title: Group IIE secretory phospholipase A2 regulates lipolysis in adipocytes.
abstract: OBJECTIVE
  To examine the function of group IIE secretory phospholipase A(2) (sPLA(2) -IIE) in adipocytes and to explore the possible signaling mechanism involved.
  
  
  METHODS
  The expression of sPLA(2) -IIE was demonstrated using real-time PCR and Western blot analysis. Lipid accumulation was evaluated via the measurement of cellular triglycerides (TG). Lipolysis was quantified by measuring the release of free glycerol. The expressions of M-type sPLA(2) receptor (PLA(2) R1) and the genes encoding adipogenic proteins were measured using real-time PCR. The activities of the Janus kinase 2 (JAK2), extracellular regulated protein kinase (ERK), and hormone-sensitive lipase (HSL) were determined using Western blot.
  
  
  RESULTS
  sPLA(2) -IIE(-/-) mice gained significantly more epididymal fat than wild-type (WT) mice. When treated with adipogenic stimuli ex vivo, stromal vascular cells isolated from the adipose tissue of sPLA(2) -IIE(-/-) mice accumulated significantly more TG than those from WT mice. Conversely, a significant reduction in lipid accumulation and an increase of free glycerol were observed in OP9 cells overexpressing sPLA(2) -IIE and in 3T3-L1 cells treated with sPLA(2) -IIE protein. Moreover, sPLA(2) -IIE significantly induced adipocyte glycerol release and HSL activity, which was inhibited by PD98059, an ERK inhibitor.
  
  
  CONCLUSIONS
  sPLA(2) -IIE regulates lipolysis in adipocytes, likely through the ERK/HSL signaling pathway.
authors.affiliation: Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China. Correspondence: Ling Chen (Chen_Ling@gibh.ac.cn); State Key Laboratory of Respiratory Diseases, Institute of Respiratory Diseases, Guangzhou College of Medicine, Guangzhou, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhi
authors.forename: Linbing
authors.initials: L
authors.lastname: Qu
authors.forename: Fang
authors.initials: F
authors.lastname: Wu
authors.forename: Ling
authors.initials: L
authors.lastname: Chen
authors.forename: Jun
authors.initials: J
authors.lastname: Tao
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000378:metabolism*; D000273:Adipose Tissue / Q000378:metabolism*; D000818:Animals; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D054501:Group II Phospholipases A2 / Q000378:metabolism*; D008066:Lipolysis / Q000502:physiology*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D015398:Signal Transduction; D002787:Sterol Esterase / Q000378:metabolism; D014280:Triglycerides / Q000378:metabolism
chemical_list: D014280:Triglycerides; D048049:Extracellular Signal-Regulated MAP Kinases; D020928:Mitogen-Activated Protein Kinases; D002787:Sterol Esterase; D054501:Group II Phospholipases A2; D005990:Glycerol