scholarly journals Alanine alters carbohydrate metabolism of rainbow trout: Glucose fluxes and cell signaling

2021 ◽  
Author(s):  
Mais Jubouri ◽  
Giancarlo G.M. Talarico ◽  
Jean-Michel Weber ◽  
Jan A. Mennigen
Keyword(s):  
Rainbow Trout ◽  
Protein Kinase ◽  
Glucose Metabolism ◽  
Cell Signaling ◽  
Glucose Levels ◽  
Dietary Amino Acid ◽  
Gluconeogenic Enzyme ◽  
Mechanistic Basis ◽  
Amp Activated Protein Kinase

In rainbow trout, dietary carbohydrates are poorly metabolized compared to other macronutrients. One prevalent hypothesis suggests that high dietary amino acid levels could contribute to the poor utilization of carbohydrates in trout. In mammals, alanine is considered an important gluconeogenic precursor, but has recently been found to stimulate AMP-activated protein kinase (AMPK) to reduce glucose levels. In trout, the effect of alanine on glucose fluxes is unknown. The goal of this study was to determine the effects of 4h exogenous alanine infusion on glucose metabolism in rainbow trout. Glucose fluxes, glucose appearance (Ra), and disposal (Rd) were measured in vivo. Key glycolytic and gluconeogenic enzyme expression and activity and cell signaling molecules relevant to glucose metabolism were assessed in liver and muscle. Results show that alanine inhibits Ra glucose (from 13.2+/-2.5 to 7.3+/-1.6 micromol / kg min) and Rd glucose (from 13.2+/-2.5 to 7.4+/-1.5 micromol / kg min) and the slight mismatch between Ra and Rd caused a reduction in glycemia, similar to the effects of insulin in trout. The reduction in Rd glucose can be partially explained by a reduction in glut4b expression in red muscle. In contrast to mammals, alanine-dependent glucose-lowering effects in trout did not involve hepatic AMPK activation, suggesting a different mechanistic basis. Interestingly, protein kinase B (AKT) activation increased only in muscle similar to effects observed in insulin-infused trout. We speculate that alanine-dependent effects were probably mediated through stimulation of insulin secretion which could indirectly promote alanine oxidation to provide the needed energy.

scholarly journals Adrenaline is a critical mediator of acute exercise-induced AMP-activated protein kinase activation in adipocytes

2007 ◽  
Vol 403 (3) ◽  
pp. 473-481 ◽  
Author(s):  
Ho-Jin Koh ◽  
Michael F. Hirshman ◽  
Huamei He ◽  
Yangfeng Li ◽  
Yasuko Manabe ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase Activity ◽  
Chronic Exercise ◽  
Rat Adipocytes ◽  
Compound C ◽  
Isolated Adipocytes ◽  
Ampk Activity ◽  
Exercise Induced ◽  
Amp Activated Protein Kinase

Exercise increases AMPK (AMP-activated protein kinase) activity in human and rat adipocytes, but the underlying molecular mechanisms and functional consequences of this activation are not known. Since adrenaline (epinephrine) concentrations increase with exercise, in the present study we hypothesized that adrenaline activates AMPK in adipocytes. We show that a single bout of exercise increases AMPKα1 and α2 activities and ACC (acetyl-CoA carboxylase) Ser79 phosphorylation in rat adipocytes. Similarly to exercise, adrenaline treatment in vivo increased AMPK activities and ACC phosphorylation. Pre-treatment of rats with the β-blocker propranolol fully blocked exercise-induced AMPK activation. Increased AMPK activity with exercise and adrenaline treatment in vivo was accompanied by an increased AMP/ATP ratio. Adrenaline incubation of isolated adipocytes also increased the AMP/ATP ratio and AMPK activities, an effect blocked by propranolol. Adrenaline incubation increased lipolysis in isolated adipocytes, and Compound C, an AMPK inhibitor, attenuated this effect. Finally, a potential role for AMPK in the decreased adiposity associated with chronic exercise was suggested by marked increases in AMPKα1 and α2 activities in adipocytes from rats trained for 6 weeks. In conclusion, both acute and chronic exercise are significant regulators of AMPK activity in rat adipocytes. Our findings suggest that adrenaline plays a critical role in exercise-stimulated AMPKα1 and α2 activities in adipocytes, and that AMPK can function in the regulation of lipolysis.

scholarly journals mTOR Inhibitor Therapy and Metabolic Consequences: Where Do We Stand?

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Aleksandra Kezic ◽  
Ljiljana Popovic ◽  
Katarina Lalic
Keyword(s):  
Protein Kinase ◽  
Glucose Metabolism ◽  
Calorie Restriction ◽  
Mtor Inhibitor ◽  
Hepatic Glucose Production ◽  
Mtor Inhibitors ◽  
Glucose Production ◽  
Metabolic Effects ◽  
Solid Organ ◽  
Amp Activated Protein Kinase

mTOR (mechanistic target of rapamycin) protein kinase acts as a central integrator of nutrient signaling pathways. Besides the immunosuppressive role after solid organ transplantations or in the treatment of some cancers, another promising role of mTOR inhibitor as an antiaging therapeutic has emerged in the recent years. Acute or intermittent rapamycin treatment has some resemblance to calorie restriction in metabolic effects such as an increased insulin sensitivity. However, the chronic inhibition of mTOR by macrolide rapamycin or other rapalogs has been associated with glucose intolerance and insulin resistance and may even provoke type II diabetes. These metabolic adverse effects limit the use of mTOR inhibitors. Metformin is a widely used drug for the treatment of type 2 diabetes which activates AMP-activated protein kinase (AMPK), acting as calorie restriction mimetic. In addition to the glucose-lowering effect resulting from the decreased hepatic glucose production and increased glucose utilization, metformin induces fatty acid oxidations. Here, we review the recent advances in our understanding of the metabolic consequences regarding glucose metabolism induced by mTOR inhibitors and compare them to the metabolic profile provoked by metformin use. We further suggest metformin use concurrent with rapalogs in order to pharmacologically address the impaired glucose metabolism and prevent the development of new-onset diabetes mellitus after solid organ transplantations induced by the chronic rapalog treatment.

scholarly journals Reactive Nitrogen Species Is Required for the Activation of the AMP-activated Protein Kinase by Statin in Vivo

2008 ◽  
Vol 283 (29) ◽  
pp. 20186-20197 ◽  
Author(s):  
Hyoung Chul Choi ◽  
Ping Song ◽  
Zhonglin Xie ◽  
Yong Wu ◽  
Jian Xu ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Reactive Nitrogen Species ◽  
Reactive Nitrogen ◽  
Nitrogen Species ◽  
Amp Activated Protein Kinase

scholarly journals Angiotensin AT1 receptor antagonism by losartan stimulates adipocyte browning via induction of apelin

2020 ◽  
Vol 295 (44) ◽  
pp. 14878-14892
Author(s):  
Dong Young Kim ◽  
Mi Jin Choi ◽  
Tae Kyung Ko ◽  
Na Hyun Lee ◽  
Ok-Hee Kim ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Protein Kinase ◽  
Metabolic Disorders ◽  
Angiotensin Ii Receptor ◽  
Adeno Associated Virus ◽  
Receptor Antagonism ◽  
White Adipocytes ◽  
Treatment Of Obesity ◽  
Amp Activated Protein Kinase

Adipocyte browning appears to be a potential therapeutic strategy to combat obesity and related metabolic disorders. Recent studies have shown that apelin, an adipokine, stimulates adipocyte browning and has negative cross-talk with angiotensin II receptor type 1 (AT1 receptor) signaling. Here, we report that losartan, a selective AT1 receptor antagonist, induces browning, as evidenced by an increase in browning marker expression, mitochondrial biogenesis, and oxygen consumption in murine adipocytes. In parallel, losartan up-regulated apelin expression, concomitant with increased phosphorylation of protein kinase B and AMP-activated protein kinase. However, the siRNA-mediated knockdown of apelin expression attenuated losartan-induced browning. Angiotensin II cotreatment also inhibited losartan-induced browning, suggesting that AT1 receptor antagonism-induced activation of apelin signaling may be responsible for adipocyte browning induced by losartan. The in vivo browning effects of losartan were confirmed using both C57BL/6J and ob/ob mice. Furthermore, in vivo apelin knockdown by adeno-associated virus carrying–apelin shRNA significantly inhibited losartan-induced adipocyte browning. In summary, these data suggested that AT1 receptor antagonism by losartan promotes the browning of white adipocytes via the induction of apelin expression. Therefore, apelin modulation may be an effective strategy for the treatment of obesity and its related metabolic disorders.

scholarly journals Withdrawal: Reactive nitrogen species is required for the activation of the AMP-activated protein kinase by statin in vivo.

2019 ◽  
Vol 294 (27) ◽  
pp. 10742-10742
Author(s):  
Hyoung Chul Choi ◽  
Ping Son ◽  
Zhonglin Xie ◽  
Yong Wu ◽  
Jian Xu ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Reactive Nitrogen Species ◽  
Reactive Nitrogen ◽  
Nitrogen Species ◽  
Amp Activated Protein Kinase

scholarly journals PRKAA1 Promotes Proliferation and Inhibits Apoptosis of Gastric Cancer Cells Through Activating JNK1 and Akt Pathways

2020 ◽  
Vol 28 (3) ◽  
pp. 213-223 ◽  
Author(s):  
Yangmei Zhang ◽  
Xichang Zhou ◽  
Long Cheng ◽  
Xiang Wang ◽  
Qinglin Zhang ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Protein Kinase ◽  
Cancer Cells ◽  
Akt Signaling ◽  
Catalytic Subunit ◽  
Gastric Cancer Cells ◽  
In Vivo Experiments ◽  
Compound C ◽  
Amp Activated Protein Kinase

PRKAA1 (protein kinase AMP-activated catalytic subunit α 1) is a catalytic subunit of AMP-activated protein kinase (AMPK), which plays a key role in regulating cellular energy metabolism through phosphorylation, and genetic variations in the PRKAA1 have been found to be associated with gastric cancer risk. However, the effect and underlying molecular mechanism of PRKAA1 on gastric cancer tumorigenesis, especially the proliferation and apoptosis, are not fully understood. Our data showed that PRKAA1 is highly expressed in BGC-823 and MKN45 cells and is expressed low in SGC-7901 and MGC-803 cells in comparison with the other gastric cancer cells. PRKAA1 downregulation by shRNA or treatment of AMPK inhibitor compound C significantly inhibited proliferation as well as promoted cell cycle arrest and apoptosis of BGC-823 and MKN45 cells. Moreover, the expression of PCNA and Bcl-2 and the activity of JNK1 and Akt signaling were also reduced in BGC-823 and MKN45 cells after PRKAA1 downregulation. In vivo experiments demonstrated that tumor growth in nude mice was significantly inhibited after PRKAA1 silencing. Importantly, inactivation of JNK1 or Akt signaling pathway significantly inhibited PRKAA1 overexpression-induced increased cell proliferation and decreased cell apoptosis in MGC-803 cells. In conclusion, our findings suggest that PRKAA1 increases proliferation and restrains apoptosis of gastric cancer cells through activating JNK1 and Akt pathways.

scholarly journals Sex Differences in the Metabolic Effects of Testosterone in Sheep

Endocrinology ◽  
2012 ◽  
Vol 153 (1) ◽  
pp. 123-131 ◽  
Author(s):  
Scott D. Clarke ◽  
Iain J. Clarke ◽  
Alexandra Rao ◽  
Michael A. Cowley ◽  
Belinda A. Henry
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Uncoupling Protein ◽  
Specific Effect ◽  
Metabolic Effects ◽  
Mrna Levels ◽  
Nonesterified Fatty Acids ◽  
Glucose Levels ◽  
Amp Activated Protein Kinase ◽  
The Brain

Adiposity is regulated in a sexually divergent manner. This is partly due to sex steroids, but the differential effects of androgens in males and females are unclear. We investigated effects of testosterone on energy balance in castrated male (n = 6) and female sheep (n = 4), which received 3 × 200 mg testosterone implants for 2 wk or blank implants (controls). Temperature probes were implanted into retroperitoneal fat and skeletal muscle. Blood samples were taken to measure metabolites and insulin. In males, muscle and fat biopsies were collected to measure uncoupling protein (UCP) mRNA and phosphorylation of AMP-activated protein kinase and Akt. Testosterone did not change food intake in either sex. Temperature in muscle was higher in males than females, and testosterone reduced heat production in males only. In fat, however, temperature was higher in the castrate males compared with females, and there was no effect of testosterone treatment in either sex. Preprandial glucose levels were lower, but nonesterified fatty acids were higher in females compared with males, irrespective of testosterone. In males, the onset of feeding increased UCP1 and UCP3 mRNA levels in skeletal muscle, without an effect of testosterone. During feeding, testosterone reduced glucose levels in males only but did not alter the phosphorylation of AMP-activated protein kinase or Akt in muscle. Thus, testosterone maintains lower muscle and fat temperatures in males but not females. The mechanism underlying this sex-specific effect of testosterone is unknown but may be due to sexual differentiation of the brain centers controlling energy expenditure.

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