Prostaglandin E₂ promotes proliferation of skeletal muscle myoblasts via EP4 receptor activation

Abstract

We recently demonstrated that conditioned media (CM) from osteocytes enhances myogenic differentiation of myoblasts, suggesting that signaling from bone may be important for skeletal muscle myogenesis. The effect of CM was closely mimicked by prostaglandin E 2 (PGE 2 ), a bioactive lipid mediator in various physiological or pathological conditions. PGE 2 is secreted at high levels by osteocytes and such secretion is further enhanced under loading conditions. Although four types of receptors, EP1 to EP4, mediate PGE 2 signaling, it is unknown whether these receptors play a role in myogenesis. Therefore, in this study, the expression of EPs in mouse primary myoblasts was characterized, followed by examination of their roles in myoblast proliferation by treating myoblasts with PGE 2 or specific agonists. All four PGE 2 receptor mRNAs were detectable by quantitative real-time PCR (qPCR), but only PGE 2 and EP4 agonist CAY 10598 significantly enhance myoblast proliferation. EP1/EP3 agonist 17-phenyl trinor PGE 2 (17-PT PGE 2 ) and EP2 agonist butaprost did not have any significant effects. Moreover, treatment with EP4 antagonist L161,982 dose-dependently inhibited myoblast proliferation. These results were confirmed by cell cycle analysis and the gene expression of cell cycle regulators. Concomitant with the inhibition of myoblast proliferation, treatment with L161,982 significantly increased intracellular reactive oxygen species (ROS) levels. Cotreatment with antioxidant Nacetyl cysteine (NAC) or sodium ascorbate (SA) successfully reversed the inhibition of myoblast proliferation and ROS overproduction caused by L161,982. Therefore, PGE 2 signaling via the EP4 receptor regulates myogenesis by promoting myoblast proliferation and blocking this receptor results in increased ROS production in myoblasts.

Crosstalk Between MLO‐Y4 Osteocytes and C2C12 Muscle Cells Is Mediated by the Wnt/β‐Catenin Pathway

“…(7) Osteocytes also secreted large amounts of PGE 2 , which we previously demonstrated to be a promoter of C2C12 myoblasts myogenesis (3) and proliferation. (33) Our concept is that bone-muscle crosstalk enhances myogenic differentiation but may also have effects on muscle function. In this study, we showed that 10% MLOY4 CM and 10% PO CM enhanced C2C12 cell differentiation in vitro.…”

Osteocalcin Induces Proliferation via Positive Activation of the PI3K/Akt, P38 MAPK Pathways and Promotes Differentiation Through Activation of the GPRC6A-ERK1/2 Pathway in C2C12 Myoblast Cells

“…However, the precise mechanisms responsible for synchronizing bone and skeletal muscle mass remain unclear. Although basic studies have helped dissect the multiple influences of skeletal muscle on bone through cytokines such as myostatin, insulin-like growth factor 1 (IGF-1), fibroblast growth factor 2 (FGF-2), interleukin-6 (IL-6), IL-15, myostatin, osteoglycin (OGN), FAM5C, and osteoactivin [9][10][11][12][13][14], few osteokines involved in the feedback control of muscle by bone have been identified, with the exception of the osteocyte-specific Wnt family member 3a (Wnt3a), prostaglandin E2 (PGE2), osteoblast-derived IGF-1 and osteocalcin [15][16][17][18].…”

Mechanism of Action of a Prostaglandin E2Receptor Antagonist with antimicrobial activity againstStaphylococcus aureus

“…A previous study had reported that the inhibitory effect of L-161,982 on the proliferation of skeletal muscle myoblasts was due to its ability to induce production of high levels of intracellular reactive oxygen species (ROS) that could be rescued by co-treatment with the antioxidants, N-acetyl cysteine or sodium ascorbate [18]. Co-treatment with these antioxidants did not circumvent the inhibitory effect of L-161,982 on S. aureus growth (Fig.…”