title: Jinlida granule inhibits palmitic acid induced-intracellular lipid accumulation and enhances autophagy in NIT-1 pancreatic β cells through AMPK activation.
abstract: BACKGROUND
  Jinlida granule (JLDG), composed of seventeen Chinese medical herbs, is a widely used Chinese herbal prescription for treating diabetes mellitus. However, the mechanism underlying this effect remains unclear. To determine the main components in JLDG and to explore the effect of JLDG on autophagy and lipid accumulation in NIT-1 pancreatic β cells exposed to politic acid (PA) through AMP activated protein kinase (AMPK) signaling pathway.
  
  
  METHODS
  JLDG was prepared and the main components contained in the granules were identified by ultra performance liquid chromatography (UPLC) fingerprint. Intracellular lipid accumulation in NIT-1 cells was induced by culturing with medium containing PA. Intracellular lipid droplets were observed by Oil Red O staining and triglyceride (TG) content was measured by colorimetric assay. The formation of autophagosomes was observed under transmission electron microscope. The expression of AMPK and phospho-AMPK (pAMPK) proteins as well as its downstream fatty acid metabolism-related proteins (fatty acid synthase, FAS; acetyl-coA carboxylase, ACC; carnitine acyltransferase 1, CPT-1) and autophagy-related genes (mammal target of rapamycin, mTOR; tuberous sclerosis complex 1, TSC1; microtubule-associated protein 1 light chain 3, LC3-II) were determined by Western blot. The expression of sterol regulating element binding protein 1c (SREBP-1c) mRNA was examined by real time PCR (RT-PCR).
  
  
  RESULTS
  Our data showed that JLDG could significantly reduce PA-induced intracellular lipid accumulation in NIT-1 pancreatic β cells. This effect was associated with increased protein expression of pAMPK and AMPK in NIT-1 cells. Treatment with JLDG also decreased the expression of AMPK downstream lipogenic genes (SREBP-1c mRNA, FAS and ACC proteins) whereas increased the expression of fatty acid oxidation gene (CPT-1 protein). Additionally, JLDG-treated cells displayed a markedly increase in the number of autophagosomes which was accompanied by the down-regulation of mTOR and the up-regulation of TSC1 and LC3-II proteins expression. However, when AMPK phosphorylation was inhibited by Compound C, JLDG supplementation did not exhibit any effect on the expression of these AMPK downstream molecules in NIT-1 cells.
  
  
  CONCLUSIONS
  The results suggest that JLDG could reduce intracellular lipid accumulation and enhance the autophagy in NIT-1 pancreatic β cells cultured with PA. The mechanism is possibly mediated by AMPK activation.
authors.affiliation: Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
authors.forename: Dingkun
authors.initials: D
authors.lastname: Wang
authors.affiliation: Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
authors.forename: Min
authors.initials: M
authors.lastname: Tian
authors.affiliation: Shijiazhuang YiLing Pharmaceutical Co., Ltd., Shijiazhuang, Hebei 050035, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Qi
authors.affiliation: Department of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
authors.forename: Guang
authors.initials: G
authors.lastname: Chen
authors.affiliation: Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
authors.forename: Lijun
authors.initials: L
authors.lastname: Xu
authors.affiliation: Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Zou
authors.affiliation: Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
authors.forename: Kaifu
authors.initials: K
authors.lastname: Wang
authors.affiliation: Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China. Electronic address: tjhdonghui@163.com.
authors.forename: Hui
authors.initials: H
authors.lastname: Dong
authors.affiliation: Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China. Electronic address: felu@tjh.tjmu.edu.cn.
authors.forename: Fuer
authors.initials: F
authors.lastname: Lu
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000818:Animals; D001343:Autophagy / Q000187:drug effects*; D002460:Cell Line; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D050417:Insulin-Secreting Cells / Q000187:drug effects* / Q000378:metabolism; D050356:Lipid Metabolism / Q000187:drug effects*; D008297:Male; D051379:Mice; D019308:Palmitic Acid; D017207:Rats, Sprague-Dawley; D014280:Triglycerides / Q000378:metabolism
chemical_list: D004365:Drugs, Chinese Herbal; D014280:Triglycerides; C000601818:jinlida; D019308:Palmitic Acid; D055372:AMP-Activated Protein Kinases
keywords: AMP activated protein kinase; Autophagy; Jinlida granule; Lipid metabolism; NIT-1 cells; Type 2 diabetes