Tumour necrosis factors have not changed in 550 million years

(written by lawrence krubner, however indented passages are often quotes). You can contact lawrence at: lawrence@krubner.com, or follow me on Twitter.

Interesting:

There are many ways of triggering apoptosis, and one route involves two large groups of proteins: the tumour necrosis factors (TNFs), and the receptors that they stick to. When they meet, they set off a chain reaction inside the cell. A large network of proteins is recruited, united, and activated, until the cell eventually dies. Think of TNF as a key twisting in the lock of a door, triggering a Rube-Goldberg machine that ends with the entire room catching fire.

Now, Steven Quistad from San Diego State University has discovered that corals—small tentacle animals that build mighty reefs—have their own TNFs and TNF receptors. Compared to our versions, these coral proteins are made of slightly different building blocks, but they fold into very similar three-dimensional shapes.

In fact, these shapes are so similar that the coral proteins are interchangeable with ours. A coral TNF can persuade our cells to kill themselves by sticking to our receptors. Likewise, human TNFs can kill coral cells by sticking to their receptors. We last shared a common ancestor with corals around 550 million years ago. Our respective lineages have been diverging ever since but our keys fit in their locks, and vice versa.

“[That’s] amazing”, says Marymegan Daly from Ohio State University. “I think this highlights that at some level, animal cells are animal cells. The differences among animals are in the ways that the cells are organized rather than in how they work.”

Quistad made his discovery after analysing the recently sequenced genome of Acropora digitifera, a coral that looks like a mound of miniature Christmas trees. And to his surprise, he didn’t just find TNFs, he found lots of them. We have genes for 18 different TNFs and 29 corresponding receptors, and the coral has a similar number—13 TNFs and 40 receptors. “That’s more receptors than anyone had ever seen in any organism,” says Quistad.

Post external references

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    http://phenomena.nationalgeographic.com/2014/06/09/half-a-billion-years-of-suicide/
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