Genome complexity: how different cells are made (Introduction)

by David Turell , Thursday, April 05, 2018, 19:10 (2213 days ago) @ David Turell

We have one DNA but it can make all sorts of different functioning cells:

https://phys.org/news/2018-04-discovery-cells-identical-genes-unique.html

"Scientists have made a significant discovery that explains how and why the billions of different cells in our bodies look and act so differently despite containing identical genes.

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"The team has discovered a completely new family of proteins in animals with vertebrae—including fish, reptiles, birds and mammals—that they have named PALI1 and PALI2. Fascinatingly, these families of proteins both originated from genes that have gained new functions since vertebrate and invertebrate species evolved from one another millions of years ago. Specifically, PALI1 is vital for embryonic development and in particular for controlling cellular identity.

"The new work helps towards understanding why a blood cell and a brain cell look and act very differently yet contain exactly the same genes. This puzzling question about the so-called 'cellular identity' is central to the field of epigenetics, which strives to explain how cells in your body, with identical sets of genes, can look and behave so differently. The study of epigenetics has provided key molecular insights into how every type of cell has its own unique pattern of genes that are either switched on or off in a tightly controlled manner.

"Central to this is a group of epigenetic regulators, called Polycombs, which are vital to regulating cellular identity in multicellular organisms of both the plant and animal kingdoms. The Bracken lab studies the biology of these Polycomb epigenetic regulators, and their newly discovered PALI1 and PALI2 proteins form a new family of Polycombs that are unique in that they are only present in vertebrates—they are not found in invertebrate animals, or plants. (my bold)

"Commenting on the findings, Professor Bracken said: "This discovery of PALI1 and PALI2 is an important step forward in our understanding of how stem cells specialise in complex animals, such as fish, reptiles, birds and mammals."

"'In addition to its relevance to stem cell biology and regenerative medicine, it may also have implications for future cancer therapies. For example, we are also studying a related Polycomb protein called EZH2, whose function is deregulated in certain blood and brain cancers. Several new drugs have been developed to target EZH2 to treat these patients, but our new results suggest these patients could also potentially be treated by drugs targeting the PALI1 and PALI2 Polycomb proteins, which might provide additional benefit.'"

Comment: Note my bold. A chance evolutionary process did not find this group of proteins to direct this differentiation method. Must be designed.