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A lipoprotein is a biochemical assembly whose primary function is to transport hydrophobic lipid molecules in water, as in blood plasma or other extracellular fluids. They consist of a triglyceride and cholesterol center, surrounded by a phospholipid outer shell, with the hydrophilic portions oriented outward toward the surrounding water and lipophilic portions oriented inward toward the lipid center. A special kind of protein, called apolipoprotein, is embedded in the outer shell, both stabilising the complex and giving it a functional identity that determines its role.
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.
Cardiolipin is an important component of the inner mitochondrial membrane, where it constitutes about 20% of the total lipid composition. It can also be found in the membranes of most bacteria. The name "cardiolipin" is derived from the fact that it was first found in animal hearts. It was first isolated from the beef heart in the early 1940s by Mary C. Pangborn. In mammalian cells, but also in plant cells, cardiolipin (CL) is found almost exclusively in the inner mitochondrial membrane, where it is essential for the optimal function of numerous enzymes that are involved in mitochondrial energy metabolism.
The liver X receptor (LXR) is a member of the nuclear receptor family of transcription factors and is closely related to nuclear receptors such as the PPARs, FXR and RXR. Liver X receptors (LXRs) are important regulators of cholesterol, fatty acid, and glucose homeostasis. LXRs were earlier classified as orphan nuclear receptors, however, upon discovery of endogenous oxysterols as ligands they were subsequently deorphanized.
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27-Hydroxycholesterol (27-HC) is an endogenous oxysterol with multiple biological functions, including activity as a selective estrogen receptor modulator (SERM) and as an agonist of the liver X receptor (LXR). It is a metabolite of cholesterol that is produced by the enzyme CYP27A1.
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24S-Hydroxycholesterol (24S-HC), also known as cholest-5-ene-3,24-diol or cerebrosterol, is an endogenous oxysterol produced by neurons in the brain to maintain cholesterol homeostasis. It was discovered in 1953 by Alberto Ercoli, S. Di Frisco, and Pietro de Ruggieri, who first isolated the molecule in the horse brain and then demonstrated its presence in the human brain.
AMBRA1 is a protein that is able to regulate cancer cells through autophagy. AMBRA1 is described as a mechanism cells use to divide and there is new evidence demonstrating the role and impact of AMBRA1 as a candidate for the treatment of several disorders and diseases, including anticancer therapy. It is known to suppress tumors and plays a role in mitophagy and apoptosis. AMBRA1 can be found in the cytoskeleton and mitochondria and during the process of autophagy, it is localized at the endoplasmic reticulum. In normal conditions, AMBRA1 is dormant and will bind to BCL2 in the outer membrane. This relocation enables autophagosome nucleation. AMBRA1 protein is involved in several cellular processes and is involved in the regulation of the immune system and nervous system.
References
- ↑ Samadi, A (Jan 2021). "A Comprehensive Review on Oxysterols and Related Diseases". Current Medicinal Chemistry. 28 (1): 110–136. doi:10.2174/0929867327666200316142659. PMID 32175830. S2CID 212729018.
- ↑ Schroepfer, Gj Jr (Jan 2000). "Oxysterols: modulators of cholesterol metabolism and other processes" (Free full text). Physiological Reviews. 80 (1): 361–554. doi:10.1152/physrev.2000.80.1.361. ISSN 0031-9333. PMID 10617772.
- ↑ Björkhem, I (Sep 2002). "Do oxysterols control cholesterol homeostasis?". The Journal of Clinical Investigation. 110 (6): 725–30. doi:10.1172/JCI16388. PMC 151135 . PMID 12235099.
- ↑ Ingemar Björkhem; Ulf Diczfalusy (2002). "Oxysterols: Friends, Foes, or Just Fellow Passengers?". Arteriosclerosis, Thrombosis, and Vascular Biology. 22 (5): 734–42. doi: 10.1161/01.ATV.0000013312.32196.49 . PMID 12006384.
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