Marshall McLuhan famously said “the medium is the message”. Who knew he was talking about molecular biology? But he was, if you think of the process of transcription of DNA into various forms of RNA as the medium and the products of transcription as the message. That’s exactly what this paper [ Cell vol. 171 pp. 103 – 119 ’17 ] says.
T cells are a type of immune cell formed in the thymus. One of the important transcription factors which turns on expression of the genes which make a T cell a Tell is called Bcl11b. Early in T cell development it is sequestered away near the nuclear membrane in highly compacted DNA. Remember that you must compress your 1 meter of DNA down by 100,000fold to have it fit in the nucleus which is 1/100,000th of a meter (10 microns).
What turns it on? Transcription of nonCoding (for protein) RNA calledThymoD. From my reading of the paper, ThymoD doesn’t do anything, but just the act of opening up compacted DNA near the nuclear membrane produced by transcribing ThymoD is enough to cause this part of the genome to move into the center of the nucleus where the gene for Bcl11b can be transcribed into RNA.
There’s a lot more to the paper, but that’s the message if you will. It’s the act of transcription rather than what is being transcribed which is important.
The paper doesn’t talk about the structure of ThymoD — how long it is, whether it binds to anything in the nucleus — etc. etc. Perhaps I’ve missed it. I’ve written the lead author. Hopefully I won’t be too embarrassed by what he responds.
Here’s more about McLuhan — https://en.wikipedia.org/wiki/Marshall_McLuhan
If some of the terms used here are unfamiliar — look at the following post and follow the links as far as you need to. https://luysii.wordpress.com/2010/07/07/molecular-biology-survival-guide-for-chemists-i-dna-and-protein-coding-gene-structure/
Chemiotics II 