title: mGluR5 stimulating Homer-PIKE formation initiates icariin induced cardiomyogenesis of mouse embryonic stem cells by activating reactive oxygen species.
abstract: Icariin (ICA) has been reported to facilitate cardiac differentiation of mouse embryonic stem (ES) cells; however, the mechanism by which ICA induced cardiomyogenesis has not been fully elucidated yet. Here, an underlying signaling network including metabotropic glutamate receptor 5 (mGluR5), Homer, phosphatidylinositol 3-Kinase Enhancer (PIKE), phosphatidylinositol 3-Kinase (PI3K), reactive oxygen species (ROS) and nuclear factor-kappaB (NF-κB) was investigated in ICA induced cardiomyogenesis. Our results showed that the co-expression of mGluR5 together with α-actinin or Troponin T in embryoid bodies (EBs) treated with ICA was elevated to 10.86% and 9.62%, compared with the case in the control (4.04% and 3.45%, respectively). Exposure of EBs to ICA for 2 h remarkably increased the dimeric form of mGluR5, which was inhibited by small interfering RNA targeting mGluR5 (si-mGluR5). Moreover, the extracellular glutamate concentration in ICA treatment medium was elevated to 28.9±3.5 μM. Furthermore, the activation of mGluR5 by ICA triggered the formation of Homer-PIKE complex and activated PI3K, stimulating ROS generation and NF-κB nuclear translocation. Knockdown of mGluR5 or inhibition of PI3K by LY294002 blocked ICA induced cardiomyogenesis via repressing mGluR5 pathway, reducing ROS and NF-κB activation. These results revealed that the inducible mechanisms of ICA were related to activate mGluR5 pathway.
authors.affiliation: Institute of Pharmacology, Toxicology and Biochemical Pharmaceutics, College of Pharmaceutical Sciences, Zhejiang University, No. 866, Yu Hang Tang Road, Hangzhou 310058, China.
authors.forename: Limin
authors.initials: L
authors.lastname: Zhou
authors.forename: Yujie
authors.initials: Y
authors.lastname: Huang
authors.forename: Yingying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Qingwei
authors.initials: Q
authors.lastname: Zhao
authors.forename: Bei
authors.initials: B
authors.lastname: Zheng
authors.forename: Yijia
authors.initials: Y
authors.lastname: Lou
authors.forename: Danyan
authors.initials: D
authors.lastname: Zhu
mesh_terms: D000199:Actins / Q000378:metabolism; D021581:Active Transport, Cell Nucleus; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002454:Cell Differentiation; D002867:Chromones / Q000494:pharmacology; D003470:Culture Media / Q000378:metabolism; D053595:Embryonic Stem Cells / Q000166:cytology / Q000187:drug effects*; D005419:Flavonoids / Q000494:pharmacology*; D020558:GTP Phosphohydrolases / Q000378:metabolism; D055785:Gene Knockdown Techniques; D018698:Glutamic Acid / Q000378:metabolism; D000072233:Homer Scaffolding Proteins; D051379:Mice; D009025:Morpholines / Q000494:pharmacology; D046912:Multiprotein Complexes / Q000378:metabolism; D024510:Muscle Development; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D055503:Protein Multimerization; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D002352:Carrier Proteins; D002867:Chromones; D003470:Culture Media; D005419:Flavonoids; C578936:Grm5 protein, mouse; D000072233:Homer Scaffolding Proteins; D009025:Morpholines; D046912:Multiprotein Complexes; D016328:NF-kappa B; D009419:Nerve Tissue Proteins; D000081082:Phosphoinositide-3 Kinase Inhibitors; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D018698:Glutamic Acid; D020558:GTP Phosphohydrolases; C529781:PIKE protein, mouse; C056599:icariin