Hormone replacement therapy, which is used to relieve symptoms of the menopause in women, caused 539 deaths from (mainly breast) cancer in Australia last year. It did, however, prevent 52 cases of colorectal cancers
A total of five people have died and 197 got sick in the outbreak, the largest E. coli outbreak in the U.S. in more than a decade, the CDC said.
Immuno-precipitation (IP) and Chromatin IP (ChIP)
Tissue or cell lysates (1 mg/ml protein) in IP incubation buffer (Active Motif, Carlsbad CA), were incubated overnight at 4°C with 20 ?g of antibodies against POLG, PARP1, or PAR molecules. Samples were then loaded on to Protein G Agarose Prepacked Columns (Active Motif), and columns were washed five times with IP wash buffer (Active Motif), to remove non-binding proteins. Immune complexes were eluted from the columns in 0.2 M glycine (pH 2.5) solution. The eluents were pooled (total 100 ?l), neutralized with 20 ?l of 1 M Tris-HCl (pH 9.0), and used for Western blotting.
For ChIP assay, Imprint Chromatin Immunoprecipitation Kit was employed (Sigma). Briefly, Hela cells (5 X 107) or tissue sections (10 mg) were incubated with 9 ml of 1% buffered formaldehyde for 30 min at room temperature on a rocking platform to cross-link DNA/proteins, neutralized by adding 1 ml of 1.25 M glycine buffer, homogenized, and then sonicated on a Misonix XL2020 sonicator (30 pulses, 30 sec on/off, 100% power) to fragment the chromatin DNA. Cross-linked samples were subjected to immune-precipitation with mouse hPARP1 N-terminus-specific monoclonal antibody (sc-74470, Santa Cruz). Mouse IgG (Sigma) was used as negative control. The formaldehyde cross-link was reversed by incubating for 15 min at 65°C. Samples were then treated with RNase H and protease K, to digest RNA and proteins, respectively, and DNA was extracted with phenol/chloroform and purified by using QIAquick PCR Purification Kit (28104, Qiagen). ChIP DNA was used as substrate for PCR amplification of PARP1-bound sequences by using the oligonucleotides listed in S1 Table.