title: Comparative proteomic analysis of cell cycle-dependent apoptosis induced by transforming growth factor-beta.
abstract: Transforming growth factor-beta (TGF-beta) can induce G2/M phase-dependent apoptosis and G1/S phase-dependent epithelial-mesenchymal transition (EMT) in hepatocytes, but the underlying mechanism remains poorly understood. In this study, we investigated alterations in the global proteome using two dimensional gel electrophoresis of AML-12 murine hepatocyte cells after treatment with TGF-beta at several time points after synchronization in the G2/M or G1/S phase. Upon TGF-beta treatment, the expression levels of 44 proteins were found to be significantly changed in cells synchronized in the G2/M phase. These proteins were identified by MALDI-TOF/TOF and classified into seven categories according to function. In addition, TGF-beta induced downregulation of glutamine synthetase in cells in G2/M but not G1/S phase, and this was further confirmed by immunoblotting. Moreover, exogenous glutamine completely blocked TGF-beta-induced apoptosis in G2/M and non-synchronized cells, whereas it had no effect on EMT, suggesting that the downregulation of glutamine synthetase is involved in G2/M phase-dependent apoptosis. These results provide new insight into the mechanism of the multifunctional effects of TGF-beta and how apoptosis and EMT are regulated in the same type of cells.
authors.affiliation: Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: Hong-Yu
authors.initials: HY
authors.lastname: Tian
authors.forename: Ke-Hua
authors.initials: KH
authors.lastname: Zhang
authors.forename: Xia
authors.initials: X
authors.lastname: Gao
authors.forename: Wei-Wei
authors.initials: WW
authors.lastname: Lei
authors.forename: Liang
authors.initials: L
authors.lastname: Zhang
authors.forename: Mei-Lan
authors.initials: ML
authors.lastname: Yu
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Song
authors.forename: Fu-Kun
authors.initials: FK
authors.lastname: Zhao
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D002453:Cell Cycle / Q000187:drug effects* / Q000502:physiology; D002460:Cell Line; D004247:DNA / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D015180:Electrophoresis, Gel, Two-Dimensional; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial; D008648:Mesoderm / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D020543:Proteome / Q000187:drug effects* / Q000302:isolation & purification; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D053719:Tandem Mass Spectrometry; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
chemical_list: D020543:Proteome; D016212:Transforming Growth Factor beta; D004247:DNA; D005974:Glutamate-Ammonia Ligase