Effect of freezing on DNA methylation? - (Jan/29/2009 )

hi everybody!

Well, it was a bit surprising to me that my account doesn't exist but ok, now I understand why.
So my question is: do you think it has any effect if I freeze cells before izolate DNA for BS studies...? Can freezing change methylation status of promoter? I haven't read anything about it but maybe it is important...

Cheers

-egerecske-

I don't think freezing cells or DNA changes its methylation, but it is not absolutely impossibe.

-pcrman-

I don't think freezing cells or dna significantly alters the methylation state. I've tried to digest previously frozen vector with an enzyme inhibited by methylation and the digest did not work. (oops)

-rkay447-

it has been reported that there's an increase in DNA methylation in plants that undergo dormancy. if you're working with plants might find this review useful:

Knowing when to grow: signals regulating bud dormancy
David P. HorvathE-mail The Corresponding Author, James V. Anderson, Wun S. Chao and Michael E. Foley
Trends in Plant Science
Volume 8, Issue 11, November 2003, Pages 534-540

-toejam-

toejam on Feb 10 2009, 11:21 AM said:

hmm saw this same question somewhere else on the forum....but again :rolleyes:

if your cells are death and the protein is denatured, thus inactive......your cytosine methylation is OK. Its a covalent modification of DNA, quite stable.

-et2b-

We have a similar problem here, we want to analyse few years old -20 stored DNA for methylation pattern. Is it still usable?

-Trof-

Trof on Mar 9 2009, 11:07 AM said:

Is it still usable?

i would say there is only one way to know it....
if the samples haven't been thawed it should be fine.

-toejam-