Why do we age?

[Helix]

I think this was said, but in a "one-word" context. The answer is in fact telomeres. For all non-biology people, telomeres are the ends of DNA that act as caps (it's an overused analogy, I know) to protect DNA and also protect DNA from getting cut down due to the "end-replication problem." Basically, it means that DNA will get progressively shorter each round of division. Telomeres are the caps that protect the actual coding DNA from being cut down, it's sort of a sacrificial peice of DNA.

 

How does this relate to aging? Well a cell will only die of natural causes when its telomeres run out. Annnnddd there's an enzyme of considerable interest, telomerase, that exists in some cells and whose function is to lengthen telomeres.

 

See the connection? Theoretically, introduce telomerase to cells and viola, immortality. But nothing is simple in nature. I was over simplifing things by saying cells only die naturally due to short telomeres. Actually there are a few less major pathways to senescene (cell death). So it works in theory and who knows? Maybe some day there can be Fountains of Youth based on this magical little enzyme....but I doubt it. And knowing humans, if we do manage it, we'll just over-use it and somehow manage to screw somthing up ...but at least we're lovable.

 

**Side note: telomerase has considerable anti-cancer potential since cancer cells use telomerase to be immortal. That's right, cancer's secret: telomerase. Without it cancer cells are boring normal cells and aren't really harmfull. (Yes, there is the ALT pathway and possible ALT1 and 2 etc. but they are the vast minority.)

 

edit: my avatar is actually a picture of telomeres...i'm into them.

Will

[GeminiinimeG]

Ok the thing is that we are made to reproduce and then die

 

Bacteria seem to never die becauser they keep replicating, so do we by passing on our genes to the next generation, we do not exactly die but keep on living though our descendants

 

All I know is that people now a days dont want to die but rather want to find a way to extend their lifetimes because were affraid of death. The answer in extending lifes lies in our DNA and thats the only way to trully advance in our ability to live very long time.

 

Good post

[DialysisBag]

Hmmmm...

 

Don't we produce telomerase? I thought I saw that we produce small amounts right before the Go phase. Compared to carcinoma, it produces it excessively in all phases. When you think about it, I think it is all but possible for us to mass produce this 'magic bullet'. This is of course refering to the gene we haven't found yet that controls telomerase. In order to take advantage of this gene besides reducing cancer, would be quite possibly mutate it ourselves (like how cancer does it).

 

No. The reason we age is BECAUSE of telomeres. We lose efficiency as we get closer and closer to our deaths. Many would agrue that free radicals accumalate over time, propagating mutations and errors within our complex systems, eventually leading to death. But our bodies have ways to counter oxidants (I know there are, but I don't remember). Just as we age, we lose functionality due to deteriorating telomeres, therefore the systems that control oxidant concentrations become lacks and less able to do their jobs. In a co-effort, DNA destruction and oxidants perform well to end the living.

 

But. If this were the case, and if telomerase were to be used to improve longevity of the human multicellular organism, then several issues arise. Like what was stated earlier, there are periods of time that activate and initiate processes as we 'age'. Hormones are released to start puberty, and to end it. How does the body know when to start and end these crucial times in our lives? Maybe at the peak of maturity, cells start responding by PCD, who knows? By inducting this enzyme we could very well start living in 'Neverland' at the point we switch on this enzyme. Ever seen 'Spirited Away'? You might be able to produce telomerase as a new born, but may forever look like that huge baby in that movie. Just maybe, 'aging' is really the time sheet everyone talks about. But a time sheet of activation and production too.

 

Another thing to think about. Once we have this (I call it cellulare longevity) there comes a time where you wonder about the cells that don't replicate and undergo mitosis. Neurons and muscular tissue for an example. Cardiac muscle replaces (if there is need to God forbit) damaged tissue with scar tissue (aka connective tissue) and not by replication of initial cells. Don't muscle cells fuse with one another, containing multiple nuclei? I might be having a bad trip, but it's been awhile since I thought about muscle cellularity. There is no proliferation, so there is no need for telomerase. Same thing with neurons, but at a complexity that is making me dizzy. With the form agelessness, there will be (I think) an advanced form of Alzheimer's Disease that contributes to nerve tissue deterioration. Since replication (if at all in nerve cells) is so slow, the amount of cellular death surpases cellular life in the CNS. Maybe by that time we will have stem cells that enable faster neuron replacements that enact our past neurons so we don't loose information.

 

Just my idea... *blushes*

 

~db

[sciborg]

There is still a lot of scientific argument about why we age. Some say we age because it is essential to the process of evolution.

 

See http://www.azinet.com/aging/

 

and

 

http://www.mathforum.org/%7Ejosh/humanist.html

[Mayflower]

Well acc. to me ' date=' it is a mixed expression of evolution, environment and the genes. The food habits, excercise and living conditions like exposure to sunlight, quality of air and water and amount of sleep all contribute to the effects and help aging.

People in Japan have an avg life span > 70 years while some places like in Ethiopia it's like 45-48only.[/quote']

 

I don't think Ethiopia's low average life span has hardly anything to do with aging.

[sciborg]

As I see it the big issue is whether we are designed to age and possess some kind of "drop dead timer" or whether aging is something that just happens because of some limitation in the organism. In connection with telomeres, is there a fundamental limit on cell division as suggested by Hayflick or is telomerase programmed by some mechanism to act as part of the self distruct mechanism? This is medically significant because if there is a self distruct mechanism there might be some way to disable it.

[DialysisBag]

p53 gene... Controls apoptosis and including PCD (programmed cell-death); cancer mutates this gene so it doesn't respond to signals propagating PCD.

 

~db

[RVonse]

That theory sounds pretty good except for the fact that there are some physical properties with our bodies that actually improve advanced age.

 

When I was a teenager I had a bad problem with acne but later in life that physical problem has now gone completely away. It is well known that many male teenagers experience the acne. Yet later in life the body learns how to correct this problem even though attracting women is no longer important. It was the same way with my dad.

 

It is pretty obvious that acne does not attract woman so this is contrary to evolution IMO.

[Helix]

Well wait...that's assuming acne would be a chronic problem independant of aging. Acne is a problem because (and this is based on vague memories) hormones and such associated with puberty. It isn't youe body learning to deal with it, the source of the problem actually dissapates.

[RVonse]

Ok, that sounds reasonable for acne.

 

Still there are problems I see with this theory. For example, why do cells appear to follow an intelligent path even after reproductive years? We may not prefer the path they take but it is hard to argue the path is not intelligent. Because if cells were not governed by dna intelligence, people would grow old in different ways and it is clear they do not. For example, when people get older they generally develope grey hair and go bald. Men almost always go bald in all the same places(forehead and top back of head) yet woman do not. Men also grow hair in other places (in ear canals). Surely there is something still instructing cells to grow this way or you would not be able to predict common traits to old age.

[Helix]

This is due to the underlying force that ensures that genetics works: biochemisty. Grey occurs in both sexes because the pigment is gradually lost. This happens in almost everyone execpt for those who have a genetic disposition. The "intelligent cell" theory is logical but it is explained by biochemistry.