In sea anemones, highly conserved genes ensure the permanent differentiation of neurons and gland cells.
Sea anemones are seemingly immortal animals. They appear to be immune to aging and the adverse effects humans experience over time. However, the exact reasons for their eternal youth are not fully understood.
Genetic imprinting of sea anemones Nematostella vectensis It reveals that members of this incredibly ancient animal phylum use the same gene cascades for neuronal differentiation as more complex organisms. These genes are also responsible for maintaining homeostasis of all cells in the organism during the life of the anemone. These results were recently published in the journal Cell reports By a group of evolutionary biologists led by Ulrich Technau of University of Vienna.
Nearly all living things are made up of millions, if not billions, of cells that come together in complex ways to form specific tissues and organs, which are made up of a range of cell types, such as a variety of neurons and gland cells. However, it is unclear how this critical balance of different cell types emerges, how it is regulated, and whether different cell types from different organisms have a common origin.
Optical longitudinal section of a sea anemone with transgenic neurons (in red) in both cell layers. Muscles stained green, cell nuclei blue. Credit: Andreas Diener
Unicellular imprinting leads to a common ancestry
The research team, led by evolutionary developmental biologist Ulrich Technau, who also heads the Single Cell Regulation Research Platform for Stem Cells (SinCeReSt) at the University of Vienna, deciphered the diversity and evolution of all types and types of neuronal and glandular cells. Origins of development in sea anemones Nematostella vectensis.
To achieve this, they used single-cell transcription, a method that has revolutionized biomedicine and evolutionary biology over the past decade.
“With this, entire organisms can be resolved into single cells and all genes that are currently expressed in each cell can be decoded individually. Different cell types differ fundamentally in the genes they express. Thus, single-cell transcriptomes can be used to determine the molecular fingerprint of each individual cell,” says Julia Steiger, first author of the current publication.
In the study, cells with overlapping fingerprints were clustered together. This allowed the scientists to distinguish between specific cell types or cells in transient stages of development, each with unique expression populations. It also allowed researchers to identify stem and progenitor cell populations from different tissues.
To their surprise, they found that, contrary to previous hypotheses, neurons, gland cells and other sensory cells come from a common ancestral population, which can be verified by genetic tagging in living animals. Since some glandular cells with neuronal functions are also known in vertebrates, this could indicate a very ancient evolutionary relationship between neurons and glandular cells.
Old genes are used constantly
The gene plays a special role in the development of these common progenitor cells. SoxC is expressed in all neuronal precursor cells, gland cells and neurons and is essential for the formation of all these cell types, and the authors were also able to demonstrate this in knockout experiments.
“Interestingly, this gene is not exotic: it also plays an important role in nervous system formation in humans and many other animals, which, together with other data, shows that these key regulatory mechanisms of neuronal differentiation appear to be conserved. throughout the animal kingdom,” says Technow.
By comparing the different life stages, the authors also found that the genetic processes for neuronal development from embryo to adult organism are preserved in sea anemones, contributing to neuronal homeostasis throughout the life of the anemone. Nematostella vectensis.
This is notable because, unlike humans, sea anemones can replace lost or damaged neurons throughout their lives. For future research, this raises the question of how sea anemones manage to maintain these mechanisms in a controlled way, which in more complex organisms occur only in the embryonic stage, in the adult organism.
Reference: “Single-cell transcription identifies conserved regulators of neuroglandular lineages” by Julia Steiger, Allison G. Cole, Andreas Diner, Tatiana Lebedeva, Grigory Genikovitch, Alexander Ries, Robert Reichel, Elisabeth Taudis, Marc Lasnig, Ulrich Technau, 20 Sept. 2022, Available here. Cell reports.
DOI: 10.1016 / j.celrep.2022.111370
