I feel apoptosis is required for the coordinated differentiation and natural turnover in multicellular organisms. If you did not have a coordinated death process for unwanted cells, you could not obtain the right morphology in any organ. Moreover, apoptosis is a very convenient tool to prevent that cells with "toxic" mutations proliferate in a organism. At the same time, through apoptosis cells infected by viruses are eliminated.

Definitely the death process is required to keep healthy and alive a multicellular organism. Accordingly, apoptosis is present throughout the phylogeny, including the most primitive forms of multicellular Eukaryotas. In some species there are variations on the themes, but the basic concepts and some of the mechanisms are shared by worms and humans.

I feel apoptosis is required for the coordinated differentiation and natural turnover in multicellular organisms. If you did not have a coordinated death process for unwanted cells, you could not obtain the right morphology in any organ. Moreover, apoptosis is a very convenient tool to prevent that cells with "toxic" mutations proliferate in a organism. At the same time, through apoptosis cells infected by viruses are eliminated.

Definitely the death process is required to keep healthy and alive a multicellular organism. Accordingly, apoptosis is present throughout the phylogeny, including the most primitive forms of multicellular Eukaryotas. In some species there are variations on the themes, but the basic concepts and some of the mechanisms are shared by worms and humans.

Hello,

Cristiano Ferlini makes some very valid points.

Unicellular eukaryotes such as yeast do in fact undergo apoptosis, correlating broadly with senescence http://www.sciencedirect.com/science/article/pii/S1369527404001365. For multicellular organisms, apoptosis serves a plethora of purposes; development (avoiding Syndactyly), preventing tumor formation, immunomodulation, cell-replacement in the liver and many more. Programmed cell death exists in various forms, apoptosis is just one of them http://www.nature.com/cdd/journal/v19/n1/pdf/cdd201196a.pdf. Certain pathogenic microbes secrete bioactives that target apoptotic machinery, preventing cells from informing the immune system that they are compromised, thereby using the cell to replicate undetected.

I would consider pro-apoptotic and anti-apoptotic mechanisms to be a necessary component multicellular homeostasis and also, a factor in the evolutionary arms race between hosts and microbes.

I hope this helps,

Christopher

I would say as with the case in most cellular systems it all started with a mutation in a gene coding for some protein suppose to activate a certain process. And in this mutation the cell was able to remove unwanted material so it adapted and carried over until it became the complex process we now know as apoptosis.

This is not much of an answer but an interesting question none the less.

It would be really difficult to trace the first apoptopic event or cells/systems it first occurred in.

Apoptosis is essential for the development and long term survival of an organism. Take for instance the insidious damge that occurs during necrosis, which is the equivalent of a nuclear meltdown occurring in the middle of an organ system (ie. sepsis, myocardial infarction). Apoptosis serves in this case of massive damage control and the maintaining of functional integrity of the organ system or organism. During apoptosis, to my knowledge, there is no massive inflammatory response, so therefore damage via inflammation is quite limited. Maybe akin to a social contract amongst eukaryotic cells working together in an organ system.

Also, apoptosis would seem to be a type of anti-neoplastic control. Once a critical mutation cannot be repaired, a cell would undergo controlled self destruction, thereby limiting the chance of uncontrolled mutation cell exapnsion ie Neoplasm. From an evolutionary standpoint, cells in an organisms that could gracefully disintegrate would be a massive survival advantage for an a colony of eukaryotic cells working together. Cellular colonies that have better "damage control" via apoptosis had a survival advantage.

Also, a good example of the benefits of apoptosis, would be during embryonic development. If there were no apoptosis, there would not be enough room for fetal development, as millions of cells undergo apoptosis during for example extremity development. If not for apoptosis, we would all have webbed hands, at minimum.

Cool question

Great question and great answers also! I would say that apoptosis is a central defense in multicellular organisms, because programmed cellular death ensures the survival of the organism on the basis of loosing some of its cells. Much like the worker ants who die for their queen. In the case of an intracellular infection (and I would guess this was the evolutionary root of it), the cell speeds up its reactive oxigen species (ROS), and blocks the antioxidant system, so accelerated senescence will occur leading to apoptosis, destroying the cell with the infection within also. Since the surrounding cells have the same genetic structure as apoptotic cell, its "worth" the death to ensure your genetic copy's survival.