The definition of apoptosis

Some of the death is physiological, and some of the death is pathological, the process of apoptosis research, in recent years has become a biological, medical research a hot spot, to this end, It is known that there are at least two ways of apoptosis, cell necrosis and apoptosis. Cell necrosis has long been recognized as a way of apoptosis, and apoptosis is gradually recognized in recent years as a apoptosis.

Apoptosis is a fundamental biological phenomenon in cells and plays a necessary role in the removal of unwanted or abnormal cells by multicellular organisms. It plays an important role in the evolution of organisms, the stability of internal environment and the development of multiple systems. Apoptosis is not only a special type of apoptosis, but also has important biological significance and complex molecular biological mechanism.

Apoptosis is a process of strict control of multiple genes. These genes are very conserved among species, such as Bcl-2 family, caspase family, oncogenes such as C-myc, tumor suppressor gene P53 and so on, with the development of molecular biology technology for a variety of cell apoptosis process , But the precise mechanism of apoptotic processes to date has not been fully understood. While the process of apoptosis disorder may be the occurrence of many diseases have a direct or indirect relationship. Such as tumors, autoimmune diseases, can induce many factors of apoptosis, such as radiation, drugs and so on.

Apoptosis refers to the autonomic, ordered death of cells controlled by genes to maintain homeostasis. Apoptosis is not a passive process, but an active process. It involves the activation, expression and regulation of a series of genes. It is not a kind of autologous damage under pathological conditions. Phenomenon, but to better adapt to the living environment and take the initiative to fight a death process.

The concept of cell

Cell apoptosis: In fact, from a strict sense of the word, the apoptosis and apoptosis are very different. The concept of programmed apoptosis (PCD) was introduced in 1956 and is a functional concept that describes certain apoptosis in a multicellular organism as a predetermined component of ontogeny and is subject to strict control of the normal components of the process. Such as tadpoles into frogs, the disappearance of the tail during the metamorphosis accompanied by a large number of apoptosis, the disappearance of the webs of the higher mammalian fingers, jaw fusion, retinal development and normal development of the immune system must be involved in apoptosis. These all kinds of apoptosis in the body development process has a common characteristic: that is scattered, one by one from the normal death and disappearance of the body, the body without inflammatory response, but also the development of the whole body is beneficial and necessary. Therefore, the process of animal development that the process of apoptosis is a developmental concept, and apoptosis is a morphological concept, describes a complete set of morphological characteristics and necrosis completely different forms of apoptosis. But the concept of apoptosis and programmed death are generally considered to be interchangeable and have the same meaning.

The difference: Although apoptosis and necrosis of the final result is very similar, but their process and performance are very different.

Necrosis: necrosis is the cell by strong physical or biological factors that cause cell disorder in the process of death. The cell swelling, cell membrane rupture, cell spillover, slow nuclear change, DNA degradation is not sufficient, causing local severe inflammatory response.

Apoptosis is a physiological process of the cells to the pathological signal stimuli, changes in environmental conditions or mitochondrial damage resulting from the orderly changes in the death process of death. The cell and tissue changes and necrosis are significantly different.

The main significance of apoptosis

Apoptosis and cell proliferation are the basic phenomena of life, and are the basic measures to maintain the dynamic balance of cells in the body. In the embryonic development stage through the removal of excess cells and has completed the mission of the cells to ensure the normal development of the embryo; in adulthood through the removal of senescence and apoptosis cells to ensure the health of the body. Like cell proliferation, apoptosis is also an exact process regulated by the gene.

The main features of apoptosis

1.  Morphological changes

Morphological observation of apoptosis changes are multi-stage, apoptosis often involves a single cell, even a small part of the cells are non-synchronous. First, the cell volume decreased, the connection disappeared, and from the surrounding cells, and then increased cytoplasm density, mitochondrial membrane potential disappeared, permeability changes, the release of cytochrome C to the cytoplasm, nuclear condensation, nucleolus fragmentation , DNA degradation into about 180bp-200bp fragment; cell membrane has vesicular formation, membrane medial phosphatidylserine eversion to the membrane surface, membrane structure is still intact, and ultimately the apoptotic cell remains divided into several small apoptosis Body, no content spillover, and therefore does not cause the surrounding inflammatory response, apoptotic bodies can quickly be around full-time or non-professional phagocytic engulfed cells.

2.  Biochemical changes

1) Fragmentation of DNA

A notable feature of apoptosis is DNA degradation on the chromosomes of cells, which is a common phenomenon.

This degradation is very specific and regular, resulting in DNA fragments of different lengths of about 180-200bp whole multiple, and this is just the length of the winding histone oligomer, suggesting that chromosomal DNA is in the nucleosome and nucleus The connection site of the body is cut off, resulting in different lengths of oligonucleosome fragments, experiments show that the controlled degradation of DNA is an endogenous endonuclease results of the enzyme in the nucleosome connection , Which showed a specific ladder pattern in agarose gel electrophoresis and necrosis in a diffuse continuous pattern.

2) macromolecular synthesis

The biochemical changes of apoptosis are not only the controlled degradation of DNA, but also the expression of new genes and the synthesis of some biological macromolecules as the regulatory factors in the process of apoptosis. If our laboratory found TFAR-19 is a high expression of a molecule in apoptosis, and as in glucocorticoid-induced apoptosis of thymocytes in rats, the addition of RNA synthesis inhibitors or protein synthesis inhibitors that can inhibit cell apoptosis.