title: SGK1 is involved in cardioprotection of urocortin-1 against hypoxia/reoxygenation in cardiomyocytes.
abstract: BACKGROUND
  Urocortin-1 (UCN1) exerts protective effects on hypoxia/reoxygenation injury in the heart. Serum- and glucocorticoid- responsive kinase-1 (SGK1), a serine-threonine kinase, has been shown to be crucial for cardiomyocyte survival. The purpose of the present study was to investigate whether SGK1 is involved in UCN1-induced cardioprotection.
  
  
  METHODS
  Cardiomyocytes were obtained from neonatal rats and used as a model to investigate UCN1 regulation of SGK1. Specific small interfering RNA targeting SGK1 was used to knock down SGK1 expression. The messenger RNA (mRNA) level of SGK1 was measured using quantitative real time reverse transcription polymerase chain reaction, and the protein levels of SGK1 and phosphorylated SGK1 were determined using Western blot analysis.
  
  
  RESULTS
  SGK1 knockdown attenuated the protective effects of UCN1 against hypoxia/reoxygenation injury in cardiomyocytes. Treatment of cardiomyocytes with UCN1 stimulated SGK1 mRNA and protein expression and time-dependently increased phosphorylated SGK1 level. These effects were completely reversed with corticotrophin-releasing hormone receptor type 2 antagonist. Adenylate cyclase and protein kinase A inhibitors abolished the stimulatory effect of UCN1 on SGK1 expression. SGK1 phosphorylation induced by UCN1 was blocked by phosphorinositide-3-kinase inhibitor.
  
  
  CONCLUSIONS
  SGK1 is involved in the cardioprotective effects of UCN1 in cardiomyocytes. UCN1 stimulates SGK1 phosphorylation via the phosphorinositide-3-kinase signalling pathway and it induces SGK1 expression via the adenylate cyclase/protein kinase A pathway.
authors.affiliation: Department of Physiology, Second Military Medical University, Shanghai, China.
authors.forename: Binhai
authors.initials: B
authors.lastname: Cong
authors.affiliation: Department of Physiology, Second Military Medical University, Shanghai, China.
authors.forename: Long
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Physiology, Second Military Medical University, Shanghai, China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Department of Physiology, Second Military Medical University, Shanghai, China.
authors.forename: Xiaohan
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Medical Education and Training, Second Military Medical University, Shanghai, China. Electronic address: themailbox@yeah.net.
authors.forename: Baohai
authors.initials: B
authors.lastname: Liu
authors.affiliation: Department of Physiology, Second Military Medical University, Shanghai, China. Electronic address: nixinsmmu@hotmail.com.
authors.forename: Xin
authors.initials: X
authors.lastname: Ni
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D055785:Gene Knockdown Techniques; D000860:Hypoxia / Q000378:metabolism / Q000517:prevention & control*; D017874:Immediate-Early Proteins / Q000235:genetics / Q000502:physiology*; D007546:Isoquinolines / Q000494:pharmacology; D023421:Models, Animal; D009025:Morpholines / Q000494:pharmacology; D032383:Myocytes, Cardiac / Q000502:physiology*; D010446:Peptide Fragments / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering; D051381:Rats; D060888:Real-Time Polymerase Chain Reaction; D018019:Receptors, Corticotropin-Releasing Hormone / Q000037:antagonists & inhibitors; D015427:Reperfusion Injury / Q000517:prevention & control*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013449:Sulfonamides / Q000494:pharmacology; D054832:Urocortins / Q000494:pharmacology*; D000099184:Serum-Glucocorticoid Regulated Kinases
chemical_list: D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002867:Chromones; D004791:Enzyme Inhibitors; D005419:Flavonoids; D017874:Immediate-Early Proteins; D007546:Isoquinolines; D009025:Morpholines; D010446:Peptide Fragments; D010456:Peptides, Cyclic; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D018019:Receptors, Corticotropin-Releasing Hormone; D013449:Sulfonamides; D054832:Urocortins; D000099184:Serum-Glucocorticoid Regulated Kinases; C549377:Ucn1 protein, mouse; C528574:astressin-2B; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one