Genome complexity: T cell transcription factors (Introduction)

by David Turell , Wednesday, January 27, 2021, 20:05 (1395 days ago) @ David Turell

A new studty of these DNA controls in T c ells:

https://phys.org/news/2021-01-behavior-transcription-factors-theories-gene.html

"Now, a new study from the Rothenberg lab examines certain proteins that supervise gene regulation in developing T cells and finds that these proteins behave in a manner quite different from that assumed in previous theory. The work suggests that theories of gene regulation may need to be reevaluated.

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"There are many different kinds of transcription factors, with each acting upon defined sets of genes, sometimes with multiple transcription factors working together to regulate gene expression. The Rothenberg laboratory focused on two very similar transcription factors, Runx1 and Runx3, to find if they play a role during the cascade of sharp changes in gene expression that cause stem cell–like progenitors to become transformed into future T cells.

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"The conventional genetics theory is that when a factor regulates a target gene, the activity of the factor is correlated with the level of the target gene. But Rothenberg's study found that this was not the case for Runx factors. Although the Runx factors themselves stay active at steady levels through key developmental events, the great majority of genes that respond to the Runx factors change dramatically in expression during this period. In fact, the Runx factors act upon "incredibly important" genes for T cell development, according to Rothenberg, and regulate them strongly.

"The findings open up new questions, such as how can the Runx factors cause these dramatic changes in gene expression when levels of Runx themselves do not change?

"The team also found that the positions where the Runx factors bind to the genome change markedly over time, bringing Runx to different target DNA sites. At any one time, the study found, the factors are only acting on a fraction of the genes they could regulate; they shift their "attention" from one set to another over time. Interestingly, in many of these shifts, large groups of Runx proteins leave their initial sites and travel to occupy clusters of new sites grouped across large distances of the genome, as they act on different genes at different times.

"'There's no good explanation yet for this group behavior, and we find that Runx are interacting with the physical genomic architecture in a complex way, as they're regulating genes that have totally different expression patterns than the transcription factors themselves," says Shin. "What is controlling the deployment of the transcription factors? We still don't know, and it's far more interesting than what we thought."

"'This work has big implications for researchers trying to model gene networks and shows that transcription factors are more versatile in their actions than people have assumed," Rothenberg says.'

Comment: Same old story. We humans have about 20,000 genes, which is a low number compared to many organisms, but we are highly complex due to transcription controls causing many variations in expression of genes. God's design of te4h genome is highly complex. Never by chance