Question about imprinted genes - (Oct/09/2005 )

Dear friends,

Now I am interested in methylation of imprinted genes and how the methylation could be affected by some other processes. I have not yet had a good grasp of the whole concept of imprinting and methodology used to analyze it.

I anlayzed DNA from two cell lines for H19 methylation and Igf2 by direct bisulfite sequencing. Cell line A shows complete methylation for H19 (so both alleles are methylated) while cell line B shows totally no methylation (both alleles are unmethylated). These cell lines are tumor cells. Loss of imprinting (in the case of cell line B ) is understandable, but how come one cell line has both alleles methylated? In addition, is complete loss of imprinting (as in B ) common in cancer cells?

Any clues are greatly appreciated.

Mario

correct me if I am mistaken, loss of imprinting describes the loss of parental specific expression and/or methylation at an imprinted locus. This would also include the case for for cell line B where both alleles are methylated.

Is it common in cancer cell lines, I would have to say most likely. Abbarent methylation (albeit hypermethylation AND hypomethylation) certainly occurs in tumoriegenesis and I won't be surprised that you also get loss of imprinting as well.

Nick

Hi Nick, thank you for the reply. I will check out if LOI also means loss of allele-specific expression. This is a new field to me and I will have a lot to learn.

hi mario, you will probably find that indeed LOI results in a loss in allele specific expression in most cases.

nick