Understanding How Sea Anemones Reorganize and Regenerate From Disorganized Cells

Researchers at the University of Vienna have discovered a key mechanism that enables sea anemones to regenerate into a fully developed organism from disorganized clusters of cells. The study, published in Nature Communications, shows that the so-called Notch signaling pathway controls tissue organisation and the formation of the body axis. The findings provide new insights into the fundamental rules of biological self-organisation and could help us better understand how tissues form, organize themselves and regenerate following disruption.

Animal development follows genetic programs that control the formation of cells, tissues and body structures. At the same time, these processes are often remarkably robust: at least some organisms are able to restore their ordered body organisation even after significant disruptions. How this capacity for self-organisation is controlled at the molecular level is as yet only partially understood.

About the Study

The research team led by Ulrich Technau, from the Faculty of Life Sciences at the University of Vienna, which is part of the Vienna BioCenter, investigated how cell aggregates of the sea anemone Nematostella vectensis regenerate into a complete organism after being separated. Despite their simple body structure, sea anemones possess numerous developmental genes and mechanisms that are also found in other animals. Among these evolutionarily conserved mechanisms is the Notch-Delta signaling pathway, a communication system between neighboring cells that was the focus of the study.

A Single Signaling Pathway Coordinates the Formation of Tissues and the Body Axis

When sea anemone cells are separated from one another and subsequently brought back together, a fully formed organism re-emerges within a few days. In this process, the body axis and tissue layers are restored in their correct spatial arrangement – reproducibly and without the addition of any growth factors. Lead author Sanjay Narayanaswamy was able to demonstrate that the Notch signaling pathway is crucial to this process. It ensures that cells sort themselves correctly and that different tissue types are distinguished from one another. If the signaling pathway is experimentally blocked, this organisation no longer occurs. At the same time, Notch also controls the formation of the body axis.

Interaction Between Key Developmental Programs

Further experiments showed that the Notch signaling pathway works closely with the Wnt signaling pathway, which also plays a central role in axis formation and body development. The interaction of such networks enables biological systems to re-establish ordered structures even after significant disruption.

Relevance Beyond the Sea Anemone

The ability of cells to organize themselves is fundamental to the formation and regeneration of tissues. As Notch and Wnt signaling pathways are also present in many other animals and in humans, the findings extend beyond the biology of the sea anemone.

Our aim is to understand why cnidarians can use these molecular mechanisms to form complete organisms so efficiently through self-organisation. We hope to be able to derive general principles of tissue organisation and regeneration from this."

Ulrich Technau, Faculty of Life Sciences, University of Vienna

Summary

• Sea anemones can form a complete organism again within a few days from randomly assembled clusters of cells.
• The Notch signaling pathway controls both the formation of the body axis and the organisation of various tissue layers.
• Notch acts in conjunction with the Wnt signaling pathway, another key communication system between cells.
• The findings provide new insights into the molecular basis of biological self-organisation, which also plays a role in humans.
• These findings contribute to our understanding of the processes by which cells organise tissues and build bodily structures.