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Aim: To confirm the role of sex-determining region Y-box 7 (Sox7) in aspirin-mediated growth inhibition of COX-independent human colorectal cancer cells., Methods: The cell survival percentage was examined by MTT (Moto-nuclear cell direc cytotoxicity) assay. SOX7 expression was assessed by using reverse transcription-polymerase chain reaction and Western blotting. SB203580 was used to inhibit the p38MAPK signal pathway. SOX7 promoter activity was detected by Luciferase reporter assay., Results: SOX7 was upregulated by aspirin and was involved in aspirin-mediated growth inhibition of SW480 human colorectal cancer cells. The p38MAPK pathway played a role in aspirin-induced SOX7 expression, during which the AP1 transcription factors c-Jun and c-Fos upregulated SOX7 promoter activities., Results: SOX7 is upregulated by aspirin and is involved in aspirin-mediated growth inhibition of human colorectal cancer SW480 cells.

The homologs of transcription factors c-Fos and c-Jun have been detected in slime mold Physarum polycephalum during progression of the synchronous cell cycle. Here we demonstrated that c-Fos-like and c-Jun-like proteins participated in G2/M transition by the regulation of the level of Cyclin B1 protein in P. polycephalum. The study of antibody neutralization revealed that interruption of the functions of c-Fos-like and c-Jun-like proteins resulted in G2/M transition arrest, implicating their functional roles in cell cycle control. When G2/M transition was blocked by histone deacetylase inhibitor trichostatin A, changes in c-Fos- and c-Jun-like protein levels, and hyperacetylation of c-Jun-like protein, were observed. The data suggest that in P. polycephalum, c-Fos- and c-Jun-like proteins may be the key factors in the regulation of histone acetylation-related G2/M transition, involving the coordinated expression and hyperacetylation of these proteins.

The human elongator complex was found to be very similar to the yeast Elongator both in composition and its interaction with RNA polymerase II. But little is known about its functions in vivo. In this study, we analyzed the functions of the help3, the catalytic subunit of human Elongator, using a yeast complementation system. The results indicated that help3 was able to significantly complement the growth defects of the elp3delta yeast strain under high temperature and caffeine conditions. Gene expression analysis showed that help3 significantly resumed the slow activation of the pho5 gene under the low phosphate condition, and when heat shocked it increased the expression level of ssa3 gene. The yhelp3 containing the HAT domain of human elp3 and the remainder of yeast elp3 had a higher complementation ability than human elp3, while the yhelp3HA T- with the catalytic HAT domain deleted had no complementation ability. These results implicate that human Elp3 subunit had similar functions to those of the yeast, and the HAT activity of human Elp3 was essential for its function.

In this study, we performed in vivo experiments to determine the function of human Elongator subunit Elp4 by using a yeast complementary system. Our results indicated that though human ELP4 was not able to complement the growth defects of the ELP4 deletion mutant strain to high concentration salt, it partially reduced the sensitivity of mutant strain to caffeine, high temperature and 6-AU. Gene expression analysis indicated that human ELP4 partially resumed the slow activation of the PHO5 gene caused by the deletion of yELP4 under the low phosphate concentration. Meanwhile, under the condition of heat shock treatment, hELP4 increased the expression level of SSA3 gene. All these data demonstrated that human ELP4 can partially complement the growth defects and restore the slow activation of certain genes of the yELP4 deletion strain. These results indicate that human Elp4 subunit has similar functions to that of the yeast.

The yeast histone acetyltransferase (HAT) gene gcn5 and histone deacetylase (HDAC) gene rpd3 were cloned from yeast genomic DNA by PCR amplification. The two genes,both with additional 6xHis tag,were subcloned into pBV220 vector to construct expression plasmids pBVgcn5 and pBVrpd3,respectively. Both pBVgcn5 and pBVrpd3 were over-expressed in Escherichia coli upon temperature induction,as revealed by SDS-PAGE. The recombinant GCN5 and RPD3 were purified by using a 6xHis affinity column. The purified GCN5 was tested to possess the HAT activity by using a (14)C-labeling assay. This work has laid down the basis for further in vitro studies into roles of histone acetylation/deacetylation in modulating chromatin conformation and transcription activity.

Chromatin silencing is the inactivation of large domains of DNA by packaging them into a specialized inaccessible chromatin structure. This type of inactivation is involved in the regulation of gene expression and is also associated with the chromosome structures required for chromosome maintenance and inheritance. Silent information protein 2(SIR2) is one of the important proteins involved in chromatin silencing. It is clear that SIR2 has two coupled enzymatic activities, histone deacetylation and NAD breakdown activities, and produces a novel compound, O-acetyl-ADP-ribose in the enzymatic reactions. The histone deacetylation activity of SIR2 provides the direct link between SIR2 and the hypoacetylation of silent chromatin. Moreover, the relationship between the NAD cleavage and the deacetylase activity of SIR2 shows that the histone deacetylase activity is not its only crucial function. The breakdown of NAD C-N bond and the synthesis of O-acetyl-ADP-ribose may also be involved in chromatin silencing.

alpha-Acetolactate decarboxylase(alpha-ALDC)gene has been cloned from Baillus brevis using PCR amplification. The amplified 0.97 kb DNA fragment was confirmed to be known alpha- ALDC gene by DNA sequencing. The fragment was inserted into the vector pBV220 to construct an expression plasmid pBVYI. This recombinant plasmid over expressed alpha-ALDC in E. coli DH5alpha. The alpha-ALDC activity of recombinant bacterium was 10 000-fold higher than that of Bacillus brevis. After purification, the properties of the recombinant alpha-ALDC were studied. The activity of this enzyme could be stimulated by Mn(2+), Sn(2+) and inhibited by Zn(2+), Cd(2+), Fe(2+), Co(2+) and Cu(2+). Moreover, amino acid modifiers could inhibit differently its activity. The optimum pH of the enzyme reaction was 5.5.