title: Metallothioneins protect cytosolic creatine kinases against stress induced by nitrogen-based oxidants.
abstract: The formation of intracellular nitrogen-based oxidants has important physiological and pathological consequences. CK (creatine kinase), which plays a key role in intracellular energy metabolism, is a main target of low concentrations of oxidative and nitrative stresses. In the present study, the interaction between cytosolic CKs [MM-CK (muscle-type CK) and BB-CK (brain-type CK)] and MTs [metallothioneins; hMT2A (human MT-IIA) and hMT3 (human MT-III)] were characterized by both in vitro and intact-cell assays. MTs could successfully protect the cytosolic CKs against inactivation induced by low concentrations of PN (peroxynitrite) and NO both in vitro and in hMT2A-overexpressing H9c2 cells and hMT3-knockdown U-87 MG cells. Under high PN concentrations, CK formed granule-like structures, and MTs were well co-localized in these aggregated granules. Further analysis indicated that the number of cells containing the CK aggregates negatively correlated with the expression levels of MTs. In vitro experiments indicated that MTs could effectively protect CKs against aggregation during refolding, suggesting that MT might function as a chaperone to assist CK re-activation. The findings of the present study provide direct evidence of the connection between the two well-characterized intracellular systems: the precisely balanced energy homoeostasis by CKs and the oxidative-stress response system using MTs.
authors.affiliation: State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Chen
authors.forename: Jie
authors.initials: J
authors.lastname: Li
authors.forename: Tong-Jin
authors.initials: TJ
authors.lastname: Zhao
authors.forename: Xu-Hui
authors.initials: XH
authors.lastname: Li
authors.forename: Fan-Guo
authors.initials: FG
authors.lastname: Meng
authors.forename: Hang
authors.initials: H
authors.lastname: Mu
authors.forename: Yong-Bin
authors.initials: YB
authors.lastname: Yan
authors.forename: Hai-Meng
authors.initials: HM
authors.lastname: Zhou
mesh_terms: D000818:Animals; D016466:CHO Cells; D052276:Creatine Kinase, BB Form / Q000037:antagonists & inhibitors / Q000378:metabolism*; D052283:Creatine Kinase, MM Form / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006224:Cricetinae; D003600:Cytosol / Q000201:enzymology; D006801:Humans; D008668:Metallothionein / Q000378:metabolism*; D000090023:Metallothionein 3; D051379:Mice; D018832:Molecular Chaperones / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009569:Nitric Oxide / Q000494:pharmacology*; D030421:Peroxynitrous Acid / Q000494:pharmacology*
chemical_list: C491053:MT2A protein, human; D000090023:Metallothionein 3; D018832:Molecular Chaperones; D009419:Nerve Tissue Proteins; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; D008668:Metallothionein; D052276:Creatine Kinase, BB Form; D052283:Creatine Kinase, MM Form