Hexokinase 2, glycogen synthase and phosphorylase play a key role in muscle glycogen supercompensation.

<h4>Background</h4>Glycogen-depleting exercise can lead to supercompensation of muscle glycogen stores, but the biochemical mechanisms of this phenomenon are still not completely understood.<h4>Methods</h4>Using chronic low-frequency stimulation (CLFS) as an exercise model, t...

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Autores principales:	José M Irimia, Jordi Rovira, Jakob N Nielsen, Mario Guerrero, Jørgen F P Wojtaszewski, Roser Cussó
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2012
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/ef687bfb77a44ed48e4d1d15d99b659a
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spelling	oai:doaj.org-article:ef687bfb77a44ed48e4d1d15d99b659a2021-11-18T07:10:11ZHexokinase 2, glycogen synthase and phosphorylase play a key role in muscle glycogen supercompensation.1932-620310.1371/journal.pone.0042453https://doaj.org/article/ef687bfb77a44ed48e4d1d15d99b659a2012-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/22860128/pdf/?tool=EBIhttps://doaj.org/toc/1932-6203<h4>Background</h4>Glycogen-depleting exercise can lead to supercompensation of muscle glycogen stores, but the biochemical mechanisms of this phenomenon are still not completely understood.<h4>Methods</h4>Using chronic low-frequency stimulation (CLFS) as an exercise model, the tibialis anterior muscle of rabbits was stimulated for either 1 or 24 hours, inducing a reduction in glycogen of 90% and 50% respectively. Glycogen recovery was subsequently monitored during 24 hours of rest.<h4>Results</h4>In muscles stimulated for 1 hour, glycogen recovered basal levels during the rest period. However, in those stimulated for 24 hours, glycogen was supercompensated and its levels remained 50% higher than basal levels after 6 hours of rest, although the newly synthesized glycogen had fewer branches. This increase in glycogen correlated with an increase in hexokinase-2 expression and activity, a reduction in the glycogen phosphorylase activity ratio and an increase in the glycogen synthase activity ratio, due to dephosphorylation of site 3a, even in the presence of elevated glycogen stores. During supercompensation there was also an increase in 5'-AMP-activated protein kinase phosphorylation, correlating with a stable reduction in ATP and total purine nucleotide levels.<h4>Conclusions</h4>Glycogen supercompensation requires a coordinated chain of events at two levels in the context of decreased cell energy balance: First, an increase in the glucose phosphorylation capacity of the muscle and secondly, control of the enzymes directly involved in the synthesis and degradation of the glycogen molecule. However, supercompensated glycogen has fewer branches.José M IrimiaJordi RoviraJakob N NielsenMario GuerreroJørgen F P WojtaszewskiRoser CussóPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 7, Iss 7, p e42453 (2012)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q José M Irimia Jordi Rovira Jakob N Nielsen Mario Guerrero Jørgen F P Wojtaszewski Roser Cussó Hexokinase 2, glycogen synthase and phosphorylase play a key role in muscle glycogen supercompensation.
description	<h4>Background</h4>Glycogen-depleting exercise can lead to supercompensation of muscle glycogen stores, but the biochemical mechanisms of this phenomenon are still not completely understood.<h4>Methods</h4>Using chronic low-frequency stimulation (CLFS) as an exercise model, the tibialis anterior muscle of rabbits was stimulated for either 1 or 24 hours, inducing a reduction in glycogen of 90% and 50% respectively. Glycogen recovery was subsequently monitored during 24 hours of rest.<h4>Results</h4>In muscles stimulated for 1 hour, glycogen recovered basal levels during the rest period. However, in those stimulated for 24 hours, glycogen was supercompensated and its levels remained 50% higher than basal levels after 6 hours of rest, although the newly synthesized glycogen had fewer branches. This increase in glycogen correlated with an increase in hexokinase-2 expression and activity, a reduction in the glycogen phosphorylase activity ratio and an increase in the glycogen synthase activity ratio, due to dephosphorylation of site 3a, even in the presence of elevated glycogen stores. During supercompensation there was also an increase in 5'-AMP-activated protein kinase phosphorylation, correlating with a stable reduction in ATP and total purine nucleotide levels.<h4>Conclusions</h4>Glycogen supercompensation requires a coordinated chain of events at two levels in the context of decreased cell energy balance: First, an increase in the glucose phosphorylation capacity of the muscle and secondly, control of the enzymes directly involved in the synthesis and degradation of the glycogen molecule. However, supercompensated glycogen has fewer branches.
format	article
author	José M Irimia Jordi Rovira Jakob N Nielsen Mario Guerrero Jørgen F P Wojtaszewski Roser Cussó
author_facet	José M Irimia Jordi Rovira Jakob N Nielsen Mario Guerrero Jørgen F P Wojtaszewski Roser Cussó
author_sort	José M Irimia
title	Hexokinase 2, glycogen synthase and phosphorylase play a key role in muscle glycogen supercompensation.
title_short	Hexokinase 2, glycogen synthase and phosphorylase play a key role in muscle glycogen supercompensation.
title_full	Hexokinase 2, glycogen synthase and phosphorylase play a key role in muscle glycogen supercompensation.
title_fullStr	Hexokinase 2, glycogen synthase and phosphorylase play a key role in muscle glycogen supercompensation.
title_full_unstemmed	Hexokinase 2, glycogen synthase and phosphorylase play a key role in muscle glycogen supercompensation.
title_sort	hexokinase 2, glycogen synthase and phosphorylase play a key role in muscle glycogen supercompensation.
publisher	Public Library of Science (PLoS)
publishDate	2012
url	https://doaj.org/article/ef687bfb77a44ed48e4d1d15d99b659a
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Hexokinase 2, glycogen synthase and phosphorylase play a key role in muscle glycogen supercompensation.

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