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Metabolism
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
The distinct reactions that occur in gluconeogenesis include the hydrolytic reactions converting glucose-6-phosphate to glucose (catalysed by glucose-6-phosphatase) and fructose-1-6-diphosphate to fructose-6-phosphate and the conversion of pyruvate to phosphoenolpyruvate (Figure 65.14). The conversion of pyruvate to phosphoenolpyruvate occurs in two separate reactions that require the enzymes pyruvate carboxylase and phosphoenolpyruvate carboxykinase. Pyruvate carboxylase enhances the conversion of pyruvate to oxaloacetate, which is then converted to phosphoenolpyruvate by phosphoenolpyruvate carboxykinase. The gluconeogenetic enzymes are present in the cytoplasm of cells, except pyruvate carboxylase, which is present in mitochondria.
Metabolism, nutrition, exercise and temperature regulation
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2015
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
The distinct reactions that occur in gluconeogenesis include the hydrolytic reactions converting glucose-6-phosphate to glucose (catalysed by glucose-6-phosphatase) and fructose-1–6-diphosphate to fructose-6-phosphate and the conversion of pyruvate to phosphoenolpyruvate (Figure 12.14). The conversion of pyruvate to phosphoenolpyruvate occurs in two separate reactions that require the enzymes pyruvate carboxylase and phosphoenolpyruvate carboxykinase. Pyruvate carboxylase enhances the conversion of pyruvate to oxaloacetate, which is then converted to phosphoenolpyruvate by phosphoenolpyruvate carboxykinase. The gluconeogenetic enzymes are present in the cytoplasm of cells, except pyruvate carboxylase, which is present in mitochondria.
Boron, Manganese, Molybdenum, Nickel, Silicon and Vanadium
Published in Judy A. Driskell, Ira Wolinsky, Sports Nutrition, 2005
Pyruvate carboxylase and phosphoenolpyruvate carboxykinase are important enzymes in the glu-coneogenic pathway. Because pyruvate carboxylase is a manganese metalloenzyme and phospho-enolpyruvate carboxykinase is a manganese-activated enzyme, it can be predicted that manganese deficiency affects carbohydrate metabolism through changing the activity of these enzymes in liver. However, even in severely manganese-deficient animals, pyruvate carboxylase activity is not affected.58 Manganese deficiency inconsistently affects phosphoenolpyruvate carboxykinase activity.59
The effects of a new antidiabetic glycinium [(pyridine-2, 6-dicarboxylato) oxovanadate (V)] complex in high-fat diet of streptozotocin-induced diabetic rats
Published in Archives of Physiology and Biochemistry, 2022
Gholamreza Komeili, Fatemeh Ghasemi, Ali Reza Rezvani, Khaled Ghasemi, Farzaneh Khadem Sameni, Mohammad Hashemi
Over the years, vanadium compounds have received special attention because of their usage as therapeutic agents in the control of diabetes mellitus (Trevino et al. 2019). Vanadium compounds are commonly observed to have insulin-enhancing properties and anti-diabetic effects both in vivo and in vitro (Li et al. 2009, Xie et al. 2014). Crans et al. (2003) investigated the impact of (4-hydroxypyridine-2,6-dicarboxylato)oxovanadate (V) on STZ-induced diabetic rats and have found that this complex lowers the diabetic hyperglycemia. The vanadium (V) complex of dipicolinate, [VO2dipic]-, was found to have insulin-like properties (Crans 2000). It has been reported that methyl and iodo derivatives of bis(picolinato) oxovanadium(IV), have insulin-like properties (Fujimoto et al. 1997, Sakurai et al. 1995). Niu et al. (2007) have found that administration of Bis(α-furancarboxylato)oxovanadium(IV) significantly improved hyperglycemia, glucose intolerance and hyperinsulinemia, as well as increased insulin sensitivity index in the fat-fed/streptozotocin-diabetic rats (a type 2-like diabetic animal model). They observed that the complex activated glucokinase, increased hepatic glycogen content and significantly decreased the expression level of phosphoenolpyruvate carboxykinase (PEPCK) in the liver and kidney of the diabetic rats, which contributed to augmentation of hepatic glucose disposal and maintenance of blood glucose homeostasis.
Experience and activity-dependent control of glucocorticoid receptors during the stress response in large-scale brain networks
Published in Stress, 2021
Damien Huzard, Virginie Rappeneau, Onno C. Meijer, Chadi Touma, Margarita Arango-Lievano, Michael J. Garabedian, Freddy Jeanneteau
Intracellular calcium (Ca2+) is a central mediator of transcriptional regulation and is controlled by neuronal activity that could gate GR and MR responsiveness either through the direct or indirect mode of transcriptional regulation (Zhang et al., 2009). Several phosphatases, proteases, and cargo transporters operating as Ca2+-sensors are involved in the response to glucocorticoids in multiple cellular compartments. Actions on synaptic neurotransmission and on nuclear gene transcription, which are mediated by GR and MR, require coincident Ca2+ mobilization from the mitochondria and the endoplasmic reticulum (Chameau et al., 2007; Harris et al., 2019; Mayanagi et al., 2008; Simard et al., 1999). Mobilization of Ca2+ and cAMP are both required for the nuclear import of the CREB-regulated transcription coactivators (CRTC1/2/3), a family of cofactors for CREB and GR (Altarejos & Montminy, 2011; Hill et al., 2016). In particular, CRTC2 can integrate BDNF and glucocorticoid signals in the hypothalamus to control the direction and magnitude of transcription at the corticotropin-releasing hormone (Crh) promoter and the response of the hypothalamic-pituitary-adrenocortical (HPA) axis to stressors (Jeanneteau et al., 2012). This molecular pathway also regulates glucose metabolism and the energetic adaptation to stress by controlling the expression of the rate-limiting enzymes glucose-6-phosphatase and phosphoenolpyruvate carboxykinase in the liver (Hill et al., 2016).
Research progress of nanocarriers for gene therapy targeting abnormal glucose and lipid metabolism in tumors
Published in Drug Delivery, 2021
Xianhu Zeng, Zhipeng Li, Chunrong Zhu, Lisa Xu, Yong Sun, Shangcong Han
Gluconeogenesis can generate free glucose from non-carbohydrate carbon substrates (such as glycerol, lactic acid, pyruvate, and glycogenic amino acids). Although it is less studied than catabolic glycolysis or oxidative phosphorylation (OXPHOS), this anabolic pathway plays the same role in controlling the aerobic glycolysis of cancer cells (Seenappa et al. 2016). The complete pathway consists of 11 enzyme-catalyzed reactions, of which there are 7 reactions that are the opposite steps of glycolysis, and 3 reactions that are not involved in gluconeogenesis: (i) the conversion of pyruvate to phosphoenolpyruvate, which is determined by the reaction that catalyzes pyruvate carboxylase (PC) and phosphoenolpyruvate carboxykinase (PEPCK); (ii) the catalyzation of the conversion of fructose-1,6-diphosphate to fructose-6-phosphate by fructose-1,6-bisphosphatase (FBPase); (iii) the catalyzation of the conversion of glucose-6-phosphate to glucose by glucose-6-phosphatase (G6Pase) (Icard et al. 2019). PEPCK, FBPase, and G6Pase are the key enzymes that control the gluconeogenesis flux, thereby affecting glycolysis, the TCA cycle, the PPP and other branched metabolic pathways (serine biosynthesis, glycogen health, gluconeogenesis, and glutamine decomposition) (Kang et al. 2016; Icard et al. 2019).