Pannexin 1 Regulates Skeletal Muscle Regeneration by Promoting Bleb-Based Myoblast Migration and Fusion Through a Novel Lipid Based Signaling Mechanism.

Katia Suarez-Berumen,Ketan Patel,Thomas E Woolley,Robert Mitchell,Robyn Meech,Valery I Shestopalov,Phil R Dash,Alessandra Sacco,Helen P Makarenkova,Henry Collins-Hooper,Anastasia Gromova,Sakthivel Vaiyapuri

doi:10.3389/fcell.2021.736813

Abstract

Adult skeletal muscle has robust regenerative capabilities due to the presence of a resident stem cell population called satellite cells. Muscle injury leads to these normally quiescent cells becoming molecularly and metabolically activated and embarking on a program of proliferation, migration, differentiation, and fusion culminating in the repair of damaged tissue. These processes are highly coordinated by paracrine signaling events that drive cytoskeletal rearrangement and cell-cell communication. Pannexins are a family of transmembrane channel proteins that mediate paracrine signaling by ATP release. It is known that Pannexin1 (Panx1) is expressed in skeletal muscle, however, the role of Panx1 during skeletal muscle development and regeneration remains poorly understood. Here we show that Panx1 is expressed on the surface of myoblasts and its expression is rapidly increased upon induction of differentiation and that Panx1–/– mice exhibit impaired muscle regeneration after injury. Panx1–/– myoblasts activate the myogenic differentiation program normally, but display marked deficits in migration and fusion. Mechanistically, we show that Panx1 activates P2 class purinergic receptors, which in turn mediate a lipid signaling cascade in myoblasts. This signaling induces bleb-driven amoeboid movement that in turn supports myoblast migration and fusion. Finally, we show that Panx1 is involved in the regulation of cell-matrix interaction through the induction of ADAMTS (Disintegrin-like and Metalloprotease domain with Thrombospondin-type 5) proteins that help remodel the extracellular matrix. These studies reveal a novel role for lipid-based signaling pathways activated by Panx1 in the coordination of myoblast activities essential for skeletal muscle regeneration.

Highlights

Adult mammalian skeletal muscle is composed of multinucleated fibers that cannot divide
We examined the temporal pattern of PANX1 protein expression during myoblast differentiation using immunocytochemical, quantitative Western blot and gene expression analyses of primary cultures
Expression of which significantly down-regulated in Panx1−/− myoblasts compared to WT myoblasts: Adamts5 – a disintegrin and metalloproteinase with thrombospondin motifs, Elastin Microfibril Interface-Located Protein 1 (Emilin1) – Elastin Microfibril Interfacer-1, Itgb1 – Integrin, Beta-1, MMP12 – Matrix Metallopeptidase 12, TgfbI – Transforming Growth Factor, Beta-Induced

Summary

Introduction

Adult mammalian skeletal muscle is composed of multinucleated fibers that cannot divide. Satellite cells are quiescent; upon injury, they become activated and divide both asymmetrically and symmetrically. This allows selfrenewal of the satellite cell pool, as well as the generation of a transit-amplifying population called myoblasts that become progressively differentiation-competent and eventually withdraw from the cell cycle and differentiate. Blebs have been implicated in the amoeboid movement of cells that lack mature focal adhesions and stress fibers (Friedl et al, 2001; Friedl and Wolf, 2009; Otto et al, 2011; Khajah et al, 2015). The reduction of hyaluronidase-sensitive pericellular coats by the ADAMTS family of versicanases is necessary for myoblast fusion (Hattori et al, 2011; Stupka et al, 2013; Taye et al, 2020)

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Results

Conclusion