Qualy #19 - A unifying theory of aging
Episode Stats
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Summary
In this episode of The Qualies, Dr. Peter T.D. Matthews, PhD, joins us to discuss his new book, "Aging and the Silent Killer: The Science of Old Cells" and his new research on aging and aging-related issues. Dr. Matthews discusses the 8 central tenets of aging and how they affect the aging process, and the role of epigenetics and epigenetics in aging.
Transcript
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welcome to the qualies a subscriber exclusive podcast qualies is just a shorthand slang for
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subscribe so without further delay i hope you enjoy today's quali earlier you spoke about sort of eight
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or nine central tenets of aging we've covered some of them but i know and i'm guessing that your book
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is going to go into this in greater detail but can you rehash what you or at least as many of those as
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you're going to recall on the spot not to put you on the spot that's a long list uh yeah sure
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there's epigenetic change the cells of cell communication and inflammation there's let me
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count this analytics so senescent cells build up there's protein misfolding there's telomere loss
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and genomic instability there's metabolic changes so mp kinase and metformin would address that
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and then there's uh responses to what you call amino acids and other nutrient inputs and those
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collectively go awry during aging but what causes all of those to happen that's something that we've
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been working on for quite a while and you think those are more coupled than they are uncoupled those
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pathways or do you think that i mean there are clearly situations in which external stressors can
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perturb more than one of those but like senescence seems somewhat uncoupled from nutrient sensing
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doesn't it uh it may but and i'm not asking that rhetorically like i just i just don't know
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no the answer is we think that we've found an explanation for all of these things to happen
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a unifying theory right so i've kept it close to my vest for a number of years but it actually goes
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all the way back to the sirtuin story in yeast and hopefully the listeners who've stuck with this
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podcast are still with us because they will punchline yeah they i promise you they are with us so the
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punchline is that so this is all off top my head here we haven't published this yet but i'm i'm gonna
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tell you my my thoughts and your listeners so the genome is digital information it's very easy to
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preserve it's the reason we went from analog to digital in the 2000s dna is four letters it's digital
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it's easy to replicate it's easy to store you can boil it it's very robust and so what we've actually
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come to discover is that the genome is fairly intact in old people and old animals we've
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sequenced the genomes of lots of old mice and all the genes are still largely intact so what's going
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wrong well the other part of information that you inherit from your parents is the epigenetic
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information okay and i use that term loosely but basically it means what's the pattern of gene
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expression which genes to turn on and off at which time and that is analog information okay that has
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to be analog because instead of just being a single code it has to operate in three dimensions actually
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four if you count time and so that's an analog system and it's constantly adapting to what we eat
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what we what we drink if we run when we sleep and you have to turn genes on and off all the time
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but that pattern of gene expression that's set down when we're young because it's analog analog
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information doesn't last very long anyone who's had a record player or magnetic tape knows that
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these things don't last and that's the problem i think with aging is that we don't lose the digital
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information so the compact disc of our lives is still intact when we're old but it's as if we've got
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a scratched cd and the cells don't read the right genes at the right time anymore and they lose their
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identity in fact if we there's a analogy which is called waddington's landscape where in the 1950s
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waddington drew a picture it's a beautiful picture of some hills it's a mountainscape and cells actually
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roll down the mountainscape and land in different valleys down below and that's to you know before we
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had he had access to the genome that was his way of saying this is how cells know what they are they
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land in these valleys and they stay there but what i think is happening during aging is due to the
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vibration of noise over time we lose that pattern of gene expression we lose that information
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epigenetic information and those cells or those marbles in waddington's landscape they jump over
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into different valleys and lose their identity so your neurons are not functional like neurons anymore
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your liver cells are more like neurons and we see that in our lab we're just writing up a couple of
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papers right now for this and we're able to actually manipulate the epigenome in cells and in mice and
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have a look what happens to those animals and the prediction is that you get all the hallmarks of
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aging you know the challenge with this entire space is you think back to the time in the 1950s when he
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made when he created that analogy and it's in some ways it's amazing that it could still be relevant 75
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80 years later whatever it is on the other hand it it humbles you to realize how much more has been
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learned about that process in that time and sometimes i think about it because you and i are interested in the
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same problem that i'm worried i just don't know anything you know i'm worried that in 10 years
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i'll look back at my hypotheses and my not even my hypothesis just my understanding of the current
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state of the art today and think you know what that was directionally right but it was so oversimplified
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and oh my goodness like you know so it's sort of like we're back in this problem of time like we're
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going to run out of time and i mean how confident are you that because you and i are almost the same age
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like how confident are you that in our lifetime we will see step function changes in human longevity
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and to put this in context there really hasn't been a step function change in human longevity
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probably since the introduction of sanitation i mean everything has been quite incremental maybe
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antibiotics vaccinations antibiotics have probably been the last step function change will we see one in
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our lifetime how confident are you i'm getting more and more confident honestly when i started in this
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field i thought we'd probably not see the type of technologies that i'm seeing now it's making my
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head spin not just in the technologies but also the uh the investment and the number of people working
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on this now this was the back order of biology when we started and there's been some new results which
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i'll just hint upon because um we haven't published and it's very early but i've seen it sounds like a
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scene out of blade runner but i've seen things you wouldn't believe no it's it's maybe not that
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dramatic but let me go back to the compact disc analogy you've got the scratched cd how do you
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find the polish what is that let's go back to the yeast analogy what causes those scratches why do you
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get loss of gene regulation anyone who was paying attention earlier on in this conversation will
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remember that these dna breaks in the chromosome broken chromosomes distract the sur complex and they
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move away and you get the expression of genes that have no right being on
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because the sirtuins have lost they're they're distracted from the deactivation function and
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they're dealing with the repair function exactly so using that what we've got a lot of evidence for
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now is that something very similar if not essentially identical in principle happens in mammals as we age
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what that means is that insults to the genome and one of the major insults is a double strand break but
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there are probably others cause these proteins sirtuins and other factors i'm not saying only
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sirtuins but factors that control gene expression silencing and other things have a dual role we
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know in dna repair and other things such as responding to stresses heat whatever but this is
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the cell's way of coordinating gene expression changes hunkering down during times of adversity
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and going off to repair the system which in this case we study dna breaks and that's a beautiful system
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when you're young it works great you get exposed to cosmic rays or you go out in the sun you got lots of
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dna breaks eventually these proteins will go repair those breaks and then go back to where they came
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from to settle down the response to turn off the inflammation to turn off the dna repair when it's
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not needed but the problem we think is it's antagonistic pleiotropy okay so peter medewar and
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the other brilliant scientists in the 50s speculated i think correctly is that things that are really good
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for you when you're young come back to bite you in the ass when you're older and i think that's what's
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happening here is that this response to these stresses like a break end up not just distracting
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these proteins but end up disrupting the actual structure of our chromatin and these proteins don't
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always go back to where they came from 100 do that for 70 or 80 years and it's not surprising that the
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genes that were once perfectly programmed and turned on at the right time lose their ability to do that and
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we've got remnants of that program when we're 70 and 80 but what's exciting is that information is
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still there to be accessed the question is how do you get the cells to remember to access at the right
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time what's that polish and i think we're pretty close to finding that i hope you enjoyed today's
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