Summary: Apoptosis Samenvatting

Read the summary and the most important questions on Apoptosis samenvatting

• 1 Les 1

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• Welke 3 TNF familie death receptors zijn er?

  1. CD95/Fas receptor
  2. DR4 en DR5 receptor
  3. TNF receptor

• What is the inhibitor of the apoptosis signaling pathway by CD95/Fas receptor?

  FLIP & IAP

• What are the 5 functions of the FAS receptor?

  1. Avoid autoimmune diseases --> you need to kill autoreactive T cells by apoptosis
  2. Terminate immune reactions when they are no longer needed
  3. Immune privileged tissues (you don't want to have an inflammation in the brain or eyes). The target cell expresses the ligand, via FAS receptor, aggressive immune cells are killed.   
  4. Inflammatory cells in a tumor.
  5. Kills virus infected cells.

• 2 Les 2

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• How does the Fas receptor work?

  A fas ligand is expressed by effectors cells, which are allowed to kill other cells. They don't to that by accident; they first recognize the cell as a target, they bind and give signals to the target cell. The target cells should express a bit for FAS receptors, which allows it to trimerize and red rid of the proteins that prevent trimerization (like FAP1). When there is enough of Fas receptor expressed, ligands binds and can activate the receptor to induce apoptosis.

• How are T-cells killed by the Fas-FasL system?

  At the end of inflammation, T-cells need to be killed. APCs (antigen presenting cells) start to express the FAS receptor. Older antigen cells express ligand and FAS receptor, instead of being activated again they are killed. They are specifically killed in an antigen dependent manner.

• How are immune prevalenced cells killed by the Fas-FasL system?

  If aggrieve cells are there, the cells express ligand also and can kill the cytotoxic T-cell. Thereby, removal of inflammatory cells in eye, testis and tumor takes place.

• How does apoptosis signalling work by DR4/DR5?

  Death complex: FADD where pro-caspase binds, activates caspase apoptosis. 
  Alternative: activated BIG and mitochondrial route cyto=chrome C and SMAC to activate caspase 9 and inhibit the inhibitor XIAP

• What is the most 'interesting' death receptor?

  Tumor necrosis factor (TNF)

• On what things has NF-kB an effect?

  Immune system, cell adhesion, cell-cycle, survival factor: producing anti-apoptosis proteins

• What is the danger of protonged TNF-receptor activation (which leads to formation of complex II(DISC) containing FASS and is able to induce apoptosis)?

  It can also induce necroptosis