In Why your fertility cells must have ‘radio silence’, researchers from Canada and Japan explain their discovery: “a previously unknown mechanism which causes embryonic germ cells – which later develop into sperm or ova – to go through a period of ‘transcriptional silence,’ during which information from the cell’s DNA cannot be copied. Without this important phase, unique to cells of this type, an organism produces sterile offspring.”
A single protein called Transcription Elongation Factor B is produced by the Polar Granule Component gene. Female fruit flies lacking the pgc gene have sterile offspring. The researchers think the protein plays a major role in initiating the transcriptional silence. Conseidering that they found this to be true in both nematodes and fruit flies, it is reasonable to expect that it is true for other animals as well.
I could be misinterpreting this (I am not an animal biologist, after all), but this discovery could advance cloning. I don’t just mean the cloning of whole organisms like sheep and cows, but cloning of adult human cells into stem cell lines that can be used to cure all sorts of diseases. Successful natural embryos require some sort of ‘reprogramming’ of their parental DNA before they can start anew. We know something happens, but don’t yet know the details. The problems of cloning, including low rate of success and developmental abnormalities could be happening because the genomes weren’t properly reprogrammed. Is this ‘transcriptional silence’ part of the ‘reprogramming’ process? It’s certainly possible. I’m looking forward to research on what happens when they induce expression of the pgc gene in cloned cells, and what happens if they add P-TEFb. Will they be able to boost the success rate while reducing the number of deformed animals? I hope so. It would be really nice to have some good therapeutic cloning methods around by the time I start to need them.
The abstract of the Nature paper “Drosophila Pgc protein inhibits P-TEFb recruitment to chromatin in primordial germ cells” can be found on PubMed.
Have researchers found a key to cloning?
