Release of cytochrome c and activation of pro-caspase-9 following lysosomal photodamage involves bid cleavage

Reiners, Jr Jj; Caruso, JA; Mathieu, Patricia; Chelladurai, Bhadrani; Yin, Xin; Kessel, David

doi:10.1038/sj.cdd.4401048

Cited by 304 publications

(297 citation statements)

References 50 publications

Supporting

Mentioning

273

Contrasting

Unclassified

Order By: Relevance

“…2). In this study, we used two photosensitizing agents: the chlorin termed NPe6 is known to target lysosomes but not Bcl-2, and mediates apoptosis via activation of the pro-apoptotic protein Bid [11]. The porphycene CPO does target Bcl-2 associated with the ER [3].…”

Section: Resultsmentioning

confidence: 99%

Protection of Bcl-2 by salubrinal

Kessel

2006

Biochemical and Biophysical Research Communications

View full text Add to dashboard Cite

The drug salubrinal has been identified as an inhibitor of phosphatases that act on the eukaryotic translation initiation factor 2 subunit (eIF2α). The resulting maintenance of protein phosphorylation results in enhanced protection from the adverse effects of initiators of the unfolded protein response. We found that salubrinal can also interact with the anti-apoptotic protein Bcl-2, inhibiting binding of the non-peptidic antagonist HA14-1 and of a porphycene that can catalyze Bcl-2 photodamage. As a result, salubrinal offers protection from the apoptotic and autophagic effects that can result from loss of Bcl-2 function. KeywordsApoptosis; Autophagy; Bcl-2; Photodynamic; Salubrinal Promotion of eIF2α phosphorylation results in a halt in protein synthesis, permitting cells to recover from consequences of endoplasmic reticulum (ER) stress that can otherwise lead to apoptosis [1]. The drug salubrinal was identified as a selective inhibitor of phosphatases that act on eIF2α [2], thereby maintaining protein phosphorylation and offering protection from the adverse effects of ER stress, e.g., as induced by the drug tunicamycin.We have now examined the ability of salubrinal to protect murine leukemia L1210 cells from another inducer of ER stress: photodamage mediated by a porphycene termed 'CPO' that binds to the ER [3]. Irradiation of cells containing CPO initiates apoptosis as a result of photodamage to the anti-apoptotic protein Bcl-2 associated with the ER [3,4]. Effects of ER photodamage on other stress-related phenomena have not been characterized. We now report that salubrinal protects cells from the pro-apoptotic effect of ER photodamage, a phenomenon that is, however, not associated with effects on eIF2α phosphorylation. We then examined the possibility that salubrinal could protect Bcl-2 from photodamage.Additional studies were carried out using HA14-1, a non-peptidic antagonist of the antiapoptotic functions of Bcl-2 family proteins. A computer screening approach was used to identify this agent as a ligand for the surface pocket on the Bcl-2 protein [5]. If the protection offered by salubrinal from the pro-apoptotic effects of ER photodamage was associated with a direct protective effect on Bcl-2, we considered it possible that this drug might also protect Bcl-2 from both pro-apoptotic [6] Cells and maintenanceMurine leukemia L1210 cells were grown in Fisher's medium (Sigma-Aldrich) containing 10% horse serum and 1 mM glutamine, 1 mM mercaptoethanol, and gentamicin. Since, Fisher's medium is no longer commercially available, we supplemented the α-MEM formulation (Sigma-Aldrich) with MgCl 2 (45 mg/l), methionine (75 mg/l), phenylalanine (30 mg/l), valine (30 mg/l), and folic acid (9 mg/l). Clonogenic assays were used to determine loss of viability (LD 90 values) after a 60 min exposure to HA14-1. Serial dilutions of cell suspensions were plated on soft agar. After 7-9 day growth in a humidified chamber under 5% CO 2 , colonies were counted and compared with untreated control values. All such experime...

show abstract

Section: Resultsmentioning

confidence: 99%

Protection of Bcl-2 by salubrinal

Kessel

2006

Biochemical and Biophysical Research Communications

View full text Add to dashboard Cite

show abstract

“…Interestingly, in mouse L5178Y-R cells exposed to low doses of PDT, cytochrome C was released from mitochondria without loss of mitochondrial membrane potential, suggesting that the release of cytochrome C is independent of the loss of mitochondrial membrane potential [70]. Photosensitization of hepatoma Hepa 1c1c7 cells with the lysosomal sensitizer Npe6 also induced the release of cytochrome C and activated caspase-9 and caspase-3-like activity before depolarization of the mitochondrial membrane [60]. It was proposed that these sensitizers may disrupt lysosomes, releasing protease(s) into the cytosol which may convert Bid into a truncated form (tBid).…”

Section: Role Of Caspases In Pdtmentioning

confidence: 95%

“…It was proposed that these sensitizers may disrupt lysosomes, releasing protease(s) into the cytosol which may convert Bid into a truncated form (tBid). In this case, tBid would trigger the release of cytochrome C, thereby activating Apaf-1/pro-caspase-9 [60].…”

Section: Role Of Caspases In Pdtmentioning

confidence: 99%

Intracellular signaling mechanisms in photodynamic therapy

Almeida

Manadas

Carvalho

et al. 2004

Biochimica et Biophysica Acta (BBA) - Reviews on Cancer

242

292

View full text Add to dashboard Cite

In photodynamic therapy (PDT) a sensitizer, light and oxygen are used to induce death of tumor cells and in the treatment of certain noncancerous conditions. Cell death in PDT may occur by apoptosis or by necrosis, depending on the sensitizer, on the PDT dose and on the cell genotype. Some sensitizers that have been used in PDT are accumulated in the mitochondria, and this may explain their efficiency in inducing apoptotic cell death, both in vitro and in vivo. In this review we will focus on the events that characterize apoptotic death in PDT and on the intracellular signaling events that are set in motion in photosensitized cells. Activation of phospholipases, changes in ceramide metabolism, a rise in the cytosolic free Ca 2 + concentration, stimulation of nitric oxide synthase (NOS), changes in protein phosphorylation and alterations in the activity of transcription factors and on gene expression have all been observed in PDT-treated cells. Although many of these metabolic reactions contribute to the demise process, some of them may antagonize cell death. Understanding the signaling mechanisms in PDT may provide means to modulate the PDT effects at the molecular level and potentiate its antitumor effectiveness. D

show abstract

“…This involved release of lysosomal proteolytic enzymes into the cytosol, leading to caspase-3 activation and DNA fragmentation [24]. A more detailed study revealed further details of this process [25]. Release of lysosomal enzymes after PDT resulted in cleavage of the pro-apoptotic protein Bid to a truncated form termed tBid.…”

Section: Apoptosis After Lysosomal Photodamagementioning

confidence: 99%

Death pathways associated with photodynamic therapy

Kessel

2006

Medical Laser Application

View full text Add to dashboard Cite

When the mitochondria and/or the endoplasmic reticulum were targeted by photodynamic therapy, photodamage to the anti-apoptotic protein Bcl-2 was observed. This led to an apoptotic outcome if that death pathway was available. Lysosomal photodamage ultimately resulted in activation of the pro-apoptotic protein Bid, also leading to apoptosis. Photodamage to the plasma membrane was associated with migration of sensitizers to the cytosol and procaspase photodamage, with apoptosis impaired. Where apoptosis was unavailable because of lack of necessary components of the program, an autophagic outcome has been observed. It is also clear that autophagy can occur along with apoptosis as a PDT response, and may play a role in immunologic responses to photodamaged tumor cells.

show abstract

Release of cytochrome c and activation of pro-caspase-9 following lysosomal photodamage involves bid cleavage

Cited by 304 publications

References 50 publications

Protection of Bcl-2 by salubrinal

Protection of Bcl-2 by salubrinal

Intracellular signaling mechanisms in photodynamic therapy

Death pathways associated with photodynamic therapy

Contact Info

Product

Resources

About