5 research outputs found
Ret function in muscle stem cells points to tyrosine kinase inhibitor therapy for facioscapulohumeral muscular dystrophy
Facioscapulohumeral muscular dystrophy (FSHD) involves sporadic expression of
DUX4, which inhibits myogenesis and is pro-apoptotic. To identify target
genes, we over-expressed DUX4 in myoblasts and found that the receptor
tyrosine kinase Ret was significantly up-regulated, suggesting a role in FSHD.
RET is dynamically expressed during myogenic progression in mouse and human
myoblasts. Constitutive expression of either RET9 or RET51 increased myoblast
proliferation, whereas siRNA-mediated knockdown of Ret induced myogenic
differentiation. Suppressing RET activity using Sunitinib, a clinically-
approved tyrosine kinase inhibitor, rescued differentiation in both
DUX4-expressing murine myoblasts and in FSHD patient-derived myoblasts.
Importantly, Sunitinib also increased engraftment and differentiation of FSHD
myoblasts in regenerating mouse muscle. Thus, DUX4-mediated activation of Ret
prevents myogenic differentiation and could contribute to FSHD pathology by
preventing satellite cell-mediated repair. Rescue of DUX4-induced pathology by
Sunitinib highlights the therapeutic potential of tyrosine kinase inhibitors
for treatment of FSHD
Satellite cells delivered in their niche efficiently generate functional myotubes in three-dimensional cell culture
<div><p>Biophysical/biochemical cues from the environment contribute to regulation of the regenerative capacity of resident skeletal muscle stem cells called satellites cells. This can be observed <i>in vitro</i>, where muscle cell behaviour is influenced by the particular culture substrates and whether culture is performed in a 2D or 3D environment, with changes including morphology, nuclear shape and cytoskeletal organization. To create a 3D skeletal muscle model we compared collagen I, Fibrin or PEG-Fibrinogen with different sources of murine and human myogenic cells. To generate tension in the 3D scaffold, biomaterials were polymerised between two flexible silicone posts to mimic tendons. This 3D culture system has multiple advantages including being simple, fast to set up and inexpensive, so providing an accessible tool to investigate myogenesis in a 3D environment. Immortalised human and murine myoblast lines, and primary murine satellite cells showed varying degrees of myogenic differentiation when cultured in these biomaterials, with C2 myoblasts in particular forming large multinucleated myotubes in collagen I or Fibrin. However, murine satellite cells retained in their niche on a muscle fibre and embedded in 3D collagen I or Fibrin gels generated aligned, multinucleated and contractile myotubes.</p></div