Precision targeting of mitochondria as a therapeutic for FSHD

Investigator: Philipp Heher PhD

Category: Research - Basic

Facioscapulohumeral muscular dystrophy (FSHD) is caused by the abnormal activation of a gene called DUX4, which damages muscle cells, thus leading to progressive muscle weakness and wasting. A peculiar feature of the disease is that, even after DUX4 is no longer active, muscle cells often continue to show persistent signs of metabolic stress and oxidative damage, suggesting that the initial genetic trigger leaves behind a lasting harmful footprint in the muscle cell’s energy machinery, the mitochondria.

We have recently discovered that a very specific mitochondrial process called reverse electron transfer (RET) is a major source of oxidative stress in FSHD models. RET not only generates large amounts of damaging small molecules called reactive oxygen species (ROS) but also acts as a signal for muscle cell death, linking metabolic stress directly to muscle loss.

Our project aims to target RET specifically, using novel small molecules that directly suppress this damaging ROS production while preserving the mitochondria’s ability to generate energy. In addition, we will explore complementary strategies that reduce RET through other mechanisms, for example by limiting certain fuels for mitochondrial energy production or by slightly modulating mitochondrial activity. We will initially test these interventions in FSHD patient-derived muscle cells and in laboratory models under conditions that mimic the natural oxygen environment of muscle tissue. The most effective and safe combination will then be evaluated in a mouse model of FSHD to determine whether it can reduce oxidative stress, protect muscle cells, and improve muscle force. Mitochondria are critical for muscle function and regeneration, so by reducing RET and improving mitochondrial health, our approach may not only protect muscle from degeneration but also aid muscle repair.

In conclusion, this strategy addresses the persistent metabolic damage left behind after DUX4 expression, rather than targeting the toxic gene itself. By combining precise, mechanism-based interventions to selectively target RET, we hope to develop a therapy that can both protect and restore muscle tissue, complement future anti-DUX4 treatments, and ultimately improve quality of life for people living with FSHD.