Why is it important to understand the mechanism of apoptosis?
An understanding of the underlying mechanism of apoptosis is important as it plays a pivotal role in the pathogenesis of many diseases. In some, the problem is due to too much apoptosis, such as in the case of degenerative diseases while in others, too little apoptosis is the culprit.
Can we measure apoptosis after treatment with an anticancer agent?
Assays that measure only apoptosis or any other single form of cell killing after treatment with an anticancer agent are likely to give misleading results.
Can apoptosis assays improve high-throughput drug screening?
Anti-cancer drug candidates failing to induce apoptosis are likely to have decreased clinical efficacy, making apoptosis assays important tools for high-throughput drug screening.
Why is the assay accuracy of my apoptosis assay low?
The loss of apoptotic cells during wash steps may lead to an underestimation of the extent of apoptosis in the sample, resulting in poor assay accuracy.
Why is annexin V used to measure apoptosis?
Annexin V, a 36-kDa calcium-binding protein, binds to PS; therefore, fluorescently labeled Annexin V can be used to detect PS that is exposed on the outside of apoptotic cells. Annexin V can also stain necrotic cells because these cells have ruptured membranes that permit Annexin V to access the entire plasma membrane.
Why is it important to study apoptosis?
Apoptosis removes cells during development. It also eliminates pre-cancerous and virus-infected cells, although “successful” cancer cells manage to escape apoptosis so they can continue dividing. Apoptosis maintains the balance of cells in the human body and is particularly important in the immune system.
What happens if apoptosis is uncontrolled?
Under normal conditions, apoptosis controls the number and types of cells present in the human body. Unregulated apoptosis, however, promotes certain disease states, such as cancer, Alzheimer's disease, and AIDS.
Why is apoptosis better than necrosis?
Because apoptosis is a normal part of an organism's cellular balance, there are no noticeable symptoms related to the process. In contrast, necrosis is an uncontrolled change in an organism's cell balance, so it is always harmful, resulting in noticeable, negative symptoms.
Why is it important to detect cell death?
Each type of cell death is mediated by multiple signaling pathways, which serve as potential targets for cellular toxicity. Understanding how a compound can activate the various pathways of cell death is essential for determining the acute, subacute, and chronic effects of drugs and chemical toxicants.
In what ways is apoptosis beneficial to organisms?
Apoptosis, programmed cell death, serves as a regulatory role in multicellular organisms for the purpose of maintaining cellular integrity, determining embryological outcomes, and for getting rid of aged cells..
Can apoptosis go wrong?
Understandably, bad things happen when apoptotic pathways are disrupted. Below are some examples of what happens when apoptosis is not well-regulated. For a deeper understanding of these processes, check out the article by Favaloro et al.
What happens if a cell is damaged but does not initiate apoptosis?
"One of the hallmarks of cancer is that the cells don't initiate apoptosis despite having defects in their genetic material. In other words the damaged cells do not commit suicide, and this develops into cancer. Failure to activate apoptosis also makes it difficult to cure cancer.
Why must apoptosis be tightly regulated?
The initiation of apoptosis is tightly regulated by activation mechanisms, because once apoptosis has begun, it inevitably leads to the death of the cell. The two best-understood activation mechanisms are the intrinsic pathway (also called the mitochondrial pathway) and the extrinsic pathway.
Why is necrosis more inflammatory than apoptosis?
Cells undergoing necrosis lose membrane integrity and leak their intracellular components some of which serve as danger signals that stimulate inflammation. Apoptotic cells may not stimulate inflammation if they are ingested by phagocytes before they release their intracellular contents.
Why does apoptosis not cause inflammation?
During apoptosis the cell membrane remains intact and the cell breaks into apoptotic bodies, which are phagocytosed. Apoptosis, in contrast to necrosis, is not harmful to the host and does not induce any inflammatory reaction.
How necrosis is different from apoptosis?
Apoptosis is described as an active, programmed process of autonomous cellular dismantling that avoids eliciting inflammation. Necrosis has been characterized as passive, accidental cell death resulting from environmental perturbations with uncontrolled release of inflammatory cellular contents.
Why is apoptosis important?
In adults, apoptosis is used to rid the body of cells that have been damaged beyond repair. Apoptosis also plays a role in preventing cancer. If apoptosis is for some reason prevented, it can lead to uncontrolled cell division and the subsequent development of a tumor.
What is the meaning of apoptosis?
"Apoptosis" is a funny word that is derived from the Latin meaning "to fall off", like a leaf falls off a tree. And a leaf falls off a tree when it's dead. And apoptosis refers to a process of what's called programmed cell death where the cell is actually in a funny kind of way committing suicide. And when this happens, there's a whole scripted choreography of pathways and proteins within a cell that get activated to actually kill the cell and without making too much of a mess. And this happens normally during development, for instance, in the development of the hand, that normally to begin with, the hand looks very much like a duck paddle foot and the webs between the fingers. Those cells apoptose, giving you the fingers. There are human conditions where that ceases to where apoptosis just does not happen and people are born with web feet. Apoptosis normally happens in cells that have been around in the body long enough that they're kind of worn out, and so they need to make way for nice, new young cells. When that doesn't happen, that's cancer. And so apoptosis can be normal, and in the absence of apoptosis, that can lead to cancer. Too much apoptosis in an otherwise normal human being will result in a number of so-called neurodegenerative diseases where cells die when they're not supposed to die. And they get messages from some place, most of which we don't understand, to tell them to die, so in a certain part of the lower part of the brain, that's what causes Parkinson's disease. This also characterizes Huntington's disease, and Alzheimer's disease, and Lou Gehrig's disease, and a number of other neurodegenerative diseases.
What is the role of apoptosis in fetal development?
The first role of apoptosis is during intrauterine development. It helps to sculpture organ shape and carve out the interdigital webs of the fingers and toes. Apoptotic mechanisms are important determinants of fetal abnormalities; experiments have shown that wild type p53 mouse embryos will readily abort after radiation induced teratogenesis, whereas p53 null embryos will not. 5 Both the nervous system and the immune system arise through overproduction of cells followed by the apoptotic death of those that fail to establish functional synaptic connections or productive antigen specificities.
Is apoptosis genetically regulated?
The term apoptosis is often used interchangeably with programmed cell death. In the strictest sense, programmed cell death may be applied to other forms of cell death that require gene expression without fulfilling some, or all, of the morphological criteria of apoptosis. 2 Whatever the definition, studies clearly show that apoptosis is genetically regulated.
Why is apoptosis important?
Apoptosis also plays an important role in allowing the immune system to turn off its response to a pathogen. When a pathogen is detected, the immune cells that recognize the pathogen divide extensively, undergoing a huge increase in numbers with the purpose of destroying the pathogen.
What happens to the cells during apoptosis?
Cells that undergo apoptosis go through a different and much more orderly process. They shrink and develop bubble-like protrusions (technical name: “blebs”) on their surface. The DNA in the nucleus gets chopped up into small pieces, and some organelles of the cell, such as the endoplasmic reticulum, break down into fragments. In the end, the entire cell splits up into small chunks, each neatly enclosed in a package of membrane.
What is the process of removing cells that should no longer be part of the organism?
Many cells in the human body have the built-in ability to undergo apoptosis (in the same way that they have the built-in ability to copy their DNA or break down fuels). Basically, apoptosis is a general and convenient way to remove cells that should no longer be part of the organism.
Does apoptosis kill cancer cells?
Apoptosis can eliminate infected or cancerous cells. In some cases, a cell can pose a threat to the rest of the body if it survives. For instance, this may be the case for cells with DNA damage, pre-cancerous cells, and cells infected by viruses.
Is apoptosis a normal part of development?
In many organisms, programmed cell death is a normal part of development. In some cases, apoptosis during development occurs in a very predictable way: in the worm C. elegans, cells will die by apoptosis as the worm develops from a single cell to an adult (and we know exactly which ones they are)!
Does Ca play a role in necrosis?
more. Ca is known to plays a role in necrosis, and high levels of Ca usually lead to necrosis of tissue. However, Ca plays a role in apoptosis as well.
Can cancer be caused by apoptosis?
By default yes. Until something goes wrong - and that is how cancer arises. I mean, one of mechnisms for cancer is faulty apoptosis. If one gene mutates or miRNA does post-translational modifications, or even if alkylating agents change DNA, you end up with a complete lack of or faulty nonfunctional proteins.
Why is apoptosis important?
Through further research, it was concluded that in addition to being a regulatable form of cell death, apoptosis plays an important role in controlling cell population. The inability for cells to undergo this process can have dramatic consequences, depending on the type of cells.
What are the factors that are involved in the apoptosis process?
These factors, however, vary depending on the signaling pathway. Caspases, initiators, and executioners of apoptosis , play an important role in the mechanism of the process.
What is the role of apoptosis in the body?
Today, apoptosis is understood to play an important role in: · Removing redundant and damaged cells - In the body, significantly damaged cells that cannot be repaired are eliminated through apoptosis. This also occurs for infected cells and auto-reactive cells of the immune system.
What is apoptosis in biology?
Definition: What is Apoptosis? Formerly referred to as shrinkage necrosis, apoptosis is a form of cell death characterized by energy-dependent biochemical mechanisms and morphological changes. Compared to other forms of cell death, apoptosis (cellular suicide/ programmed cell death) is an intrinsic, orderly process that is activated by such stimuli ...
Which enzyme binds to ATP and forms a complex with ATP?
This process also requires another proapoptotic protein to ensure the release of cytochrome c as well as content within the mitochondria intermembrane. Cytochrome c then binds and forms a complex with ATP (adenosine triphosphate) and the enzyme Apaf-1 in the cytoplasm to activate caspase- 9.
Which molecule is responsible for caspase 3 and 7 activation?
Together with the energy molecule and Apaf-1, cytochrome c forms the apoptosome that is responsible for caspase- 3 and 7 activation which in turn initiates cell degradation (cell death and fragmentation of the DNA ). During intrinsic apoptosis, the membrane of the mitochondria is compromised.
How many cells do mitosis produce?
· Maintaining a specific number of cells in an organism - With mitosis producing well over 100,000 cell s each second in the human body, other cells die through apoptosis, which helps maintain a constant number of cells present in the body.
What is the annexin V for apoptosis?
The PE Annexin V/ Dead Cell Apoptosis Kit and APC Annexin V/Dead Cell Apoptosis Kit ( V35112, V35113) are similar to the Single Channel Annexin V/Dead Cell Apoptosis Kit, except that they contain either R-phycoerythrin (R-PE) annexin V or allophycocyanin (APC) annexin V instead of Alexa Fluor 488 annexin V. In addition to the phycobiliprotein-conjugated annexin V, these kits include the SYTOX Green nucleic acid stain, which is impermeant to live cells and apoptotic cells but stains necrotic cells with intense green fluorescence. After staining a cell population with R-PE annexin V and SYTOX Green stain, apoptotic cells show orange fluorescence with very little green fluorescence, late apoptotic cells show a higher level of green and orange fluorescence and live cells show little or no fluorescence; these populations can easily be distinguished using a flow cytometer with the 488 nm spectral line of an argon-ion laser for excitation. After staining a cell population with APC annexin V and the SYTOX Green stain, apoptotic cells show far-red fluorescence with very little green fluorescence, late apoptotic cells show a higher level of green and far-red fluorescence and live cells show little or no fluorescence ( Figure 15.5.9 ); these populations can easily be distinguished using a flow cytometer with both the 488 nm spectral line of an argon-ion laser and the 633 nm spectral line of a He-Ne laser for excitation. The kit components, number of assays and assay principles are summarized in Molecular Probes apoptosis assay kits—Table 15.4.
What is apoptosis in biology?
Apoptosis (programmed cell death) is the genetically controlled ablation of cells during normal development. Inappropriately regulated apoptosis is implicated in disease states such as Alzheimer disease, stroke and cancer. Apoptosis is distinct from necrosis in both the biochemical and the morphological changes that occur.
What is the Vybrant apoptosis kit?
The Vybrant Apoptosis Assay Kit #6 ( V23200) is similar to the Alexa Fluor 488 Annexin V/Dead Cell Apoptosis Kit , except that it contains biotin-X annexin V and Alexa Fluor 350 streptavidin in place of the Alexa Fluor 488 conjugate. After staining a cell population with biotin-X annexin V in the provided binding buffer, Alexa Fluor 350 streptavidin is added to fluorescently label the bound annexin V. Finally, propidium iodide is added to detect necrotic cells. Apoptotic cells show blue fluorescence, dead cells show red and blue fluorescence and live cells show little or no fluorescence. These populations can easily be distinguished using a flow cytometer with UV excitation for the Alexa Fluor 350 fluorophore and 488 nm excitation for the propidium iodide. With this kit, fluorescence in the green channel is minimal. In the same experiment for apoptosis detection, the researcher can apply a green-fluorescent probe, for example an antibody labeled with the Alexa Fluor 488 dye or with fluorescein. The kit components, number of assays and assay principles are summarized in Molecular Probes apoptosis assay kits—Table 15.4.
What is the annexin V/dead cell apoptosis kit?
With the Single Channel Annexin V/Dead Cell Apoptosis Kit ( V13240 ), apoptotic cells are detected based on the externalization of phosphatidylserine. This kit contains recombinant annexin V conjugated to the Alexa Fluor 488 dye, our brightest and most photostable green fluorophore, to provide maximum sensitivity. In addition, the kit includes a ready-to-use solution of the SYTOX Green nucleic acid stain. The SYTOX Green dye is impermeant to live cells and apoptotic cells but stains necrotic cells with intense green fluorescence by binding to cellular nucleic acids. After staining a cell population with Alexa Fluor 488 annexin V and SYTOX Green dye in the provided binding buffer, apoptotic cells show green fluorescence, dead cells show a higher level of green fluorescence and live cells show little or no fluorescence ( Figure 15.5.7 ). These populations can easily be distinguished using a flow cytometer with the 488 nm spectral line of an argon-ion laser for excitation. Both Alexa Fluor 488 annexin and the SYTOX Green dye emit a green fluorescence that can be detected in the green channel, freeing the other channels for the detection of additional probes in multicolor labeling experiments. The kit components, number of assays and assay principles are summarized in Molecular Probes apoptosis assay kits—Table 15.4.
What is the chromatin condensation kit?
Chromatin Condensation/Dead Cell Apoptosis Kit ( V13244) provides a rapid and convenient assay for apoptosis based upon fluorescence detection of the compacted state of the chromatin in apoptotic cells. This kit contains ready-to-use solutions of the blue-fluorescent Hoechst 33342 dye (excitation/emission maxima ~350/461 nm when bound to DNA), which stains the condensed chromatin of apoptotic cells more brightly than the chromatin of nonapoptotic cells, and the red-fluorescent propidium iodide (excitation/emission maxima ~535/617 nm when bound to DNA), which is permeant only to dead cells with compromised membranes. The staining pattern resulting from the simultaneous use of these dyes makes it possible to distinguish normal, apoptotic and dead cell populations by flow cytometry or fluorescence microscopy. The 351 nm spectral line of an argon-ion laser or other suitable UV source is required for excitation of the Hoechst 33342 dye, whereas propidium iodide can be excited with the 488 nm spectral line of an argon-ion laser. The kit components, number of assays and assay principles are summarized in Molecular Probes apoptosis assay kits—Table 15.4.
What is the violet asymmetry probe?
The violet ratiometric membrane asymme try probe F2N12 S (4'- N, N -diethylamino-6- ( N -dodecyl- N -methyl- N - (3-sulfopropyl))ammoniomethyl-3-hydroxyflavone) is a novel violet diode–excitable dye for the detection of membrane phospholipid asymmetry changes during apoptosis. This dye exhibits an excited-state intramolecular proton transfer (ESIPT) reaction, resulting in a dual fluorescence with two emission bands corresponding to 530 nm and 585 nm and producing a two-color ratiometric response to variations in surface charge. This ratiometric probe is therefore a self-calibrating indicator of apoptotic transformation, which is independent of probe concentration, cell size and instrument variation, such as fluctuations of laser intensity or sensitivity of the detectors.
How is apoptosis different from necrosis?
Apoptosis is distinct from necrosis in both the biochemical and the morphological changes that occur. In contrast to necrotic cells, apoptotic cells are characterized morphologically by compaction of the nuclear chromatin, shrinkage of the cytoplasm and production of membrane-bound apoptotic bodies.
Why do we have apoptosis?
In humans for example, brain cells undergo apoptosis prior to and following birth to eliminate excess brain cells and streamline nerve impulses. Apoptosis also occurs in some cells that the body identifies as cancerous to prevent the spread of the cancer and kill the cancerous cells.
Who brought the idea of apoptosis to greater scientific attention?
With their 1972 article, Kerr and his team brought the idea of apoptosis to greater scientific attention. Kerr, Wyllie, and Currie's research clarified the process of apoptosis as a series of specific steps, later verified by other researchers.
What is apoptosis in embryonic development?
Apoptosis in Embryonic Development. Apoptosis, or programmed cell death, is a mechanism in embryonic development that occurs naturally in organisms. Apoptosis is a different process from cell necrosis, which is uncontrolled cell death usually after infection or specific trauma. As cells rapidly proliferate during development, ...
What did Kerr and his colleagues say about apoptosis?
They claimed that cell death from apoptosis was not accidental, and that it followed the same pattern in both developing and developed cells. With their 1972 article, Kerr and his team brought the idea of apoptosis to greater scientific attention.
What is the role of cell lineages in preventing disease?
Research on cell lineages before and after embryonic development may lead to new ways to reduce or promote cell death, which can be important in preventing diseases such as Alzheimer's or cancer. Karl Vogt observed the phenomenon of apoptosis in Neuchâtel, Switzerland, in 1842, but Vogt did not use the term apoptosis.
What did Vogt observe in midwife toad?
Vogt noticed in midwife toad ( Alytes obstetricans) embryos that cells in the notochord, a cartilaginous skeletal structure, disappeared and were replaced by cells of the vertebrae. Although Vogt documented that some cells disappeared during development, he did not focus his research on that phenomenon.
When did Kerr first study cell death?
Kerr had first studied cell death in 1965 when he noticed atrophy, or shrinkage, in rat liver cells under an electron microscope. Kerr noticed that the shrinkage was distinct from necrosis due to trauma, which normally causes the cell to rupture and release its contents.