If we think about human life stages, our genes, or genetics are almost always ringing the bell. Fortunately, they’ve since found out that’s not true. Earlier human development was controlled by something called ‘selfish DNA,’ or transposons.
Surprise element
Historically, transposons have been viewed as DNA parasitic intruders — virus-like ‘entities’ that break into our cells and use them to reproduce themselves.
But this is flipped on its head by recent research. Wouldn’t it be better if these so-called intruders aren’t simply ‘somebody we’d have to get rid of’ but instead part of our early development that we get rid of?
The study’s senior co-author is Dr. Miguel Ramalho-Santos, Senior Investigator at the Lunenfeld-Tanenbaum Research Institute (LTRI), part of Sinai Health and Professor at the University of Toronto’s Department of Molecular Genetics, who makes an astonishing find.
LINE 1 was the focus of the research team’s investigation because this type of transposon is so prevalent in the human genome. Those numbers: while our genes make up only 20% of the parts of our genome, LINE 1 elements make up an equal 20%.
They discovered that these LINE-1 elements are essential to ensure human embryonic cells progress normally through early development. If inhibited it transports cells back into a more primitive stage.
When thinking of the stages of human development we tend to think of genetics or genes giving the orders. We know now that’s not true. The early development of humans is in the hands of something called “selfish dna,” or transposons.
Human development transposons
Only 2% of the genome (our genes) make up a large amount, but LINE-1 elements account for 20%.
What they found is that these LINE-1 elements are absolutely necessary for human embryonic cells to move on as they should if they are to survive through the early stages of development. Inhibited, it would transport the cells back to a more primitive state.
Caught in between
Gopalakrishnan echoes this sentiment as one of the senior co-authors on this research, along with postdoctoral fellow at LTRI Dr. Juan Zhang, who spearheaded the research.
If transposons are bad and dangerous, why then do we find them active during the early embryo? “All this is an embryo just at the start of formation,” Dr. Zhang said.
Life-altering discovery
It’s not random activity, either, says Dr. Zhang.
On the contrary, it’s a key evolutionary mechanism. LINE-1 elements do not wreak genomic havoc, they promote developmental progression.
Reference:
“Selfish DNA” controls early human development, not our genes
