title: TRAIL-induced apoptosis proceeding from caspase-3-dependent and -independent pathways in distinct HeLa cells.
abstract: The apoptotic pathway in higher eukaryotes remains controversial with respect to the necessity of activation of caspase-3 in TRAIL (tumor necrosis factor-related apoptosis-inducing ligand)-treated cells. In this study, a fluorescence resonance energy transfer (FRET) probe was developed to image the activation of caspase-3 and the related apoptotic pathway in TRAIL-treated cells in real time. Both kinds of apoptotic pathways were observed simultaneously in the same experiment proceeding from activation and non-activation of caspase-3. The total apoptotic rate was 56.08%, the apoptotic rates for activation and non-activation of caspase-3 pathways were 21.5% and 34.58%, respectively, which were examined later for Hoechst 33258 staining and morphological characteristics. The apoptotic rate due to the activation of caspase-3 pathways in TRAIL-treated cells has been independently measured to be around 25.11% by capillary electrophoresis (CE) analysis, which confirmed the apoptotic rate due to activation of caspase-3 pathways as found by FRET analysis. This result also suggests that rest apoptosis is preceded by caspase-3-independent pathways, as CE has the ability to quantitatively detect caspase-dependent apoptosis. The observation of the coexistence of caspase-3-dependent and caspase-3-independent apoptotic pathways in the TRAIL-treated cells was unusual in comparison with the previous reports.
authors.affiliation: The Key Laboratory of Biomedical Photonics of Ministry of Education, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, PR China.
authors.forename: Juqiang
authors.initials: J
authors.lastname: Lin
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Zhang
authors.forename: Shaoqun
authors.initials: S
authors.lastname: Zeng
authors.forename: Shixia
authors.initials: S
authors.lastname: Zhou
authors.forename: Bi-Feng
authors.initials: BF
authors.lastname: Liu
authors.forename: Qian
authors.initials: Q
authors.lastname: Liu
authors.forename: Jie
authors.initials: J
authors.lastname: Yang
authors.forename: Qingming
authors.initials: Q
authors.lastname: Luo
mesh_terms: D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000502:physiology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008562:Membrane Glycoproteins / Q000502:physiology*; D053221:TNF-Related Apoptosis-Inducing Ligand; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*
chemical_list: D051017:Apoptosis Regulatory Proteins; D008562:Membrane Glycoproteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases