Nerve tissue is a biological molecule related to the function and maintenance of normal nervous tissue. An example would include, for example, the generation of myelin which insulates and protects nerves.
These are typically calcium-binding proteins. Beclin-1 is a protein that in humans is encoded by the BECN1 gene. It is an E3 ubi autophagic cell death. ATG5 is a key protein involved in the extension of the phagophoric membrane in autophagic vesicles. ATG5 can also act as a pro-apoptotic molecule targeted to the mitochondria. Neurotrophic factor receptors or neurotrophin receptors are a group of growth factor receptors which specifically bind to neurotrophins.
Ferroptosis is a type of programmed cell death dependent on iron and characterized by the accumulation of lipid peroxides, and is genetically and biochemically distinct from other forms of regulated cell death such as apoptosis.
Ferroptosis is initiated by the failure of the glutathione-dependent antioxidant defenses, resulting in unchecked lipid peroxidation and eventual cell death. Lipophilic antioxidants and iron chelators can prevent ferroptotic cell death. Although the connection between iron and lipid peroxidation has been appreciated for years, it was not until that Brent Stockwell and Scott J. Dixon coined the term ferroptosis and described several of its key features. Paraptosis is a type of programmed cell death, morphologically distinct from apoptosis and necrosis.
The defining features of paraptosis are cytoplasmic vacuolation, independent of caspase activation and inhibition, and lack of apoptotic morphology. Paraptosis lacks several of the hallmark characteristics of apoptosis, such as membrane blebbing, chromatin condensation, and nuclear fragmentation.
Like apoptosis and other types of programmed cell death, the cell is involved in causing its own death, and gene expression is required. This is in contrast to necrosis, which is non-programmed cell death that results from injury to the cell. Death regulator Nedd2-like caspase was firstly identified and characterised in Drosophila in as a cysteine protease containing an amino-terminal caspase recruitment domain.
At first, it was thought of as an effector caspase involved in apoptosis, but subsequent findings have proved that it is, in fact, an initiator caspase with a crucial role in said type of programmed cell death. Death of a cell mediated by intracellular program, often as part of development. For the protein, see Programmed cell death protein 1.
Main article: Phenoptosis. Bibcode : Natur. ISSN PMID S2CID PLOS Genetics. PMC Means To An End. ISBN Nature Chemical Biology. Nat Rev Mol Cell Biol. Endocrine potentiation of the breakdown of the intersegmental muscles of silkmoths". Journal of Insect Physiology. Biological Theory. The Nobel Foundation. Retrieved Bibcode : PNAS Apoptosis, autophagic PCD, or others?
Annals of the New York Academy of Sciences. Bowen, Ivor Cell Biology International. Archived from the original on Nature Medicine. Cell Death and Differentiation. Journal of Cellular Physiology. Nutrition, Metabolism, and Cardiovascular Diseases. Histology: A Text and Atlas 7th ed. Journal of Cell Biology. Neuronal cell death and some related regressive phenomena during neurogenesis: a selective historical review and progress report.
Annual Review of Neuroscience. Trends in Neurosciences. Progress in Neurobiology. Developmental Cell. Academic Press. The chemotactic hypothesis of Cajal: a century behind. Progress in Brain Research. J Cell Biol. New England Regional Allergy Proceedings. Bibcode : Sci November Journal of Neuroscience. Journal of Computational Neurology. Vision Research. Behavior of transgenic mice reveals a role for developmental cell death".
Brain Research Bulletin. ISSN X. Developmental Biology. Journal of Developmental Biology. Journal of Comparative Neurology. Archived from the original PDF on The Plant Cell. JSTOR As indicated, two of the cleaved fragments more Activation of the intracellular cell death pathway, like entry into a new stage of the cell cycle, is usually triggered in a complete, all-or-none fashion.
The protease cascade is not only destructive and self-amplifying but also irreversible, so that once a cell reaches a critical point along the path to destruction, it cannot turn back. All nucleated animal cells contain the seeds of their own destruction, in the form of various inactive procaspases that lie waiting for a signal to destroy the cell. It is therefore not surprising that caspase activity is tightly regulated inside the cell to ensure that the death program is held in check until needed.
How are procaspases activated to initiate the caspase cascade? A general principle is that the activation is triggered by adaptor proteins that bring multiple copies of specific procaspases, known as initiator procaspases, close together in a complex or aggregate. In some cases, the initiator procaspases have a small amount of protease activity, and forcing them together into a complex causes them to cleave each other, triggering their mutual activation.
In other cases, the aggregation is thought to cause a conformational change that activates the procaspase. Within moments, the activated caspase at the top of the cascade cleaves downstream procaspases to amplify the death signal and spread it throughout the cell see Figure B. Procaspase activation can be triggered from outside the cell by the activation of death receptors on the cell surface. Killer lymphocytes discussed in Chapter 24 , for example, can induce apoptosis by producing a protein called Fas ligand , which binds to the death receptor protein Fas on the surface of the target cell.
The clustered Fas proteins then recruit intracellular adaptor proteins that bind and aggregate procaspase-8 molecules, which cleave and activate one another. The activated caspase -8 molecules then activate downstream procaspases to induce apoptosis Figure A. Some stressed or damaged cells kill themselves by producing both the Fas ligand and the Fas protein, thereby triggering an intracellular caspase cascade.
Induction of apoptosis by either extracellular or intracellular stimuli. A Extracellular activation. A killer lymphocyte carrying the Fas ligand binds and activates Fas proteins on the surface of the target cell. Adaptor proteins bind to the intracellular more When cells are damaged or stressed, they can also kill themselves by triggering procaspase aggregation and activation from within the cell.
In the best understood pathway, mitochondria are induced to release the electron carrier protein cytochrome c see Figure into the cytosol , where it binds and activates an adaptor protein called Apaf-1 Figure B.
This mitochondrial pathway of procaspase activation is recruited in most forms of apoptosis to initiate or to accelerate and amplify the caspase cascade. DNA damage, for example, as discussed earlier, can trigger apoptosis. This response usually requires p53 , which can activate the transcription of genes that encode proteins that promote the release of cytochrome c from mitochondria.
These proteins belong to the Bcl-2 family. The Bcl-2 family of intracellular proteins helps regulate the activation of procaspases. Some members of this family, like Bcl-2 itself or Bcl-X L , inhibit apoptosis , at least partly by blocking the release of cytochrome c from mitochondria. Other members of the Bcl-2 family are not death inhibitors, but instead promote procaspase activation and cell death.
Some of these apoptosis promoters, such as Bad , function by binding to and inactivating the death-inhibiting members of the family, whereas others, like Bax and Bak, stimulate the release of cytochrome c from mitochondria. If the genes encoding Bax and Bak are both inactivated, cells are remarkably resistant to most apoptosis-inducing stimuli, indicating the crucial importance of these proteins in apoptosis induction.
Bax and Bak are themselves activated by other apoptosis-promoting members of the Bcl-2 family such as Bid. Another important family of intracellular apoptosis regulators is the IAP inhibitor of apoptosis family. These proteins are thought to inhibit apoptosis in two ways: they bind to some procaspases to prevent their activation, and they bind to caspases to inhibit their activity. IAP proteins were originally discovered as proteins produced by certain insect viruses, which use them to prevent the infected cell from killing itself before the virus has had time to replicate.
When mitochondria release cytochrome c to activate Apaf-1, they also release a protein that blocks IAPs, thereby greatly increasing the efficiency of the death activation process.
The intracellular cell death program is also regulated by extracellular signals, which can either activate apoptosis or inhibit it. These signal molecules mainly act by regulating the levels or activity of members of the Bcl-2 and IAP families. We see in the next section how these signal molecules help multicellular organisms regulate their cell numbers. Kill, die, learn, repeat.
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