Genome complexity: newly found epigenetic controls (Introduction)

by David Turell , Wednesday, March 08, 2017, 18:54 (2816 days ago) @ David Turell

A new study finds a different level of epigenetic controls than methylation or acetyl markings:

https://phys.org/news/2017-03-proteins-domesticated-genomes.html

"EPFL scientists have carried out a genomic and evolutionary study of a large and enigmatic family of human proteins, to demonstrate that it is responsible for harnessing the millions of transposable elements in the human genome. The work reveals the largely species-specific gene-regulatory networks that impact all of human biology, in both health and disease.

"The human genome contains millions of sequences derived from so-called transposable elements, genetic units that "jump" around the entire genome. Long considered as junk DNA, transposable elements are now recognized as influencing the expression of genes. However, the extent of this regulation and how it is harnessed were so far unknown. EPFL scientists have now taken the first extensive look at a family of ~350 human proteins, showing that they establish a complex interplay with transposable elements to create largely human-specific gene regulatory networks.

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" The lab of Didier Trono at EPFL revealed a few years ago that a protein serving as cofactor to many KZFPs (KRAB-containing zinc-finger proteins) was involved in silencing transposable elements during the first few days of embryogenesis. Now he and his collaborators have carried out an extensive analysis of human KZFPs, retracing their evolutionary history and identifying their genomic targets.

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"Trono's team then mapped out the genomic targets of most human KZFPs, finding that the greatest fraction recognizes transposable elements. "The vast majority of KZFPs binds to specific motifs in transposable elements," says Trono. "For each KZFP we were able to assign one subset of transposable elements, and also found that one transposable element can often interact with several KZFPs. It is a highly combinatorial and versatile system."

"'After emerging some 420 million years ago, KZFPs evolved rapidly in a lineage-specific fashion, parallel to the invasion of host genomes by transposable elements," says Trono. "This co-evolution resulted in shaping human gene regulatory networks that are largely proper to our species or at least primate-restricted—the farther away in evolution, the fewer the similarities."

"The data from the study demonstrate that KZFP partner up with transposable elements to create what the authors call "a largely species-restricted layer of epigenetic regulation". Epigenetics refers to biological processes—mostly biochemical modifications of the DNA and its associated proteins—that condition the expression or repression of genes. As a field, epigenetics has come into prominence in recent years, revealing a previously unimagined complexity and elegance in genetics.

"'KZFPs contribute to make human biology unique," says Trono. "Together with their genomic targets, they likely influence every single event in human physiology and pathology, and do so by being largely species-specific—the general system exists in many vertebrates, but most of its components are different in each case." (my bold)

"'This paper lifts the lid off something that had been largely unsuspected: the tremendous species-specific dimension of human gene regulation", says Trono. "It has profound implications for our understanding of human development and physiology,"(my bold)

Comment: Note the bolded areas! This is a whole newly discovered level of epigenetic control of gene expression control, and shows us the probable genetic area where God could drive human development from the apes! Remember this: over the past eight million years the only major evolutionary drive we see is in human development, nothing else!