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Do Muscle-Less and Heartless Sea Anemones Hold Key to Heart Regeneration?

A team of researchers at the University of Florida has found genes known to form heart cells in humans and other animals in the gut of the starlet sea anemone (Nematostella vectensis), a brainless, muscle-less and heartless marine animal native to the east coast of the United States. The findings point to potential for tweaking communication between human genes and advancing our ability to treat heart conditions and stimulate regenerative healing.

The starlet sea anemone (Nematostella vectensis). Image credit: Sinigaglia et al / University of Vienna.

The starlet sea anemone (Nematostella vectensis). Image credit: Sinigaglia et al / University of Vienna.

“So why does the sea anemone regenerate while humans cannot? When analyzing the function of its ‘heart genes,’ we discovered a difference in the way these genes interact with one another, which may help explain its ability to regenerate,” said senior author Prof. Mark Martindale, Director of the Whitney Lab for Marine Bioscience at the University of Florida.

“Our study shows that if we learn more about the logic of how genes that give rise to heart cells talk to each other, muscle regeneration in humans might be possible.”

“These heart genes generate what engineers call lockdown loops in vertebrates and flies, which means that once the genes are turned on, they tell each other to stay on in an animal’s cells for its entire lifetime.”

In other words, animals with a lockdown on their genes cannot grow new heart parts or use those cells for other functions.

“This ensures that heart cells always stay heart cells and cannot become any other type of cell,” Prof. Martindale said.

“But in sea anemone embryos, the lockdown loops do not exist. This finding suggests a mechanism for why the gut cells expressing heart genes in sea anemones can turn into other kinds of cells, such as those needed to regenerate damaged body parts.”

This work supports the idea that definitive muscle cells found in the majority of animals arose from a bifunctional gut tissue that had both absorptive and contractile properties.

And while the gut tissue of a sea anemone might not look like a beating heart, it does undergo slow, rhythmic peristaltic waves of contraction, much like the human digestive system.

“The first animal muscle cells might have been very heart-like,” Prof. Martindale said.

“The idea is these genes have been around a long time and preceded the twitchy muscles that cover our skeleton.”

“Continued research could one day allow scientists to coax muscles cells into regenerating different kinds of new cells, including more heart cells,” he concluded.

The findings were published this week online in the Proceedings of the National Academy of Sciences.

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Naveen Wijesena et al. Antagonistic BMP-cWNT signaling in the cnidarian Nematostella vectensis reveals insight into the evolution of mesoderm. PNAS, published online June 26, 2017; doi: 10.1073/pnas.1701607114