scholarly journals Cytosolic phosphoenolpyruvate carboxykinase as a cataplerotic pathway in the small intestine

2018 ◽  
Vol 315 (2) ◽  
pp. G249-G258 ◽  
Author(s):  
Austin Potts ◽  
Aki Uchida ◽  
Stanislaw Deja ◽  
Eric D. Berglund ◽  
Blanka Kucejova ◽  
...  
Keyword(s):  
Amino Acids ◽  
Small Intestine ◽  
Fatty Acid ◽  
Amino Acid ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Postprandial Triglyceride ◽  
Amino Acid Profiles ◽  
Gluconeogenic Enzyme ◽  
Acid Esterification ◽  
Fatty Acid Esterification

Cytosolic phosphoenolpyruvate carboxykinase (PEPCK) is a gluconeogenic enzyme that is highly expressed in the liver and kidney but is also expressed at lower levels in a variety of other tissues where it may play adjunct roles in fatty acid esterification, amino acid metabolism, and/or TCA cycle function. PEPCK is expressed in the enterocytes of the small intestine, but it is unclear whether it supports a gluconeogenic rate sufficient to affect glucose homeostasis. To examine potential roles of intestinal PEPCK, we generated an intestinal PEPCK knockout mouse. Deletion of intestinal PEPCK ablated ex vivo gluconeogenesis but did not significantly affect glycemia in chow, high-fat diet, or streptozotocin-treated mice. In contrast, postprandial triglyceride secretion from the intestine was attenuated in vivo, consistent with a role in fatty acid esterification. Intestinal amino acid profiles and 13C tracer appearance into these pools were significantly altered, indicating abnormal amino acid trafficking through the enterocyte. The data suggest that the predominant role of PEPCK in the small intestine of mice is not gluconeogenesis but rather to support nutrient processing, particularly with regard to lipids and amino acids. NEW & NOTEWORTHY The small intestine expresses gluconeogenic enzymes for unknown reasons. In addition to glucose synthesis, the nascent steps of this pathway can be used to support amino acid and lipid metabolisms. When phosphoenolpyruvate carboxykinase, an essential gluconeogenic enzyme, is knocked out of the small intestine of mice, glycemia is unaffected, but mice inefficiently absorb dietary lipid, have abnormal amino acid profiles, and inefficiently catabolize glutamine. Therefore, the initial steps of intestinal gluconeogenesis are used for processing dietary triglycerides and metabolizing amino acids but are not essential for maintaining blood glucose levels.

Development of fatty acid esterification mechanisms in rat small intestine.

1979 ◽  
Vol 237 (5) ◽  
pp. E399 ◽  
Author(s):  
Y F Shiau ◽  
C Umstetter ◽  
K Kendall ◽  
O Koldovsky
Keyword(s):  
Small Intestine ◽  
Fatty Acid ◽  
Total Fatty Acid ◽  
Fetal Programming ◽  
Rat Small Intestine ◽  
Adult Rats ◽  
Major Pathway ◽  
Acid Esterification ◽  
Fatty Acid Esterification

Fatty acid esterification was measured in fetal jejunal and ileal isografts implanted under the kidney capsules of adult host rats and compared to the age-controlled intestine grown in situ. Studies were conducted on the 21st, 35th, 49th, and 63rd postconceptional days, corresponding to prenatal, suckling, weaning, and weaned rats. Substantial fatty acid esterification activity was found in prenatal jejunum but not in ileum. A proximal-distal gradient of fatty acid esterification was observed in all groups grown in situ, but not in isografts. The monoglyceride pathway (MG-P) accounted for about one-third of total fatty acid esterification (TFAE) in jejunum grown in situ and remained constant through the study. In the ileum, MG-P was the major esterification pathway during the first 4 postnatal weeks, but decreased progressively after weaning to become insignificant in adult rats. TFAE fell in the jejunal isografts, whereas it increased in the ileum. MG-P remained as the major pathway in the implanted jejunum and ileum. Our studies suggest that luminal contents are probably the most important modulator for the development and maintenance of intestinal fatty acid esterification, and "fetal programming" manifested by changes in fatty acid esterification mechanisms in the isografts is less important.

scholarly journals Digestion of alfalfa and grass silages in sheep. 2. Digestion of protein in reticulorumen and intestines.

1988 ◽  
Vol 36 (4) ◽  
pp. 365-374
Author(s):  
J. van Bruchem ◽  
A.K. Kies ◽  
R. Bremmers ◽  
M.W. Bosch ◽  
H. Boer ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Small Intestine ◽  
Amino Acid ◽  
Milk Protein ◽  
Diaminopimelic Acid ◽  
Microbial Protein ◽  
Grass Silage ◽  
Amino Acid Profiles ◽  
Limiting Amino Acids

Wilted lucerne and grass silages were given to mature wethers. Estimates of degradability of proteins in the reticulorumen were lower with diaminopimelic acid (38-71%) than those based on amino acid profiles of dietary, microbial and duodenal proteins (64-87%). Microbial protein synthesis was related to extent of organic matter fermentation in the reticulorumen. Efficiency of protein synthesis was not different between silages. Apparent digestibility of protein and amino acids in the small intestine was lower for lucerne silage (54%) than for grass silage (60-63%), probably caused by a higher DM passage in the small intestine of lucerne silage. Relative to the amino acid profiles of milk protein and beef, histidine and methionine were the first limiting amino acids. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Changes in Amino Acid Profiles and Bioactive Compounds of Thai Silk Cocoons as Affected by Water Extraction

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 2033
Author(s):  
Chuleeporn Bungthong ◽  
Sirithon Siriamornpun
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Biological Activities ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Silk Protein ◽  
Extraction Time ◽  
Antioxidant Power ◽  
Silk Cocoon ◽  
Amino Acid Profiles

Silk proteins have many advantageous components including proteins and pigments. The proteins—sericin and fibroin—have been widely studied for medical applications due to their good physiochemical properties and biological activities. Various strains of cocoon display different compositions such as amino-acid profiles and levels of antioxidant activity. Therefore, the objectives of this study were to find a suitable silk protein extraction method to obtain products with chemical and biological properties suitable as functional foods in two strains of Bombyx mori silk cocoon (Nangsew strains; yellow cocoon) and Samia ricini silk cocoon (Eri strains; white cocoon) extracted by water at 100 °C for 2, 4, 6 and 8 h. The results showed that Nangsew strains extracted for 6 h contained the highest amounts of protein, amino acids, total phenolics (TPC) and total flavonoids (TFC), plus DPPH radical-scavenging activity, ABTS radical scavenging capacity, and ferric reducing antioxidant power (FRAP), anti-glycation, α-amylase and α-glucosidase inhibition. The longer extraction time produced higher concentrations of amino acids, contributing to sweet and umami tastes in both silk strains. It seemed that the bitterness decreased as the extraction time increased, resulting in improvements in the sweetness and umami of silk-protein extracts.

scholarly journals Insulin-independent regulation of hepatic triglyceride synthesis by fatty acids

2015 ◽  
Vol 112 (4) ◽  
pp. 1143-1148 ◽  
Author(s):  
Daniel F. Vatner ◽  
Sachin K. Majumdar ◽  
Naoki Kumashiro ◽  
Max C. Petersen ◽  
Yasmeen Rahimi ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Fatty Acids ◽  
Fatty Acid ◽  
Insulin Signaling ◽  
Plasma Fatty Acid ◽  
Hepatic Triglyceride ◽  
Triglyceride Synthesis ◽  
Hepatic Glucose ◽  
Acid Esterification ◽  
Fatty Acid Esterification

A central paradox in type 2 diabetes is the apparent selective nature of hepatic insulin resistance—wherein insulin fails to suppress hepatic glucose production yet continues to stimulate lipogenesis, resulting in hyperglycemia, hyperlipidemia, and hepatic steatosis. Although efforts to explain this have focused on finding a branch point in insulin signaling where hepatic glucose and lipid metabolism diverge, we hypothesized that hepatic triglyceride synthesis could be driven by substrate, independent of changes in hepatic insulin signaling. We tested this hypothesis in rats by infusing [U-13C] palmitate to measure rates of fatty acid esterification into hepatic triglyceride while varying plasma fatty acid and insulin concentrations independently. These experiments were performed in normal rats, high fat-fed insulin-resistant rats, and insulin receptor 2′-O-methoxyethyl chimeric antisense oligonucleotide-treated rats. Rates of fatty acid esterification into hepatic triglyceride were found to be dependent on plasma fatty acid infusion rates, independent of changes in plasma insulin concentrations and independent of hepatocellular insulin signaling. Taken together, these results obviate a paradox of selective insulin resistance, because the major source of hepatic lipid synthesis, esterification of preformed fatty acids, is primarily dependent on substrate delivery and largely independent of hepatic insulin action.

scholarly journals Serum Amino Acid Profiles in Childhood Predict Triglyceride Level in Adulthood: A 7-Year Longitudinal Study in Girls

2016 ◽  
Vol 101 (5) ◽  
pp. 2047-2055 ◽  
Author(s):  
Petri Wiklund ◽  
Xiaobo Zhang ◽  
Xiao Tan ◽  
Sirkka Keinänen-Kiukaanniemi ◽  
Markku Alen ◽  
...  
Keyword(s):  
Amino Acids ◽  
Longitudinal Study ◽  
Amino Acid ◽  
High Risk ◽  
Triglyceride Level ◽  
Early Adulthood ◽  
Health Science ◽  
Model Assessment ◽  
Pubertal Growth ◽  
Amino Acid Profiles

AbstractContext:Branched-chain and aromatic amino acids are associated with high risk of developing dyslipidemia and type II diabetes in adults.Objective:This study aimed to examine whether serum amino acid profiles associate with triglyceride concentrations during pubertal growth and predict hypertriglyceridemia in early adulthood.Design:This was a 7.5-year longitudinal study.Setting:The study was conducted at the Health Science Laboratory, University of Jyväskylä.Participants:A total of 396 nondiabetic Finnish girls aged 11.2 ± 0.8 years at the baseline participated in the study.Main Outcome Measures:Body composition was assessed by dual-energy x-ray absorptiometry; serum concentrations of glucose, insulin, and triglyceride by enzymatic photometric methods; and amino acids by nuclear magnetic resonance spectroscopy.Results:Serum leucine and isoleucine correlated significantly with future triglyceride, independent of baseline triglyceride level (P < .05 for all). In early adulthood (at the age of 18 years), these amino acids were significantly associated with hypertriglyceridemia, whereas fat mass and homeostasis model assessment of insulin resistance were not. Leucine was the strongest determinant discriminating subjects with hypertriglyceridemia from those with normal triglyceride level (area under the curve, 0.822; 95% confidence interval, 0.740–0.903; P = .000001).Conclusions:Serum leucine and isoleucine were associated with future serum triglyceride levels in girls during pubertal growth and predicted hypertriglyceridemia in early adulthood. Therefore, these amino acid indices may serve as biomarkers to identify individuals at high risk for developing hypertriglyceridemia and cardiovascular disease later in life. Further studies are needed to elucidate the role these amino acids play in the lipid metabolism.

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