Active hepatic glycogen synthesis from gluconeogenic precursors despite high tissue levels of fructose 2,6-bisphosphate

M. Kuwajima, S. Golden, J. Katz, Roger H Unger, Daniel W Foster, J. D. McGarry

Research output: Contribution to journalArticle

60 Citations (Scopus)

Abstract

When fasted rats are regular lab chow there was a lag time of about 2 before concentration of fructose 2,6-bisphosphate (Fru-2,6-P2) in liver began to rise from its low basal level. By contrast, in animals refed on a sucrose-based diet hepatic [Fru-2,6-P2] increased 20-fold (to a value of ~ 12 nmol/g wet weight) during the first hour. These responses correlated with differences in the ability of the two diets to increase the circulating [insulin]/[glucagon] ratio and thus to elevate the ratio of 6-phosphofructo-2-kinase to fructose-2,6-bisphosphate. Liver glycogen was deposited briskly in both groups of rats. To assess its mechanism of synthesis (directly from glucose versus indirectly via the gluconeogenic pathway), animals eating the chow or sucrose diets received intravenous infusions of [14C]bicarbonate, [1-14C]fructose, and 3H2O. After isolation, the glycogen was subjected to positional isotopic analysis of its glucose residues. The results established that regardless of the diet the bulk of liver glycogen was gluconeogenic in origin. The fact that with sucrose feeding carbon flow through hepatic fructose-1,6-bisphosphatase remained active despite high levels of Fru-2,6-P2 (a potent inhibitor of this enzyme in vitro) presents a metabolic paradox. Conceivably, the suppressive effect of Fru-2,6-P2 on hepatic fructose-1,6-bisphosphatase is overridden in vivo by some unknown factor or factors generated in response to sucrose feeding. Alternatively, metabolic zonation in liver might result in the coexistence of hepatocytes rich in Fru-2,6-P2 (high glycolytic, low gluconeogenic, low glycogenic capacities) with cells depleted of Fru-2,6-P2 (low glycolytic, high gluconeogenic, high glycogenic capacities).

Original languageEnglish (US)
Pages (from-to)2632-2637
Number of pages6
JournalJournal of Biological Chemistry
Volume261
Issue number6
StatePublished - 1986

Fingerprint

Liver Glycogen
Nutrition
Sucrose
Tissue
Fructose-Bisphosphatase
Liver
Diet
Rats
Animals
Phosphofructokinase-2
Glucose
Enzyme Inhibitors
Bicarbonates
Fructose
Glucagon
Glycogen
Carbon
Intravenous Infusions
Insulin
Hepatocytes

ASJC Scopus subject areas

  • Biochemistry

Cite this

Active hepatic glycogen synthesis from gluconeogenic precursors despite high tissue levels of fructose 2,6-bisphosphate. / Kuwajima, M.; Golden, S.; Katz, J.; Unger, Roger H; Foster, Daniel W; McGarry, J. D.

In: Journal of Biological Chemistry, Vol. 261, No. 6, 1986, p. 2632-2637.

Research output: Contribution to journalArticle

@article{cb0321b8ceff4a9fb26751f5429d54a1,
title = "Active hepatic glycogen synthesis from gluconeogenic precursors despite high tissue levels of fructose 2,6-bisphosphate",
abstract = "When fasted rats are regular lab chow there was a lag time of about 2 before concentration of fructose 2,6-bisphosphate (Fru-2,6-P2) in liver began to rise from its low basal level. By contrast, in animals refed on a sucrose-based diet hepatic [Fru-2,6-P2] increased 20-fold (to a value of ~ 12 nmol/g wet weight) during the first hour. These responses correlated with differences in the ability of the two diets to increase the circulating [insulin]/[glucagon] ratio and thus to elevate the ratio of 6-phosphofructo-2-kinase to fructose-2,6-bisphosphate. Liver glycogen was deposited briskly in both groups of rats. To assess its mechanism of synthesis (directly from glucose versus indirectly via the gluconeogenic pathway), animals eating the chow or sucrose diets received intravenous infusions of [14C]bicarbonate, [1-14C]fructose, and 3H2O. After isolation, the glycogen was subjected to positional isotopic analysis of its glucose residues. The results established that regardless of the diet the bulk of liver glycogen was gluconeogenic in origin. The fact that with sucrose feeding carbon flow through hepatic fructose-1,6-bisphosphatase remained active despite high levels of Fru-2,6-P2 (a potent inhibitor of this enzyme in vitro) presents a metabolic paradox. Conceivably, the suppressive effect of Fru-2,6-P2 on hepatic fructose-1,6-bisphosphatase is overridden in vivo by some unknown factor or factors generated in response to sucrose feeding. Alternatively, metabolic zonation in liver might result in the coexistence of hepatocytes rich in Fru-2,6-P2 (high glycolytic, low gluconeogenic, low glycogenic capacities) with cells depleted of Fru-2,6-P2 (low glycolytic, high gluconeogenic, high glycogenic capacities).",
author = "M. Kuwajima and S. Golden and J. Katz and Unger, {Roger H} and Foster, {Daniel W} and McGarry, {J. D.}",
year = "1986",
language = "English (US)",
volume = "261",
pages = "2632--2637",
journal = "Journal of Biological Chemistry",
issn = "0021-9258",
publisher = "American Society for Biochemistry and Molecular Biology Inc.",
number = "6",

}

TY - JOUR

T1 - Active hepatic glycogen synthesis from gluconeogenic precursors despite high tissue levels of fructose 2,6-bisphosphate

AU - Kuwajima, M.

AU - Golden, S.

AU - Katz, J.

AU - Unger, Roger H

AU - Foster, Daniel W

AU - McGarry, J. D.

PY - 1986

Y1 - 1986

N2 - When fasted rats are regular lab chow there was a lag time of about 2 before concentration of fructose 2,6-bisphosphate (Fru-2,6-P2) in liver began to rise from its low basal level. By contrast, in animals refed on a sucrose-based diet hepatic [Fru-2,6-P2] increased 20-fold (to a value of ~ 12 nmol/g wet weight) during the first hour. These responses correlated with differences in the ability of the two diets to increase the circulating [insulin]/[glucagon] ratio and thus to elevate the ratio of 6-phosphofructo-2-kinase to fructose-2,6-bisphosphate. Liver glycogen was deposited briskly in both groups of rats. To assess its mechanism of synthesis (directly from glucose versus indirectly via the gluconeogenic pathway), animals eating the chow or sucrose diets received intravenous infusions of [14C]bicarbonate, [1-14C]fructose, and 3H2O. After isolation, the glycogen was subjected to positional isotopic analysis of its glucose residues. The results established that regardless of the diet the bulk of liver glycogen was gluconeogenic in origin. The fact that with sucrose feeding carbon flow through hepatic fructose-1,6-bisphosphatase remained active despite high levels of Fru-2,6-P2 (a potent inhibitor of this enzyme in vitro) presents a metabolic paradox. Conceivably, the suppressive effect of Fru-2,6-P2 on hepatic fructose-1,6-bisphosphatase is overridden in vivo by some unknown factor or factors generated in response to sucrose feeding. Alternatively, metabolic zonation in liver might result in the coexistence of hepatocytes rich in Fru-2,6-P2 (high glycolytic, low gluconeogenic, low glycogenic capacities) with cells depleted of Fru-2,6-P2 (low glycolytic, high gluconeogenic, high glycogenic capacities).

AB - When fasted rats are regular lab chow there was a lag time of about 2 before concentration of fructose 2,6-bisphosphate (Fru-2,6-P2) in liver began to rise from its low basal level. By contrast, in animals refed on a sucrose-based diet hepatic [Fru-2,6-P2] increased 20-fold (to a value of ~ 12 nmol/g wet weight) during the first hour. These responses correlated with differences in the ability of the two diets to increase the circulating [insulin]/[glucagon] ratio and thus to elevate the ratio of 6-phosphofructo-2-kinase to fructose-2,6-bisphosphate. Liver glycogen was deposited briskly in both groups of rats. To assess its mechanism of synthesis (directly from glucose versus indirectly via the gluconeogenic pathway), animals eating the chow or sucrose diets received intravenous infusions of [14C]bicarbonate, [1-14C]fructose, and 3H2O. After isolation, the glycogen was subjected to positional isotopic analysis of its glucose residues. The results established that regardless of the diet the bulk of liver glycogen was gluconeogenic in origin. The fact that with sucrose feeding carbon flow through hepatic fructose-1,6-bisphosphatase remained active despite high levels of Fru-2,6-P2 (a potent inhibitor of this enzyme in vitro) presents a metabolic paradox. Conceivably, the suppressive effect of Fru-2,6-P2 on hepatic fructose-1,6-bisphosphatase is overridden in vivo by some unknown factor or factors generated in response to sucrose feeding. Alternatively, metabolic zonation in liver might result in the coexistence of hepatocytes rich in Fru-2,6-P2 (high glycolytic, low gluconeogenic, low glycogenic capacities) with cells depleted of Fru-2,6-P2 (low glycolytic, high gluconeogenic, high glycogenic capacities).

UR - http://www.scopus.com/inward/record.url?scp=0023000317&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0023000317&partnerID=8YFLogxK

M3 - Article

C2 - 3753973

AN - SCOPUS:0023000317

VL - 261

SP - 2632

EP - 2637

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 6

ER -