Apoptotic signalling cascade in photosensitized human epidermal carcinoma A431 cells: involvement of singlet oxygen, c-Jun N-terminal kinase, caspase-3 and p21-activated kinase 2

2000 ◽  
Vol 351 (1) ◽  
pp. 221-232 ◽  
Author(s):  
Wen-Hsiung CHAN ◽  
Jau-Song YU ◽  
Shiaw-Der YANG

Photodynamic treatment (PDT) elicits diverse cellular responses and can also cause apoptosis. In the present study the cascade of signalling events involved in PDT-induced apoptosis was investigated using Rose Bengal (RB) as the photosensitizer, and human epidermal carcinoma A431 cells as the cell model. We show that a 36-kDa kinase detected by an in-gel kinase assay is markedly activated during PDT-triggered apoptosis. Immunoblot analysis revealed that this 36-kDa kinase represents the C-terminal catalytic fragment of p21-activated kinase (PAK)2. Generation of this active fragment of PAK2 is mediated by the caspase family of proteases, which are activated by PDT. The specific caspase inhibitors (acetyl-Asp-Glu-Val-Asp-aldehyde and acetyl-Tyr-Val-Ala-Asp-chloromethylketone) block the PDT-induced caspase-3 activation and subsequent PAK2 cleavage/activation, indicating a major role for the caspase family proteases in PDT-induced apoptosis. Both PDT-induced caspase-3 activation and PAK2 cleavage/activation can be inhibited by the singlet oxygen scavengers, L-histidine and α-tocopherol, but not the hydroxyl radical scavenger, mannitol, demonstrating that singlet oxygen is an immediate early-apoptotic signal generated by PDT. In addition, PDT can induce a two-stage activation of the c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) in A431 cells; the early-stage JNK activation is singlet oxygen-dependent, whereas the late-stage JNK activation is mediated by the singlet oxygen-triggered caspase activation. Experiments using anti-sense oligonucleotides against JNK1 and PAK2 further show that during PDT-induced apoptosis the early-stage JNK activation is required for caspase activation, and that the late-stage JNK activation is regulated by the caspase-mediated cleavage/activation of PAK2. Collectively, a model for the PDT-triggered apoptotic signalling cascade with RB is proposed, which involves singlet oxygen, JNK, caspase-3 and PAK2, sequentially.

2000 ◽  
Vol 46 (3) ◽  
pp. 241-245 ◽  
Author(s):  
Hiroshi Mese ◽  
Akira Sasaki ◽  
Shuko Nakayama ◽  
Rafael E. Alcalde ◽  
Tomohiro Matsumura

1999 ◽  
Vol 19 (8) ◽  
pp. 5659-5674 ◽  
Author(s):  
Rakesh K. Srivastava ◽  
Steven J. Sollott ◽  
Leila Khan ◽  
Richard Hansford ◽  
Edward G. Lakatta ◽  
...  

ABSTRACT The proteins Bcl-2 and Bcl-XL prevent apoptosis, but their mechanism of action is unclear. We examined the role of Bcl-2 and Bcl-XL in the regulation of cytosolic Ca2+, nitric oxide production (NO), c-Jun NH2-terminal kinase (JNK) activation, and apoptosis in Jurkat T cells. Thapsigargin (TG), an inhibitor of the endoplasmic reticulum-associated Ca2+ATPase, was used to disrupt Ca2+ homeostasis. TG acutely elevated intracellular free Ca2+ and mitochondrial Ca2+ levels and induced NO production and apoptosis in Jurkat cells transfected with vector (JT/Neo). Buffering of this Ca2+ response with 1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid tetra(acetoxymethyl) ester (BAPTA-AM) or inhibiting NO synthase activity with N G-nitro-l-arginine methyl ester hydrochloride (l-NAME) blocked TG-induced NO production and apoptosis in JT/Neo cells. By contrast, while TG produced comparable early changes in the Ca2+ level (i.e., within 3 h) in Jurkat cells overexpressing Bcl-2 and Bcl-XL (JT/Bcl-2 or JT/Bcl-XL), NO production, late (36-h) Ca2+ accumulation, and apoptosis were dramatically reduced compared to those in JT/Neo cells. Exposure of JT/Bcl-2 and JT/Bcl-XL cells to the NO donor,S-nitroso-N-acetylpenacillamine (SNAP) resulted in apoptosis comparable to that seen in JT/Neo cells. TG also activated the JNK pathway, which was blocked by l-NAME. Transient expression of a dominant negative mutant SEK1 (Lys→Arg), an upstream kinase of JNK, prevented both TG-induced JNK activation and apoptosis. A dominant negative c-Jun mutant also reduced TG-induced apoptosis. Overexpression of Bcl-2 or Bcl-XL inhibited TG-induced loss in mitochondrial membrane potential, release of cytochromec, and activation of caspase-3 and JNK. Inhibition of caspase-3 activation blocked TG-induced JNK activation, suggesting that JNK activation occurred downstream of caspase-3. Thus, TG-induced Ca2+ release leads to NO generation followed by mitochondrial changes including cytochrome c release and caspase-3 activation. Caspase-3 activation leads to activation of the JNK pathway and apoptosis. In summary, Ca2+-dependent activation of NO production mediates apoptosis after TG exposure in JT/Neo cells. JT/Bcl-2 and JT/Bcl-XL cells are susceptible to NO-mediated apoptosis, but Bcl-2 and Bcl-XL protect the cells against TG-induced apoptosis by negatively regulating Ca2+-sensitive NO synthase activity or expression.


2003 ◽  
Vol 285 (5) ◽  
pp. G980-G991 ◽  
Author(s):  
Sujoy Bhattacharya ◽  
Ramesh M. Ray ◽  
Mary Jane Viar ◽  
Leonard R. Johnson

Intracellular polyamine homeostasis is important for the regulation of cell proliferation and apoptosis and is necessary for the balanced growth of cells and tissues. Polyamines have been shown to play a role in the regulation of apoptosis in many cell types, including IEC-6 cells, but the mechanism is not clear. In this study, we analyzed the mechanism by which polyamines regulate the process of apoptosis in response to tumor necrosis factor-α (TNF-α). TNF-α or cycloheximide (CHX) alone did not induce apoptosis in IEC-6 cells. Significant apoptosis was observed when CHX was given along with TNF-α, as indicated by a significant increase in the detachment of cells, caspase-3 activity, and DNA fragmentation. Polyamine depletion by treatment with α-difluoromethylornithine significantly reduced the level of apoptosis, as judged by DNA fragmentation and the caspase-3 activity of attached cells. Apoptosis in IEC-6 cells was accompanied by the activation of upstream caspases-6, -8, and -9 and NH2-terminal c-Jun kinase (JNK). Inhibition of JNK activation prevented caspase-9 activation. Polyamine depletion prevented the activation of JNK and of caspases-6, -8, -9, and -3. SP-600125, a specific inhibitor of JNK activation, prevented cytochrome c release from mitochondria, JNK activation, DNA fragmentation, and caspase-9 activation in response to TNF-α/CHX. In conclusion, we have shown that polyamine depletion delays and decreases TNF-α-induced apoptosis in IEC-6 cells and that apoptosis is accompanied by the release of cytochrome c, the activation of JNK, and of upstream caspases as well as caspase-3. Polyamine depletion prevented JNK activation, which may confer protection against apoptosis by modulation of upstream caspase-9 activation.


1999 ◽  
Vol 338 (1) ◽  
pp. 161-166 ◽  
Author(s):  
Wen-Chun HUNG ◽  
Hui-Chiu CHANG ◽  
Lea-Yea CHUANG

Sphingosine and other long-chain bases (including sphinganine, dimethylsphingosine and stearylamine), but not octylamine (a short-chain analogue of sphinganine), induced apoptosis in Hep3B hepatoma cells. Because both d- and l-erythrosphingosine and stearylamine exert potent apoptotic effects on Hep3B cells, it is possible that these long-chain bases may activate apoptosis by inhibiting protein kinase C (PKC) activity. However, pretreatment with the PKC activator PMA could not rescue cells from apoptosis triggered by long-chain bases. Therefore the involvement of PKC in this apoptotic process requires further characterization. We also investigated whether these long-chain bases might be metabolized into ceramide in order to elicit their apoptotic action. We found that long-chain bases acted independently of ceramide in the induction of apoptosis, since addition of fumonisin B1, a fungal agent which effectively inhibits ceramide synthesis from sphingosine, did not protect against apoptosis. Additionally, we found that sphingosine-induced apoptosis was accompanied by activation of caspases. The functional role of caspases in this apoptotic process was examined by using specific caspase inhibitors. The general caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp fluoromethyl ketone, which exhibits a broad specificity for caspase-family proteases, effectively blocked sphingosine-induced apoptosis. Furthermore, our results indicate that caspase-3-like proteases, but not caspase-1, are activated during apoptosis triggered by sphingosine. Enhancement of caspase-3-like activity and cleavage of poly(ADP-ribose) polymerase, an in vivo substrate for caspase-3, was clearly demonstrated in sphingosine-treated Hep3B cells. Considered together, these results suggest that caspase-3-like proteases participate in apoptotic cell death induced by sphingosine.


1998 ◽  
Vol 274 (4) ◽  
pp. C855-C860 ◽  
Author(s):  
King-Teh Lin ◽  
Ji-Yan Xue ◽  
Marie C. Lin ◽  
Eric G. Spokas ◽  
Frank F. Sun ◽  
...  

Apoptosis is an active process critical for the homeostasis of organisms. Enzymes of the caspase family are responsible for executing this process. We have previously shown that peroxynitrite (ONOO−), a biological product generated from the interaction of nitric oxide and superoxide, induces apoptosis of HL-60 cells. The aim of this study was to elucidate the mechanisms involved in the execution process of peroxynitrite-induced apoptosis. Proteolytic cleavage of poly(ADP-ribose) polymerase, an indication of caspase-3 family protease activation and an early biochemical event accompanying apoptosis, was observed in a time-dependent manner during peroxynitrite-induced apoptosis of HL-60 cells. Activation of caspase-3 during peroxynitrite-induced apoptosis was substantiated by monitoring proteolysis of the caspase-3 proenzyme and by measuring caspase-3 activity with a fluorogenic substrate. Furthermore, pretreatment of HL-60 cells with N-acetyl-Asp-Glu-Val-Asp-aldehyde, a specific inhibitor of caspase-3, but not N-acetyl-Tyr-Val-Ala-Asp-aldehyde, a specific inhibitor of caspase-1, decreased peroxynitrite-induced apoptosis. These results suggest that the activation of a caspase-3 family protease is essential for initiating the execution process of peroxynitrite-induced apoptosis of HL-60 cells.


1999 ◽  
Vol 73 (1) ◽  
pp. 702-708 ◽  
Author(s):  
Michael Bitzer ◽  
Florian Prinz ◽  
Manuel Bauer ◽  
Martin Spiegel ◽  
Wolfgang J. Neubert ◽  
...  

ABSTRACT Sendai virus (SV) infection and replication lead to a strong cytopathic effect with subsequent death of host cells. We now show that SV infection triggers an apoptotic program in target cells. Incubation of infected cells with the peptide inhibitor z-VAD-fmk abrogated SV-induced apoptosis, indicating that proteases of the caspase family were involved. Moreover, proteolytic activation of two distinct caspases, CPP32/caspase-3 and, as shown for the first time in virus-infected cells, FLICE/caspase-8, could be detected. So far, activation of FLICE/caspase-8 has been described in apoptosis triggered by death receptors, including CD95 and tumor necrosis factor (TNF)-R1. In contrast, we could show that SV-induced apoptosis did not require TNF or CD95 ligand. We further found that apoptosis of infected cells did not influence the maturation and budding of SV progeny. In conclusion, SV-induced cell injury is mediated by CD95- and TNF-R1-independent activation of caspases, leading to the death of host cells without impairment of the viral life cycle.


Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1782 ◽  
Author(s):  
Azarakhsh Oladzad ◽  
Maryam Nikkhah ◽  
Saman Hosseinkhani

The apoptotic protease-activating factor 1 (Apaf-1) split luciferase biosensor has been used as a biological tool for the detection of early stage of apoptosis. The effect of doxorubicin in a cell-based assay and the addition of cytochrome c and ATP in a cell-free system have been used to test the functionality of the reporter for the detection of apoptosome formation. Here, our data established a drug- and cytochrome c/ATP-independent way of apoptosis induction relying on the expression of the biosensor itself to induce formation of apoptosome. Overexpression of Apaf-1 constructs led to increased split luciferase activity and caspase-3 activity in the absence of any drug treatment. Caspase-3 activity was significantly inhibited when caspase-9DN was co-overexpressed, while the activity of the Apaf1 biosensor was significantly increased. Our results show that the Apaf-1 biosensor does not detect etoposide-induced apoptosis.


2021 ◽  
Author(s):  
qianqian chen ◽  
Yaqin Hou ◽  
Bingjie Hao ◽  
Zhou Ding ◽  
Qing Xia ◽  
...  

Abstract BackgroundNon-small cell lung cancer (NSCLC) accounts for approximately 85% of all lung cancers. Berberine (BBR), as an isoquinoline alkaloid, is commonly utilized in traditional Chinese medicine. Previous studies have proven that BBR possesses potential anti-tumor effect. However, the mechanism of on mitochondrial function in anti-NSCLC are still unknown.MethodsCell Counting Kit-8 (CCK-8), flow cytometry and western blotting were utilized to characterize the roles and relationships among BBR, ROS, ASK1, JNK, coxIV,caspase-3, cytochrome c ,bcl-2 and bax in NSCLC. Immunohistochemical (IHC) analysis was built to examine their expression in vivo.ResultsIn this study, we found that BBR potently suppressed NSCLC cells (A549 and PC9) growth by inducing apoptosis in a dose- and time-dependent manner. BBR induced apoptosis in NSCLC as evidenced by caspase-3 cleavage, cytochrome c release, and mitochondrial membrane depolarization. Furthermore, BBR induced ROS generation and ASK1 and JNK activation. To explore whether such apoptosis was linked to ROS production and ASK1 and JNK activation, we treated cells with a JNK inhibitor (SP600125), which significantly suppressed BBR-induced apoptosis. We further found that treating these cells with the anti-oxidant N-acetyl cysteine (NAC) was sufficient to both suppress ASK1 and JNK activation and to disrupt apoptotic induction.ConclusionsTogether, these data suggest that BBR induces NSCLC cells apoptosis via ROS-mediated ASK1/JNK and mitochondrial pathway activation.


Sign in / Sign up

Export Citation Format

Share Document