Targeting latent TGFβ release in muscular dystrophy

Area of Science:

• Biochemistry
• Molecular Biology
• Genetics

Background:

• Latent transforming growth factor-beta binding proteins (LTBPs) sequester inactive TGFβ in the extracellular matrix.
• LTBP hinge region polymorphisms exacerbate muscular dystrophy symptoms in mice by increasing proteolytic susceptibility and TGFβ release.

Purpose of the Study:

• To investigate the proteolytic susceptibility of human LTBP4 hinge region.
• To evaluate the impact of human LTBP4 expression on muscular dystrophy in a mouse model.

Main Methods:

• Proteolysis assays of human LTBP4 hinge region.
• Generation of transgenic mice expressing human LTBP4.
• Assessment of muscle pathology, TGFβ signaling, and LTBP4 cleavage in transgenic mice and mdx mice.

Main Results:

• Human LTBP4 hinge region is susceptible to proteolysis, which can be inhibited by antibodies.
• Transgenic mice expressing human LTBP4 exhibit larger myofibers, increased injury susceptibility, and enhanced TGFβ signaling.
• Human LTBP4 exacerbates muscular dystrophy in mdx mice, leading to weaker muscles, inflammation, and increased in vivo LTBP4 cleavage.

Conclusions:

• LTBP4 cleavage contributes to TGFβ release and muscle pathology in muscular dystrophy.
• Blocking LTBP4 cleavage represents a potential therapeutic strategy for muscular dystrophy by reducing TGFβ activity, inflammation, and muscle damage.