title: Involvement of metabotropic glutamate receptor 5 in cardiomyocyte differentiation from mouse embryonic stem cells.
abstract: Metabotropic glutamate receptors (mGluRs) are G-protein coupled receptors (GPCRs) activated by glutamate. The function of mGluRs is not restricted to the regulation of synaptic transmission. Although some roles of mGluR5 in mouse embryonic stem cells (ESCs) have been proposed, little is known about the significance of mGluR5 in cardiomyocyte differentiation from ESCs. We demonstrated that mGluR5 expression increased during cardiomyocyte differentiation. Activation of mGluR5 with (RS)-3, 5-dihydroxy phenylglycine (DHPG) promoted cardiomyocyte differentiation in a dose-dependent manner. DHPG significantly enhanced PI 3-kinase enhancer (PIKE) and PI3K p110α expression, but had no significant effect on Homer1b/c. The coexpression of PIKE or PI3K p110α together with Troponin T in embryoid bodies (EBs) treated with DHPG was elevated to 9.51% and 12.05%, respectively. Inhibition of mGluR5 with 2-methyl-6-(phenylethynyl)pyridine (MPEP) treating the ESCs, did hold back the cardiogenesis from the ESCs at the early differentiation stage. However, EBs applied by MPEP could not inhibit cardiomyocyte differentiation. Small interfering RNA (siRNA) of mGluR5 blocked cardiomyocyte differentiation by repressing PIKE and PI3K p110α expression, but had no notable influence on Homer1b/c. mGluR5 siRNA also decreased the DHPG-induced Ca²⁺ transient peak amplitude in the isolated ESC-derived cardiomyocytes. The amplitude of Ca²⁺ oscillation was reduced by ∼90% with si-mGluR5-3 compared with si-control. The protein expression of T-type Ca²⁺ channel and L-type Ca²⁺ channel was decreased in si-mGluR5-3-treated EBs. Taken together, these results revealed that mGluR5/PIKE/PI3K signaling pathway was involved in cardiomyocyte differentiation from ESCs. The key function of mGluR5 is probably associated with cardiogenesis and Ca²⁺ signal in ESC-derived cardiomyocytes.
authors.affiliation: Institute of Pharmacology, Toxicology, and Biochemical Pharmaceutics, Zhejiang University, Hangzhou, China. zdyzxb@zju.edu.cn
authors.forename: Dan-Yan
authors.initials: DY
authors.lastname: Zhu
authors.forename: Li-Min
authors.initials: LM
authors.lastname: Zhou
authors.forename: Ying-Ying
authors.initials: YY
authors.lastname: Zhang
authors.forename: Jia-Qi
authors.initials: JQ
authors.lastname: Huang
authors.forename: Xing
authors.initials: X
authors.lastname: Pan
authors.forename: Yi-Jia
authors.initials: YJ
authors.lastname: Lou
mesh_terms: D000818:Animals; D020746:Calcium Channels, L-Type / Q000378:metabolism; D020747:Calcium Channels, T-Type / Q000378:metabolism; D020013:Calcium Signaling; D002352:Carrier Proteins / Q000378:metabolism; D002454:Cell Differentiation; D002460:Cell Line; D002470:Cell Survival; D018920:Coculture Techniques; D058732:Embryoid Bodies / Q000378:metabolism / Q000502:physiology*; D005260:Female; D020558:GTP Phosphohydrolases / Q000378:metabolism; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D000072233:Homer Scaffolding Proteins; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D034622:RNA Interference; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012118:Resorcinols / Q000494:pharmacology
chemical_list: D020746:Calcium Channels, L-Type; D020747:Calcium Channels, T-Type; D002352:Carrier Proteins; C578936:Grm5 protein, mouse; D000072233:Homer Scaffolding Proteins; D009419:Nerve Tissue Proteins; D011725:Pyridines; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate; D012118:Resorcinols; C079215:3,5-dihydroxyphenylglycine; C121465:6-methyl-2-(phenylethynyl)pyridine; D019869:Phosphatidylinositol 3-Kinases; D020558:GTP Phosphohydrolases; C529781:PIKE protein, mouse; D005998:Glycine