Newer cell deaths

Apart from apoptosis and necrosis, there are newer cell deaths that are-

  • Necroptosis
  • Pyroptosis
  • Ferroptosis
  • Anoikis

Necroptosis –

  • As the word Suggests, Necroptosis consists of two words NECROSIS and APOPTOSIS.
  • We can define Necroptosis as caspase independent programmed cell death.
  • By the name we know that necroptosis is both necrosis and apoptosis
  • The property of necrosis is inflammation and the property of apoptosis is programmed cell death in necroptosis.
  • Necroptosis includes both physiological and pathological cell deaths –
  • Physiological – Growth plate formation in human body
  • Pathological – Steatohepatitis [fatty liver]
    – Pancreatitis
    – Reperfusion injury
  • In case of CMV [cytomegalovirus], caspase inhibitors are present that doesn’t allow apoptosis to happen but in this case Necroptosis can be a way of cell death.
  • Mechanism of Necroptosis –
  • 1-2-3 death
  • Step 1 :-
    In this step, TNF comes and binds to TNF receptor
  • Step 2 :-
    Due to this binding trio occurs – RIPK1, RIPK3 [receptor interacting protein] and Procaspase8
  • Step 3 :-
    MLKL phosphorylation occurs in this step and cell death occurs.

Pyroptosis –

  • The word Pyroptosis is made up of pyro and ptosis.
  • The word pyro means fire that refers to fever here and the word ptosis means falling.
  • Pyroptosis is associated with microorganisms.
    Examples for Pyroptosis are – Shiegella and Salmonella
  • In case of bacteria it binds to NOD receptor, this leads to the formation of inflammosome which is bacteria plus NOD receptor.
  • This inflammosome activates several caspase which are –
    Caspase 1
    Caspase 4
    Caspase 5
    Caspase 11
  • Caspase 1 helps in activation of interleukin 1 which is responsible for the fever
  • The remaining caspases which are caspase 4, caspase 5 and caspase 11 are responsible for the cell death.

Anoikis –

  • It is a type of apoptosis occurring in case of lack of natural environment.
  • Examples for Anoikis includes –
    Cardiovascular diseases
    Infectious diseases
    Hyperglycemia in diabetic microangiopathy
  • It appears in anchorage-dependent cells when cells detach from ECM[extracellular matrix]

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