Three-dimensional niche stiffness synergizes with Wnt7a to modulate the extent of satellite cell symmetric self-renewal divisions.
Mol Biol Cell. 2020 Jun 03;:mbcE20010078
Authors: Moyle LA, Cheng RY, Liu H, Davoudi S, Ferreira SA, Nissar AA, Sun Y, Gentleman E, Simmons CA, Gilbert PM
Satellite cells (SCs), the resident adult stem cells of skeletal muscle, are required for tissue repair throughout life. While many signaling pathways are known to control SC self-renewal, less is known about the mechanisms underlying the spatiotemporal control of self-renewal during skeletal muscle repair. Here, we measured biomechanical changes that accompany skeletal muscle regeneration and determined the implications on SC fate. Using atomic force microscopy, we quantified a 2.9-fold stiffening of the SC niche at time-points associated with planar-oriented symmetric self-renewal divisions. Immunohistochemical analysis confirms increased extracellular matrix deposition within the basal lamina. To test whether three-dimensional (3D) niche stiffness can alter SC behavior or fate, we embedded isolated SC-associated muscle fibers within biochemically inert agarose gels tuned to mimic native tissue stiffness. Time-lapse microscopy revealed that a stiff 3D niche significantly increased the proportion of planar-oriented divisions, without effecting SC viability, fibronectin deposition, or fate change. We then found that 3D niche stiffness synergizes with WNT7a, a biomolecule shown to control SC symmetric self-renewal divisions via the non-canonical WNT/planar cell polarity pathway, to modify stem cell pool expansion. Our results provide new insights into the role of 3D niche biomechanics in regulating SC fate choice. [Media: see text] [Media: see text].
PMID: 32491970 [PubMed - as supplied by publisher]