FOXO transcription factors are important regulators of cell survival in response to a variety of stimuli, among which are
hypoxic stress, oxidative stress, and growth factor deprivation. Subcellular localization of FOXO proteins plays a major
role in the regulation of their activity. In this study, using confocal imaging of the cells transfected with GFP-FOXO3a
and fluorescence recovery after photobleaching technique, we visualized the dynamic nuclear translocation of
GFP-FOXO3a in ASTC-a-1 cells under growth factor stimulus. In healthy cells, GFP-FOXO3a was well-distributed in
the cytoplasm or widespread distributed in the cytoplasm and the nucleus but the cytoplasm was significantly more than
the nucleus. Deprivation of growth factor, we monitored the nuclear localization of GFP-FOXO3a and the dynamic
translocation of it from cytoplasm to nucleus. Interestingly, upon stimulation with growth factor in cells again, we
visualized the dynamic nuclear exclusion of GFP-FOXO3a and cytoplasm distribution rapidly. In conclusion, these
results demonstrated that FOXO3a can reversible shuttling between cytoplasm and nucleus upon stimulation with growth
factor.
BimL is an important BH3-only protein, whose function is act upstream of apoptosis. However, the molecular role of
BimL in apoptosis remains not well understood. Our previous reported shown that BimL was involved in the UV
irradiation-induced apoptosis. Based on RNAi, FRET and co-immunoprecipitation techniques, in this study, in addition
to well determine the role of BimL in UV-induced apoptosis, we particularly monitor the relationship between BimL and
Bcl-xL during UV irradiation in both living and extracted cells. First, Knockdown of BimL by a small hairpin RNA
confirmed this BH3-only member play an important role in the UV-induced apoptosis. Moreover, using FRET technique,
we further revealed that BimL directly binds to Bcl-xL, and the combination of these complexes became more and more
obviously during UV irradiation, which results were further highlighted by co-immunoprecipitation analysis. Thus, the
data suggested that BimL directly binds Bcl-xL and play an important role during UV irradiation-induced apoptosis
through suppresses the function of Bcl-xL.
Cisplatin, an efficient anticancer agent, can trigger multiple apoptotic pathways in cancer cells. However, the signal
transduction pathways in response to cisplatin-based chemotherapy are complicated, and the mechanism is not fully
understood. In current study, we showed that, during
cisplatin-induced apoptosis of human lung adenocarcinoma cells,
both the caspase-dependent and -independent pathways were activated. Herein, we reported that after cisplatin treatment,
the activities of caspase-9/-3 were sharply increased; pre-treatment with Z-LEHD-fmk (inhibitor of caspase-9),
Z-DEVD-fmk (inhibitor of caspase-3), and Z-VAD-fmk (a pan-caspase inhibitor) increased cell viability and decreased
apoptosis, suggesting that caspase-mediated apoptotic pathway was activated following cisplatin treatment. Confocal
imaging of the cells transfected with AIF-GFP demonstrated that AIF release occurred about 9 h after cisplatin treatment.
The event proceeded progressively over time, coinciding with a nuclear translocation and lasting for more than 2 hours.
Down-regulation of AIF by siRNA also significantly increased cell viability and decreased apoptosis, these results
suggested that AIF-mediated caspase-independent apoptotic pathway was involved in cispatin-induced apoptosis. In
conclusion, the current study demonstrated that both
caspase-dependent and -independent apoptotic pathways were
involved in cisplatin-induced apoptosis in human lung adenocarcinoma cells.
Photodynamic therapy (PDT) induces cell apoptosis mainly by the mitochondrial pathway. The Bcl-2 family proteins
play an important role in this pathway. However, the detailed mechanism is not elucidated. The current study was
aimed to determine whether Bim, a BH3-only protein of Bcl-2 family, was involved during Photofrin-PDT-induced
apoptosis in ASTC-a-1 and MCF-7 cell lines. The data show that massive reactive oxygen species (ROS) were
generated firstly after Photofrin-PDT treatment, leading to the disappearance of the mitochondrial membrane potential.
Furthermore, the activation of Bim and Bax were dynamically observed. Confocal imaging of the cells transfected with
GFP-BimL demonstrated that BimL translocate to mitochondria occurred about 12 min after PDT treatment. Bax
activation occurred about 15 min after PDT treatment. These results suggest that Bim, as an effectors, was involved in
Photofrin-PDT-induced apoptosis.
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