That mysterious part is called lncRNAs. Those are Long, Non-Coding, RNA molecules, that are transcribed from your DNA but do not produce any proteins. They tend to just exist in the cell doing nothing. At least that’s what we used to think.
It’s been a long time since we discovered that lncRNAs have a purpose in the cell, but recent articles keep showing what those molecules really do. And they do a lot.
RNA is single stranded, unlike DNA, so when it “floats” alone it can fold and form different bonds with itself. Sometimes this folding leads to a specific shape that has a particular function. It is similar to how protein folding determines protein function. This folded RNA molecule can do many things, it can activate other proteins or inhibit their function, it can influence histone methylation and acetylation or even be used as a messenger molecule between cells.
It is possible that those molecules are used by the cell as signals to itself and other cells. lncRNAs may change gene expression in response to a stimulus and this may cause a paracrine signaling like effect, or even be transferable through the circulation.
It has been shown that certain lncRNAs (lincRNA-Cox2) can regulate the inflammatory response by producing knockdown cells for this gene. This showed Ccl5 and Cx3cl1 are regulated by lincRNA-Cox2. This can result in a significant regulation of the inflammatory response by lncRNAs.
This is just one of the examples of how lncRNAs influence us and we are now starting to accumulate sufficient data to analyze about them. Analyzing the genome is getting cheaper and more efficient. As a result we may start to see more people focusing on lncRNAs to treat diseases or improve medicine by targeting those molecules specifically.
This article gives a lot of great and detailed explanations on how lncRNAs influence our immune system, in case you want to read more about the subject.