scholarly journals Effect of serum proteins on sodium-linked transport processes in cultured kidney cells.

1995 ◽  
Vol 5 (11) ◽  
pp. 1964-1970
Author(s):  
S S Blumenthal ◽  
D L Lewand ◽  
P A Tipnis ◽  
J G Kleinman
Keyword(s):  
Amino Acid ◽  
Dextran Sulfate ◽  
Cultured Cells ◽  
Serum Proteins ◽  
Fluid Phase ◽  
Defined Medium ◽  
Transport Processes ◽  
Transport Systems ◽  
Heat Treated ◽  
Fluid Phase Endocytosis

The mechanism for increased Na+ retention in the nephrotic syndrome is unknown. To determine if Na+ transport systems in the proximal tubule might be affected by filtered proteins, mouse cortical tubule cells grown in defined medium were exposed to concentrations of bovine serum albumin (BSA) ranging from 0.01 to 0.5%. Activity of the Na(+)-glucose cotransporter, measured as Na(+)-dependent uptake of alpha-methylglucoside, increased progressively to a maximum of 2.3-fold above baseline (P < 0.001; N = 10). The increase in transporter activity was due to an increased Vmax, and the magnitude of the increase was inversely related to the basal cotransporter activity of the cultures. Increased cotransporter activity was detectable 6 h after exposure, was sustained for 24 h after cells were removed from an albumin-free medium, and was prevented by cycloheximide. Heat-treated BSA, fatty-acid and globulin-free BSA, and gamma-globulins were as effective at increasing Na(+)-glucose cotransporter activity as untreated Fraction V BSA. Dextran, dextran-sulfate, and amino acid supplements were ineffective. Neither protease inhibitors nor chloroquine added to an albumin-containing medium prevented increased alpha-methylglucoside uptake. Albumin did not change the rate of fluid-phase endocytosis in the cultured cells. Na(+)-amino acid cotransport and Na(+)-H+ exchange were either decreased or unchanged after BSA exposure. Exposing apical surfaces of cells grown on permeable membranes to BSA led to a greater increase in activity of the Na(+)-glucose cotransporter relative to controls than did exposing the basolateral surface (145 versus 89%; P < 0.05; N = 5).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino acid uptake systems in Bacteroides ruminicola

1979 ◽  
Vol 25 (10) ◽  
pp. 1161-1168 ◽  
Author(s):  
Roselynn M. W. Stevenson
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Nitrogen Sources ◽  
Amino Acid Uptake ◽  
Defined Medium ◽  
High Rate ◽  
Transport Systems ◽  
Acid Uptake ◽  
Chemical Structures ◽  
Kinetic Inhibition

Uptake of amino acids by Bacteroides ruminicola was observed in cells grown in a complete defined medium, containing ammonia as the nitrogen source. A high rate of uptake occurred only in fresh medium, as an inhibitory substance, possibly acetate, apparently accumulated during growth. All amino acids except proline were taken up and incorporated into cold trichloroacetic acid precipitable material. Different patterns of incorporation and different responses to 2,4-dinitrophenol and potassium ferricyanide indicated multiple uptake systems were involved. Kinetic inhibition patterns suggested six distinct systems were present for amino acid uptake, with specificities related to the chemical structures of the amino acids. Thus, the failure of free amino acids to act as sole nitrogen sources for growth of B. ruminicola is not due to the absence of transport systems for these compounds.

Cadmium inhibits glucose uptake in primary cultures of mouse cortical tubule cells

1990 ◽  
Vol 258 (6) ◽  
pp. F1625-F1633 ◽  
Author(s):  
S. S. Blumenthal ◽  
D. L. Lewand ◽  
M. A. Buday ◽  
J. G. Kleinman ◽  
S. K. Krezoski ◽  
...  
Keyword(s):  
Amino Acid ◽  
Glucose Uptake ◽  
Cultured Cells ◽  
Primary Cultures ◽  
Defined Medium ◽  
Isobutyric Acid ◽  
Cell Permeability ◽  
Dependent Manner ◽  
Lactate Dehydrogenase Activity ◽  
Tubule Cells

We studied the effect of cadmium (Cd2+) on transport of alpha-methylglucoside in primary cultures of mouse kidney cortical tubule cells grown in defined medium. When cultured cells were exposed to Cd2+ concentrations from 0 to 6 microM for 24 h, uptake of alpha-methylglucoside was inhibited in a dose-dependent manner by up to 50%. By contrast, acute exposure of the cells to 7 microM Cd2+ for 60 min did not inhibit alpha-methylglucoside uptake. Increasing Cd2+ concentrations progressively decreased the Vmax of Na(+)-dependent glucose cotransport but not the Km for glucose. Cell ATP/ADP ratios of unexposed monolayers and of cells exposed to 4.5 microM Cd2+ for 24 h were 5.0 and 4.9, respectively (n = 3). Intracellular volume, lactate dehydrogenase activity, and cell Na+ and K+ concentrations were unaltered even after 24 h of exposure to 7 microM Cd2+. Untreated and Cd2+-treated monolayers preloaded with alpha-methylglucoside released the sugar analogue into the medium at nearly identical rates, indicating that Cd2+ did not alter cell permeability to glucose. Uptake of the amino acid analogue alpha-(methylamino)isobutyric acid was not affected by prior Cd2+ exposure. Whereas cell DNA content declined in Cd2(+)-exposed plates, both Na(+)-glucose and Na(+)-amino acid cotransport were enhanced at lower cell densities. Protein and DNA synthesis, estimated, respectively, by incorporation of [3H]leucine and [3H]thymidine into acid-insoluble material, were not significantly affected at 6 microM Cd2+. We conclude that after a lag time Cd2+ selectively inhibits renal Na(+)-dependent glucose transport despite an unchanged gradient for Na+ across the cell membrane.

A Deficiency in Aspartate Biosynthesis inLactococcus lactis subsp. lactis C2 Causes Slow Milk Coagulation

1998 ◽  
Vol 64 (5) ◽  
pp. 1673-1679 ◽  
Author(s):  
Hua Wang ◽  
Weizhu Yu ◽  
Tim Coolbear ◽  
Dan O’Sullivan ◽  
Larry L. McKay
Keyword(s):  
Carbon Dioxide ◽  
Amino Acid ◽  
Aspartic Acid ◽  
Pyruvate Carboxylase ◽  
Defined Medium ◽  
Transport Systems ◽  
Chemically Defined Medium ◽  
Acid Transport ◽  
Amino Acid Requirements ◽  
Milk Coagulation

ABSTRACT A mutant of fast milk-coagulating (Fmc+)Lactococcus lactis subsp. lactis C2, designatedL. lactis KB4, was identified. Although possessing the known components essential for utilizing casein as a nitrogen source, which include functional proteinase (PrtP) activity and oligopeptide, di- and tripeptide, and amino acid transport systems, KB4 exhibited a slow milk coagulation (Fmc−) phenotype. When the amino acid requirements of L. lactis C2 were compared with those of KB4 by use of a chemically defined medium, it was found that KB4 was unable to grow in the absence of aspartic acid. This aspartic acid requirement could also be met by aspartate-containing peptides. The addition of aspartic acid to milk restored the Fmc+phenotype of KB4. KB4 was found to be defective in pyruvate carboxylase and thus was deficient in the ability to form oxaloacetate and hence aspartic acid from pyruvate and carbon dioxide. The results suggest that when lactococci are propagated in milk, aspartate derived from casein is unable to meet fully the nutritional demands of the lactococci, and they become dependent upon aspartate biosynthesis.

Regulation of cellular glutathione

1989 ◽  
Vol 257 (4) ◽  
pp. L163-L173 ◽  
Author(s):  
S. M. Deneke ◽  
B. L. Fanburg
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Cultured Cells ◽  
Feedback Inhibition ◽  
Reductase Activity ◽  
Transport Systems ◽  
Synthetase Activity ◽  
Gamma Glutamyl Transpeptidase ◽  
Gamma Glutamyl ◽  
Glutamyl Transpeptidase

In addition to its participation in a variety of other biochemical reactions, glutathione (GSH) is a major antioxidant. It is regularly generated intracellularly from its oxidized form by glutathione reductase activity that is coupled with a series of interrelated reactions. Synthesis of GSH also takes place intracellularly by a two-step reaction, the first of which is catalyzed by rate-limiting gamma-glutamylcysteine synthetase activity. Intracellular substrates for GSH are provided both by direct amino acid transport and by a gamma-glutamyl transpeptidase reaction that salvages circulating GSH by coupling the gamma-glutamyl moiety to a suitable amino acid acceptor for transport into the cell. Although the liver is a net synthesizer of circulating GSH, organs such as the kidney salvage GSH through the gamma-glutamyl transpeptidase reaction. Intracellular GSH may be consumed by GSH transferase reactions that conjugate GSH with certain xenobiotics. Elevation of cellular GSH levels in cultured cells in response to hyperoxia or electrophilic agents such as diethylmaleate is coupled with an increase in activity of the Xc- transport system for the amino acids cystine and glutamate. Strategies may be developed for protection against oxidant injury by enhancement of transport systems for precursor amino acids of GSH or by providing substrate that circumvents feedback inhibition of GSH synthesis.

scholarly journals Development of a probenecid-sensitive Lucifer Yellow transport system in vacuolating oat aleurone protoplasts

1992 ◽  
Vol 102 (1) ◽  
pp. 133-139 ◽  
Author(s):  
K. M. WRIGHT ◽  
T. G. E. DAVIES ◽  
S. H. STEELE ◽  
R. A. LEIGH ◽  
K. J. OPARKA
Keyword(s):  
Developmental Stages ◽  
Lucifer Yellow ◽  
Fluid Phase ◽  
Transport Systems ◽  
Uptake System ◽  
Cytoplasmic Staining ◽  
Simple Diffusion ◽  
Fluid Phase Endocytosis ◽  
Membrane Transport Systems ◽  
Early Developmental

Oat aleurone protoplasts, maintained in liquid culture over a period of five days, have been shown to develop an uptake system capable of transporting the membrane-impermeant probe Lucifer Yellow CH (LYCH). The dye was completely excluded from the densely cytoplasmic, early developmental stages but its uptake increased exponentially after the protoplasts had been cultured for between 2 and 5 days. Culturing induced vacuolation and uptake of the dye was largely restricted to highly vacuolate protoplasts. No cytoplasmic staining was evident. In vacuolate protoplasts uptake was linear with time and saturated with increasing substrate concentration. Low temperature, and addition of the drug probenecid to the incubation medium, completely eliminated LYCH uptake. In contrast to unconjugated LYCH, LYCH-dextrans (Mr 10,000 and 40,000) were excluded from the protoplasts. The data negate simple diffusion and fluid-phase endocytosis as possible candidates for dye uptake and suggest, instead, the development of highly co-ordinated membrane transport systems on both plasmalemma and tonoplast.

scholarly journals Isolation and Characterization of a Slowly Milk-Coagulating Variant of Lactobacillus helveticus Deficient in Purine Biosynthesis

2001 ◽  
Vol 67 (4) ◽  
pp. 1846-1850 ◽  
Author(s):  
Elvira M. Hebert ◽  
Graciela S. De Giori ◽  
Raul R. Raya
Keyword(s):  
Amino Acid ◽  
Wild Type Strain ◽  
Defined Medium ◽  
Lactobacillus Helveticus ◽  
Transport Systems ◽  
Wild Type ◽  
Isolation And Characterization ◽  
Essential Components ◽  
Amino Acid Requirements

ABSTRACT A slowly milk-coagulating variant (Fmc−) ofLactobacillus helveticus CRL 1062, designated S1, was isolated and characterized. Strain S1 possessed all the known essential components required to utilize casein as a nitrogen source, which include functional proteinase and peptidase activities as well as functional amino acid, di- and tripeptide, and oligopeptide transport systems. The amino acid requirements of strain S1 were similar to those of the parental strain. However, on a purine-free, chemically defined medium, the growth rate of the Fmc− strain was threefold lower than that of the wild-type strain. L. helveticusS1 was found to be defective in IMP dehydrogenase activity and therefore was deficient in the ability to synthesize XMP and GMP. This conclusion was further supported by the observation that the addition of guanine or xanthine to milk, a substrate poor in purine compounds, restored the Fmc+ phenotype of L. helveticusS1.

scholarly journals Acquisition of Cell–Cell Fusion Activity by Amino Acid Substitutions in Spike Protein Determines the Infectivity of a Coronavirus in Cultured Cells

PLoS ONE ◽  
2009 ◽  
Vol 4 (7) ◽  
pp. e6130 ◽  
Author(s):  
Yoshiyuki Yamada ◽  
Xiao Bo Liu ◽  
Shou Guo Fang ◽  
Felicia P. L. Tay ◽  
Ding Xiang Liu
Keyword(s):  
Amino Acid ◽  
Cell Fusion ◽  
Cultured Cells ◽  
Spike Protein ◽  
Amino Acid Substitutions ◽  
Fusion Activity ◽  
Cell Cell

scholarly journals Itaconate Alters Succinate and Coenzyme A Metabolism via Inhibition of Mitochondrial Complex II and Methylmalonyl-CoA Mutase

Metabolites ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 117
Author(s):  
Thekla Cordes ◽  
Christian M. Metallo
Keyword(s):  
Amino Acid ◽  
Metabolic Pathways ◽  
Mammalian Cells ◽  
Coenzyme A ◽  
Cultured Cells ◽  
Tca Cycle ◽  
Regulatory Function ◽  
Reversible Inhibitor ◽  
Complex Ii ◽  
Branched Chain

Itaconate is a small molecule metabolite that is endogenously produced by cis-aconitate decarboxylase-1 (ACOD1) in mammalian cells and influences numerous cellular processes. The metabolic consequences of itaconate in cells are diverse and contribute to its regulatory function. Here, we have applied isotope tracing and mass spectrometry approaches to explore how itaconate impacts various metabolic pathways in cultured cells. Itaconate is a competitive and reversible inhibitor of Complex II/succinate dehydrogenase (SDH) that alters tricarboxylic acid (TCA) cycle metabolism leading to succinate accumulation. Upon activation with coenzyme A (CoA), itaconyl-CoA inhibits adenosylcobalamin-mediated methylmalonyl-CoA (MUT) activity and, thus, indirectly impacts branched-chain amino acid (BCAA) metabolism and fatty acid diversity. Itaconate, therefore, alters the balance of CoA species in mitochondria through its impacts on TCA, amino acid, vitamin B12, and CoA metabolism. Our results highlight the diverse metabolic pathways regulated by itaconate and provide a roadmap to link these metabolites to potential downstream biological functions.

Sign in / Sign up

Export Citation Format

Share Document