The science of cells that never get old | Elizabeth Blackburn

Summary

In this insightful talk, the speaker embarks on a scientific journey starting with the study of Tetrahymena, a single-celled organism, to uncover the mysteries of telomeres and telomerase. She explains how telomeres protect chromosome ends and how their shortening is linked to aging and disease. The discovery of telomerase, an enzyme that can lengthen telomeres, offers a promising yet complex view on aging. The speaker further explores how stress, mindset, and social factors can influence telomere health, emphasizing our power to affect our own and others' aging process at a cellular level.

Takeaways

• 🔬 The speaker's career began with studying Tetrahymena, a single-celled organism, to understand the fundamental building blocks of life, specifically chromosomes and telomeres.
• 🧬 Telomeres are protective caps at the ends of chromosomes that shorten as cells divide, which is a natural part of the aging process.
• 🏅 The discovery of telomerase, an enzyme that can lengthen telomeres, was a groundbreaking finding that earned the speaker and her student Carol Greider a Nobel Prize.
• 🌟 Tetrahymena cells do not experience telomere shortening and thus do not age, which was a significant clue in understanding telomere maintenance.
• 🚫 Contrary to what one might think, increasing telomerase in humans is not a simple solution to aging as it can also increase the risk of certain cancers.
• 🧠 Psychological stress can have a tangible impact on telomere length, with chronic stress leading to shorter telomeres and potentially earlier onset of age-related diseases.
• 💪 Resilience to stress can help maintain telomere length, suggesting that our mindset and how we cope with stress can influence our biological aging.
• 🤔 Attitude matters when it comes to telomere health; viewing stress as a challenge rather than a threat can positively affect telomere maintenance.
• 🌐 Social factors such as community, relationships, and even one's home environment can influence telomere length, highlighting the interconnectedness of our social lives and cellular health.
• 🔮 The speaker concludes by emphasizing the power of curiosity and the potential for each individual to make a difference in their own health and the health of future generations.

Q & A

What is Tetrahymena and how does it relate to the speaker's career?

Tetrahymena is a single-celled organism, also known as pond scum, which the speaker found adorable and used as a subject of study early in her career. It has many short linear chromosomes, providing a rich source for studying telomeres.

What are telomeres and why are they significant in the context of the speech?

Telomeres are the protective caps at the ends of chromosomes, made of noncoding DNA. They are significant because they protect the DNA from damage during cell division but shorten with each cell replication, which is linked to aging and disease.

What discovery did the speaker and Carol Greider make regarding telomeres?

The speaker and Carol Greider discovered an enzyme called telomerase, which can replenish and lengthen telomeres, preventing them from shortening and thus contributing to the aging process.

How does the shortening of telomeres affect human health?

Shortening of telomeres is associated with aging and an increased risk of various diseases such as cardiovascular diseases, Alzheimer's, some cancers, and diabetes. Longer telomeres are generally indicative of better health and slower aging.

What is the role of telomerase in the context of telomere maintenance?

Telomerase is an enzyme that can extend telomeres, counteracting their natural shortening. It is crucial for maintaining telomere length and thus plays a role in the aging process and disease risk.

Why can't simply increasing telomerase levels be a solution to aging?

While increasing telomerase can help maintain telomere length, it also increases the risk of certain cancers. Therefore, it's not a straightforward solution to aging as it comes with its own health risks.

What does the term 'health span' refer to as used in the speech?

Health span refers to the number of years in a person's life when they are free of disease, healthy, and able to enjoy life productively, as opposed to 'disease span,' which is the time spent feeling old, sick, and dying.

How do psychological factors like stress impact telomere length according to the speech?

Chronic stress has been found to shorten telomeres, which can lead to an increased risk of early disease and potentially untimely death. However, individuals who are resilient to stress can maintain their telomere length despite stress.

What are some ways individuals can influence their telomere health as discussed in the speech?

Individuals can influence their telomere health by managing stress through practices like meditation, maintaining a positive attitude towards life's challenges, and engaging in supportive social relationships.

How do social factors outside an individual's control affect telomere length?

Social factors such as childhood emotional neglect, exposure to violence, bullying, racism, and living in unsafe neighborhoods can negatively impact telomere length. Conversely, supportive communities, long-term relationships, and lifelong friendships can improve telomere maintenance.

What is the speaker's call to action regarding curiosity and the future?

The speaker encourages investing in curiosity for future generations, implying that supporting curiosity can lead to significant discoveries that could benefit the world, just as her own curiosity about Tetrahymena and telomeres has had far-reaching implications.

Outlines

00:00

🔬 The Beginning of a Scientific Journey with Tetrahymena

The speaker's scientific journey starts with the study of Tetrahymena, a single-celled organism also known as pond scum. Despite its humble beginnings, this organism was crucial for investigating the fundamental mysteries of life, specifically the structure and function of chromosomes and telomeres. The speaker's curiosity was piqued by the protective role of telomeres during cell division, and the quest to understand their composition led to significant discoveries. Tetrahymena, with its numerous short linear chromosomes, provided an abundance of telomeres for study. The speaker and her student Carol Greider, who later shared the Nobel Prize for this work, discovered that telomeres are made up of special segments of noncoding DNA at the chromosome ends. They also found that while telomeres naturally shorten with cell division, Tetrahymena's telomeres did not, hinting at a natural mechanism to counteract this wear and tear.

05:03

🌟 The Discovery of Telomerase and Its Impact on Aging

The speaker and Carol Greider discovered an enzyme named telomerase, which is capable of extending telomeres, thus countering their natural shortening. This discovery was revolutionary as it suggested a way to maintain the integrity of chromosomes and potentially slow down the aging process. The implications for human health were profound, as shorter telomeres are associated with aging and an increased risk of various diseases. The speaker explains that while increasing telomerase levels could theoretically extend health and lifespan, it also carries the risk of promoting certain types of cancer, thus highlighting the delicate balance in human biology. The focus shifts from merely extending lifespan to enhancing 'health span,' the period of life free from disease and disability.

10:04

🧠 The Psychological Impact on Telomere Length and Health

The narrative shifts to the influence of psychological stress on telomere length. The speaker recounts a collaboration with psychologist Elissa Epel, who introduced the idea that chronic stress might affect telomere maintenance. This led to a study on caregiving mothers, particularly those with children suffering from chronic conditions, to understand the impact of prolonged stress on their telomeres. The study revealed a correlation between the duration of stress and telomere shortening, suggesting that stress not only affects mental health but also has tangible effects on cellular aging. However, the study also identified resilient individuals who managed to maintain their telomere length despite stress, indicating that psychological resilience and perception of stress can influence cellular health.

15:09

🌐 The Broader Social and Environmental Influences on Telomeres

The final paragraph delves into the broader social and environmental factors that can influence telomere health. The speaker discusses how early life experiences, such as emotional neglect and exposure to violence, can have long-term effects on telomere length. The importance of social connections, safe neighborhoods, and lifelong friendships in maintaining telomere health is highlighted. The speaker concludes by emphasizing the interconnectedness of human health and the power of individual and collective actions to influence telomere maintenance. The narrative ends on a hopeful note, encouraging curiosity and investment in scientific exploration for the betterment of future generations.

Keywords

💡Tetrahymena

Tetrahymena is a genus of ciliates, which are single-celled organisms. In the video, Tetrahymena is referred to as 'pond scum' and is used as a model organism for scientific research. The speaker's career started with studying Tetrahymena, highlighting its significance in understanding the basic building blocks of life. The organism's abundance of short linear chromosomes makes it an ideal subject for studying telomeres.

💡Chromosomes

Chromosomes are thread-like structures made of DNA and protein found in the nucleus of cells, carrying genetic information. The video discusses chromosomes in the context of their ends, known as telomeres, which are crucial for protecting the DNA during cell division. The study of chromosomes is central to the speaker's research on aging and cellular health.

💡Telomeres

Telomeres are the protective caps at the ends of chromosomes that prevent the DNA from fraying. In the video, the speaker's curiosity about telomeres leads to significant discoveries about their composition and function. The health of telomeres is directly linked to the aging process and the risk of various diseases, making them a key focus of the speaker's research.

💡Telomerase

Telomerase is an enzyme that can extend or maintain the length of telomeres, counteracting the shortening that occurs with cell division. The discovery of telomerase is a pivotal moment in the video, as it reveals a mechanism by which cells can potentially avoid aging. The speaker and her student Carol Greider were awarded the Nobel Prize for their work on telomerase.

💡DNA replication

DNA replication is the process by which a cell duplicates its DNA before cell division. The video explains that during DNA replication, the ends of chromosomes, or telomeres, are at risk of shortening because the replication process cannot fully copy the very ends. This shortening is a natural part of the aging process and is a central theme in the speaker's exploration of cellular aging.

💡Aging

Aging is the natural process of growing older, involving a decline in various bodily functions. In the video, aging is discussed in the context of telomere shortening and its impact on health. The speaker suggests that maintaining telomere length could potentially delay the signs of aging and reduce the risk of age-related diseases.

💡Health span

Health span refers to the period of life during which a person is generally healthy and free from chronic diseases. The video contrasts health span with disease span, emphasizing the importance of not just living longer, but living healthily. The speaker's research on telomeres and telomerase is aimed at understanding how to extend health span.

💡Chronic stress

Chronic stress is ongoing, long-term stress that can have detrimental effects on health. In the video, the speaker discusses how chronic stress can negatively impact telomere length, potentially leading to premature aging and increased risk of disease. This insight underscores the importance of managing stress for overall health.

💡Resilience

Resilience is the ability to bounce back from adversity or stress. The video highlights that some individuals, despite being under chronic stress, can maintain their telomere length due to their resilience. This concept suggests that mindset and coping mechanisms can influence cellular health at the level of telomeres.

💡Social factors

Social factors refer to elements of our environment and relationships that can influence our health. The video discusses how factors such as emotional neglect, violence, and social support can impact telomere length. This highlights the interconnectedness of our social lives and our biology, emphasizing the importance of community and relationships for health.

💡Curiosity

Curiosity is the desire to learn or know something. In the video, the speaker's own curiosity about the mysteries of life led her to a career in science and significant discoveries about telomeres. The video concludes by encouraging the audience to embrace their curiosity, which can drive scientific discovery and personal fulfillment.

Highlights

The speaker's career began with studying Tetrahymena, a single-celled organism also known as pond scum.

Tetrahymena has around 20,000 short linear chromosomes, providing an abundance of telomeres for study.

Telomeres are special segments of noncoding DNA at the ends of chromosomes that protect them during cell division.

Each cell division results in the shortening of telomeres, which can signal cells to stop dividing and die.

Telomerase, an enzyme discovered by the speaker and Carol Greider, can replenish and lengthen telomeres.

In humans, telomere shortening is associated with aging and increased risk of diseases.

Telomere length is a biomarker of biological age, not just chronological age.

Chronic stress has been found to negatively impact telomere length, potentially leading to early disease.

Resilience to stress can help maintain telomere length, suggesting we have some control over our aging process.

Meditation can improve telomere maintenance capacity, as shown in a study with dementia caregivers.

A positive attitude towards stress can help protect telomeres from the damaging effects of cortisol.

Social factors such as emotional neglect, violence, and racism can impact telomere length from childhood.

Strong social connections, like long-term marriages and friendships, can improve telomere maintenance.

Telomere science reveals the interconnectedness of human health and the importance of social environments.

Investing in curiosity and research can lead to discoveries that impact global health and well-being.

The speaker encourages individuals to consider how they can protect their telomeres and make a positive impact on others' health.

Transcripts

Where does the end begin?

Well, for me, it all began with this little fellow.

This adorable organism --

well, I think it's adorable --

is called Tetrahymena and it's a single-celled creature.

It's also been known as pond scum.

So that's right, my career started with pond scum.

Now, it was no surprise I became a scientist.

Growing up far away from here,

as a little girl I was deadly curious

about everything alive.

I used to pick up lethally poisonous stinging jellyfish and sing to them.

And so starting my career,

I was deadly curious about fundamental mysteries

of the most basic building blocks of life,

and I was fortunate to live in a society where that curiosity was valued.

Now, for me, this little pond scum critter Tetrahymena

was a great way to study the fundamental mystery

I was most curious about:

those bundles of DNA in our cells called chromosomes.

And it was because I was curious about the very ends of chromosomes,

known as telomeres.

Now, when I started my quest,

all we knew was that they helped protect the ends of chromosomes.

It was important when cells divide.

It was really important,

but I wanted to find out what telomeres consisted of,

and for that, I needed a lot of them.

And it so happens that cute little Tetrahymena

has a lot of short linear chromosomes,

around 20,000,

so lots of telomeres.

And I discovered that telomeres consisted of special segments

of noncoding DNA right at the very ends of chromosomes.

But here's a problem.

Now, we all start life as a single cell.

It multiples to two. Two becomes four. Four becomes eight,

and on and on to form the 200 million billion cells

that make up our adult body.

And some of those cells have to divide thousands of times.

In fact, even as I stand here before you,

all throughout my body, cells are furiously replenishing

to, well, keep me standing here before you.

So every time a cell divides, all of its DNA has to be copied,

all of the coding DNA inside of those chromosomes,

because that carries the vital operating instructions

that keep our cells in good working order,

so my heart cells can keep a steady beat,

which I assure you they're not doing right now,

and my immune cells

can fight off bacteria and viruses,

and our brain cells can save the memory of our first kiss

and keep on learning throughout life.

But there is a glitch in the way DNA is copied.

It is just one of those facts of life.

Every time the cell divides and the DNA is copied,

some of that DNA from the ends gets worn down and shortened,

some of that telomere DNA.

And think about it

like the protective caps at the ends of your shoelace.

And those keep the shoelace, or the chromosome, from fraying,

and when that tip gets too short, it falls off,

and that worn down telomere sends a signal to the cells.

"The DNA is no longer being protected."

It sends a signal. Time to die.

So, end of story.

Well, sorry, not so fast.

It can't be the end of the story,

because life hasn't died off the face of the earth.

So I was curious:

if such wear and tear is inevitable,

how on earth does Mother Nature make sure

we can keep our chromosomes intact?

Now, remember that little pond scum critter Tetrahymena?

The craziest thing was, Tetrahymena cells never got old and died.

Their telomeres weren't shortening as time marched on.

Sometimes they even got longer.

Something else was at work,

and believe me, that something was not in any textbook.

So working in my lab with my extraordinary student Carol Greider --

and Carol and I shared the Nobel Prize for this work --

we began running experiments

and we discovered cells do have something else.

It was a previously undreamed-of enzyme

that could replenish, make longer, telomeres,

and we named it telomerase.

And when we removed our pond scum's telomerase,

their telomeres ran down and they died.

So it was thanks to their plentiful telomerase

that our pond scum critters never got old.

OK, now, that's an incredibly hopeful message

for us humans to be receiving from pond scum,

because it turns out

that as we humans age, our telomeres do shorten,

and remarkably, that shortening is aging us.

Generally speaking, the longer your telomeres,

the better off you are.

It's the overshortening of telomeres

that leads us to feel and see signs of aging.

My skin cells start to die

and I start to see fine lines, wrinkles.

Hair pigment cells die.

You start to see gray.

Immune system cells die.

You increase your risks of getting sick.

In fact, the cumulative research from the last 20 years

has made clear that telomere attrition

is contributing to our risks of getting cardiovascular diseases,

Alzheimer's, some cancers and diabetes,

the very conditions many of us die of.

And so we have to think about this.

What is going on?

This attrition,

we look and we feel older, yeah.

Our telomeres are losing the war of attrition faster.

And those of us who feel youthful longer,

it turns out our telomeres are staying longer

for longer periods of time,

extending our feelings of youthfulness

and reducing the risks of all we most dread

as the birthdays go by.

OK,

seems like a no-brainer.

Now, if my telomeres are connected

to how quickly I'm going to feel and get old,

if my telomeres can be renewed by my telomerase,

then all I have to do to reverse the signs and symptoms of aging

is figure out where to buy that Costco-sized bottle

of grade A organic fair trade telomerase, right?

Great! Problem solved.

(Applause)

Not so fast, I'm sorry.

Alas, that's not the case.

OK. And why?

It's because human genetics has taught us

that when it comes to our telomerase,

we humans live on a knife edge.

OK, simply put,

yes, nudging up telomerase does decrease the risks of some diseases,

but it also increases the risks of certain and rather nasty cancers.

So even if you could buy that Costco-sized bottle of telomerase,

and there are many websites marketing such dubious products,

the problem is you could nudge up your risks of cancers.

And we don't want that.

Now, don't worry,

and because, while I think it's kind of funny that right now,

you know, many of us may be thinking, "Well, I'd rather be like pond scum," ...

(Laughter)

there is something for us humans

in the story of telomeres and their maintenance.

But I want to get one thing clear.

It isn't about enormously extending human lifespan

or immortality.

It's about health span.

Now, health span is the number of years of your life

when you're free of disease, you're healthy, you're productive,

you're zestfully enjoying life.

Disease span, the opposite of health span,

is the time of your life spent feeling old and sick and dying.

So the real question becomes,

OK, if I can't guzzle telomerase,

do I have control over my telomeres' length

and hence my well-being, my health,

without those downsides of cancer risks?

OK?

So, it's the year 2000.

Now, I've been minutely scrutinizing little teeny tiny telomeres

very happily for many years,

when into my lab walks a psychologist named Elissa Epel.

Now, Elissa's expertise is in the effects of severe, chronic psychological stress

on our mind's and our body's health.

And there she was standing in my lab,

which ironically overlooked the entrance to a mortuary, and --

(Laughter)

And she had a life-and-death question for me.

"What happens to telomeres in people who are chronically stressed?"

she asked me.

You see, she'd been studying caregivers,

and specifically mothers of children with a chronic condition,

be it gut disorder, be it autism, you name it --

a group obviously under enormous and prolonged psychological stress.

I have to say, her question

changed me profoundly.

See, all this time I had been thinking of telomeres

as those miniscule molecular structures that they are,

and the genes that control telomeres.

And when Elissa asked me about studying caregivers,

I suddenly saw telomeres in a whole new light.

I saw beyond the genes and the chromosomes

into the lives of the real people we were studying.

And I'm a mom myself,

and at that moment,

I was struck by the image of these women

dealing with a child with a condition

very difficult to deal with, often without help.

And such women, simply,

often look worn down.

So was it possible their telomeres were worn down as well?

So our collective curiosity went into overdrive.

Elissa selected for our first study a group of such caregiving mothers,

and we wanted to ask: What's the length of their telomeres

compared with the number of years that they have been caregiving

for their child with a chronic condition?

So four years go by

and the day comes when all the results are in,

and Elissa looked down at our first scatterplot

and literally gasped,

because there was a pattern to the data,

and it was the exact gradient that we most feared might exist.

It was right there on the page.

The longer, the more years that is,

the mother had been in this caregiving situation,

no matter her age,

the shorter were her telomeres.

And the more she perceived

her situation as being more stressful,

the lower was her telomerase and the shorter were her telomeres.

So we had discovered something unheard of:

the more chronic stress you are under, the shorter your telomeres,

meaning the more likely you were to fall victim to an early disease span

and perhaps untimely death.

Our findings meant that people's life events

and the way we respond to these events

can change how you maintain your telomeres.

So telomere length wasn't just a matter of age counted in years.

Elissa's question to me,

back when she first came to my lab, indeed had been a life-and-death question.

Now, luckily, hidden in that data there was hope.

We noticed that some mothers,

despite having been carefully caring for their children for many years,

had been able to maintain their telomeres.

So studying these women closely revealed that they were resilient to stress.

Somehow they were able to experience their circumstances

not as a threat day in and day out

but as a challenge,

and this has led to a very important insight for all of us:

we have control over the way we age

all the way down into our cells.

OK, now our initial curiosity became infectious.

Thousands of scientists from different fields

added their expertise to telomere research,

and the findings have poured in.

It's up to over 10,000 scientific papers and counting.

So several studies rapidly confirmed our initial finding

that yes, chronic stress is bad for telomeres.

And now many are revealing

that we have more control over this particular aging process

than any of us could ever have imagined.

A few examples:

a study from the University of California, Los Angeles

of people who are caring for a relative with dementia, long-term,

and looked at their caregiver's telomere maintenance capacity

and found that it was improved

by them practicing a form of meditation

for as little as 12 minutes a day for two months.

Attitude matters.

If you're habitually a negative thinker,

you typically see a stressful situation with a threat stress response,

meaning if your boss wants to see you,

you automatically think, "I'm about to be fired,"

and your blood vessels constrict,

and your level of the stress hormone cortisol creeps up,

and then it stays up,

and over time, that persistently high level of the cortisol

actually damps down your telomerase.

Not good for your telomeres.

On the other hand,

if you typically see something stressful as a challenge to be tackled,

then blood flows to your heart and to your brain,

and you experience a brief but energizing spike of cortisol.

And thanks to that habitual "bring it on" attitude,

your telomeres do just fine.

So ...

What is all of this telling us?

Your telomeres do just fine.

You really do have power to change what is happening

to your own telomeres.

But our curiosity just got more and more intense,

because we started to wonder,

what about factors outside our own skin?

Could they impact our telomere maintenance as well?

You know, we humans are intensely social beings.

Was it even possible that our telomeres were social as well?

And the results have been startling.

As early as childhood,

emotional neglect, exposure to violence,

bullying and racism

all impact your telomeres, and the effects are long-term.

Can you imagine the impact on children

of living years in a war zone?

People who can't trust their neighbors

and who don't feel safe in their neighborhoods

consistently have shorter telomeres.

So your home address matters for telomeres as well.

On the flip side,

tight-knit communities, being in a marriage long-term,

and lifelong friendships, even,

all improve telomere maintenance.

So what is all this telling us?

It's telling us that I have the power to impact my own telomeres,

and I also have the power to impact yours.

Telomere science has told us just how interconnected we all are.

But I'm still curious.

I do wonder

what legacy all of us

will leave for the next generation?

Will we invest

in the next young woman or man

peering through a microscope at the next little critter,

the next bit of pond scum,

curious about a question we don't even know today is a question?

It could be a great question that could impact all the world.

And maybe, maybe you're curious about you.

Now that you know how to protect your telomeres,

are you curious what are you going to do

with all those decades of brimming good health?

And now that you know you could impact the telomeres of others,

are you curious

how will you make a difference?

And now that you know the power of curiosity to change the world,

how will you make sure that the world invests in curiosity

for the sake of the generations that will come after us?

Thank you.

(Applause)