Potential compensatory mechanisms preserving cardiac function in myotubular myopathy

Area of Science:

• Genetics and Molecular Biology
• Neuromuscular Disorders
• Organelle Biology

Background:

• X-Linked myotubular myopathy (XLMTM) presents with severe muscle weakness and reduced lifespan.
• The underlying pathomechanisms and non-muscular organ involvement, particularly liver dysfunction, remain unclear.

Purpose of the Study:

• To investigate organ-specific effects of XLMTM in the Mtm1^-/y mouse model.
• To identify common skeletal muscle pathomechanisms and explore cardiac and hepatic phenotypes.
• To elucidate compensatory mechanisms in non-skeletal muscles.

Main Methods:

• RNA-sequencing of skeletal muscles, heart, and liver.
• In vivo and in vitro assessment of cardiac and hepatic function and structure.
• Biochemical and cellular analyses of MTM1 molecular activity biomarkers.

Main Results:

• No liver dysfunction or morphological defects were observed.
• Skeletal muscles showed dysregulation in development, inflammation, cell adhesion, and oxidative phosphorylation.
• The heart exhibited mild functional alterations without structural defects, with transcriptomic data showing opposite dysregulation of mitochondrial and cell adhesion pathways compared to skeletal muscle.

Conclusions:

• Skeletal muscle defects in XLMTM involve specific molecular pathways, including MTM1 biomarkers.
• The heart appears to possess a compensatory mechanism that preserves its function.
• Findings suggest potential therapeutic targets for skeletal muscle defects in XLMTM.