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<p>The extracellular matrix protein laminin-α2 is essential for preserving the integrity of skeletal muscle fibers during contraction. Its importance is reflected by the severe, congenital LAMA2-related muscular dystrophy (LAMA2 MD) caused by loss-of-function mutations in the <i>LAMA2</i> gene. While laminin-α2 has an established role in structurally supporting muscle fibers, it remains unclear whether it exerts additional functions that contribute to the maintenance of skeletal muscle integrity. Here, we report that in healthy muscle, activated muscle stem cells (MuSCs) express <i>Lama2</i> and remodel their microenvironment with laminin-α2. By characterizing LAMA2 MD-afflicted MuSCs and generating MuSC-specific <i>Lama2</i> knockouts, we show that MuSC-derived laminin-α2 is essential for rapid MuSC expansion and regeneration. In humans, we identify <i>LAMA2</i> expression in MuSCs and demonstrate that loss-of-function mutations impair cell-cycle progression of myogenic precursors. In summary, we show that self-secreted laminin-α2 supports MuSC proliferation post-injury, thus implicating MuSC dysfunction in LAMA2 MD pathology.</p>

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Loss of cell-autonomously secreted laminin-α2 drives muscle stem cell dysfunction in LAMA2-related muscular dystrophy

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年11月27日

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  • Timothy J. McGowan,
  • Judith R. Reinhard,
  • Nicolas Lewerenz,
  • Marta Białobrzeska,
  • Shuo Lin,
  • Jacek Stępniewski,
  • Krzysztof Szade,
  • Józef Dulak,
  • Markus A. Rüegg

摘要

The extracellular matrix protein laminin-α2 is essential for preserving the integrity of skeletal muscle fibers during contraction. Its importance is reflected by the severe, congenital LAMA2-related muscular dystrophy (LAMA2 MD) caused by loss-of-function mutations in the LAMA2 gene. While laminin-α2 has an established role in structurally supporting muscle fibers, it remains unclear whether it exerts additional functions that contribute to the maintenance of skeletal muscle integrity. Here, we report that in healthy muscle, activated muscle stem cells (MuSCs) express Lama2 and remodel their microenvironment with laminin-α2. By characterizing LAMA2 MD-afflicted MuSCs and generating MuSC-specific Lama2 knockouts, we show that MuSC-derived laminin-α2 is essential for rapid MuSC expansion and regeneration. In humans, we identify LAMA2 expression in MuSCs and demonstrate that loss-of-function mutations impair cell-cycle progression of myogenic precursors. In summary, we show that self-secreted laminin-α2 supports MuSC proliferation post-injury, thus implicating MuSC dysfunction in LAMA2 MD pathology.