Tethered Jagged-1 Synergizes with Culture Substrate Stiffness to Modulate Notch-Induced Myogenic Progenitor Differentiation

Helia Safaee; Mohsen A Bakooshli; Sadegh Davoudi; Richard Y Cheng; Aditya J Martowirogo; Edward W Li; Craig A Simmons; Penney M Gilbert

doi:10.1007/s12195-017-0506-7

Tethered Jagged-1 Synergizes with Culture Substrate Stiffness to Modulate Notch-Induced Myogenic Progenitor Differentiation

Cell Mol Bioeng. 2017 Aug 28;10(5):501-513. doi: 10.1007/s12195-017-0506-7. eCollection 2017 Oct.

Authors

Helia Safaee¹, Mohsen A Bakooshli¹, Sadegh Davoudi¹, Richard Y Cheng¹, Aditya J Martowirogo¹, Edward W Li¹, Craig A Simmons^{1

2

3}, Penney M Gilbert^{4

5

6}

Affiliations

¹ 1Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON M5S 3E1 Canada.
² Translational Biology and Engineering Program, The Ted Rogers Centre for Heart Research, Toronto, ON M5G 1M1 Canada.
³ 3Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, ON M5S 3G8 Canada.
⁴ 4Department of Biochemistry, University of Toronto, Toronto, ON Canada.
⁵ 5Donnelly Centre for Cellular and Biomolecular Research, Toronto, ON Canada.
⁶ 6Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Rosebrugh Building, Rm. 407, Toronto, ON M5S 3E1 Canada.

Abstract

Introduction: Notch signaling is amongst the key intrinsic mechanisms regulating satellite cell fate, promoting the transition of activated satellite cells to highly proliferative myogenic progenitor cells and preventing their premature differentiation. Although much is known about the biochemical milieu that drives myogenic progression, less is known about the spatial cues providing spatiotemporal control of skeletal muscle repair in the context of Notch signaling.

Methods: Using a murine injury model, we quantified in vivo biophysical changes that occur within the skeletal muscle during regeneration. Employing tunable poly(ethylene glycol)-based hydrogel substrates, we modeled the measured changes in bulk stiffness in the context of Notch ligand signaling, which are present in the regenerative milieu at the time of injury.

Results: Following injury, there is a transient increase in the bulk stiffness of the tibialis anterior muscle that may be explained in part by changes in extracellular matrix deposition. When presented to primary myoblasts, Jagged-1, Jagged-2, and Dll1 in a tethered format elicited greater degrees of Notch activity compared to their soluble form. Only tethered Jagged-1 effects were tuned by substrate stiffness, with the greatest Notch activation observed on stiff hydrogels matching the stiffness of regenerating muscle. When exposed to tethered Jagged-1 on stiff hydrogels, fewer primary myoblasts expressed myogenin, and pharmacological inhibitor studies suggest this effect is Notch and RhoA dependent.

Conclusion: Our study proposes that tethered Jagged-1 presented in the context of transient tissue stiffening serves to tune Notch activity in myogenic progenitors during skeletal muscle repair and delay differentiation.

Keywords: Biochemical cues; Biophysical cues; Compression testing; Extracellular matrix; Hydrogel; Ligand presentation; Niche; Regeneration; Skeletal muscle; Spatiotemporal.