Subjects: Biology >> Biophysics >> Biochemistry & Molecular Biology submitted time 2016-05-12
Abstract： The insulin-mimetic and anti-diabetic properties of vanadium and related compounds have been well documented both in vitro and in vivo. However, the molecular basis of the link between vanadium and the insulin signaling pathway in diabetes mellitus is not fully described. We investigated the effects of reactive oxygen species (ROS) induced by oxidovanadium(IV) sulfate (VOSO4) on glucose uptake and the insulin signaling pathway in human hepatoma cell line HepG2. Exposure of cells to VOSO4 (5-50 mu M) resulted in an increase in glucose uptake, insulin receptor (IR) and protein kinase B (Akt) phosphorylation and intracellular ROS generation. Using Western blot, we found that catalase and sodium formate, but not superoxide dismutase, prevented the increase of hydroxyl radical (center dot OH) generation and significantly decreased VOSO4-induced IR and Akt phosphorylation. These results suggest that VOSO4-induced center dot OH radical, which is a signaling species, promotes glucose uptake via the IR/Akt signaling pathway. (C) 2015 Elsevier Inc. All rights reserved.
Peer Review Status:
Awaiting Review
Subjects: Biology >> Biophysics >> Biochemistry & Molecular Biology submitted time 2016-05-12
Bai, Cuicui
Guo, Peng
Zhao, Qian
Lv, Zongyang
Zhang, Shijia
Gao, Fei
Tian, Zhixi
Liu, Cuimin
Gao, Liyan
Wang, Yingchun
Bai, Cuicui
Guo, Peng
Zhao, Qian
Zhang, Shijia
Wang, Jifeng
Yang, Fuquan
Wang, Jifeng
Yang, Fuquan
Abstract： The individual roles of three chloroplast CPN60 protomers (CPN60 alpha, CPN60 beta 1, and CPN60 beta 2) and whether and how they are assembled into functional chaperonin complexes are investigated in Chlamydomonas reinhardtii. Protein complexes containing all three potential subunits were identified in Chlamydomonas, and their co-expression in Escherichia coli yielded a homogeneous population of oligomers containing all three subunits (CPN60 alpha beta 1 beta 2), with a molecular weight consistent with a tetradecameric structure. While homo-oligomers of CPN60 beta could form, they were dramatically reduced when CPN60 alpha was present and homo-oligomers of CPN60 beta 2 were readily changed into hetero-oligomers in the presence of ATP and other protomers. ATP hydrolysis caused CPN60 oligomers to disassemble and drove the purified protomers to reconstitute oligomers in vitro, suggesting that the dynamic nature of CPN60 oligomers is dependent on ATP. Only hetero-oligomeric CPN60 alpha beta 1 beta 2, containing CPN60 alpha, CPN60 beta 1, and CPN60 beta 2 subunits in a 5: 6: 3 ratio, cooperated functionally with GroES. The combination of CPN60 alpha and CPN60 beta subunits, but not the individual subunits alone, complemented GroEL function in E. coli with subunit recognition specificity. Down-regulation of the CPN60 alpha subunit in Chlamydomonas resulted in a slow growth defect and an inability to grow autotrophically, indicating the essential role of CPN60 alpha in vivo.
Peer Review Status:Awaiting Review
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