ChIP acH3 Human Donkey

Short hairpin or small hairpin RNA (shRNA) is artificial RNA, which has a hairpin loop structure, and uses inherent microRNA (miRNA) machinery to silence target gene expression. This is called RNA interference (RNAi). These can be delivered via plasmids or viral/bacterial vectors. Challenges in shRNA-mediated gene silencing include 1. Off-target silencing, 2. Packaging shRNA encoding lentivirus, and 3. Stable transduction in cells. RNAi has been designed to have anywhere from 19-27 bs, but the most effective design has 19 bp. In case commercial shRNAs are not available, potential target sites can be chosen within exon, 5’- or 3’ UTR, depending on which splice variants of the gene are desired. One should use the latest algorithms and choose at least two different sequences, targeting different regions, in order to have confidence in overcoming off-target effects. A BLAST search after selecting potential design will eliminate potential off-target sequences. For the second challenge, sequencing the vector using primers for either strand (50-100 bp upstream) is suggested, along with using enzymatic digestion on agarose gel for the vector. Next, once the shRNA-containing vector is packaged in a virus, it is important to check the viral titer before transduction. Finally, using a marker in the lentiviral vector (fluorescent protein or antibiotic resistance), along with qPCR for target gene expression can help in determining the efficacy of transduction and shRNA on its target site.

The process of RNA extraction from bacteria, in general, involves an RNA-protective, effective lysis of bacterial cell wall (which may pose difficulties). EDTA promotes loss of outer membrane to provide lysozyme with access to peptidoglycan. Another common method for cell wall lysis is mechanical disruption using a homogenizer (applied for gram-positive bacteria and some strains of gram-negative bacteria). Following lysis, it is necessary to disrupt protein-nucleic acid interactions, which can be achieved by adding sodium dodecyl sulfate (SDS). Next step involves using phenol-chloroform-isoamyl alcohol extraction, where RNA can be obtained from the bottom organic phase, the top phase consists of DNA and the interphase contains proteins. Isoamyl alcohol is an inert and optional addition to this mixture and is added as an anti-foaming reagent to reduce the interphase. Following RNA extraction, the samples should be checked for its quality by gel electrophoresis (23S and 16S rRNAs and 5s rRNA and tRNA bands) or UV spectrophotometric or fluorescence methods.

Get tips on using PARP-1 C-terminal antibody (pAb) to perform ChIP Anti-bodies PARP

Get tips on using Recombinant Anti-PARP1 antibody [E102] (ab32138) to perform ChIP Anti-bodies PARP

Get tips on using Anti-RPA32/RPA2 antibody [9H8] (ab2175) to perform ChIP Anti-bodies RPA

Get tips on using Sall4 Antibody (EE-30): sc-101147 to perform ChIP Anti-bodies Sall4

Get tips on using Anti-Estrogen Receptor Antibody, clone AER304 to perform ChIP Anti-bodies ERα

Get tips on using Anti-trimethyl-Histone H3 (Lys9) Antibody to perform ChIP Anti-bodies H3K9me3

Get tips on using Anti-trimethyl-Histone H3 (Lys27) Antibody to perform ChIP Anti-bodies H3K27me3

Get tips on using Anti-dimethyl-Histone H3 (Lys27) Antibody to perform ChIP Anti-bodies H3K27me2