Cross-section through tentacles of a transgenic sea anemone showing differentiation outgrowths of SoxC cell clusters (purple) and connective muscle (yellow). Credit: Andreas Diener
In sea anemones, highly conserved genes ensure continuous differentiation between neurons and glandular cells.
Sea anemones are apparently immortal animals. They appear to be immune to aging and the negative effects that humans experience over time. However, the exact reasons for their eternal youth are not fully understood.
The genetic imprint of the anemone Nematostella vectensis It reveals that members of this incredibly ancient animal phylum use the same gene sequences for neuronal differentiation as more complex organisms. These genes are also responsible for maintaining the 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 headed by Ulrich Technau of Vienna University.
Almost all living things are made up of millions, if not billions, of cells that combine 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 glandular cells. However, it is unclear how this critical balance of diverse cell types appears, how it is regulated, and whether the different cell types of different organisms have a common origin.
Optical longitudinal section of a sea anemones with 1 transgenic neuron 1 (red) in both cell layers. Muscles are stained green, and cell nuclei are blue. Credit: Andreas Diener
Single-celled imprinting leads to common ancestors
The research group, led by developmental evolutionary biologist Ulrich Technau, who also heads the Single Cell Regulation of Stem Cells (SinCeReSt) Research Platform at the University of Vienna, has deciphered the diversity and evolution of all types and types of neurons and glands. Developmental origins of sea anemones Nematostella vectensis.
In order to achieve this, they used single cell transcription, a method that has revolutionized biomedicine and evolutionary biology over the past decade.
With this, whole organisms can be resolved into single cells – and all genes currently expressed in each cell can be decoded separately. Different cell types differ fundamentally in the genes they express. Therefore, single-cell transcripts can be used to determine the molecular fingerprint of each individual cell,” explains Julia Steiger, first author of the current publication.
In the study, cells with overlapping fingerprints were grouped. This allowed scientists to distinguish specific cell types or cells in transitional stages of development, each with unique expressive groups. It also allowed researchers to identify the common lineage and stem cell populations of different tissues.
To their surprise, they found that, contrary to previous assumptions, neurons, glandular cells, and other sensory cells arise from a single common ancestral population, which can be verified by genetic labeling in living animals. Since some gland cells with neuronal functions are also known in vertebrates, this may indicate a very ancient evolutionary relationship between gland cells and neurons.
Ancient genes in constant use
A gene plays a special role in the development of these common progenitor cells. SoxC is expressed in all primary cells of neurons, gland cells, and neurons and is essential for the formation of all these cell types, as the authors were also able to demonstrate it in knockout experiments.
“Interestingly, this gene is not unusual: it also plays an important role in the formation of the nervous system in humans and many other animals, which, along with other data, shows that these key regulatory mechanisms of neuronal differentiation appear to be conserved across the animal kingdom. ‘, says Technow.
By comparing different life stages, the authors also found that in sea anemones, the genetic processes of neuronal development from embryo to adult organism are maintained, thus contributing to neuronal homeostasis throughout life. Nematostella victensis.
This is remarkable 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, which occur in more complex organisms only at the embryonic stage, in the adult organism in a controlled manner.
Reference: “Single-cell transcriptomes identify conserved regulators of glandular neuronal lineages” by Julia Steiger, Alison J. Cole, Andreas Diener, Tatiana Lebedeva, Grigory Jenkovic, Alexander Reis, Robert Rischel, Elizabeth Taudes, Mark Lassnig, and Ulrich Technau, 20 September 2022 and cell reports.
DOI: 10.1016 / j.celrep.2022.111370