ChIP Human - HepG2

DNA-protein interactions are studied by using ChIP. The basic steps in this technique are crosslinking, sonication, immunoprecipitation, and analysis of the immunoprecipitated DNA. During ChIP, if chromatin is under-fragmented or fragments are too large which can lead to the increased background and lower resolution. Shorter cross-linking times (5-10 min) and/or lower formaldehyde concentrations (<1%) may improve shearing efficiency. If Chromatin is over-fragmented, then optimize shearing conditions for each cell type to improve ChIP efficiency. Over-sonication of chromatin may disrupt chromatin integrity and denature antibody epitopes. If you do not see any product or very little product in the input PCR reactions, add 5–10 μg chromatin per IP.

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Found 3 matching solutions for this experiment

Upstream tips
-After cell harvesting, chromatin must be sheared to 200 to 600 bp before ChIP.
-Optimize shearing conditions for your specific cell type and fixation protocol before starting a ChIP. Therefore, start with a small sample (1x 10e5 to 1x 10e6 cells) and check the shearing efficiency.
Protocol tips
-Keep the beads homogenously in suspension at all times when pipetting. Variation in the amount of beads will lead to lower reproducibility.
-Make sure that there are no crystals in the Buffer B. Gently heat and mix until crystals disappear.
- Chromatin from 1,000 cells is sufficient for one ChIP assay.
Downstream tips
-For longer term storage, aliquot 130 µl of sheared chromatin into cryotubes, snap-freeze in liquid nitrogen, and store at -80°C.
Upstream tips
-If any reagent has formed a precipitate, warm at 55 °C until dissolved. Allow to equilibrate to room temperature before use.
Protocol tips
-Use 1 µg of antibody per well.
-The range of cells that can be used with this kit is 0.2–2.5 x 105/well/ChIP sample. Using more than 0.5 million cells per well will increase the non-specific binding and reduce the yield and specificity of the ChIP reaction. If higher yield of ChIP DNA is desired for downstream applications (e.g. ChIP-Seq., ChIP-chip): a) DNA could be pooled by eluting consecutively (with 50 µl of elution buffer) from multiple individual ChIP reactions.
Protocol tips
-Always cap spin columns before placing them in the microcentrifuge.
-Ensure that all buffers are in clear solution. Shake or vortex if these buffers precipitate.
-The conditions of cross-linked DNA shearing can be optimized based on cells and sonicator equipment.
If desired, remove 5 µl of sonicated cell lysate for agarose gel analysis.
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