title: Icariin promotes expression of PGC-1alpha, PPARalpha, and NRF-1 during cardiomyocyte differentiation of murine embryonic stem cells in vitro.
abstract: OBJECTIVE
  To investigate the effect of icariin on the expression of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1alpha), peroxisome proliferator-activated receptor alpha (PPARalpha), and nuclear respiratory factor 1 (NRF-1) on cardiomyocyte differentiation of murine embryonic stem (ES) cells in vitro.
  
  
  METHODS
  The cardiomyocytes derived from murine ES cells were verified by immunocytochemistry using confocal laser scanning microscopy. Cardiac-specific sarcomeric proteins (ie alpha-actinin, troponin T) were evaluated when embryoid bodies (EB) were treated with icariin or retinoid acid. The expression of PGC-1alpha, PPARalpha, and NRF-1 were analyzed using both semiquantitative RT-PCR and Western blotting in cardiomyocyte differentiation. The phosphorylation of the p38 mitogen-activated protein kinase (MAPK) was studied in the differentiation process, and its specific inhibitor SB203580 was employed to confirm the function of the p38 MAPK on icariin-induced cardiac differentiation.
  
  
  RESULTS
  The application of icariin significantly induced the cardiomyocyte differentiation of EB as indicated by the promoted expression of alpha-actinin and troponin T. The expression of PGC-1alpha, PPARalpha, and NRF-1 increased coincidently in early differentiation and the increase was dose-dependently upregulated by icariin treatment. The phosphorylation of the p38 MAPK peaked on d 6 and decreased after d 8, and the activation was further enhanced and prolonged when the EB were subjected to icariin, which was concurrent with the elevation of PGC-1alpha, PPARalpha, and NRF-1. Moreover, the inhibition of the p38 MAPK pathway by SB203580 efficiently abolished icariin-stimulated cardiomyocyte differentiation and resulted in the capture of the upregulation of PGC-1alpha, PPARalpha, and NRF-1.
  
  
  CONCLUSIONS
  Taken together, icariin promoted the expression of PGC-1alpha, PPARalpha, and NRF-1 during cardiomyocyte differentiation of murine ES cells in vitro and the effect was partly responsible for the activation of the p38 MAPK.
authors: Institute of Pharmacology and Toxicology and Biochemical Pharmaceutics, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China.
authors: Ling
authors: L
authors: Ding
authors: Xing-Guang
authors: XG
authors: Liang
authors: Dan-Yan
authors: DY
authors: Zhu
authors: Yi-Jia
authors: YJ
authors: Lou
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D034181:Epimedium / Q000737:chemistry; D005419:Flavonoids / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology*; D007093:Imidazoles / Q000494:pharmacology; D051379:Mice; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000378:metabolism; D051266:Nuclear Respiratory Factor 1 / Q000096:biosynthesis / Q000235:genetics; D047493:PPAR alpha / Q000096:biosynthesis / Q000235:genetics; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D010766:Phosphorylation / Q000187:drug effects; D010946:Plants, Medicinal / Q000737:chemistry; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000096:biosynthesis / Q000235:genetics; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D005419:Flavonoids; D007093:Imidazoles; C495634:Nrf1 protein, mouse; D051266:Nuclear Respiratory Factor 1; D047493:PPAR alpha; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C485290:Ppargc1a protein, mouse; D011725:Pyridines; D012333:RNA, Messenger; D015534:Trans-Activators; D014157:Transcription Factors; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580; C056599:icariin