Apoptotic regulation is critical to organismal homeostasis and protection against many human disease processes such as cancer. Significant research efforts over the past several decades have illuminated many signaling molecules and effecter proteins responsible for this form of programmed cell death. Recent evidence suggests that transfer RNA (tRNA) regulates apoptotic sensitivity at the level of cytochrome c-mediated apoptosome formation. This finding unexpectedly places tRNA at the nexus of cellular biosynthesis and survival. Here we review the current understanding of both the apoptotic machinery and tRNA biology. We describe the evidence linking tRNA and cytochrome c in depth, and speculate on the implications of this link in cell biology.
Animals ; Apoptosis ; genetics ; physiology ; Caspase 9 ; physiology ; Cytochromes c ; physiology ; Humans ; Models, Biological ; Nucleic Acid Conformation ; RNA, Transfer ; chemistry ; genetics ; physiology

To investigate the role of mitochondria in neuronal apoptosis, ischemia-reperfusion mediated neuronal cell injury model was established by depriving of glucose, serum and oxygen in media. DNA fragmentation, cell viability, cytochrome C releasing, caspase3 activity and mitochondrial transmembrane potential were observed after N2a cells suffered the insults. The results showed that N2a cells in ischemic territory exhibited survival damage, classical cell apoptosis change, DNA ladder and activation of caspase3. Apoptosis-related alterations in mitochondrial functions, including release of cytochrome C and depression of mitochondrial transmembrane potential (deltapsim) were testified in N2a cells after mimic ischemia-reperfusion. Moreover, activation of caspase3 occurred following the release of cytochrome C. However, the inhibitor of caspase3, Ac-DEVD-CHO, couldn't completely rescue N2a cells from apoptosis. Administration of cyclosporine A, an inhibitor of mitochondria permeability transition pore only partly inhibited caspase3 activity and reduced DNA damage. Interestingly, treatment of Z-IETD-FMK, an inhibitor of caspase8 could completely reverse DNA fragmentation, but can't completely inhibit caspase3 activity. It was concluded that there were caspase3 dependent and independent cellular apoptosis pathways in N2a cells suffering ischemia-reperfusion insults. Mitochondria dysfunction may early trigger apoptosis and amplify apoptosis signal.
Animals ; Apoptosis ; physiology ; Caspase 3 ; Caspases ; biosynthesis ; Cytochromes c ; biosynthesis ; Mice ; Mitochondria ; physiology ; Neuroblastoma ; pathology ; Neurons ; pathology ; Reperfusion Injury ; metabolism ; pathology ; Tumor Cells, Cultured

delta12-Prostaglandin (PG) J2 is known to elicit an anti-neoplastic effects via apoptosis induction. Previous study showed delta12-PGJ2-induced apoptosis utilized caspase cascade through cytochrome c-dependent pathways in HeLa cells. In this study, the cellular mechanism of delta12-PGJ2- induced apoptosis in HeLa cells, specifically, the role of two mitochondrial factors; bcl-2 and apoptosis-inducing factor (AIF) was investigated. Bcl-2 attenuated delta12-PGJ2-induced caspase activation, loss of mitochondrial transmembrane potential (delta psi m), nuclear fragmentation, DNA laddering, and growth curve inhibition for approximately 24 h, but not for longer time. AIF was not released from mitochondria, even if the delta psi m was dissipated. One of the earliest events observed in delta12-PGJ2-induced apoptotic events was dissipation of delta psi m, the process known to be inhibited by bcl-2. Pre-treatment of z-VAD- fmk, the pan-caspase inhibitor, resulted in the attenuation of delta psi m depolarization in delta12-PGJ2- induced apoptosis. Up-regulation of Sox-4 protein by delta12-PGJ2 was observed in HeLa and bcl-2 overexpressing HeLa B4 cell lines. Bcl-2 overexpression did not attenuate the expression of Sox-4 and its expression coincided with other apoptotic events. These results suggest that delta12-PGJ2 induced Sox-4 expression may activate another upstream caspases excluding the caspase 9-caspase 3 cascade of mitochondrial pathway. These and previous findings together suggest that delta12-PGJ2-induced apoptosis in HeLa cells is caspase-dependent, AIF-independent events which may be affected by Sox-4 protein expression up-regulated by delta12-PGJ2.
Amino Acid Chloromethyl Ketones/pharmacology ; Antineoplastic Agents/*pharmacology ; Apoptosis/drug effects/*physiology ; Caspases/physiology ; Cytochromes c/physiology ; Female ; Flavoproteins/metabolism/*physiology ; Hela Cells ; High Mobility Group Proteins/*physiology ; Humans ; Membrane Proteins/metabolism/*physiology ; Mitochondria/metabolism/physiology ; Prostaglandin D2/*pharmacology ; Protein Transport/physiology ; Proto-Oncogene Proteins c-bcl-2/biosynthesis/*physiology ; Research Support, Non-U.S. Gov't ; Trans-Activation (Genetics) ; Trans-Activators/*physiology

OBJECTIVETo construct a plasmid carrying granulysin (GLS) and to study the effect of the GLS on apoptosis, mitochondrial transmembrane potential and cytochrome C release of SMMC-7721 cells.

METHODSThe coding sequence of the GLS was amplified from the total RNA of human CTL cells, and it was inserted into pBudCE4.1 plasmid and then it was used to transfect SMMC-7721 cells. The expression of GLS was detected by RT-PCR and confirmed by immunocytochemistry method. Cell apoptosis was ascertained by Hoechst staining and electron microscopy; mitochondrial transmembrane potential was detected using Mitocapture and cytochrome C release was studied using Western blot.

RESULTSRecombinant pBudCE4.1/GLS plasmid was successfully constructed. GLS protein was successfully expressed in the SMMC-7721 cells and it induced apoptosis of the SMMC-7721 cells, and at the same time, mitochondrial transmembrane potential was reduced and cytochrome C was released from mitochondria into the cytosol.

CONCLUSIONSGLS gene carried by recombinant plasmid could express in SMMC-7721 cells and induce cells apoptosis. The change of mitochondrial transmembrane potential and the release of cytochrome C might be one of the key factors of apoptosis induced by GLS.

Antigens, Differentiation, T-Lymphocyte ; pharmacology ; Apoptosis ; drug effects ; Cell Line, Tumor ; Cytochromes c ; metabolism ; Humans ; Membrane Potential, Mitochondrial ; drug effects ; Mitochondria ; drug effects ; metabolism ; physiology

BACKGROUNDNeuroblastoma (NB) is one of the most common malignant solid tumors of childhood. It is still not clear whether the apoptosis of tumor cells or the non-tumor cells contributes to the increase of concentration of cytochrome c (Cyt c) in the serum of the cancer patients. The aim of this research was to identify the source of the Cyt c in the serum when the tumor grows up by subcutaneous inoculation of human NB cells into nude mice.

METHODSWe subcutaneously inoculated human NB cells (KP-N-NS) into nude mice and collected the sera of tumor-bearing mice (n = 14) and control mice (n = 25) 4 weeks later in order to screen for and identify differentially expressed proteins in the serum. Differentially expressed proteins in the serum were screened by surface-enhanced laser desorption/ionization-time-of-flight (SELDI-TOF) mass spectrometry.

RESULTSThe relative intensity of a protein having a mass-to-charge ratio (m/z) of 11 609 was 3338.37 ± 3410.85 in the tumor group and 59.84 ± 40.74 in the control group, indicating that the expression level of this protein in the tumor group was 55.8 times higher than that in the control group. Serum proteins were separated and purified by high-performance liquid chromatography (HPLC). Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was performed to produce peptide mass fingerprints (PMFs). Spectrum analysis and a database search revealed that the highly expressed protein (m/z = 11 605.4) from the serum of tumor-bearing mice was the mouse Cyt c.

CONCLUSIONSIncreased concentration of Cyt c in the serum of tumor-bearing nude mice might be partially attributed to the secretion of this protein by non-tumor cells.

Animals ; Apoptosis ; physiology ; Cell Line, Tumor ; Chromatography, High Pressure Liquid ; Cytochromes c ; blood ; Female ; Humans ; Mice ; Mice, Nude ; Neuroblastoma ; blood ; Tandem Mass Spectrometry ; Xenograft Model Antitumor Assays

OBJECTIVETo investigate cell apoptosis, mitochondrial membrane potential, cytochrome C and mechanisms of mitochondria in lymphocyte apoptosis of sepsis.

METHODSIn the research, female C57BL/6 mice whose body weight ranged from 17 to 25 grams were utilized and assigned randomly to two groups: sham operated group (Control), cecal ligation and puncture group (CLP). The present study was undertaken by using the mice splenic lymphocyte to investigate cell apoptosis, mitochondrial membrane potential, cytochrome C. The apoptosis alteration was evaluated by Annexin V-FITC/PI double staining with flow cytometry. The alteration of mitochondrial membrane potential was investigated by Rhodamine-123 staining of cells. Cytochrome C of mitochondria and cytosol was investigated by Western blot methods. Statistical analysis was performed using SPSS 11.5 for Windows software. Experiment data was indicated with mean ± standard.

RESULTSThe splenic lymphocyte apoptosis was significantly accelerated in the CLP group when compared with that in control group (17.3% ± 2.2% vs. 3.5% ± 0.5%, P < 0.05). The Rhodamine-123 fluorescent intensity in splenic lymphocyte apoptosis was reduced in CLP group (76.2% ± 1.6%). Comparison between sham group (99.6% ± 0.4%) and CLP group had statistical significance (P < 0.05). Apoptosis could induce mitochondrial cytochrome C release into cytoplasm. In the CLP group, elevation of cytochrome C in cytosol was concurrently in accordance with decline in mitochondrial cytochrome C content.

CONCLUSIONThese data suggest that mitochondria and mitochondria signal pathway play an important role in lymphocyte apoptosis of sepsis.

Animals ; Apoptosis ; Cells, Cultured ; Cytochromes c ; metabolism ; Disease Models, Animal ; Female ; Lymphocytes ; metabolism ; pathology ; Mice ; Mice, Inbred C57BL ; Mitochondria ; metabolism ; physiology ; Sepsis ; metabolism ; pathology

Cyclopentenone prostaglandins (PGs) have antiproliferative activity on various tumor cell growth in vitro. Particularly, 9-deoxy-(9,12)-13,14-dihydro PGD2( delta12-PGJ2) was reported for its antineoplastic and apoptotic effects on various cancer cells, but its mechanism inducing apoptosis is still not clear. In this study, we have characterized apoptosis induced by delta12-PGJ2in HeLa cells. Treatment of delta12-PGJ2induced apoptosis as indicated by DNA fragmentation, chromatin condensation, and formation of apoptotic body. We also observed release of cytochrome c from mitochondria and activation of caspase cascade including caspase-3, -8, and -9. And the pan-caspase inhibitor z-Val-Ala-Asp (OMe) fluoromethyl-ketone (z-VAD-fmk) and Q-Val-Asp (OMe)-CH2-OPH (Q-VD (OMe)-OPH) prevented cell death induced by delta12-PGJ2 showing participation of caspases in this process. However, protein expression level of Bcl-2 family was not altered by delta12-PGJ2, seems to have no effect on HeLa cell apoptosis. And ZB4, an antagonistic Fas-antibody, exerted no effect on the activation of caspase 8 indicating that Fas receptor-ligand interaction was not involved in this pathway. Treatment of delta12-PGJ2 also leads to suppression of nuclear factor kappaB (NF-kappaB) as indicated by nuclear translocation of p65/RelA and c-Rel and its DNA binding ability analyzed by EMSA. Taken together, our results suggest that delta12-PGJ2-induced apoptosis in HeLa cell utilized caspase cascade without Fas receptor-ligand interaction and accompanied with NF-kappaB inactivation.
Antigens, CD95/metabolism ; Apoptosis/*physiology ; Caspases/metabolism ; Cytochromes c/*metabolism ; Hela Cells ; Human ; NF-kappa B/metabolism ; Prostaglandin D2/*analogs & derivatives/*metabolism ; Proto-Oncogene Proteins c-bcl-2/metabolism

OBJECTIVETo explore the effects of hyperbaric oxygen (HBO) treatment on the neuronal apoptosis at an earlier stage and the expressions of Cytochrome C (Cyt C), Bcl-2 (B-cell lymphoma-2 family) and Bax (Bcl-2 associated X protein) in rat brain tissues after traumatic brain injury (TBI).

METHODSForty adult rats were divided into two groups, i.e., Group A (the rats with untreated TBI) and Group B (rats with HBO treatment after TBI). Sections of brain tissues of these two groups were then detected at 3, 6, 12, 24, 72 hours after TBI by immunohistochemistry and electronmicroscope, respectively.

RESULTSHBO treatment could up-regulate the expression of Bcl-2 within 72 hours, reduce the release of Cyt C from mitochondria, attenuate the formation of dimeric Bax and alleviate the mitochondrial edema within 24 hours after TBI.

CONCLUSIONSHBO treatment can alleviate neuronal apoptosis after TBI by reducing the release of Cyt C and the dimers of Bax and up-regulating the expression of Bcl-2.

Analysis of Variance ; Animals ; Apoptosis ; physiology ; Brain Injuries ; pathology ; therapy ; Cytochromes c ; biosynthesis ; Disease Models, Animal ; Hyperbaric Oxygenation ; Immunohistochemistry ; Male ; Proto-Oncogene Proteins c-bcl-2 ; biosynthesis ; Rats ; Rats, Sprague-Dawley ; bcl-2-Associated X Protein ; biosynthesis

The objective of this paper was to investigate the contribution of mitochondrial ATP-sensitive K+ channel (mitoK(ATP)) and mitochondrial membrane potential (Deltapsim) to the distribution of cytochrome C in human pulmonary arterial smooth muscle cells (HPASMCs) and to the proliferation of HPASMCs induced by hypoxia. HPASMCs were divided into 6 groups, as following: (1) control group: cultured under normoxia; (2) diazoxide group: cultured in normoxia with diazoxide, an opener of mitoK(ATP); (3) 5-HD group: cultured in normoxia with 5-hydroxydecanoate (5-HD), an antagonist of mitoK(ATP); (4) 24-hour hypoxia group: cultured in hypoxia for 24 h; (5) 24-hour hypoxia + diazoxide group: cultured in hypoxia with diazoxide for 24 h; (6) 24-hour hypoxia + 5-HD group: cultured in hypoxia with 5-HD for 24 h. The relative changes in mitochondrial potential were tested with rhodamine fluorescence (R-123) technique. Western blot was used to detect the expression of cytochrome C protein in cell plasma and mitochondria,respectively. The expression of cell caspase-9 protein was determined with Western blot. The proliferation of HPASMCs was examined by cell cycle analysis and MTT colorimetric assay. The results were as following: after exposure to diazoxide for 24 h, the intensity of R-123 fluorescence in normoxic HPASMCs was significantly increased compared with that in the control group (P<0.05), but there was no significant change of the intensity of R-123 fluorescence after the HPASMCs had been exposed to 5-HD for 24 h; 24-hour hypoxia or 24-hour hypoxia + diazoxide could markedly increase the intensity of R-123 fluorescence in HPASMCs compared with normoxia (P<0.05), and the change was more significant in 24-hour hypoxia + diazoxide group than that in 24-hour hypoxia group (P<0.05); 5-HD could weaken the effect of 24-hour hypoxia on the intensity of R-123 fluorescence. After exposure to diazoxide for 24 h, the ratio of the expression of cytosolic cytochrome C protein to that of mitochondrial cytochrome C protein was significantly decreased compared with that in the control group (P<0.05), and the expression of caspase-9 protein was significantly decreased compared with that in the control group (P<0.05). The percentage of S phase and A value of MTT were significantly increased compared with those in the control group (P<0.05). But there were no significant changes in these tests after HPASMCs had been exposed to 5-HD for 24 h (P>0.05). After exposure to hypoxia or hypoxia + diazoxide for 24 h, the ratio of the expression of cytosolic cytochrome C protein to that of mitochondrial cytochrome C protein and the expression of caspase-9 protein were significantly decreased compared with those in the control group (P<0.05). The percentage of S phase and A value of MTT were significantly increased compared with those in the control group (P<0.05). These changes were more significant in 24-hour hypoxia + diazoxide group than those in 24-hour hypoxia group (P<0.05). 5-HD could weaken the effect of hypoxia on the changes of the distribution of cytochrome C, the expression of caspase-9 in HPASMCs and the proliferation of HPASMCs induced by hypoxia (P<0.05). All these results suggest that the opening of mitoK(ATP) followed by a depolarization of Deltapsim induced by hypoxia might contribute to the inhibition of the release of cytochrome C from mitochondria to plasma in HPASMCs. This might be a mechanism of the development of hypoxic pulmonary hypertension. The signal transduction pathway of mitochondria might play an important role in the relationship between Deltapsim and apoptosis of HPASMCs.
Cell Hypoxia ; Cell Proliferation ; Cells, Cultured ; Cytochromes c ; metabolism ; Humans ; Hypertension, Pulmonary ; physiopathology ; Membrane Potential, Mitochondrial ; physiology ; Muscle, Smooth, Vascular ; cytology ; pathology ; Myocytes, Smooth Muscle ; metabolism ; pathology ; Potassium Channels ; physiology ; Pulmonary Artery ; cytology ; metabolism ; pathology ; Signal Transduction

The purpose of study was to explore the possible functions of Bcl-xL in the glucosamine sulfate-induced apoptosis of chronic myeloid leukemia K562 cells. Light microscopy and Wright-Giemsa staining were used to investigate the morphologic evidences for apoptosis of K562 cells induced by glucosamine sulfate (GS); immunofluorescence was used to observe the translocation of cathepsin D and cytochrome C during the apoptosis; Western blot was performed to detect the expression of Bcl-xL, Bid, Bax in K562 cells treated by GS. The results showed that many vacuoles were observed in the cytoplasma of the K562 cells treated by GS; fluorescent signals of cathepsin D and cytochrome were fransformed from granules to disperse form by using immunofluorescence; the expression of Bcl-xL was found down-regulated in K562 cells treated by GS, but not in the cells pre-treated with pepstatin A; the significant changes were not detected in expression of Bax and Bid protein before or after apoptosis. It is concluded that Bcl-xL protein may mediate relationship between cathepsin D and mitochondia pathway, Cathepsin D may play an important role in the GS inducing apoptosis of K562 cells through downregulation of Bcl-xL expression.
Apoptosis ; drug effects ; physiology ; BH3 Interacting Domain Death Agonist Protein ; metabolism ; Blotting, Western ; Cathepsin D ; metabolism ; Cytochromes c ; metabolism ; Fluorescent Antibody Technique ; Glucosamine ; pharmacology ; Humans ; K562 Cells ; bcl-2-Associated X Protein ; metabolism ; bcl-X Protein ; metabolism ; physiology