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Cell biology is a branch of biology that studies the structure, function, and behavior of cells. All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living and functioning of organisms. Cell biology is the study of the structural and functional units of cells. Cell biology encompasses both prokaryotic and eukaryotic cells and has many subtopics which may include the study of cell metabolism, cell communication, cell cycle, biochemistry, and cell composition. The study of cells is performed using several microscopy techniques, cell culture, and cell fractionation. These have allowed for and are currently being used for discoveries and research pertaining to how cells function, ultimately giving insight into understanding larger organisms. Knowing the components of cells and how cells work is fundamental to all biological sciences while also being essential for research in biomedical fields such as cancer, and other diseases. Research in cell biology is interconnected to other fields such as genetics, molecular genetics, molecular biology, medical microbiology, immunology, and cytochemistry.
A lysosome is a membrane-bound organelle found in many animal cells. They are spherical vesicles that contain hydrolytic enzymes that can break down many kinds of biomolecules. A lysosome has a specific composition, of both its membrane proteins, and its lumenal proteins. The lumen's pH (~4.5–5.0) is optimal for the enzymes involved in hydrolysis, analogous to the activity of the stomach. Besides degradation of polymers, the lysosome is involved in various cell processes, including secretion, plasma membrane repair, apoptosis, cell signaling, and energy metabolism.
Programmed cell death is the death of a cell as a result of events inside of a cell, such as apoptosis or autophagy. PCD is carried out in a biological process, which usually confers advantage during an organism's lifecycle. For example, the differentiation of fingers and toes in a developing human embryo occurs because cells between the fingers apoptose; the result is that the digits are separate. PCD serves fundamental functions during both plant and animal tissue development.
Autophagy is the natural, conserved degradation of the cell that removes unnecessary or dysfunctional components through a lysosome-dependent regulated mechanism. It allows the orderly degradation and recycling of cellular components. Although initially characterized as a primordial degradation pathway induced to protect against starvation, it has become increasingly clear that autophagy also plays a major role in the homeostasis of non-starved cells. Defects in autophagy have been linked to various human diseases, including neurodegeneration and cancer, and interest in modulating autophagy as a potential treatment for these diseases has grown rapidly.
In chemistry and biology, reactive oxygen species (ROS) are highly reactive chemicals formed from diatomic oxygen (O2), water, and hydrogen peroxide. Some prominent ROS are hydroperoxide (O2H), superoxide (O2-), hydroxyl radical (OH.), and singlet oxygen. ROS are pervasive because they are readily produced from O2, which is abundant. ROS are important in many ways, both beneficial and otherwise. ROS function as signals, that turn on and off biological functions. They are intermediates in the redox behavior of O2, which is central to fuel cells. ROS are central to the photodegradation of organic pollutants in the atmosphere. Most often however, ROS are discussed in a biological context, ranging from their effects on aging and their role in causing dangerous genetic mutations.
Cell death is the event of a biological cell ceasing to carry out its functions. This may be the result of the natural process of old cells dying and being replaced by new ones, as in programmed cell death, or may result from factors such as diseases, localized injury, or the death of the organism of which the cells are part. Apoptosis or Type I cell-death, and autophagy or Type II cell-death are both forms of programmed cell death, while necrosis is a non-physiological process that occurs as a result of infection or injury.
In cell biology, a phagosome is a vesicle formed around a particle engulfed by a phagocyte via phagocytosis. Professional phagocytes include macrophages, neutrophils, and dendritic cells (DCs).
The bafilomycins are a family of macrolide antibiotics produced from a variety of Streptomycetes. Their chemical structure is defined by a 16-membered lactone ring scaffold. Bafilomycins exhibit a wide range of biological activity, including anti-tumor, anti-parasitic, immunosuppressant and anti-fungal activity. The most used bafilomycin is bafilomycin A1, a potent inhibitor of cellular autophagy. Bafilomycins have also been found to act as ionophores, transporting potassium K+ across biological membranes and leading to mitochondrial damage and cell death.
Hemolysins or haemolysins are lipids and proteins that cause lysis of red blood cells by disrupting the cell membrane. Although the lytic activity of some microbe-derived hemolysins on red blood cells may be of great importance for nutrient acquisition, many hemolysins produced by pathogens do not cause significant destruction of red blood cells during infection. However, hemolysins are often capable of lysing red blood cells in vitro.
Vojo Deretic, is distinguished professor and chair of the Department of Molecular Genetics and Microbiology at the University of New Mexico School of Medicine. Deretic was the founding director of the Autophagy, Inflammation and Metabolism (AIM) Center of Biomedical Research Excellence. The AIM center promotes autophagy research nationally and internationally.
BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 is a protein found in humans that is encoded by the BNIP3 gene.
Autophagy related 5 (ATG5) is a protein that, in humans, is encoded by the ATG5 gene located on Chromosome 6. It is an E3 ubi autophagic cell death. ATG5 is a key protein involved in the extension of the phagophoric membrane in autophagic vesicles. It is activated by ATG7 and forms a complex with ATG12 and ATG16L1. This complex is necessary for LC3-I conjugation to PE (phosphatidylethanolamine) to form LC3-II. ATG5 can also act as a pro-apoptotic molecule targeted to the mitochondria. Under low levels of DNA damage, ATG5 can translocate to the nucleus and interact with survivin.
Autophagy related 16 like 1 is a protein that in humans is encoded by the ATG16L1 gene. This protein is characterized as a subunit of the autophagy-related ATG12-ATG5/ATG16 complex and is essentially important for the LC3 (ATG8) lipidation and autophagosome formation. This complex localizes to the membrane and is released just before or after autophagosome completion.
Mitophagy is the selective degradation of mitochondria by autophagy. It often occurs to defective mitochondria following damage or stress. The process of mitophagy was first described over a hundred years ago by Margaret Reed Lewis and Warren Harmon Lewis. Ashford and Porter used electron microscopy to observe mitochondrial fragments in liver lysosomes by 1962, and a 1977 report suggested that "mitochondria develop functional alterations which would activate autophagy." The term "mitophagy" was in use by 1998.
Immunity Related Guanosine Triphosphatases or IRGs are proteins activated as part of an early immune response. IRGs have been described in various mammals but are most well characterized in mice. IRG activation in most cases is induced by an immune response and leads to clearance of certain pathogens.
An autophagosome is a spherical structure with double layer membranes. It is the key structure in macroautophagy, the intracellular degradation system for cytoplasmic contents. After formation, autophagosomes deliver cytoplasmic components to the lysosomes. The outer membrane of an autophagosome fuses with a lysosome to form an autolysosome. The lysosome's hydrolases degrade the autophagosome-delivered contents and its inner membrane.
Chaperone-assisted selective autophagy is a cellular process for the selective, ubiquitin-dependent degradation of chaperone-bound proteins in lysosomes.
Stimulator of interferon genes (STING), also known as transmembrane protein 173 (TMEM173) and MPYS/MITA/ERIS is a protein that in humans is encoded by the STING1 gene.
Omegasome is a cell organelle consisting of lipid bilayer membranes enriched for phosphatidylinositol 3-phosphate, and related to a process of autophagy. It is a subdomain of the Endoplasmic Reticulum (ER), and has a morphology resembling the Greek capital letter Omega (Ω). Omegasomes are the sites from which phagophores form, which are sack-like structures that mature into autophagosomes, and fuse with lysosomes in order to degrade the contents of the autophagosomes. The formation of omegasomes depends on various factors, however in general, formation of omegasomes is increased as a response to starvation, and in some biochemical situations the presence of PI(3)P leads to the formation of omegasomes.
Tripartite motif-containing 14 is a protein encoded by the TRIM14 gene in the human genome. It belongs to the TRIM family of proteins which contain the TRIM motif on the N-terminus. TRIM14 lacks the RING domain within the motif and therefore it loses the function of E3 ubiquitin ligase in eukaryotic cells. Instead, the PRYSPRY domain on the C-terminus allows TRIM14 to be categorized into an evolutionarily younger group of TRIM proteins which are involved in the regulation of innate immunity. TRIM 14 is localized in both the cytoplasm and the cell nucleus.
References
- ↑ Exton, M. S. (December 1997). "Infection-induced anorexia: active host defence strategy". Appetite. 29 (3): 369–383. doi:10.1006/appe.1997.0116. ISSN 0195-6663. PMID 9468766. S2CID 10465902.
- ↑ van Niekerk, Gustav; Isaacs, Ashwin W.; Nell, Theo; Engelbrecht, Anna-Mart (2016). "Sickness-Associated Anorexia: Mother Nature's Idea of Immunonutrition?". Mediators of Inflammation. 2016: 1–12. doi: 10.1155/2016/8071539 . PMC 4942670 . PMID 27445441.
Material was copied from this source, which is available under a Creative Commons Attribution 4.0 International License. - ↑ van Niekerk, Gustav; Loos, Ben; Nell, Theo; Engelbrecht, Anna-Mart (2016-04-06). "Autophagy—A free meal in sickness-associated anorexia". Autophagy. 12 (4): 727–734. doi:10.1080/15548627.2016.1147672. ISSN 1554-8627. PMC 4836003 . PMID 27050464.
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