scholarly journals Injury-mediated stiffening persistently activates muscle stem cells through YAP and TAZ mechanotransduction

2021 ◽  
Vol 7 (11) ◽  
pp. eabe4501
Author(s):  
Jason S. Silver ◽  
K. Arda Günay ◽  
Alicia A. Cutler ◽  
Thomas O. Vogler ◽  
Tobin E. Brown ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Stem Cells ◽  
Muscle Injury ◽  
Muscle Stiffness ◽  
Post Injury ◽  
Muscle Stem Cells ◽  
Transcription Regulator

The skeletal muscle microenvironment transiently remodels and stiffens after exercise and injury, as muscle ages, and in myopathic muscle; however, how these changes in stiffness affect resident muscle stem cells (MuSCs) remains understudied. Following muscle injury, muscle stiffness remained elevated after morphological regeneration was complete, accompanied by activated and proliferative MuSCs. To isolate the role of stiffness on MuSC behavior and determine the underlying mechanotransduction pathways, we cultured MuSCs on strain-promoted azide-alkyne cycloaddition hydrogels capable of in situ stiffening by secondary photocrosslinking of excess cyclooctynes. Using pre- to post-injury stiffness hydrogels, we found that elevated stiffness enhances migration and MuSC proliferation by localizing yes-associated protein 1 (YAP) and WW domain–containing transcription regulator 1 (WWTR1; TAZ) to the nucleus. Ablating YAP and TAZ in vivo promotes MuSC quiescence in postinjury muscle and prevents myofiber hypertrophy, demonstrating that persistent exposure to elevated stiffness activates mechanotransduction signaling maintaining activated and proliferating MuSCs.

scholarly journals Skeletal muscle stem cell self-renewal and differentiation kinetics revealed by EdU lineage tracing during regeneration

2019 ◽  
Author(s):  
Bradley Pawlikowski ◽  
Nicole Dalla Betta ◽  
Tiffany Antwine ◽  
Bradley B. Olwin
Keyword(s):  
Skeletal Muscle ◽  
Stem Cells ◽  
Stem Cell ◽  
Young Adult ◽  
Muscle Injury ◽  
Lineage Tracing ◽  
Stem Cell Population ◽  
Post Injury ◽  
Self Renewal ◽  
Muscle Stem Cell

SummarySkeletal muscle maintenance and repair is dependent on the resident adult muscle stem cell (MuSC). During injury, and in diseased muscle, stem cells are engaged to replace or repair damaged muscle, which requires the stem cells to exit quiescence and expand, followed by differentiation to regenerate myofibers and self-renewal to replenish the stem cell population. Following an injury, little is known regarding the timing of MuSC (skeletal muscle stem cell) self-renewal, myoblast expansion or myoblast differentiation. To determine the timing and kinetics of these cell fate decisions, we employed DNA-based lineage tracing to label newly replicated cells and followed cell fates during skeletal muscle regeneration. MuSCs activate and expand as myoblasts rapidly following injury, where the majority differentiate into myonuclei, establishing the centrally located myonuclear pool. Re-establishing the majority MuSC pool by self-renewal occurs after 5 days post-muscle injury, accompanied by low levels of myonuclear accretion that generate only peripheral myonuclei. In aged mice, possessing ∼1/2 the number of MuSCs present in young adult mice, the timing of post injury MuSC self-renewal is delayed, and although MuSCs expansion as myoblasts in aged muscle is impaired, the number of MuSC unexpectedly recovers to young adult levels during regeneration. Following an induced muscle injury, we found that myonuclei are generated within the first four days post injury derived from myoblasts expanding from activated MuSCs. Only later during regeneration, from 5 d to 14 d post injury, is the MuSC pool replenished by self-renewal, accompanied by generation of peripheral myonuclei.

scholarly journals Pro-myogenic small molecules revealed by a chemical screen on primary muscle stem cells

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Sean M. Buchanan ◽  
Feodor D. Price ◽  
Alessandra Castiglioni ◽  
Amanda Wagner Gee ◽  
Joel Schneider ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Stem Cells ◽  
Stem Cell ◽  
Small Molecules ◽  
Satellite Cell ◽  
Satellite Cells ◽  
Muscle Repair ◽  
Muscle Stem Cells

Abstract Satellite cells are the canonical muscle stem cells that regenerate damaged skeletal muscle. Loss of function of these cells has been linked to reduced muscle repair capacity and compromised muscle health in acute muscle injury and congenital neuromuscular diseases. To identify new pathways that can prevent loss of skeletal muscle function or enhance regenerative potential, we established an imaging-based screen capable of identifying small molecules that promote the expansion of freshly isolated satellite cells. We found several classes of receptor tyrosine kinase (RTK) inhibitors that increased freshly isolated satellite cell numbers in vitro. Further exploration of one of these compounds, the RTK inhibitor CEP-701 (also known as lestaurtinib), revealed potent activity on mouse satellite cells both in vitro and in vivo. This expansion potential was not seen upon exposure of proliferating committed myoblasts or non-myogenic fibroblasts to CEP-701. When delivered subcutaneously to acutely injured animals, CEP-701 increased both the total number of satellite cells and the rate of muscle repair, as revealed by an increased cross-sectional area of regenerating fibers. Moreover, freshly isolated satellite cells expanded ex vivo in the presence of CEP-701 displayed enhanced muscle engraftment potential upon in vivo transplantation. We provide compelling evidence that certain RTKs, and in particular RET, regulate satellite cell expansion during muscle regeneration. This study demonstrates the power of small molecule screens of even rare adult stem cell populations for identifying stem cell-targeting compounds with therapeutic potential.

Reparative dysfunction during muscle regeneration in Duchenne muscular dystrophy: therapeutic approaches to modulating the muscle environment and muscle stem cells

2019 ◽  
Author(s):  
◽  
Michael Everette Nance
Keyword(s):  
Skeletal Muscle ◽  
Stem Cells ◽  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Muscle Regeneration ◽  
Genetic Mutation ◽  
Critical Determinant ◽  
Muscle Stem Cells ◽  
Dystrophin Protein

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Duchenne muscular dystrophy (DMD) is a lethal muscular dystrophy resulting from functional loss of the dystrophin protein, a critical sub-sarcolemmal protein involved in membrane stability. While reparative dysfunction is thought to be a critical determinant of disease progression in humans, regeneration is not significantly impaired in the murine muscular dystrophy (mdx) model. Furthermore, it is not well understood if reparative dysfunction is related to inherent defects in stem cells or chronic alterations in the muscle environment due to disease related remodeling. To address these observed discrepancies, we adapted a whole muscle transplant model to study the in vivo regeneration of intact pieces of skeletal muscle from normal and dystrophic dogs (cDMD), a physiological and clinically relevant model to humans. Regeneration in cDMD muscle grafts was significantly attenuated compared to normal and predisposed to the development of skeletal muscle tumors. We used an adeno-associated virus (AAV) expressing a micro-dystrophin protein to specifically rescue the muscle environment by preventing fiber damage while retaining dystrophin-null SCs. AAV.micro-dystrophin rescued the environment by improving fibrosis, stiffness, and fiber orientation, which significantly improved early muscle regeneration but not late regeneration (2 greater than and less than 4 months post-transplant) via enhancing muscle stem cells differentiation. We next developed Cre- and CRISPR-cas9 gene editing strategies to test the ability of AAV serotype 9 to transduce and treat the genetic mutation in muscle stem cells. We observed efficient SC transduction when used as a single vector expressing Cre. Dual-vector CRISPR-cas9 SC transduction was inefficient and likely related to the requirement for two vectors, promoter usage, and mechanistic differences between Cre-recombination and CRISPR genome editing.

scholarly journals Tubastatin A maintains adult skeletal muscle stem cells in a quiescent state ex vivo and improves their engraftment ability in vivo

2022 ◽  
Vol 17 (1) ◽  
pp. 82-95
Author(s):  
Marina Arjona ◽  
Armon Goshayeshi ◽  
Cristina Rodriguez-Mateo ◽  
Jamie O. Brett ◽  
Pieter Both ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Stem Cells ◽  
Ex Vivo ◽  
Quiescent State ◽  
Adult Skeletal Muscle ◽  
Muscle Stem Cells ◽  
Skeletal Muscle Stem Cells

scholarly journals Non-viral induction of transient cell reprogramming in skeletal muscle to enhance tissue regeneration

2017 ◽  
Author(s):  
Irene de Lázaro ◽  
Acelya Yilmazer ◽  
Yein Nam ◽  
Sarah Qubisi ◽  
Fazilah Maizatul Abdul Razak ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Tissue Regeneration ◽  
Muscle Injury ◽  
Mouse Strains ◽  
Functional Regeneration ◽  
Reprogramming Factors ◽  
Novel Strategy ◽  
Teratoma Formation

AbstractSomatic cells can be reprogrammed to pluripotency in vivo by overexpression of defined transcription factors. While their sustained expression triggers tumorigenesis, transient reprogramming induces pluripotency-like features and proliferation only temporarily, without teratoma formation. We sought to achieve transient reprogramming within mouse skeletal muscle with a localized injection of plasmid DNA (pDNA) and hypothesized that this would enhance regeneration after severe injury. Intramuscular administration of reprogramming pDNA rapidly upregulated pluripotency (Nanog, Ecat1, Rex1) and early myogenesis genes (Pax3) in the healthy gastrocnemius of various mouse strains. Mononucleated cells expressing such markers appeared promptly in clusters among myofibers, but proliferated only transiently and did not lead to the generation of teratomas. Nanog was also upregulated in the gastrocnemius when reprogramming factors were administered 7 days after laceration of its medial head. Enhanced tissue regeneration after reprogramming was manifested by the accelerated appearance of centro-nucleated myofibers and reduced fibrosis. These results suggest that in vivo transient reprogramming may constitute a novel strategy towards the acceleration of regeneration following muscle injury, based on the induction of transiently-proliferative, pluripotent-like cells in situ. Further research to achieve clinically meaningful functional regeneration is warranted.

Skeletal muscle stem cells: a symposium

2006 ◽  
Vol 31 (6) ◽  
pp. 771-772 ◽  
Author(s):  
David A. Hood ◽  
Thomas J. Hawke
Keyword(s):  
Skeletal Muscle ◽  
Stem Cells ◽  
Growth Factor ◽  
Muscle Regeneration ◽  
Muscle Hypertrophy ◽  
Insulin Like Growth Factor ◽  
Muscle Stem Cells ◽  
Skeletal Muscle Stem Cells

Muscle stem cells are a population of cells that are important for both adaptations to exercise and muscle regeneration. This symposium was designed to highlight the role of these cells during muscle hypertrophy and development, and in response to insulin-like growth factor-1 (IGF-1) induced stimulation.

scholarly journals mTORC2 affects the maintenance of the muscle stem cell pool

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Nathalie Rion ◽  
Perrine Castets ◽  
Shuo Lin ◽  
Leonie Enderle ◽  
Judith R. Reinhard ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Mammalian Target Of Rapamycin ◽  
Adult Skeletal Muscle ◽  
Muscle Stem Cells ◽  
And Function ◽  
Muscle Homeostasis ◽  
Biological Methods

Abstract Background The mammalian target of rapamycin complex 2 (mTORC2), containing the essential protein rictor, regulates cellular metabolism and cytoskeletal organization by phosphorylating protein kinases, such as PKB/Akt, PKC, and SGK. Inactivation of mTORC2 signaling in adult skeletal muscle affects its metabolism, but not muscle morphology and function. However, the role of mTORC2 in adult muscle stem cells (MuSCs) has not been investigated. Method Using histological, biochemical, and molecular biological methods, we characterized the muscle phenotype of mice depleted for rictor in the Myf5-lineage (RImyfKO) and of mice depleted for rictor in skeletal muscle fibers (RImKO). The proliferative and myogenic potential of MuSCs was analyzed upon cardiotoxin-induced injury in vivo and in isolated myofibers in vitro. Results Skeletal muscle of young and 14-month-old RImyfKO mice appeared normal in composition and function. MuSCs from young RImyfKO mice exhibited a similar capacity to proliferate, differentiate, and fuse as controls. In contrast, the number of MuSCs was lower in young RImyfKO mice than in controls after two consecutive rounds of cardiotoxin-induced muscle regeneration. Similarly, the number of MuSCs in RImyfKO mice decreased with age, which correlated with a decline in the regenerative capacity of mutant muscle. Interestingly, reduction in the number of MuSCs was also observed in 14-month-old RImKO muscle. Conclusions Our study shows that mTORC2 signaling is dispensable for myofiber formation, but contributes to the homeostasis of MuSCs. Loss of mTORC2 does not affect their myogenic function, but impairs the replenishment of MuSCs after repeated injuries and their maintenance during aging. These results point to an important role of mTORC2 signaling in MuSC for muscle homeostasis.

scholarly journals Ciliation of muscle stem cells is critical to maintain regenerative capacity and is lost during aging

2020 ◽  
Author(s):  
A.R. Palla ◽  
K.I. Hilgendorf ◽  
A.V. Yang ◽  
J.P. Kerr ◽  
A.C. Hinken ◽  
...  
Keyword(s):  
Stem Cells ◽  
Small Molecule ◽  
Hedgehog Signaling ◽  
Intrinsic Defect ◽  
Post Injury ◽  
Regenerative Capacity ◽  
Muscle Stem Cells ◽  
Library Screen

AbstractDuring aging, the regenerative capacity of muscle stem cells (MuSCs) decreases, diminishing the ability of muscle to repair following injury. We performed a small molecule library screen and discovered that the proliferation and expansion of aged MuSCs is regulated by signal transduction pathways organized by the primary cilium, a cellular protrusion that serves as a sensitive sensory organelle. Abolishing MuSC cilia in vivo severely impaired injury-induced muscle regeneration. In aged muscle, a cell intrinsic defect in MuSC ciliation leading to impaired Hedgehog signaling was associated with the decrease in regenerative capacity. This deficit could be overcome by exogenous activation of Hedgehog signaling which promoted MuSC expansion, both in vitro and in vivo. Delivery of the small molecule Smoothened agonist (SAG) to muscles of aged mice restored regenerative capacity leading to increased strength post-injury. These findings provide fresh insights into the signaling dysfunction in aging and identify the ciliary Hedgehog signaling pathway as a potential therapeutic target to counter the loss of muscle regenerative capacity which accompanies aging.

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