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Bioenergetics
Published in Michael H. Stone, Timothy J. Suchomel, W. Guy Hornsby, John P. Wagle, Aaron J. Cunanan, Strength and Conditioning in Sports, 2023
Michael H. Stone, Timothy J. Suchomel, W. Guy Hornsby, John P. Wagle, Aaron J. Cunanan
In adipocytes, there are two enzymes that are involved in degrading triglycerides: hormone-sensitive lipase and adipose triglyceride lipase. Adipose triglyceride lipase has a greater affinity for triglycerides compared to hormone sensitive lipase, and acts as the primary enzyme for triglyceride hydrolysis in adipocytes. Hormone sensitive lipase is found in small concentrations in muscle and can provide an intramuscular source of FFA and glycerol. In the sarcoplasm of muscle fibers, FFA are bound to CoA. Using a carnitine carrier, the FFA -acyl CoA molecule enters the mitochondria (35, 51, 129, 143). The triglyceride “backbone” glycerol can be converted to glycerol 3 phosphate and enter glycolysis for energy production.
Atherosclerosis
Published in George Feuer, Felix A. de la Iglesia, Molecular Biochemistry of Human Disease, 2020
George Feuer, Felix A. de la Iglesia
Triglyceride lipase catalyzes the initial step in the catabolism of chylomicron and VLDL, producing diglycerides and fatty acids from triglycerides. In normal individuals, the enzyme activity is low, and heparin causes a release of triglyceride lipase from tissues, mainly from the liver. The postheparin lipolytic enzyme is activated by apoC-I, and this governs the breakdown of di- and monoglycerides. The total clearing of chylomicrons is therefore dependent on the function of the postheparin lipoprotein lipase.
Summation of Basic Endocrine Data
Published in George H. Gass, Harold M. Kaplan, Handbook of Endocrinology, 2020
The activation of the rate of synthesis of adrenal cortical steroids by ACTH is by its stimulation of cholesterol to pregnenolone. ACTH brings about skin darkening by dispersing skin melanin. It has a lipolytic action by activating triglyceride lipase. It stimulates adenylate cyclase, producing a cascade of reactions.
Sulfur mustard analog 2-chloroethyl ethyl sulfide increases triglycerides by activating DGAT1-dependent biogenesis and inhibiting PGC1ɑ-dependent fat catabolism in immortalized human bronchial epithelial cells
Published in Toxicology Mechanisms and Methods, 2023
Feng Ye, Qinya Zeng, Guorong Dan, Yuanpeng Zhao, Wenpei Yu, Jin Cheng, Mingliang Chen, Bin Wang, Jiqing Zhao, Yan Sai, Zhongmin Zou
TG hydrolysis encompasses three steps known as triacylglycerol (TG)-diglyceride (DG)-monoglyceride (MG)-glycerol (G). Each step is accompanied by fatty acid production. Cytosolic neutral and acid lipases including adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), and monoacylglycerol lipase (MGL), participate in hydrolysis at different steps. ATGL and MGL modulate the hydrolysis of TG and MG, respectively. Phosphorylated HSL (p-HSL) modulates the hydrolysis of DG and TG, but its efficiency is commonly lower than that of ATGL degradation of TG (Anthonsen et al. 1998; Grabner et al. 2021). ATGL is abundant in fat cells but also functions in non-fat cells. In a study using ATGL knockout (KO) transgenic mice, fat levels in many organs, such as the heart, liver, kidney, and testis, were markedly increased (Haemmerle et al. 2011). Co-activator CGI-58 (comparative gene identification-58) and co-inhibitor G0S2 (G0/G1 switch gene 2) are two essential regulators of ATGL activity that bind the ATGL protein but have no effects after dissociation (Lass et al. 2006; Schweiger et al. 2008; Yang et al. 2010).
A comprehensive insight into the potential roles of VDR gene polymorphism in obesity: a systematic review
Published in Archives of Physiology and Biochemistry, 2022
Amir Hossein Faghfouri, Elnaz Faghfuri, Vahid Maleki, Laleh Payahoo, Adam Balmoral, Yaser Khaje Bishak
The role of vitamin D in obesity has not fully been understood. A piece of crucial evidence in this area is the result of a study on the transgenic mice, which revealed that the expression of the human vitamin D receptor gene in adipose tissues reduced energy consumption. This effect might be due to the upregulation of uncoupling proteins (UCPs) and activation of enzymes involved in β-oxidation and lipolysis (Wong et al.2011). Another in vivo study proposed the role of VDR in decreasing hormone-sensitive lipase and adipose triglyceride lipase gene expression in rats via increasing intracellular calcium and decreasing the intracellular cAMP level (He et al.2011). Also, it has been found that VDR is expressed in human adipocytes and, thereby, vitamin D suppresses adipogenesis and regulates the differentiation of adipocytes through the inhibition of transcription factors (Ding et al.2012).
Arsenic: an emerging role in adipose tissue dysfunction and muscle toxicity
Published in Toxin Reviews, 2022
Kaviyarasi Renu, Aditi Panda, Balachandar Vellingiri, Alex George, Abilash Valsala Gopalakrishnan
Adipose tissue is subdivided into two types, such as white adipose tissue (WAT) and brown adipose tissue (BAT). The distribution of the adipose tissue is mainly based on environmental factors and nutritional factors. In this, we have focused mainly on the storage of energy, communication by the endocrine, and sensitivity by insulin (Fantuzzi 2005, Frühbeck and Gómez-Ambrosi 2013, Choe et al.2016). Adipose tissue is mainly involved in the storage of fat, accumulation of energy excessively and releases it via lipogenesis [Triglyceride (TAG)] and lipolysis via [adipose triglyceride lipase (ATGL), Hormone-sensitive lipase (HSL), and monoglyceride lipase (MGL)]. The adipose tissue status is depending on the cellular composition changes, such as number, structure and site of deposit. Alteration of cell numbers of adipose (hyperplasia), size, and shape (hypertrophy) is the indication of the dysfunction of adipose tissue. Loss of fat or lipodystrophy is due to the attenuation of the number of adipocytes and the size of the adipocyte. These changes lead to the intolerance of glucose, hyperlipidemia, and insulin resistance (Choe et al.2016, Schoettl et al.2018, Henriques et al.2019, Recinella et al.2020). Adipose tissue acts as the main organ for the accumulation of arsenic. Augmented accumulation of arsenic in adipose tissue avert from differentiation of cells and mediates disproportion in the metabolism of fat, a function of mitochondria, and leads to obesity and diabetes (Bae et al.2019).