In a groundbreaking study, scientists have successfully created a mouse using stem cells derived from the genes of a single-celled microorganism, marking a significant step in understanding the molecular tools that might have aided the transition from unicellular to multicellular life, the Washington Post reports.
Published in Nature Communications, the research sheds light on the ancient molecular mechanisms that could have played a role in the evolution of complex organisms, including humans.
This remarkable achievement was made possible by using genes from a protist called a choanoflagellate, a single-celled organism closely related to animals. The study challenges previous assumptions, revealing that some of the key genetic components necessary for stem cell development are much older than scientists previously thought, potentially dating back to the common ancestors of animals and microorganisms.
Stem cells are unique because they can both self-renew and differentiate into various specialized cell types. In animals, stem cells are essential for growth, healing, and tissue regeneration. Until recently, it was believed that the genes responsible for stem cell development were unique to animals and did not exist in single-celled organisms like protists.
However, in a surprising turn of events, scientists uncovered evidence that choanoflagellates—microscopic organisms typically not classified as animals, plants, or fungi—possess versions of the genes responsible for stem cell function in animals. These genes, part of the Sox and Pou families, had been previously thought to be exclusive to animals, particularly after the groundbreaking work of Shinya Yamanaka, who won the Nobel Prize for discovering how to reprogram adult cells into stem cells.
“Finding these genes in a unicellular organism was unexpected… We didn’t expect to see them there, but it opens up new avenues for understanding how these crucial genetic tools evolved,” said Alex de Mendoza, a study author at Queen Mary University of London.
To test whether these ancient genes could induce stem cell-like behavior, the research team, led by Ralf Jauch from the University of Hong Kong, introduced a choanoflagellate version of the Sox2 gene into mouse cells. Sox2 is vital for reprogramming cells into stem cells in mammals. The results were successful: the mouse cells were reprogrammed into stem cells, and when injected into a developing mouse embryo, the cells contributed to the formation of a living, breathing mouse.
While the Sox2 gene worked as expected, the team’s efforts to use the choanoflagellate’s version of the Pou gene were less successful. The Pou gene did not induce stem cell behavior in mouse cells, possibly due to differences in how the unicellular and animal versions of the gene interact with DNA. This suggests that some evolutionary adaptations may still be needed for the full functionality of these genes in multicellular organisms.
The study also provides valuable insights into the evolutionary origins of stem cells. The choanoflagellate’s genes, found in organisms that are the closest living relatives to animals, suggest that the capacity for stem cell-like behavior predates the evolution of multicellular animals themselves. By tracing back through evolutionary history using molecular algorithms, the team identified genetic traits in ancient organisms that are still present in today’s choanoflagellates.
“The ability to transition between different cellular states may have been a critical trait for early animal ancestors… This flexibility would have provided a significant advantage, allowing cells to adapt to a variety of environmental challenges,” said Sandie Degnan, a professor of biology at the University of Queensland.
The discovery holds promise for advancing stem cell research, as it suggests that stem cell capabilities are much older and more widespread than previously understood. Understanding how these ancient genes function could lead to new techniques for generating stem cells, potentially offering breakthroughs in treating diseases or reversing the effects of aging.
The team’s research also underscores the adaptability of life forms, demonstrating that evolution often works with existing genetic components to create new functions.
“Evolution doesn’t always need to invent new tools… It often repurposes existing ones, building complexity from what is already available,” de Mendoza explained.
