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Cell Death Nets 2002 Nobel Prize in Medicine
An anonymous reader writes "The recent press release at the Nobel website details the first of the 2002 Nobel Prizes. This year the Medicine prize goes to Sydney Brenner, H. Robert Horvitz, and John E. Sulston for their discovery of programmed cell death (also called apoptosis). Their seminal work in the model organism C. elegans established the foundation of cell suicide as a normal physiologic process. The implications are wide ranging including understanding organ development and cancer."
NPR has a pretty good link to an explanation. At the top of the article, there's an real audio recording of the actual report that I listened to this morning. I thought it was fairly accurate, and should give some explanations.
To be precise about it, these fellows did not "discover" apoptosis, they have done a lot of very good work defining the genes and methods responsible for triggering it. From what I've read, though, they certainly deserve the prize.
hmmmm?
There are a number of issues in going from making a cell live forever, and making us do so.
First, you have to develop. Wouldn't want to make a 6 year old's cells live forever.
Then, you have to repair. You need to balance growth with externally induced damage (injury, sickness). If you make cells live forever, you also have to stop them from dividing... Or you'd end up quite the mess.
Many cells in the body, like skin, grow and die and that is very important to us. If the didn't die, you'd slowly erode the dead surface and end up one quivering blob of ozing red pain.
"To be precise, the Horvitz lab at MIT discovered apoptosis. Brenner and Sulston were honored for their roles in establishing C. elegans as an experimental system."
I believe Horvitz actually conducted the seminal work (first discovering and characterizing genes controlling cell death) while working (along with Sulston & Brenner) as a postdoc at the MRC (in the UK).
Yes, but not in the way you think. We can use apoptosis to kill harmful cells, like cancer cells. This is a "natural purpose" of apoptosis, and drugs are under development to "encourage" cancer cells (and virally infected cells) to die by this mechanism.
The theory that apoptosis plays a central role in human aging is part-and-parcel of the "free radical" theory of aging, which I think is bullshit.
The basic idea is that reactive oxygen species - these are chemicals that want to take electrons away from biological molecules and can do in such a fashion that the biological molecule is damaged - damage your mitochondria in such a fashion that the mitochondria signal the cell to die. This definitely CAN happen - however, I don't believe that it actually does, or that any of the pathologies we observe in human aging actually depend on this pathway. Btw, I'm a bioinformatician (grad student); when I worked with my Dad, I studied oxidative stress - he still does but he does not think it plays a role in normal aging. Certain conditions - being a chain smoker, being on hemodialysis, whatever - may actually put enough of these reactive oxygen species into your system that this could happen, but I doubt it.
FYI: some people try to sell you antioxidant dietary supplements (or other treatments.) I cannot emphasise enough - these products are snake oil. Even if reactive oxygen species do play a significant role in aging (which I doubt,) taking spills to scavenge them or soak them up is utter malarky.
The opinion of someone with whom I disagree almost completely. More of the same - the summary is fairly accesible.
To sum up - I can't say conclusively that there is no aging-related process that depends on apoptosis, but I don't find the evidence at all convincing. The one that people are fond of at the moment, which is oxidative stress-come-apoptosis, is hogwash.
Aptoptosis serves two functions:
1) Developmental. Developmental Aptoptosis is necesarry to "carve out" your body. For example, when your fingers form, the tissue between what will become the fingers goes aptoptotic and dies. There is no real evidence that this is what happens when you get old.
2) Defensive. Cells which are pre-cancerous, or which have been infected with viruses, can become apoptotic. Certain conditions that some old people get - autoimmune disorders, for example - depend on apoptosis to do harm. However, this is not a part of normal aging.
P.S. Most scientists pronounce it "apo-tosis," the p is silent (like pterodactyl.) On the other hand, by this reasoning, helicopter (which comes from the same root as pterodactyl) would be "heli-coter", so say the p if you want.
The good and new comes from no quarter where it is looked for, and is always something different from what is expected.
It is vital to development of many tissues, such as nervous tissue in the spinal cord or the brain. Death of a human is not massive PCD.
Programmed cell death / apoptosis is caused by intercellular communication.
Apoptosis can be stimulated in a cell through a variety of ways, for example in an antigen-presenting immunoreactive T-Cell which binds through a Fas / FasLigand compliment, the t cell will undergo apoptosis and kill itself so that it cant kill the other cell.
So in reality, no, it has nothing to do with human death, just regular cell death.
It is both. The cell would stop reproducing and die if it were working properly. It _may_ also reproduce at an accelerated rate or detach and float around in the blood stream.
But the main problem is that it and it's "children" won't die. If they did, the problem would fix itself (due to the limited number of times the cell can divide plus the limited lifetime).
Sorry abut the raw-HTML post above. I forgot to switch from code mode. Here is the correct version:
Because it is an interesting and often misunderstood subject, here is a small primer on the topic of apoptosis (Programmed Cell Death).
FYI I work in an immuno lab which uses apoptosis as a main treatment for transplant tolerance.
Death by suicide
Cells that are induced to commit suicide:
The pattern of events in death by suicide is so orderly that the process is often called programmed cell death or PCD. The cellular machinery of programmed cell death turns out to be as intrinsic to the cell as, say, mitosis.
Why should a cell commit suicide?
There are two different reasons.
1. Programmed cell death is as needed for proper development as mitosis is.
2. Programmed cell death is needed to destroy cells that represent a threat to the integrity of the organism.
In the example he gave:
Say a cell is infected by a virus, it will present pieces of the virus on the cell surface.
A T-Cell comes along, checks out this virus piece, and sends a signal saying
"Hey, that's a virus! You're infected! It would be better for all of us if you just commit suicide."
After getting this signal, the infected cell turns on its apoptosis genes and kills itself in a sensible, precisely controlled manner.
This is just one example of apoptosis, but you can see how the controlled suicide of a few cells is beneficial to an organism.
You need to realise that an animal model doesn't necessarily fit with the human one e.g. leptin. Moral of the story: Don't get your hopes up!