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The prostate apoptosis response factor-4 (Par-4) gene was originally identified by differential screening for genes that are up-regulated when prostate cells are induced to undergo apoptosis. Par-4 was found to possess potent apoptotic activity in various cellular systems in response to numerous stimuli. The aim of this study was to explore the effects of small interfering RNA (siRNA) against Par-4 gene on the apoptosis of human bone marrow mesenchymal stem cells (hBMSCs) exposed to glutamate.Primary culture of hBMSCs was carried out and siRNAs targeted Par-4 gene (Par-4-SiRNA) were chemically synthesized. Eukaryocytic expression vector was built and were transfected into hBMSCs with liposome. After selecting with G418, the stable cell clones were treated with glutamate. The expression of Par-4 mRNA was determined by real-time PCR. The apoptosis of hBMSCs was quantified by flow cytometry. Western blotting was used to detect the protein levels of phosphorylated Akt1 (Thr308). Relative Caspase-3 activity was determined by colorimetric assay.The Par-4-SiRNA-1 and Par-4-siRNA-2 could markedly down-regulate the mRNA levels of Par-4 gene in hBMSCs. With the transfections of Par-4-SiRNA-1 and Par-4-SiRNA-2, the levels of Par-4 mRNA were respectively decreased by 88% and 67%. Both Par-4-SiRNA-1 and Par-4-SiRNA-2 inhibited significantly the apoptosis of hBMSCs induced by glutamate, in which the percentages of apoptotic cells were respectively decreased to 38.80% +/- 3.97% (P0.01) and 45.49% +/- 4.32% (P0.01) from 60.30% +/- 6.82%. Western blot assays demonstrated that, glutamate down-regulated the expression of phosphorylated Akt1 proteins in hBMSCs (89.07 +/- 6.42 and 28.30 +/- 5.65, respectively, P0.01). However, Par-4-SiRNA-1 and Par-4-SiRNA-2 could markedly recover the down-regulation of Akt1 proteins induced by glutamate (63.56 +/- 6.75 and 45.59 +/- 4.88, respectively, P0.01). And the relative Caspase-3 activity which was enhanced by the treatment with glutamate (0.1428 +/- 0.0495 and 0.8616 +/- 0.1051, P0.01), was suppressed by Par-4-SiRNA-1 and Par-4-SiRNA-2 (0.8616 +/- 0.1051 and 0.6581 +/- 0.0555, respectively, P0.01).SiRNA against Par-4 gene could inhibit the apoptosis of hBMSCs induced by glutamate, and its inhibitory effects may be mediated by the up-regulation of phosphorylated Akt1 and the suppression of the relative Caspase-3 activity.

Second mitochondria-derived activator of caspase (Smac) is a recently identified, novel pro-apoptotic molecule, which is released from mitochondria into the cytosol during apoptosis. Smac promotes activation of caspases by neutralizing members of the inhibitor of apoptosis proteins (IAPs) family, such as X-linked inhibitor of apoptosis protein (XIAP). The objective of the study was to examine the pro-apoptotic effect of human Smac gene on Burkitt's lymphoma Raji cells.The full length cDNA of human Smac gene was amplified by reverse transcription-PCR from total RNA of HEK-293 cells. The PCR product was ligated with linearized vector pGEM-T-easy supplied in the TA cloning kit and sequenced. The correct cDNA of full length Smac was subcloned into eukaryocytic expression vector pcDNA3.1/myc-his and transfected into human Burkitt's lymphoma cell line Raji by lipofectamine-mediated transfection. The expression of full length Smac was determined by Western blot. Morphological observation was done with the laser scanning confocal microscope by double staining the Raji cells with Hoechest 33,258 and propidium iodide. Flow cytometry was used to evaluate apoptosis. Relative caspase-3 activity was determined by colorimetric assay.Recombinant eukaryocytic expression vector pcDNA3.1/Smac, which contained full length Smac, was successfully constructed. After pcDNA 3.1/Smac was transfected into human Burkitt's lymphoma Raji cell line for 24 hours, Raji cells showed apparent apoptosis with a percentage of (43.7 +/- 2.5)%, which was higher than that of non-transfected group and free vector-transfected group (P0.05). Compared with non-transfected group (0.136 +/- 0.036) and free vector-transfected group (0.138 +/- 0.026), the relative caspase-3 activity of Raji cells transfected by pcDNA3.1/Smac (0.936 +/- 0.041) was significantly enhanced (P0.05).Transfection and expression of human Smac gene could significantly induce apoptosis of human Burkitt's lymphoma Raji cells. The mechanism is associated with the increase of caspase-3 activity.

Lipoxin A(4) is formed by the metabolism of arachidonic acid. Anti-inflammatory and anti-proliferative effect of lipoxin A(4) has been shown in many human diseases. Recently, as a novel high affinity receptor for ligand lipoxin A(4), Lipoxin A(4) receptor-like protein (LRLP) has been identified. Currently close attention is paid to the important contribution of connective tissue growth factor (CTGF) in lung fibrosis. The purpose of the study was to transfect LRLP gene into human lung fibroblasts and investigate the mechanism of its enhancing antagonistic effect of Lipoxin A(4) on human lung fibroblasts proliferation induced by connective tissue growth factor.Eukaryocytic expression vector pEGFP/LRLP which contained LRLP and green fluorescence protein fusion gene (GFP) was constructed and transfected into human lung fibroblasts (HLF). After selecting with G418, HLF/LRLP cell clone which stably expressed LRLP/GFP fusion protein was isolated and characterized by the laser scanning confocal microscope. Cultured HLF and HLF/LRLP were stimulated for 24 h with CTGF (1 microg/ml) in the presence and absence of pretreatment of Lipoxin A(4) (10.0 nmol/L) for 30 min. Inhibition of cell proliferation was determined by MTT assay. Cell cycle analysis was performed by flow cytometry. Western blot was used to detect the expression of cyclin D(1) protein. Electrophoretic mobility shift assay (EMSA) was employed to detect the DNA binding activity of STAT(3).(1) HLF/LRLP cell clone which stably expressed LRLP and GFP fusion protein was successfully obtained. (2) Proliferation of HLF and HLF/LRLP was induced by 1 microg/ml CTGF. Pretreatment with 10 nm Lipoxin A(4) inhibited the proliferation of HLF and HLF/LRLP. And the inhibitory rate of HLF/LRLP was significantly higher than that of HLF [(54.1 +/- 4.2)%, (21.2 +/- 3.7)%, P0.05]. (3) The flow cytometry analysis showed that compared with HLF, more HLF/LRLP were arrested at G(0)/G(1) phase in the presence of pretreatment of Lipoxin A(4). [(76.3 +/- 3.5)%, (60.8 +/- 2.0)%, P0.05]. (4) Ten nmol/L Lipoxin A(4) antagonized CTGF induced increase of cyclin D(1) protein expression in HLF and HLF/LRLP. And its antagonistic effect on HLR/LRLP was stronger than that on HLF (P0.05). (5) Ten nmol/L Lipoxin A(4) antagonized CTGF induced increase of STAT(3) DNA binding activity, and its antagonistic effect on HLF/LRLP was more powerful than that on HLF (P0.05).Transfection of Lipoxin A(4) receptor-like protein gene enhanced the inhibitory effect of Lipoxin A(4) on human lung fibroblasts proliferation induced by CTGF. Its mechanism might be related to regulation of cyclin D(1) protein expression and STAT(3) DNA binding activity.