does DNA isolation affect methylation of genes?

[methylgenie]

Hi Everyone,
Im new to methylation studies and hope to learn more about methylation.
i want to know if the isolation procedure of DNA has an impact on methylation of genes?
should i use column purification kits or can i even used standard phenol-chloroform method for DNA isolation?
thanks in advance.

[Warthaug]

I assume you're talking about direct DNA methylation, not methylation of the chromatin proteins associated with eukaryotic DNA.

Methylation of DNA is pretty robust and should survive isolation. To maximize the maintenance of methylation make sure that the proteins in the sample source are denatured early in the isolation process. Most purification kits (mammalian or bacterial) denature proteins immediately after the first (lysis) step; ensuring the maximum maintenance of methylation.

Bryan

[methylgenie]

Thank you Bryan for your reply. So I understand that DNA methylation is robust, It will withstand isolation and also storage at -80C? Sorry for bothering you with my suspicious questions
Thanks (these smiles are great!)

[Warthaug]

It should persist at -80C for a long time, although I don't know exactly how long. We use methyl-sensitive protocols from time-to-time, and having samples frozen for a few weeks doesn't seem to change their methylation to any meaningful extent.

Bryan