Sensitive ChIP-DSL technology reveals an extensive estrogen receptor alpha-binding program on human gene promoters.

ChIP coupled with microarray provides a powerful tool to determine in vivo binding profiling of transcription factors to deduce regulatory circuitries in mammalian cells. Aiming at improving the specificity and sensitivity of such analysis, we developed a new technology called ChIP-DSL using the DNA selection and ligation (DSL) strategy, permitting robust analysis with much reduced materials compared with standard procedures. We profiled general and sequence-specific DNA binding transcription factors using a full human genome promoter array based on the ChIP-DSL technology, revealing an unprecedented number of the estrogen receptor (ERalpha) target genes in MCF-7 cells.

Hepatitis B virus X protein protects against anti-Fas-mediated apoptosis in human liver cells by inducing NF-kappa B.

The hepatitis B virus-encoded X antigen (HBxAg) may contribute to the development of liver cancer, in part, by stimulating the growth and survival of infected cells in the face of ongoing immune responses. Given that the Fas ligand/receptor system contributes to the pathogenesis of chronic hepatitis B, experiments were designed to test the hypothesis that HBxAg mediates resistance of liver cells to anti-Fas killing. Accordingly, when HBxAg was introduced into HepG2 cells, it rendered these cells partially resistant to killing by anti-Fas.