title: 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 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.
authors.affiliation: a Muscle Biology Research Group-MUBIG ; School of Nursing and Health Studies; University of Missouri-Kansas City ; Kansas City , MO USA.
authors.forename: Chenglin
authors.initials: C
authors.lastname: Mo
authors.forename: Ruonan
authors.initials: R
authors.lastname: Zhao
authors.forename: Julian
authors.initials: J
authors.lastname: Vallejo
authors.forename: Orisa
authors.initials: O
authors.lastname: Igwe
authors.forename: Lynda
authors.initials: L
authors.lastname: Bonewald
authors.forename: Lori
authors.initials: L
authors.lastname: Wetmore
authors.forename: Marco
authors.initials: M
authors.lastname: Brotto
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000527:Alprostadil / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D015232:Dinoprostone / Q000494:pharmacology*; D059585:G1 Phase Cell Cycle Checkpoints / Q000187:drug effects; D007150:Immunohistochemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D032446:Myoblasts / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000378:metabolism; D058306:Receptors, Prostaglandin E, EP1 Subtype / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D058307:Receptors, Prostaglandin E, EP2 Subtype / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D058308:Receptors, Prostaglandin E, EP3 Subtype / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D058309:Receptors, Prostaglandin E, EP4 Subtype / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013876:Thiophenes / Q000494:pharmacology; D014230:Triazoles / Q000494:pharmacology
chemical_list: C508711:L-161982; D017382:Reactive Oxygen Species; D058306:Receptors, Prostaglandin E, EP1 Subtype; D058307:Receptors, Prostaglandin E, EP2 Subtype; D058308:Receptors, Prostaglandin E, EP3 Subtype; D058309:Receptors, Prostaglandin E, EP4 Subtype; D013876:Thiophenes; D014230:Triazoles; D000527:Alprostadil; C048491:butaprost; D015232:Dinoprostone; D000111:Acetylcysteine
keywords: CDK, cyclin dependent kinase; CM, conditioned media; EP4; Keap1/Nrf2, Kelch-like ECH-associated protein 1/NF-E2-related factor 2; NAC, N-acetyl cysteine; PGC-1α, proliferator-activated receptor gamma coactivator 1-α; PGD2, prostaglandin D2; PGE2, prostaglandin E2; PGF2α, prostaglandin F2α; PGI2, prostaglandin I2; Prostaglandin E2; RB, retinoblastoma protein; ROS, reactive oxygen species; SA, sodium ascorbate; SOD1, superoxide dismutase 1; bone-muscle crosstalk; myogenesis; proliferation; qPCR, quantitative real-time PCR; reactive oxygen species