Abstract | OBJECTIVE: METHODS: L6 cells differentiated into myotubes in differentiation medium with 2%FBS. An in vitro insulin resistant model in L6 myotubes was established by 500 µmol/L of palmitate acid (PA). SREBP-1c, p-IRS-1(Tyr608/612), IRS-1, p-AKT (Ser473) and AKT were detected by Western blot after incubating L6 myobutes with 500 µmol/L of PA for 0.5, 1, 3, 6, 12, 18 or 24 h.SREBP-1c, FAS and molecules related to insulin signaling pathway were detected by Western blot when L6 myotubes over-expressed SREBP-1c or after a treatment of liver X receptor (LXR) agonist (TO901317, 5 µmol/L). The regulatory effects of transcription factor SREBP-1c on promoter region of IRS-1 were assessed by dual- luciferase reporter assay. RESULTS:
SREBP-1c protein expression increased significantly after 1-hour exposure to PA. The protein levels of p-IRS-1(Tyr608/612),IRS-1 and p-AKt (Ser473) decreased significantly after a 6-hour incubation of PA. However AKT protein levels were unaffected. The protein expressions of SREBP-1c and FAS were up-regulated by LXR agonist treatment versus controls. By contrast, LXR agonist treatment led to decreased expressions of IRS-1, p-IRS-1(Tyr608/612) and p-AKt (Ser473)/AKT proteins versus controls. The expressions of related proteins were similar to the observations made with LXR agonist intervention. The results of dual- luciferase reporter assay indicated that IRS-1 promoter activity was repressed significantly by SREBP-1c over-expression or TO901317 treatment whereas the dominant negative form of SREBP-1c (a mutant of Tyr320Ala lacking the ability of binding DNA) had no effect. CONCLUSION:
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Authors | Wenjun Wu, Yan Bi, Yinyan Tangsun, Wenwen Yin, Yingying Chen, Dalong Zhu |
Journal | Zhonghua yi xue za zhi
(Zhonghua Yi Xue Za Zhi)
Vol. 95
Issue 8
Pg. 611-5
(Mar 03 2015)
ISSN: 0376-2491 [Print] China |
PMID | 25917039
(Publication Type: Journal Article)
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Chemical References |
- Insulin
- Insulin Receptor Substrate Proteins
- Liver X Receptors
- Orphan Nuclear Receptors
- Palmitates
- Sterol Regulatory Element Binding Protein 1
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Topics |
- Cell Line
- Insulin
- Insulin Receptor Substrate Proteins
- Insulin Resistance
- Liver X Receptors
- Orphan Nuclear Receptors
- Palmitates
- Promoter Regions, Genetic
- Signal Transduction
- Sterol Regulatory Element Binding Protein 1
- Up-Regulation
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