Thread: Cell material after apoptosis/necrosis

I am familiar with apoptosis and necrosis, but my question is, what happens to the cellular componets (DNA, proteins, lipids,...) that remain after the cell dies? I thought they were recycled and reused, but what is the mechanism or structure that collects these components and how are the reintergrated into new cells? Thanks.

Sincerely,

Beau

that would be dealt with by phagocytes

Apoptosis, as you are probably aware, is programmed cell suicide. Necrosis can be thought of as accidental death.

The pathologic consequences of apoptosis and necrosis are very different.

Apoptosis requires energy to attain its goal. The cellular components of the apoptosome are designed, through expenditure of ATP to cause the cell to 'bleb' (forming bobbles on its membrane surface) and split all its components into small, membrane bound vessicles. The cell breaks up and dies, but no cytosolic components are freely released into the extracellular space. This is a good thing: the cytosoic milieu is very pro-inflammatory. This makes sense because spewed cell guts usually means an infection is causing death, and loads of inflammatory cytokines are released. In development, because more cells apoptose than are actually present in the final organism, then if these cells were to spill their guts in an incoordinated way, the immune system would go into overdrive and probably kill the foetus. Fortunately, apoptosis uses energy to ensure things remain nice and tidy. As Marnix rightly points out, the phagocytes would then safely ingest these vessicles and degrade them. Recycling of proteins would not happen: they would travel to the lysosome of the phagocytes and be degraded into amino acids.

Necrosis, on the other hand, is a different game altogether. Here, cells die and spew their cytosolic components everywhere and many immune cells have receptors that recognise proteins that should only be in the cytosol. They are recruited en-masse, and you end up with really red skin, high fevers, pain and it can cause death via cytokine storms.

A lot of the pain and suffering from cancer is a result of necrotic tumours. Cancer cells disable apoptosis via a mutation and this helps fuel their endless proliferation. It does however mean that an energetically strained cell is more prone to necrosis than apoptosis, and so you can end up with large amounts of necrotic tissue in tumours, causing a lot of pain and inflammation. Switching back on apoptosis in tumour cells is at the forefront of cancer therapy.

Originally Posted by mascott

Apoptosis, as you are probably aware, is programmed cell suicide. Necrosis can be thought of as accidental death.

The pathologic consequences of apoptosis and necrosis are very different.

Apoptosis requires energy to attain its goal. The cellular components of the apoptosome are designed, through expenditure of ATP to cause the cell to 'bleb' (forming bobbles on its membrane surface) and split all its components into small, membrane bound vessicles. The cell breaks up and dies, but no cytosolic components are freely released into the extracellular space. This is a good thing: the cytosoic milieu is very pro-inflammatory. This makes sense because spewed cell guts usually means an infection is causing death, and loads of inflammatory cytokines are released. In development, because more cells apoptose than are actually present in the final organism, then if these cells were to spill their guts in an incoordinated way, the immune system would go into overdrive and probably kill the foetus. Fortunately, apoptosis uses energy to ensure things remain nice and tidy. As Marnix rightly points out, the phagocytes would then safely ingest these vessicles and degrade them. Recycling of proteins would not happen: they would travel to the lysosome of the phagocytes and be degraded into amino acids.

Necrosis, on the other hand, is a different game altogether. Here, cells die and spew their cytosolic components everywhere and many immune cells have receptors that recognise proteins that should only be in the cytosol. They are recruited en-masse, and you end up with really red skin, high fevers, pain and it can cause death via cytokine storms.

A lot of the pain and suffering from cancer is a result of necrotic tumours. Cancer cells disable apoptosis via a mutation and this helps fuel their endless proliferation. It does however mean that an energetically strained cell is more prone to necrosis than apoptosis, and so you can end up with large amounts of necrotic tissue in tumours, causing a lot of pain and inflammation. Switching back on apoptosis in tumour cells is at the forefront of cancer therapy.

Good post.

I am familiar with apoptosis/necrosis as I mentioned in my original post. So my question isn't related to that. I was wondering how the broken down cellular components are re-integrated into new cells? What is the mechanim for this "recycling" process?

Originally Posted by links0311

I am familiar with apoptosis/necrosis as I mentioned in my original post. So my question isn't related to that. I was wondering how the broken down cellular components are re-integrated into new cells? What is the mechanim for this "recycling" process?

You mean, after the phagocytes have engulfed the apoptotic bodies etc?

Yes after the process of ingestion by the phagocyte what happens to the broken down cellular components and how are they re-integrated into new cells? I thought that some of the components (base pairs, proteins,..) were recycled and integrated into newly forming cells. Is this not the case?

They'll be broken down to smaller constituents and reused, or for some molecules like cholesterol, reused directly. Most will just be oxidized for energy.