A neutral genetic mutation—a fluke in the evolutionary process with no apparent biological purpose—that appeared over 700 million years ago in biological evolution could help explain the origin of complex organs and structures in human beings and other vertebrates, according to an article published in Nature Communications by a team led by Professor Jordi García-Fernàndez, from the Faculty of Biology and the Institute of Biomedicine of the UB (IBUB), Manuel Irimia (CRG) and Maria Ina Arnone (Anton Dohrn Zoological Station, Italy).
Specifically, this mutation -which would have taken place after the separation of jellyfishes and sea anemones, and prior to the appearance of vertebrates in evolution- affected a gene of the Fgfr (fibroblast growth factor receptors) family. Curiously, this genetic change triggered, millions of years later, the connection between two gene regulatory networks (those controlled by ESRP and by Fgfr), which became essential for the origin of many vertebrate organs and structures (lungs, forelimbs and inner ear).
The article in Nature Communications, whose first author is Demian Burguera (UB-IBUB and CRG), there is a new approach from the field of evolutionary developmental biology (evo-devo). This is a relatively new paradigm in the study of evolution, which analyses the mechanisms and evolutionary processes related to the development and morphogenesis of living beings.
From chance mutation to the formation of organs in vertebrates
A gene can code for different proteins—with diverse functionality—through the genetic mechanism of alternative splicing. In some human cell types, this process is controlled by regulatory proteins such as ESRP1 and ESRP2, involved in morphogenic processes. Therefore the genome controls all embryonic developmental processes and interaction processes among cells. If this interaction model changes, it can also alter the morphology of biological structures. However, the molecular basis that modulates these interactions is still unknown.
The authors of the study have studied the functions of the ESPR genes to modify the cell motility and adherence in the embryogenesis of different animals. The authors point out that the ESPR1 and ESPR2 were part of an ancient genetic machinery shared by animals and fish –even urchins- that integrated cells in the surface of embryonic organs (a basic process to make organs).
The article published in Nature Communications shows how the same regulatory genes have been used to generate different organs and biological structures in living beings during the evolutionary process. In the same vein, the article describes how an accidental mistake—an apparently meaningless mutation that took place over 700 million years ago—became the molecular driver for complex morphological developments in a number of vertebrates (including the human species).
“Clearly, the most exceptional result of the work is the proof of how important serendipity is for evolution. It is surprising to find that a single gene (ESRP), -through its ancestral biological role (cell adherence and motility)- has been used throughout the animal scale for very different purposes: from the immune system of an echinoderm to the lips, lungs or inner ears of humans,” states Professor Jordi Garcia-Fernàndez.
“The new discovery confirms how versatile biological evolution is: the same foundation and gene tools can be used to build a wood cabin or a skyscraper,” concludes professor Garcia-Fernàndez.
Universitat de Barcelona