Prostaglandin E2 promotes proliferation of skeletal muscle myoblasts via EP4 receptor activation |
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Authors: | Chenglin Mo Ruonan Zhao Julian Vallejo Orisa Igwe Lynda Bonewald Lori Wetmore Marco Brotto |
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Affiliation: | 1.Muscle Biology Research Group-MUBIG; School of Nursing and Health Studies; University of Missouri-Kansas City; Kansas City, MO USA;2.Department of Biology and Chemistry; William Jewell College; Liberty; MO USA;3.Division of Pharmacology & Toxicology; School of Pharmacy; University of Missouri-Kansas City, MO USA;4.Department of Oral and Craniofacial Sciences; School of Dentistry; University of Missouri-Kansas City; Kansas City, MO USA |
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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 E2 (PGE2), a bioactive lipid mediator in various physiological or pathological conditions. PGE2 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 PGE2 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 PGE2 or specific agonists. All four PGE2 receptor mRNAs were detectable by quantitative real-time PCR (qPCR), but only PGE2 and EP4 agonist CAY 10598 significantly enhance myoblast proliferation. EP1/EP3 agonist 17-phenyl trinor PGE2 (17-PT PGE2) 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 N-acetyl cysteine (NAC) or sodium ascorbate (SA) successfully reversed the inhibition of myoblast proliferation and ROS overproduction caused by L161,982. Therefore, PGE2 signaling via the EP4 receptor regulates myogenesis by promoting myoblast proliferation and blocking this receptor results in increased ROS production in myoblasts. |
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Keywords: | bone-muscle crosstalk EP4 myogenesis Prostaglandin E2 proliferation reactive oxygen species |
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