Small-molecule activation of lysosomal TRP channels ameliorates Duchenne muscular dystrophy in mouse models

Area of Science:

• Biochemistry
• Cell Biology
• Genetics

Background:

• Duchenne muscular dystrophy (DMD) is a severe genetic disorder caused by dystrophin deficiency, leading to progressive muscle degeneration.
• Current treatments for DMD are limited, highlighting the need for novel therapeutic strategies.
• Mutations in the transient receptor potential mucolipin 1 (ML1) gene, encoding a lysosomal Ca2+ channel, result in a phenotype resembling DMD.

Purpose of the Study:

• To investigate the therapeutic potential of modulating ML1 activity in Duchenne muscular dystrophy.
• To determine if enhancing ML1 function can improve sarcolemma integrity and ameliorate dystrophic phenotypes in a mouse model of DMD.

Main Methods:

• Utilized transgenic overexpression and pharmacological activation of ML1 in mdx mice (a model for DMD).
• Assessed sarcolemma integrity, muscle function, and histological hallmarks of muscular dystrophy.
• Investigated the role of ML1-dependent activation of transcription factor EB (TFEB) in lysosomal function and muscle repair.

Main Results:

• Transgenic or pharmacological activation of ML1 significantly improved sarcolemma repair in skeletal and cardiac muscles of mdx mice.
• Hallmark dystrophic features, including muscle necrosis, fibrosis, reduced muscle force, and cardiomyopathy, were ameliorated.
• ML1 activation led to TFEB activation, correcting lysosomal insufficiency and reducing muscle damage.

Conclusions:

• Modulating lysosomal Ca2+ channels, specifically ML1, offers a promising therapeutic avenue for Duchenne muscular dystrophy.
• Enhancing ML1 activity can restore sarcolemma integrity and alleviate major pathological and functional deficits in DMD.
• Targeting ML1 and its downstream effects on TFEB presents a novel strategy for treating DMD and related muscle disorders.