title: HEK293 cells exposed to microcystin-LR show reduced protein phosphatase 2A activity and more stable cytoskeletal structure when overexpressing α4 protein.
abstract: Microcystin-LR (MC-LR) is one of the most toxic members of microcystins released by freshwater cyanobacterial. The major mechanism of MC-LR toxicity has been attributed to its inhibition of protein phosphatases 1 (PP1) and 2A (PP2A). In our prior research, α4 protein, a regulator of PP2A, was found not only crucial for PP2A regulation but also for the overall response of HEK 293 cells encountering MC-LR. To explore the role of α4 in MC-LR toxicity via PP2A regulation, here, HEK 293 cells overexpressing α4 protein were exposed to MC-LR and PP2A, cytoskeletal organization, and cytoskeleton-related proteins were investigated. The results showed that PP2A activity decreased and PP2A/C subunit expression and phosphorylation at Tyr307 increased significantly in the group exposed to high MC-LR. Vimentin IF became concentrated and formed perinuclear bundles. However, the assembly of actin filament and microtubules remained unchanged and the expression and phosphorylation of the cytoskeleton-related proteins HSP27 and VASP did not increase significantly. Some of these results differ from those of our previous study in which normal HEK293 cells were exposed to MC-LR. Our results indicate that elevated α4 expression confers some resistance to MC-LR-induced cytoskeletal change These new findings provide helpful insights into the mechanism of MC-LR toxicity and the role of α4 in regulating PP2A function. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 255-264, 2017.
authors.affiliation: Department of Biochemistry, School of Medicine, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Pu
authors.initials: P
authors.lastname: Huang
authors.affiliation: Department of Biochemistry, School of Medicine, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Beilei
authors.initials: B
authors.lastname: Wang
authors.affiliation: Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, 310051, China.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Wang
authors.affiliation: Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, 310051, China.
authors.forename: Mingluan
authors.initials: M
authors.lastname: Xing
authors.affiliation: Department of Biosystem Engineering, College of Biosystem Engineering and Food Science, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Zonglou
authors.initials: Z
authors.lastname: Guo
authors.affiliation: Department of Biochemistry, School of Medicine, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Lihong
authors.initials: L
authors.lastname: Xu
mesh_terms: D003599:Cytoskeleton / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects*; D057809:HEK293 Cells; D055551:HSP27 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D062792:MARVEL Domain-Containing Proteins / Q000235:genetics / Q000378:metabolism*; D008387:Marine Toxins; D052998:Microcystins / Q000633:toxicity*; D008856:Microscopy, Fluorescence; D008868:Microtubule Proteins / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D054648:Protein Phosphatase 2 / Q000378:metabolism*; D000071636:Protein Phosphatase 2C / Q000378:metabolism; D021122:Protein Subunits / Q000378:metabolism; D011510:Proteolipids / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases; D014746:Vimentin / Q000378:metabolism
chemical_list: D055551:HSP27 Heat-Shock Proteins; D062792:MARVEL Domain-Containing Proteins; D008387:Marine Toxins; D052998:Microcystins; D008868:Microtubule Proteins; D009687:Nuclear Proteins; C094765:PLP2 protein, human; D021122:Protein Subunits; D011510:Proteolipids; D014157:Transcription Factors; D014746:Vimentin; C109052:MID1 protein, human; D044767:Ubiquitin-Protein Ligases; D054648:Protein Phosphatase 2; D000071636:Protein Phosphatase 2C; C057862:cyanoginosin LR
keywords: cytoskeleton; microcystin-LR; protein phosphatase 2A; α4 protein