abstract

Duchenne muscular dystrophy (DMD) is an X chromosome-linked disease caused by the absence of the sarcolemmal protein dystrophin. The skeletal muscles of DMD have disrupted dystrophin-glycoprotein complex (DGC) and impaired sarcolemma integrity. In this study, we show that clonally derived dystrophin-deficient myoblasts PD50A are differentiation impaired. Coculture with osteoblasts improves the differentiation efficiency of PD50A myoblasts. We also establish that supplementation of combinations of IGF-1/IGF-2, IGF-1/LIF and IGF- 2/LIF in cultured PD50A myoblasts ameliorates the differentiation impairment. We establish that there are elevated levels of Cav-3 and Cav-1 proteins in dystrophin-deficient myoblasts and mdx mouse embryos and that Cav-3 and Cav-1 form heterooligomers in adult skeletal muscles. We show that overexpression of Pax7 suppresses Cav-3 in dystrophin-deficient myoblasts. Using a genetic mouse model (mdx/cav3\(^{+/-}\)) embryo we further establish that immunohistochemistry staining of Cav-1 and Cav-3 coincides with the mouse heart development. The DGC of skeletal muscles plays a role in signal transduction and mechanical response. Here we show that AKT/mTOR and IGF-2/p57\(^{kip2}\) (but not ERK) signalling pathways are upregulated in dystrophin-deficient myoblasts and mouse embryos. Using atomic force microscope we show that Cav-1 helps maintain the stiffness of dystrophindeficient myotubes while Cav-3 help maintain that of dystrophin-deficient myoblasts. This study suggests that Cav-1 and Cav-3 have both compensatory and compromising roles in mdx.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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