Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Effects of nutritional status and acute variation in substrate supply on cardiac and skeletal-muscle fructose 2,6-bisphosphate concentrations.

ABSTRACT: We examined the long-term effects of nutritional status and the acute effects of changes in exogenous carbohydrate- and lipid-substrate supply and utilization on fructose 2,6-bisphosphate (Fru-2,6-P2) concentrations in heart, gastrocnemius and soleus. Starvation decreased Fru-2,6-P2 concentrations in all three muscles. The acute administration of insulin and glucose increased skeletal-muscle Fru-2,6-P2 in the fed, but not in the starved, state, but cardiac Fru-2,6-P2 was unchanged. Cardiac and skeletal-muscle Fru-2,6-P2 concentrations were unaffected by acute increases in fatty acid supply produced by the administration of corn oil plus heparin, or by acute decreases in fatty acid supply produced by inhibition of lipolysis. Differences in cardiac and skeletal-muscle Fru-2,6-P2 concentrations observed in response to starvation were not reversed by administration of glucose or glucose plus insulin, or by inhibition of lipolysis, even though changes in citrate (heart), acylcarnitine (heart) and glycogen (skeletal muscle) were observed. Concentrations remained low for at least 8 h after chow re-feeding, but the fed value was restored by 24 h.

SUBMITTER: French TJ

PROVIDER: S-EPMC1148923 | biostudies-other | 1988 Mar

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

14-3-3s regulate fructose-2,6-bisphosphate levels by binding to PKB-phosphorylated cardiac fructose-2,6-bisphosphate kinase/phosphatase.

Project description:The cardiac isoform of 6-phosphofructo-2-kinase/ fructose-2,6-bisphosphatase (PFK-2), regulator of the glycolysis-stimulating fructose-2,6-bisphosphate, was among human HeLa cell proteins that were eluted from a 14-3-3 affinity column using the phosphopeptide ARAApSAPA. Tryptic mass fingerprinting and phospho-specific antibodies showed that Ser466 and Ser483 of 14-3-3-affinity-purified PFK-2 were phosphorylated. 14-3-3 binding was abolished by selectively dephosphorylating Ser483, and 14-3-3 binding was restored when both Ser466 and Ser483 were phosphorylated with PKB, but not when Ser466 alone was phosphorylated by AMPK. Furthermore, the phosphopeptide RNYpS(483)VGS blocked binding of PFK-2 to 14-3-3s. These data indicate that 14-3-3s bind to phosphorylated Ser483. When HeLa cells expressing HA-tagged PFK-2 were co-transfected with active PKB or stimulated with IGF-1, HA-PFK-2 was phosphorylated and bound to 14-3-3s. The response to IGF-1 was abolished by PI 3-kinase inhibitors. In addition, IGF-1 promoted the binding of endogenous PFK-2 to 14-3-3s. When cells were transduced with penetratin-linked AARAApSAPA, we found that this reagent bound specifically to 14-3-3s, blocked the IGF-1-induced binding of HA-PFK-2 to 14-3-3s, and completely inhibited the IGF-1-induced increase in cellular fructose-2,6-bisphosphate. These findings suggest that PKB-dependent binding of 14-3-3s to phospho-Ser483 of cardiac PFK-2 mediates the stimulation of glycolysis by growth factor.

| S-EPMC165633 | biostudies-literature

Fructose 2,6-bisphosphate in rat skeletal muscle during contraction.

Project description:Fructose 2,6-bisphosphate and several glycolytic intermediates were measured in two rat muscles, extensor digitorum longus and gastrocnemius, which were electrically stimulated in situ. Both the duration and the frequency of stimulation were varied to obtain different rates of glycolysis. There was no relationship between fructose 2,6-bisphosphate content and the increase in tissue lactate in contracting muscle. However, in gastrocnemius stimulated at low frequencies (less than or equal to 5 Hz), there was a 2-fold increase in fructose 2,6-bisphosphate at 10s, followed by a return to basal values, whereas lactate increased only after 1 min of contraction. The concentrations of hexose 6-phosphates, fructose 1,6-bisphosphate and triose phosphates were all increased during the 3 min stimulation. During tetanus (frequencies greater than or equal to 10 Hz) fructose 2,6-bisphosphate was not increased, whereas glycolysis was maximally stimulated and resulted in an accumulation of tissue lactate, mostly from glycogen. The concentrations of hexose 6-phosphate increased continuously during the 1 min tetanus, whereas fructose 1,6-bisphosphate was increased at 10s and then decreased progressively. It therefore appears that fructose 2,6-bisphosphate does not play a role in the stimulation of glycolysis during tetanus; it may, however, be involved in the control of glycolysis when the muscles are stimulated at low frequencies for short periods of time.

| S-EPMC1144266 | biostudies-other

Fructose 2,6-bisphosphate in rat erythrocytes. Inhibition of fructose 2,6-bisphosphate synthesis and measurement by glycerate 2,3-bisphosphate.

Project description:The concentration of fructose 2,6-bisphosphate found in freshly isolated erythrocytes was below the limit of detection (20 pmol/ml of packed cells). However, it increased to about 250 pmol/ml of cells when erythrocytes were incubated with glucose at pH 6.9, but not at pH 7.4 or 8.2. This could be explained by variations in the content of glycerate 2,3-bisphosphate, which was found to inhibit 6-phosphofructo-2-kinase, the enzyme responsible for fructose 2,6-bisphosphate synthesis. Glycerate 2,3-bisphosphate was also found to inhibit the potato enzyme (pyrophosphate:fructose-6-phosphate 1-phosphotransferase) used for the measurement of fructose 2,6-bisphosphate.

| S-EPMC1147977 | biostudies-other

Central cavity of fructose-1,6-bisphosphatase and the evolution of AMP/fructose 2,6-bisphosphate synergism in eukaryotic organisms.

Project description:The effects of AMP and fructose 2,6-bisphosphate (Fru-2,6-P2) on porcine fructose-1,6-bisphosphatase (pFBPase) and Escherichia coli FBPase (eFBPase) differ in three respects. AMP/Fru-2,6-P2 synergism in pFBPase is absent in eFBPase. Fru-2,6-P2 induces a 13° subunit pair rotation in pFBPase but no rotation in eFBPase. Hydrophilic side chains in eFBPase occupy what otherwise would be a central aqueous cavity observed in pFBPase. Explored here is the linkage of AMP/Fru-2,6-P2 synergism to the central cavity and the evolution of synergism in FBPases. The single mutation Ser(45) → His substantially fills the central cavity of pFBPase, and the triple mutation Ser(45) → His, Thr(46) → Arg, and Leu(186) → Tyr replaces porcine with E. coli type side chains. Both single and triple mutations significantly reduce synergism while retaining other wild-type kinetic properties. Similar to the effect of Fru-2,6-P2 on eFBPase, the triple mutant of pFBPase with bound Fru-2,6-P2 exhibits only a 2° subunit pair rotation as opposed to the 13° rotation exhibited by the Fru-2,6-P2 complex of wild-type pFBPase. The side chain at position 45 is small in all available eukaryotic FBPases but large and hydrophilic in bacterial FBPases, similar to eFBPase. Sequence information indicates the likelihood of synergism in the FBPase from Leptospira interrogans (lFBPase), and indeed recombinant lFBPase exhibits AMP/Fru-2,6-P2 synergism. Unexpectedly, however, AMP also enhances Fru-6-P binding to lFBPase. Taken together, these observations suggest the evolution of AMP/Fru-2,6-P2 synergism in eukaryotic FBPases from an ancestral FBPase having a central aqueous cavity and exhibiting synergistic feedback inhibition by AMP and Fru-6-P.

| S-EPMC3961670 | biostudies-literature

The rate of substrate cycling between fructose 6-phosphate and fructose 1,6-bisphosphate in skeletal muscle.

Project description:Substrate cycling of fructose 6-phosphate through reactions catalysed by 6-phosphofructokinase and fructose-1,6-bisphosphatase was measured in skeletal muscles of the rat in vitro. The rate of this cycle was calculated from the steady-state values of the 3H/14C ratio in hexose monophosphates and fructose 1,6-bisphosphate after the metabolism of either [5-3H,6-14C]glucose or [3-3H,2-14C] glucose. Two techniques for the separation of hexose phosphates were studied; t.l.c. chromatography on poly(ethyleneimine)-cellulose sheets or ion-exchange chromatography coupled with enzymic conversion. These two methods gave almost identical results, suggesting that either technique could be used for determination of rates of fructose 6-phosphate/fructose 1,6-bisphosphate cycling. It was found that more than 50% of the 3H was retained in the fructose 1,6-bisphosphate; it is therefore probable that previous measurement of cycling rates, which have assumed complete loss of 3H, have underestimated the rate of this cycle. The effects of insulin, adrenaline and adrenergic agonists and antagonists on rates of fructose 6-phosphate/fructose 1,6-bisphosphate cycling were investigated. In the presence of insulin, adrenaline (1 microM) increased the cycling rate by about 10-fold in epitrochlearis muscle in vitro; the maximum rate under these conditions was about 2.5 mumol/h per g of tissue. The concentration of adrenaline that increased the cycling rate by 50% was about 50 nM. This effect of adrenaline appears to be mediated by the beta-adrenergic receptor, since the rate was increased by beta-adrenergic agonists and blocked by beta-adrenergic antagonists. From the knowledge of the precise rate of this cycle, the possible physiological importance of cycling is discussed.

| S-EPMC1144014 | biostudies-other

Fructose-2,6-bisphosphate synthesis by 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 4 (PFKFB4) is required for the glycolytic response to hypoxia and tumor growth.

Project description:Fructose-2,6-bisphosphate (F2,6BP) is a shunt product of glycolysis that allosterically activates 6-phosphofructo-1-kinase (PFK-1) resulting in increased glucose uptake and glycolytic flux to lactate. The F2,6BP concentration is dictated by four bifunctional 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatases (PFKFB1-4) with distinct kinase:phosphatase activities. PFKFB4 is over-expressed in human cancers, induced by hypoxia and required for survival and growth of several cancer cell lines. Although PFKFB4 appears to be a rational target for anti-neoplastic drug development, it is not clear whether its kinase or phosphatase activity is required for cancer cell survival. In this study, we demonstrate that recombinant human PFKFB4 kinase activity is 4.3-fold greater than its phosphatase activity, siRNA and genomic deletion of PFKFB4 decrease F2,6BP, PFKFB4 over-expression increases F2,6BP and selective PFKFB4 inhibition in vivo markedly reduces F2,6BP, glucose uptake and ATP. Last, we find that PFKFB4 is required for cancer cell survival during the metabolic response to hypoxia, presumably to enable glycolytic production of ATP when the electron transport chain is not fully operational. Taken together, our data indicate that the PFKFB4 expressed in multiple transformed cells and tumors functions to synthesize F2,6BP. We predict that pharmacological disruption of the PFKFB4 kinase domain may have clinical utility for the treatment of human cancers.

| S-EPMC4196155 | biostudies-literature

The effect of experimental hypothyroidism on phosphofructokinase activity and fructose 2,6-bisphosphate concentrations in rat heart.

Project description:Experimental hypothyroidism was induced in rats by the administration of NaClO4. Hearts from normal and hypothyroid rats were homogenized, and the extracts were assayed for phosphofructokinase-1 and phosphofructokinase-2 activity and fructose 2,6-bisphosphate concentrations. Hypothyroidism was associated with a drastic loss of phosphofructokinase-1 activity. A hyperbolic relationship between plasma thyroxine concentrations and phosphofructokinase-1 activity was found. As treatment with NaClO4 progressed, the decrease in blood thyroxine was faster than the decrease in enzyme activity. After prolonged hypothyroidism (a decrease in thyroxine of more than 10-fold), a 4-fold decrease in phosphofructokinase-1 activity was observed. In this metabolic condition 2-fold decreases in phosphofructokinase-2 activity and in fructose 2,6-bisphosphate were observed. A similar decrease in phosphofructokinase-1 activity in a partially purified preparation was found. The addition of L-thyroxine in the diet had little effect on phosphofructokinase-1 activity. However, exposure of minced pieces of hearts of hypothyroid rats to tri-iodothyronine for 5 h resulted in a clear increase in phosphofructokinase-1 activity, which was partially prevented by the simultaneous addition of cycloheximide. These results could account for the decrease in carbohydrate metabolism in heart from hypothyroid rats.

| S-EPMC1147964 | biostudies-other

Subunit interactions and composition of the fructose 6-phosphate catalytic site and the fructose 2,6-bisphosphate allosteric site of mammalian phosphofructokinase.

Project description:Mammalian phosphofructokinase originated by duplication, fusion, and divergence of a primitive prokaryotic gene, with the duplicated fructose 6-phosphate catalytic site in the C-terminal half becoming an allosteric site for the activator fructose 2,6-bisphosphate. It has been suggested that both sites are shared across the interface between subunits aligned in an antiparallel orientation, the N-terminal half of one subunit facing the C-terminal half of the other. The composition of these binding sites and the way in which subunits interact to form the dimer within the tetrameric enzyme have been reexamined by systematic point mutations to alanine of key amino acid residues of human muscle phosphofructokinase. We found that residues His-199, His-298, Arg-201, and Arg-292 contribute to the catalytic site and not to the allosteric site, because their mutation decreased the affinity for fructose 6-phosphate without affecting the activation by fructose 2,6-bisphosphate or its binding affinity. In contrast, residues Arg-566, Arg-655, and His-661 were critical components of the fructose bisphosphate allosteric site, because their mutation strongly reduced the action and affinity of the activator, with no alteration of substrate binding to the active site. Our results suggest that mammalian phosphofructokinase subunits associate with the N-terminal halves facing each other to form the two catalytic sites/dimer and the C-terminal halves forming the allosteric sites. Additionally, mutation of certain residues eliminated activation by fructose 1,6-bisphosphate, but not its binding, with little effect on activation by fructose 2,6-bisphosphate, indicating a divergence in the signal transduction route despite their binding to the same site.

| S-EPMC2666562 | biostudies-literature

Structure of fructose bisphosphate aldolase from Bartonella henselae bound to fructose 1,6-bisphosphate.

Project description:Fructose bisphosphate aldolase (FBPA) enzymes have been found in a broad range of eukaryotic and prokaryotic organisms. FBPA catalyses the cleavage of fructose 1,6-bisphosphate into glyceraldehyde 3-phosphate and dihydroxyacetone phosphate. The SSGCID has reported several FBPA structures from pathogenic sources, including the bacterium Brucella melitensis and the protozoan Babesia bovis. Bioinformatic analysis of the Bartonella henselae genome revealed an FBPA homolog. The B. henselae FBPA enzyme was recombinantly expressed and purified for X-ray crystallographic studies. The purified enzyme crystallized in the apo form but failed to diffract; however, well diffracting crystals could be obtained by cocrystallization in the presence of the native substrate fructose 1,6-bisphosphate. A data set to 2.35 Å resolution was collected from a single crystal at 100 K. The crystal belonged to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a=72.39, b=127.71, c=157.63 Å. The structure was refined to a final free R factor of 22.2%. The structure shares the typical barrel tertiary structure and tetrameric quaternary structure reported for previous FBPA structures and exhibits the same Schiff base in the active site.

| S-EPMC3169401 | biostudies-literature

Fructose 2,6-bisphosphate in livers of genetically obese rats.

Project description:Livers of genetically obese (fa/fa) rats, starved for 24 h, contained more fructose 2,6-bisphosphate, glucose 6-phosphate, fructose 6-phosphate and glycogen, and more pyruvate kinase and phosphofructokinase 2 activities, than livers of control lean rats. These changes may be explained in terms of cyclic AMP concentration, which was decreased in livers of obese starved rats.

| S-EPMC1152349 | biostudies-other

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data