Researchers have conducted an impressive experiment: integrating a gene from unicellular microorganisms, the choanoflagellates, into mouse cells. These organisms, 600 million years old, are considered the closest living ancestors of multicellular animals. They harbor essential genes, such as Sox, involved in the pluripotency of stem cells.
This ability of cells to transform into any cell type was previously associated only with multicellular organisms. However, the discovery of these genes in unicellular organisms challenges this view, suggesting that the foundations of pluripotency predate the emergence of animals.
Chimeric mice derived from complete Salhel-Sox-I iPSC lines, displaying black spots on their fur and black eyes (arrows), contrasting with a wild-type mouse with white fur and red eyes. The team thus embarked on a bold experiment. They replaced the Sox2 gene of mouse stem cells with its equivalent from choanoflagellates. These reprogrammed cells were then injected into embryos, leading to the birth of chimeric mice. A feat that validates the functionality of these ancestral genes.
The mice created in this manner exhibited hybrid traits, visible evidence of the presence of choanoflagellate genes. This functional continuity illustrates the evolutionary reuse of primitive mechanisms in more complex organisms, an idea that challenges traditional hypotheses.
This research also sheds light on the role of evolution in recycling ancient genes to address new biological needs. Sox genes, originally linked to simple cellular processes, appear to have been adapted to construct today's multicellular organisms.
Their study opens new horizons in regenerative medicine. Understanding how these ancestral genes influence pluripotency could optimize cell reprogramming techniques, crucial for treating illnesses such as neurodegenerative disorders or regenerating damaged tissues.
These discoveries mark a turning point in the study of the evolutionary origins of cellular mechanisms. They demonstrate that evolution is not linear but exploitative: it shapes life by reusing and refining ancient strategies.
What is pluripotency?
Pluripotency refers to the unique ability of certain cells to transform into any cell type in the body. It is a fundamental process in developmental biology.
In mammals, it occurs naturally in embryonic stem cells. These cells, present at the very beginning of development, can give rise to the various organs and tissues. This potential relies on specific genes, such as Sox and POU. They act as switches, activating or deactivating the mechanisms that shape cells.
Understanding pluripotency helps better manipulate stem cells, with promising applications for tissue regeneration or disease treatment.
Article author: Cédric DEPOND