45 replies to this topic

[manofsan]

Hmm, who would've thought that simply knocking out a couple of genes can extend lifespan by so much?

http://www.guardian....1645418,00.html

Well, these were cultured cells, but if they're extending the genemods to mouse trials, then we'll have some Methuselah Mouse Prize candidates.

But I wonder what the effect on the wider physiology of an organism would be?

[123456]

But I wonder what the effect on the wider physiology of an organism would be?

I am thinking similarly. What are the genes being discarded responible for? Secondly; What effects, if any, to other genes are observed when certain genes are taken out?

[manofsan]

Well, the only way to tell for sure will be to make some organisms with those genes deleted. The more complex, the better -- if mice work out well, then next how about some chimps?

But hopefully it won't take too long to make some knockout mice.

Haha, I once heard a radio talkshow host ask -- if you could be a healthy long-lived imbecile or a sickly short-lived genius, then which would you pick? To heck with these Hobbes' Choices - I want it all, thanks.

Anyway, even if there are some drawbacks, perhaps some compromise intermediate state could be found, where we only live 3 times as long, but are still reasonably functional.

Anyway, here's another link:

http://www.betterhum...18/Default.aspx

This discovery sounds serendipitous. Sort of makes the case for some brute force combinatorial search method, trying to knock out or augment all different combinations of various genes.

These altered cells look like they're generating huge amounts of anti-oxidant, or otherwise why would they stand upto oxidants so well? Is there any mitochondrial connection here?

[olaf.larsson]

I think its the C. elegans dauer study they are talking about. The problem is that there is no such thing as dauer in most animals.

[apocalypse]

I think its the C. elegans dauer study they are talking about. The problem is that there is no such thing as dauer in most animals.

No they're talking about a new study done on yeast, showing a similar 6 fold increase lifespan extension.

As for the absence of dauer in other more complex animals it may be that such a strategy is probably not beneficial for more complex animals, were the resources are better allocated into producing the next-gen rather than the preservation of the organism. A species doing this would probably be at a disadvantage to other competing species that dedicated more resources into producing offspring, and allowed mutations to more easily occur. The latter would offer faster rate of adaptation(more possible combinations given more offspring, shorter generation time, greater mutation rate.), and thus unless it was necessary due to some other beneficial trait that required such, say traits such as a large brain, large size, flight, or the like it would be a detrimental thing. And even with such traits it'd only be beneficial to better preserve the organism to a point were the adaptability vs benefit of such trait would lvl off.

The existence of animals showing increased lifespans from even single gene mutations, and many of such genes, points to this, IMHO. If such mutations allowing better preservation were beneficial at the species lvl, they would spread throughout such, and slowly accumulate yielding ever longer lifespans. Even the c-elegans can have substantially extended lifespan while avoiding the dauer state by subtle mutations of the genes involved. As for the older and similarly large 6 fold lifespan extension on c-elegans, accomplished by removing the entire reproductive system, we saw a compromise in reproductive ability. But even the well-known researcher that performed the experiment believed it was the built-in signalling not the reproductive potential.

“If we could intervene in the hormone signalling pathways directly, we think the animals would still live six times as long as normal, but would be fertile as well.”-Cynthia Kenyon.

Given that it seems to show similar results in human liver cells, but the mice study hinted at it being necessary for fetal dev. It would appear this could be introduced through g-modified s-cells, to replenish tissues or through g-modified engineered tissues, organs. More knowledge is obviously required, and it'll be interesting to see what further research indicates. If one can mod such protection limiting regulative genes in more complex animals, protection similar to the dauer state or this new induced similar state in yeast(not ocurring commonly naturally either.) may be possible.

[kevin]

Slashdot Link to thread on this topic..

http://science.slash...&tid=214&tid=14

[apocalypse]

In any case, it would appear that if the life extension effects of Sir2/Sirt1 downmodulation are to be applied to mammalian systems they must be done so only in somatic cells (not germline or stem cells) and then only once development has been completed.

Are you sure this applies to more differentiated adult-like stem cells that are already precursors to specific tissues? Anyway given that, IIRC, s-cells have been shown to be able to develop into cancer cells, if not with this particular gene but through others, it'd be nice to increase stress resistance and dna repair in such cells.

[manofsan]

Prometheus, consider that physiological signs of aging become most pronounced when development has been completed (ie. in humans, from age 25 onward)

So then if some kind of gene-targetting could be done on a normal creature (mouse? chimp?) that has already reached maturity, then could it be possible to specifically target these 2 specific genes to knock them out across most cells in the adult organism, if not all?

Heh, it's funny, uptil now we've talked about the problem of trying to insert new genes into every cell of an adult organism to help fight aging. But nobody's considered the possibly much simpler challenge of trying to knock out particular gene(s) in every cell of the adult organism to fight aging.

This revelation about these 2 genes kind of opens up that path in that opposite direction, of knocking out the genes in the already developed adult.

Really, shouldn't that be doable with today's technology? Shouldn't we be able to take a normal adult mouse/chimp/sheep and knock out those 2 genes in every cell of their body? (well, most cells, if not all)

Answers, please?



[Hah, consider that in the 20th century, the modern rite of passage into adulthood has included the removal of wisdom teeth. Perhaps in the 21st century, not only do you get your wisdom teeth removed upon reaching adulthood, but you also get a couple of genes knocked out. ]

Edited by manofsan, 20 November 2005 - 02:24 AM.

[John Schloendorn]

But nobody's considered the possibly much simpler challenge of trying to knock out particular gene(s) in every cell of the adult organism to fight aging. [...] Really, shouldn't that be doable with today's technology?

One could consider an inducible cre/loxP knockout, if one really wanted to know if adult-onset therapy would be effective in principle. (i.e. the gene is tagged with loxP, which is a germ-line modification. The tagged gene can then be removed upon administration of an inducer at any age or condition. Google for more details.) This may provide an answer as for the late onset, and it is a shame that no one is interested enough to try it with any of the life-extending germ-line modifications that have been described in mice so far. Doing anything like that in wild-type (i.e. non loxp-tagged) vertebrates of course remains science fiction.

[manofsan]

Ah, I get you - you build in an off-switch for testing purposes. Hmm, then you could try switch-offs at various points in the lifespan. So is this switch reversible - can you undo the switchoff from the inducer to bring the gene back online again?

Hmm, so one can't knock out those genes in situ, for a regular organism -- too bad, that might be a quick answer for someone who received massive radiation poisoning for example. Then it could put the repair mechanisms into high gear.

If even the mature adult does still have some stem cells active in the body for tissue repair purposes, then what effect would the knockout have, if it's known to cause developmental problems? Hopefully the effects would not be so severe so as to impair the vestigial repair capabilities of these remaining pluripotent cells.

Anyway, John, if experiments based on your tagging approach worked, and the mice/sheep/chimps were to live significantly longer -- say 30% longer even -- then it could veer anti-aging research towards this more feasible and identifiable goal of figuring out how to disable those genes in adult human beings. Perhaps gene knockout could be investigated, or even drugs or small molecules designed to block the expression of those genes.

Trying that tag/inducer thing seems to be an interesting idea.

Edited by manofsan, 20 November 2005 - 05:13 AM.

[manofsan]

Ah, of course, I should've remembered RNAi as an obvious way. And all you need to do is use a complementary RNA sequence strand for that, right?

Tell me, how effective is RNAi compared to total silence? 98% effective? 80%?
Will it achieve effect similar to down-regulation (ie. not total silencing) or will it achieve absolute silencing of the gene?

Hmm, since RNAi is already entering the marketplace, it seems like a good way to trial some methuselah mice.

What are the actual abnormalities that result from the gene being silenced during development? Perhaps these abnormalities themselves can indicate how soon in the developmental/maturity cycle one could start the silencing. For instance, would it stunt growth if initiated during puberty? After all, that's still a far cry from embryonic state.

It would be interesting to try initiating the silencing at different points during the lifecycle. Or since RNAi can stopped at will, what about intermittent periodic application of it?

Wow, RNAi for life-extension -- has anyone mentioned that before? I've heard about it for disease treatment of course, but not anti-aging as discussed here. Hmm, definitely merits at least a look.

[manofsan]

I read you, Prometheus-- like that Foxo3a gene that Sirt1 silences would be upregulated if Sirt1 itself were silenced.

So moving away from particular genes themselves, do you feel the strategy should be to upregulate all the anti-oxidant pathways, and correspondingly downgrade all development-related/reproductive-related pathways as a tradeoff? After all, once we're at full maturity, certain pathways/genes are then less essential as compared to while we were developing.

Should our perspective be framed by a schism between developmental metabolism vs post-developmental? Rank in order of priority the genes/pathways that are more crucial for proper development, and likewise rank in order of priority the genes/pathways that are more crucial for lifespan extension. Then try to upregulate all the life-extension pathways at the expense of developmental-related pathways (ie. downregulate these latter ones).

[John Schloendorn]

So is this switch reversible

Cre/loxP is not reversible. When the target sequence is eliminated from the genome, its info is fundamentally lost. The system can be used to knock in genes that are initially off, e.g. by tagging a truncating stop codon with loxP. There are reversible systems too, such as inducible promoters that fire only when a certain drug is present (also germ-line modifications). They tend to be more fuzzy than knockouts (this is the reason one has the inducible promoter control cre, rather than the target gene itself), but may still get you a good effect.

how effective is RNAi compared to total silence

As effective as the introduction of the vector carrying the gene for the RNAi, which is about as efficient as the introduction of a vector for any gene.

[manofsan]

What would it take to get a trial started, for testing the effect of RNAi silencing of the Sir2/Sirt1 gene on mature mice, drosophila flies, or whatever?

Hey dnamechanic -- have you guys ever done any RNAi on your Methuselah Flies?
Do they have any equivalent of Sir2/Sirt1??

[manofsan]

What about nematode worms, aren't they the poor man's guinea pig? Do nematode worms have any Sir2/Sirt1 equivalent that could be silenced with RNAi?? Has anyone tried this yet?

[olaf.larsson]

What about nematode worms, aren't they the poor man's guinea pig?

Well nematodes have the advantage of reproducing fast and dying fast. They are multicellular animals much more similar to humans then yeast. Would you like to spend ~2 years drinking coffé and waiting for your mice to die, before you can publish your paper?

[manofsan]

Haha, hopefully the mice would not die in 2 years! Hopefully they'd die after 10!

But do nematode worms have some equivalent of Sir2/Sirt1 that could be silenced with RNAi??

Surely it should be worth it for some intrepid lab techie to find out

[jays]

This new approach is definitely very interesting, the study speaks of an extreme survival mode, is this special mode observed in mammals in general? Are there any studies fully documenting it? Actually there are experiments with young adult apes showing that in captivity or isolation they tend to deal better with aging, halting it at some level so to speak, sort of like waiting for better times and holding on to their physiologic peak. It’s very probable that the extreme survival mode also happens in humans, since we’re talking about primary and basic homolog genes here. I think switching the genes that regulate DNA and cell protection systems using technologies as RNAi would be a relatively simple method to achieve a major boost of life span.

[spiritus]

Come come, we let discussion on this just die?

I'm here to discuss this in any format. Who here is going to contact their local genetics lab and discuss this?

[manofsan]

Haha, it's interesting to think that deep down in our genomic operating system, there is a "Safe Mode" that can be triggered, so that our cells are brought to some conservative self-protective state.

I wonder what the expression patterns of Sir2/Sirt1 are, relative to natural circadian rhythms. Is this Safe Mode ever triggered naturally by us, perhaps when we sleep, or are Sir2/Sirt1 always actively being expressed?

If some RNAi silencing of Sir2/Sirt1 was devised as a therapeutic application, then how often could we resort to silencing these genes, without adverse effect? Could everyone take an oral dose of RNAi at bedtime before sleeping, and then wake up extra refreshed and cleansed in the morning?

Too bad we can't find some super-autophagic recycle mode, so that we can recycle our cellular parts better while we sleep.

[spiritus]

There lies a billion interesting triggers in our system just waiting to be tickled.

I beleive in a way this is pandora's box. We've opened cells and unleashed the research on genes. Now we can manipulate (well, to be proposed) every cell in the human body. If we can create immmortals, who is to stop from becoming one and how can this be calculated into human population forumlae, wealth formulae and other considerations?

If someone accumulates wealth and does not stop and pass down (like a tree falling in the forest to provide other trees with nutrients), then we will literally deplete our soils of all valuebles. Then the solar system.

Nanotechnology will help us conserve in major ways however so the future of immortals looks bright IF everything turns out right.

Now, what I worry about is the condition of the yeast cells that lived 6 times longer. The structural condition of the DNA.

Manofsan it could very well be triggered as we sleep. The brain produces an array of chemicals and antioxidants such as melatonin float through your system.

Personally I think we could only silence this gene once.

The key to immortality seems to me to be our discover of a gene that catalyses another, which catalyses that gene. This is an example of the symbol of infinity. Picture the symbol. To reach infinity and immortality, one has to contribute to another.

Personally I think human antioxidants and free radicals have to catalyse each other in a genetically engineered altered human. If we trigger a permanent safe mode we still have to fight free radicals which cause disease, or trauma. With aging stopped we do need to develop some form of anti trauma treatment. Damaged cells would trigger genetically engineered response systems, and the nessesary evil of damage would make this immunity system very active and strong.

No need to evolve to fight disease after the concious mind evolves. We realise the threats and then create the soloutions. Perhaps one day with the aid of drugs, amino acids, nanotechnology and the literal form of personal computers we will be able to take a stabbing and rebuild fast enough to recover.

Going slightly off topic but this does contribute to immortalist views:

The issue is... will we make it through an oil war which seems bound to happen. The arabs deff. have nukes. Can we shoot them down fast enough, then flatten the areas responsible for the launch?

I have the deepest respect for muslims (my girlfriend is one), but I do beleive muslim extreamists could turn some princes in Saudi for the worse. With the poor Russians dying to sell off nukes, I think only the ignorant cannot beleive in WMD's in the mid east exist. The American eagle needs to swoop down on the cobras... the American goverment may be corrupt but they sure as fuck are God fearing. And that's where the hope of our pandora's box lies...

[spiritus]

those studies of gene know out of the SirT1 were done while constructing genomic library of Drosophila using YAC as the vector. The problem is that the SirT1 knock out with HindIII or NotI also causes a defection in the argI and lacZ expression, meaning tha the yeast spores that lived 6 times over the normal life expetnacy did so in an artifical medium. Read: they would have died sooner if placed in a natural media with the SirT1 knockout.

And also understand that the basic idea of a cancer is a cell linage that has become "immortal" and no longer express the stop growth codon and continue to grow regardless of pressure or resource stress.

This is a quote taken from a popular online forum. The person behind it... direct quote "And if you were wondering about my background, I am studying oncology at Mercer University"

I do not like hype and I would like to see the communities response to what I read.

edit: He adds

it is still quite an achievement but they need a different restriction enzyme (such as TaqI or Sau3AI) that cuts a shorter base pari sequence allowing the lacZ and argI to continue to be expressed. If they can do this and can successfully clone the sequence it would be HUGE. Scarey almost

[spiritus]

www.offtopic.com

The worlds largest forum that makes sense. The others are anime forums ^_^

I wouldn't even be able to track down that specific post because I do not have a subscription, which you need to search (I'd need to search my own thread). Great forum though.

[spiritus]

The guy is a cancer researcher. His friend recently turned down a job that could produce 750k+ yearly because when he was done his research he could make more...

[veronica]

Does anybody have pdf of this article:

Cell Metabolism, Vol 2, 67-76, July 2005
Article
Mammalian SIRT1 limits replicative life span in response to chronic genotoxic stress
Katrin F. Chua,1,2,5,6 Raul Mostoslavsky,1,2,5 David B. Lombard,1,2,4 Wendy W. Pang,1,2 Shin’ichi Saito,3 Sonia Franco,1,2 Dhruv Kaushal,1,2 Hwei-Ling Cheng,1,2 Miriam R. Fischer,1,2 Nicole Stokes,1,2 Michael M. Murphy,1,2 Ettore Appella,3 and Frederick W. Alt1,2,*

Or any other article describing SIRT1 knockout mice? What effect do you think it has on IGF-I signaling?

[veronica]

How about SIRT1 specific inhibitor?

http://www.genengnew..._NEWSML_WEB.xml
http://pubs.acs.org/.../jm050522v.html