Cynthia Kenyon: How Do You Make An Elderly Worm Feel Young Again? What controls aging? Biochemist Cynthia Kenyon has found a genetic mutation that can more than double the lifespan of a tiny worm, which points to how we might one day significantly extend human life.
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How Do You Make An Elderly Worm Feel Young Again?

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How Do You Make An Elderly Worm Feel Young Again?

How Do You Make An Elderly Worm Feel Young Again?

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GUY RAZ, HOST:

So forget science-fiction, forget 20 years from now, Cynthia Kenyon is already there.

CYNTHIA KENYON: It was absolutely thrilling. I mean, unbelievable. I mean, it still makes my hair stand up just thinking about it.

RAZ: Cynthia's a molecular geneticist. She studies the biology of aging.

KENYON: It's something that you did not think would ever be possible. You would just get this feeling like you're looking into something that who knew was there? And I still feel that way. It's an amazing feeling.

RAZ: She's talking about a breakthrough in her lab, something she found in an unlikely specimen, a breakthrough that could change how long we humans live. Here's how Cynthia Kenyon explained it in her TED Talk.

(SOUNDBITE OF TED TALK)

KENYON: Have you ever wanted to stay young a little longer and put off aging? This is a dream of the ages, but scientists have for a long time thought this was just never going to be possible. They thought, you know, you just wear out - there's nothing you can do about it, kind of like an old shoe. But if you look at nature, you see that different kinds of animals can have really different life spans. Now, these animals are different from one another because they have different genes. So that suggests that somewhere in these genes, somewhere in the DNA, are genes for aging, genes that allow them to have different life spans. So if there are genes like that then you can imagine that if you could change one of the genes in an experiment, an aging gene, maybe you could slow down aging and extend life span. And if you could do that then you could find the genes for aging, and if they exist, and you can find them then maybe one could eventually do something about it.

RAZ: So Cynthia decided to try. And of all the species to answer these questions, she started with worms - a very strange sounding worm.

KENYON: Caenorhabditis elegans, or C. elegans. And they're beautiful, they're shaped like little horses' tails, but they're tiny. They're about the size of a comma.

RAZ: A comma.

KENYON: A comma, in a sentence, yeah. Very, very small. But they're really neat. They're cheap. You can grow lots of them. They have a very short life span. They only live a few weeks, but they get old, so that makes them very, very practical for scientific studies of aging.

RAZ: And what Cynthia and other researchers did with these worms is nothing short of amazing because by changing a single gene that's called the DAF-2, the C. elegans ended up living twice as long, and that was just the beginning.

KENYON: First, we doubled their life span. Then we extended it by six-fold, and then another lab was able to extend the life span for 10 times as long. The normal average life span of a worm is 18 days and these worms were 144 days old.

RAZ: Wow.

KENYON: OK so they were more - just almost 10 times as long as the average life span of a normal worm.

(SOUNDBITE OF TED TALK)

KENYON: In just two weeks, the normal worms are old. You can see the little head moving down at the bottom there. But everything else is just lying there. The animal's clearly in the nursing home. And if you look at the tissues of the animal, they're starting to deteriorate. You know, even if you've never see one of these little C. elegans - which, probably most of you haven't seen one - you can tell they're old. Isn't that interesting? So there's something about aging that's kind of universal. And now here is the DAF-2 mutants. One gene is changed out of 20,000. It's the same age, but it's not in the nursing home. It's going skiing.

(LAUGHTER)

KENYON: So it's aging, actually - this is what's really cool - it's aging more slowly. It takes this worm two days to age as much as the normal worm ages in one day. And when I tell people about this, they tend to think of maybe a 90 or 80 or 90-year-old person who looks really good for being 90 or 80, but it's really more like this - suppose you're - let's say you're a 30-year-old guy or 30 - in your 30s. And you're a bachelor and you're dating people, and you meet someone that you really like. You get to know her and you're in a restaurant and you say, well, how old are you? She says, I'm 60. That's what it's like. You would never know. You never know till she told you.

You would think to extend the life span of an animal for such a long time, you know, you'd have to kind of go around in a way and fix things or shore them up. You'd have to do something for the skin and something for the intestine, something for the nervous system. You'd have to - it would be really hard because old tissues all look old, but they all have their own separate problems. But what's the big surprise is that there are these systemic or system-wide control circuits that you can tap into. And what happens is that there are circulating factors, factors in the blood that can move through the animal and tell all the tissues to slow down their aging. Not to slow down their movement, but to slow down their aging. The great secret of all this is that, you know, all animals are much more similar to one another than they are different. Worms have muscles, they have nerve cells, they have serotonin, they have acetylcholine, they have all the neurotransmitters we have, the very same ones. So what that means is, you can easily interrogate the genome by making mutations to find genes that control things, things that you didn't even know were controlled, like aging. And there are actually hints that gene changes in humans that mimic the effects of these changes in animals may contribute to exceptional longevity to becoming a centenarian, in a human.

(SOUNDBITE OF TED TALK)

KENYON: So after we found - made our discoveries with little C. elegans, people who worked on other kinds of animals started asking, if we make the same DAF-2 mutation in other animals, will they live longer? And that is the case in flies. If you change those hormone pathway in flies, they live longer. And also in mice, and mice are mammals like us. So it's an ancient pathway because it must've arisen a long time ago in evolution so that it still works in all these animals and they also - the common precursor - also gave rise to people. So maybe it's working in people the same way. So for example, there is one study that was done in a population of Ashkenazi Jews in New York City. And just like any population, most of the people, you know, will live to about 70 or 80, but some live to be 90 or 100. And what they found was that there were - people who live to 90 or 100 were more likely to have DAF-2 mutations.

RAZ: It's so interesting because, you know, the whole idea of a fountain of youth is so steeped in human mythology, like, you know, these mythical fountains that people would go and drink from. But it actually seems like, I don't know, like, we might actually be getting closer to that.

KENYON: I think so, and I think to great benefit, I think so particularly because of this link between natural aging, which is a way bigger risk factor for, for example, cancer, than smoking is. I mean, it's huge. Aging is such a risk factor. If we could, you know, slow it down, then we should be able to counteract all these diseases. And those - I mean, those worms did have a terrifically wonderful health span, as well as life span. So we see it, so we know it can happen in these animals. Whether it can happen in people, we just don't know. But what I do think is that we can harness our bodies' own abilities that are kind of kept under wraps to allow the aging process to be slowed down. And that's the hope, is that we can do it in a way that counteracts lots of diseases and keeps us healthy right until the end.

RAZ: Cynthia Kenyon studies the biology of aging. You can see her entire talk at ted.npr.org. In a moment - could we evolve into a disease-free species? I'm Guy Raz, and this is the TED Radio Hour from NPR.

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