This study was aimed to investigate the relation of MCL-1 and BAK proteins with incidence and development of nutritional anemia (NA) and their clinical significance. The MCL-1 and BAK protein levels in serum of 66 patients with NA were determined by using ELISA. Eighteen healthy people were randomly selected as normal controls. The results indicated that: (1) as compared with normal control group, the expression level of MCL-1 protein in 3 NA groups (iron-deficiency anemia, macrocytic anemia, mixed anemia) significantly decreased (P < 0.001), while the expression level of BAK protein obviously increased (P < 0.001), but the expression level of MCL-1 and BAK proteins among 3 NA groups showed no obvious differences; (2) the MCL-1 protein expression level increased and BAK protein expression level decreased in 3 NA groups after treatment (P < 0.05). (3) there was negative correlation of expression levels of MCL-1 protein with BAK protein in NA group (r = -0.858 P < 0.05). It is concluded that the MCL-1 and BAK proteins may play an important role in the incidence and development of NA, and can be used as the assist index for defining diagnosis and evaluate prognosis of NA.
Anemia ; metabolism ; pathology ; Apoptosis ; Case-Control Studies ; Humans ; Malnutrition ; metabolism ; pathology ; Myeloid Cell Leukemia Sequence 1 Protein ; metabolism ; bcl-2 Homologous Antagonist-Killer Protein ; metabolism

OBJECTIVETo investigate the growth inhibition effect, cytotoxicity and apoptotic induction of harringtonine (HT) in human acute promyelocytic leukemia (APL) NB4 cells,and the related mechanism.

METHODSNB4 cells were treated with HT. Total cell numbers were counted by hemocytometer, and cell viabilities were determined by trypan blue exclusion. Apoptotic cells were determined by fluorescence microscopy and FACS after staining with AO and EB or PI, respectively. The cleavage of PARP and the activation of Bax and the expression of anti-apoptotic proteins were determined by Western Blot. siRNA was used to silence the expression of target genes. Primary cells were isolated following Ficoll-Hypaque density gradient centrifugation method.

RESULTSHT inhibited cell growth and induced apoptosis of NB4 cells in a dose- and time-dependent manner. Apoptosis induced by HT was correlated with the down-regulation of Mcl-1 and the cleavage of PARP, while HT did not affect the protein level of Bax and Bak or change the protein level of Bcl-2. The silence of Bcl-XL sensitized HT-induced apoptosis in NB4 cells.Apoptosis induced by HT in primarily cultured APL cells was also correlated with the down-regulation of Mcl-1.

CONCLUSIONHT inhibits cell growth and induces apoptosis in NB4 cells and primarily cultured APL cells, which may be associated with down-regulation of Mcl-1.

Apoptosis ; drug effects ; Cell Line, Tumor ; Harringtonines ; pharmacology ; Humans ; Leukemia, Promyelocytic, Acute ; metabolism ; pathology ; Proteins ; metabolism ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; bcl-2 Homologous Antagonist-Killer Protein ; metabolism ; bcl-2-Associated X Protein ; metabolism

OBJECTIVETo investigate miR- 125b regulation mechanism by identifying miR-125b target genes and its function in acute myeloid leukemia (AML).

METHODSThe bioinformatics software and database were applied to predict and analyze target genes of miR-125b. The vector contained the target gene 3'-UTR portion cloned into a luciferase reporter construct. A luciferase reporter assay was performed following co-transfection of small molecular miR-125b mimics and target gene wild-type or mutant plasmid into HEK-293T cells. Further in leukemia cell lines NB4 and HL-60, the protein level of target gene was measured by Western blot after overexpression miR-125b. Finally, the viabilities of NB4 and HL-60 cells were measured by CCK-8 assay at 24 h, 48 h, 72 h, 96 h after electroporation.

RESULTSBcl-2-antagonist/killer 1 (Bak1), a pro-apoptotic gene, was a target gene of miR-125b by software predicts. Reporter vector containing the 3'-UTR Bak1 wild and mutation sites were co-transfected with small molecule analogues of miR-125b in HEK-293T cells. Dual luciferase reporter gene assay system showed that miR-125b significantly suppresses the reporter gene activity containing Bak1 3'-UTR by about 53.8% (P<0.05), but it didn't suppresses the reporter gene activity containing 3'-UTR Bak1 mutation. Western blot showed that miR-125b mimics significantly down-regulated the expression of Bak1 in human leukemia cell lines NB4 and HL-60. Meanwhile, the growth rate of cells treated with miR-125b obviously increased compared with that in control by CCK-8 test (P<0.05).

CONCLUSIONOur findings strongly indicated that BAK1 was a downstream target gene of miR-125b, and miR-125b promoted proliferation in human AML cells at least partially by targeting Bak1, so we speculated that miR-125b as an oncogene could be a potential therapeutic target for treating AML.

Cell Line, Tumor ; Cell Proliferation ; Genetic Vectors ; HEK293 Cells ; HL-60 Cells ; Humans ; MicroRNAs ; genetics ; Transfection ; bcl-2 Homologous Antagonist-Killer Protein ; genetics ; metabolism

OBJECTIVETo investigate the inhibitory effect of small interfering RNA (siRNA) targeting Bax-Bak on the apoptosis of human granulosa cells.

METHODSHuman granulosa cells were transfected with Bax-siRNA and Bak-siRNA either alone or in comibnation, and the cell morphological changes were obsered and the cell apoptosis was detected with flow cytometry. Western blotting was performed to examine the changes in Bax and Bak expressions in the transfected cells.

RESULTSWestern blotting demonstrated significantly weakened expressions of Bax and Bak in the transfected cells. The cell morphology of the cells tranfected with Bak siRNA and with both Bak and Bax siRNA remained normal; the cells with exclusive Bax siRNA transfection presented with basically normal cell morphology, but black spots were noted in the cytoplasm. In the positive and negative control groups, the cells became rounded and shrank with expanded intercellular spaces and numerous black spots in the cytoplasm. Flow cytometry showed apoptotic indexes of 3.44% and 3.97% in cells transfected with Bak siRNA and Bax-Bak siRNA, respectively, significantly lower than that in the negative group. Bax siRNA transfection resulted in an apoptotic index of 19.98%, similar to that in the negative group.

CONCLUSIONInterference of the expression of Bak gene inhibits the apoptosis of human granulosa cells, and the inhibitory effect can be enhanced by simultaneous Bax interference, which, when used alone, does not obviosuly inhibit the apoptosis of human granulosa cells.

Apoptosis ; genetics ; Cells, Cultured ; Female ; Granulosa Cells ; cytology ; Humans ; RNA Interference ; RNA, Small Interfering ; genetics ; Transfection ; bcl-2 Homologous Antagonist-Killer Protein ; genetics ; metabolism ; bcl-2-Associated X Protein ; genetics ; metabolism

This study was aimed to investigate the effects of valproic acid sodium (VPA) on the proliferation and apoptosis of acute T-lymphoblastic leukemia Jurkat cells. Jurkat cells were treated with different concentration of VPA. Proliferation-inhibition curve was assayed and plotted by CCK-8 method and the cell apoptosis was detected by flow cytometry with Annexin V/PI double staining. The expression level of anti-apoptotic gene BCL-2 and pro-apoptosis gene Bak1 were detected by semi-quantitative RT-PCR. The results showed that the VPA inhibited the proliferation of Jurkat cells in concentration-dependent manner. As compared with the control group, the apoptosis of cells increased along with adding concentration of VPA; VPA could decrease the expression of BCL-2 gene, but did not show obvious effect on the expression of Bak1. It is concluded that the VPA can inhibit proliferation of Jurkat cells which possibly associates with the decrease of BCL-2 expression.
Apoptosis ; drug effects ; Cell Proliferation ; drug effects ; Humans ; Jurkat Cells ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Sodium ; pharmacology ; Valproic Acid ; pharmacology ; bcl-2 Homologous Antagonist-Killer Protein ; metabolism

One group of Bcl-2 protein family, which shares only the BH3 domain (BH3-only), is critically involved in the regulation of programmed cell death. Herein we demonstrated a novel human BH3-only protein (designated as Bop) which could induce apoptosis in a BH3 domain-dependent manner. Further analysis indicated that Bop mainly localized to mitochondria and used its BH3 domain to contact the loop regions of voltage dependent anion channel 1 (VDAC1) in the outer mitochondrial membrane. In addition, purified Bop protein induced the loss of mitochondrial transmembrane potential (Δψm) and the release of cytochrome c. Furthermore, Bop used its BH3 domain to contact pro-survival Bcl-2 family members (Bcl-2, Bcl-X(L), Mcl-1, A1 and Bcl-w), which could inhibit Bop-induced apoptosis. Bop would be constrained by pro-survival Bcl-2 proteins in resting cells, because Bop became released from phosphorylated Bcl-2 induced by microtubule-interfering agent like vincristine (VCR). Indeed, knockdown experiments indicated that Bop was partially required for VCR induced cell death. Finally, Bop might need to function through Bak and Bax, likely by releasing Bak from Bcl-X(L) sequestration. In conclusion, Bop may be a novel BH3-only factor that can engage with the regulatory network of Bcl-2 family members to process intrinsic apoptotic signaling.
Amino Acid Sequence ; Animals ; Apoptosis ; Cell Line ; Cell Survival ; Humans ; Mice ; Mitochondria ; metabolism ; Mitochondrial Membranes ; metabolism ; Molecular Sequence Data ; Protein Structure, Tertiary ; Protein Transport ; Proto-Oncogene Proteins c-bcl-2 ; chemistry ; metabolism ; Signal Transduction ; Time Factors ; Voltage-Dependent Anion Channel 1 ; metabolism ; bcl-2 Homologous Antagonist-Killer Protein ; metabolism ; bcl-2-Associated X Protein ; metabolism

OBJECTIVETo establish osteoblast apoptosis model induced by gingipains, and to examine the expression of pro-apoptotic protein Bcl-2 interacting mediator (Bim), Bcl-2 associated X protein (Bax) and Bcl-2 antagonist/killer (Bak).

METHODSGingipain and gingipain acticity were extracted and measured. Mouse osteoblast cell line MC3T3-E1 cells were cultured in the presence of 0.453, 0.906, 1.812 U/L gingipains for 0, 16, 24 and 48 h. Apoptosis was examined by 4',6-diamidino-2-phenylindole (DAPI) staining or annexin V/propidine iodide (PI) staining.Protein expression of Bim, Bax and Bak was determined by Western blotting after osteoblasts were cultured with 1.812 U/L gingipain for 0, 4, 8, 16, 24 and 48 h. Osteoblasts were cultured with 1.812 U/L gingipain which had been inhibited with N-alpha-tosyl L-lysyl-chlorom ethylketone (TLCK). Western blotting was used to detect Bim expression and DAPI staining to measure apoptosis.

RESULTSArginine-specific proteinases (Rgp) activity was (18.11 ± 2.11) U/L and specific proteinases (Kgp) was (1.02 ± 0.25) U/L. Percentage of osteoblast apoptosis induced by 1.812 U/L gingipain rose to (6.31 ± 0.37)% after 16 h, and reached (11.20 ± 0.35)% at 24 h and (10.80 ± 0.46)% after 48 h with DAPI staining. Annexin V/PI staining supported the result from DAPI staining.Bim protein level increased during osteoblast apoptosis, the relative fold rose to (0.31 ± 0.03) after 4 h (about 2 fold compared to control), peaking at 24 h (0.57 ± 0.05, 3-4 fold compared to control). Proteinase inhibitor TLCK effectively blocked the activity of gingipain and inhibited up-regulation of Bim induced by gingipains from (0.58 ± 0.04) to (0.14 ± 0.03). The percentage of osteoblast apoptosis decreased from (11.20 ± 0.35)% to (4.31 ± 0.38)% in the presence of TLCK. Expression of Bax remained unchanged when cells were cultured with or without gingipains. Bak was under the detectable level in MC3T3-E1.

CONCLUSIONS1.812 U/L gingipains induced osteoblast apoptosis. Protein expression of Bim was up-regulated during cell apoptosis and was down-regulated when gingipain inhibited with TLCK, suggesting that Bim was involved in osteoblast apoptosis induced by gingipain. Inhibition of Bim protein expression protected osteoblast from apoptosis.

Adhesins, Bacterial ; pharmacology ; Animals ; Apoptosis ; drug effects ; Apoptosis Regulatory Proteins ; metabolism ; Bcl-2-Like Protein 11 ; Cell Line ; Cysteine Endopeptidases ; pharmacology ; Humans ; MCF-7 Cells ; Membrane Proteins ; metabolism ; Mice ; Osteoblasts ; cytology ; metabolism ; Proto-Oncogene Proteins ; metabolism ; Tosyllysine Chloromethyl Ketone ; pharmacology ; bcl-2 Homologous Antagonist-Killer Protein ; metabolism ; bcl-2-Associated X Protein ; metabolism

OBJECTIVETo find the optimal design of small interfering RNA compounds, transfection concentration and transfection time to reduce the Al-induced apoptosis in SH-SY5Y cells.

METHODSThree siRNA sequences on bak gene were designed and transfected into SH-SY5Y cells, which were treated at various concentrations of aluminum. Cell viability was detected by CCK-8 kit on different siRNA sequences, various transfection concentrations, and diverse transfection courses. Transfection efficiency was determined by fluorescent staining of CY3, and interference efficiency was measured by QRT-PCR. Besides, immunohistochemical staining was used to express Bak protein content. Finally, apoptotic rate and necrotic rate in Al treated SH-SY5Y cells transfecting by the selected bak siRNA 1 were detected.

RESULTSBased on the viability of siRNA sequences, siRNA 1 was selected as the optimal siRNA sequences. The optimal transfection concentration was 10 nmol/L, and the optimal time course was 24 h after transfection. The transfection efficiency was above 90% and the interference efficiency with bak gene was 57.76%. Furthermore, there was significant transfection effect on Bak protein. The apoptotic rate in Al treated SH-SY5Y cells were significantly decreased by bak siRNA 1 transfection.

CONCLUSIONApoptosis is one of the major cell death pathways in SH-SY5Y cells induced by aluminum. When chemically synthesized siRNA is inducted to neural cells, it can significantly reduce bak gene level, decrease Bak protein expression and apoptotic rate, which may serve as the basis for preventing neural cells apoptosis and inhibiting the development of neurodegenerative diseases.

Aluminum ; pharmacology ; Apoptosis ; drug effects ; genetics ; Cell Line, Tumor ; Cell Survival ; drug effects ; genetics ; Humans ; Neuroblastoma ; genetics ; metabolism ; pathology ; RNA, Small Interfering ; genetics ; Transfection ; bcl-2 Homologous Antagonist-Killer Protein ; genetics ; metabolism

Pore-formation and protein-protein interactions are considered to play critical roles in the regulation of apoptosis by Bcl-2 family proteins. During the initiation of apoptosis, the anti-apoptotic Bcl-2 and the pro-apoptotic Bax form different pores to regulate the permeability of mitochondrial outer membrane, playing their opposite functions. Overexpression of Bcl-2 has been found in various cancer cells, therefore it is gaining widespread interest to discover small molecules to compromise Bcl-2 function for anti-cancer treatment. Since Bax binds to Bcl-2's hydrophobic groove via its BH3 domain (composed of helices 2 and 3), by which their functions are inhibited each other, the H2-H3 peptide that contains the functional BH3 domain of Bax has been considered as a potential Bcl-2 antagonist. We recently reported that Bax peptide H2-H3 promotes cell death by inducing Bax-mediated cytochrome c release and by antagonizing Bcl-2's inhibitory effect on Bax. However, the mechanism of how H2-H3 inhibits the anti-apoptotic activity of Bcl-2 remains poorly understood. To address this question, we reconstituted the Bcl-2 or Bax pore-forming process in vitro. We found that H2-H3 inhibited Bcl-2's pore formation and neutralized Bcl-2's inhibitory effect on Bax pore formation in the membrane, whereas the mutant H2-H3 peptide that does not induce apoptosis in cells was shown to have no effect on Bcl-2's activities. Thus, inhibiting Bcl-2's pore-forming and anti-Bax activities in the membrane is strongly correlated with H2-H3's pro-apoptosis function in cells.
Apoptosis ; physiology ; BH3 Interacting Domain Death Agonist Protein ; chemistry ; Humans ; Membrane Proteins ; chemistry ; metabolism ; Mitochondrial Membrane Transport Proteins ; Mitochondrial Membranes ; metabolism ; Proto-Oncogene Proteins c-bcl-2 ; antagonists & inhibitors ; chemistry ; bcl-2 Homologous Antagonist-Killer Protein ; chemistry ; bcl-2-Associated X Protein ; chemistry

We have recently reported that Ginsenoside Rh2 (G-Rh2) induces the activation of two initiator caspases, caspase-8 and caspase-9 in human cancer cells. However, the molecular mechanism of its death-inducing function remains unclear. Here we show that G-Rh2 stimulated the activation of both caspase-8 and caspase-9 simultaneously in HeLa cells. Under G-Rh2 treatment, membrane death receptors Fas and TNFR1 are remarkably upregulated. However, the induced expression of Fas but not TNFR1 was contributed to the apoptosis process. Moreover, significant increases in Fas expression and caspase-8 activity temporally coincided with an increase in p53 expression in p53-non-mutated HeLa and SK-HEP-1 cells upon G-Rh2 treatment. In contrast, Fas expression and caspase-8 activity remained constant with G-Rh2 treatment in p53-mutated SW480 and PC-3 cells. In addition, siRNA-mediated knockdown of p53 diminished G-Rh2-induced Fas expression and caspase-8 activation. These results indicated that G-Rh2-triggered extrinsic apoptosis relies on p53-mediated Fas over-expression. In the intrinsic apoptotic pathway, G-Rh2 induced strong and immediate translocation of cytosolic BAK and BAX to the mitochondria, mitochondrial cytochrome c release, and subsequent caspase-9 activation both in HeLa and in SW480 cells. p53-mediated Fas expression and subsequent downstream caspase-8 activation as well as p53-independent caspase-9 activation all contribute to the activation of the downstream effector caspase-3/-7, leading to tumor cell death. Taken together, we suggest that G-Rh2 induces cancer cell apoptosis in a multi-path manner and is therefore a promising candidate for anti-tumor drug development.
Apoptosis ; drug effects ; Caspase 3 ; metabolism ; Caspase 8 ; metabolism ; Caspase 9 ; metabolism ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Cytochromes c ; metabolism ; Enzyme Activation ; drug effects ; Ginsenosides ; chemistry ; pharmacology ; HeLa Cells ; Humans ; Inhibitory Concentration 50 ; Mitochondria ; drug effects ; metabolism ; Protein Transport ; drug effects ; Receptors, Death Domain ; metabolism ; Receptors, Tumor Necrosis Factor, Type I ; metabolism ; Signal Transduction ; drug effects ; Tumor Suppressor Protein p53 ; metabolism ; Up-Regulation ; drug effects ; bcl-2 Homologous Antagonist-Killer Protein ; metabolism ; bcl-2-Associated X Protein ; metabolism ; fas Receptor ; metabolism