Pre- and posttranslational upregulation of muscle-specific glycogen synthase in athletes
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Pre- and posttranslational upregulation of muscle-specific glycogen synthase in athletes. / Vestergaard, H; Andersen, P H; Lund, S; Schmitz, O; Junker, S; Pedersen, O.
In: American Journal of Physiology (Consolidated), Vol. 266, No. 1 Pt 1, 01.1994, p. E92-101.Research output: Contribution to journal › Journal article › Research › peer-review
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T1 - Pre- and posttranslational upregulation of muscle-specific glycogen synthase in athletes
AU - Vestergaard, H
AU - Andersen, P H
AU - Lund, S
AU - Schmitz, O
AU - Junker, S
AU - Pedersen, O
PY - 1994/1
Y1 - 1994/1
N2 - Expression of muscle-specific glycogen synthase (GS) and phosphofructokinase (PFK) was analyzed in seven athletes and eight control subjects who were characterized using the euglycemic, hyperinsulinemic (2 mU.kg-1.min-1) clamp technique in combination with indirect calorimetry and biopsy sampling of vastus lateralis muscle. In the basal state, total GS activity and half-maximal GS activation by glucose 6-phosphate (G-6-P) were respectively 34% (P < 0.03) and 50% (P < 0.005) higher in athletes than in control subjects. In parallel, GS mRNA/microgram total RNA in athletes was 40% (P < 0.005) higher. No difference in GS immunoreactive protein abundance was found between the groups. PFK activity and protein levels were respectively 15% (P < 0.05) and 20% (P < 0.02) lower in athletes, whereas no differences was found in the level of PFK mRNA. After 4 h of hyperinsulinemia, total glucose disposal rate (P < 0.005) and both nonoxidative (P < 0.02) and oxidative (P < 0.03) glucose metabolism were significantly higher in athletes. In parallel, after hyperinsulinemia, the relative activation of GS by G-6-P was significantly higher in athletes, whereas total activity and gene expression of both GS and PFK were unaffected by insulin. We conclude that athletes have increased whole body insulin-stimulated nonoxidative glucose metabolism associated with both pretranslational (mRNA) and posttranslational (enzyme activity) upregulation of GS. However, the immunoreactive mass of GS is normal, emphasizing that posttranslational regulation of the GS protein activity is important for the increased glycogen synthesis rate of muscle in endurance-trained individuals.
AB - Expression of muscle-specific glycogen synthase (GS) and phosphofructokinase (PFK) was analyzed in seven athletes and eight control subjects who were characterized using the euglycemic, hyperinsulinemic (2 mU.kg-1.min-1) clamp technique in combination with indirect calorimetry and biopsy sampling of vastus lateralis muscle. In the basal state, total GS activity and half-maximal GS activation by glucose 6-phosphate (G-6-P) were respectively 34% (P < 0.03) and 50% (P < 0.005) higher in athletes than in control subjects. In parallel, GS mRNA/microgram total RNA in athletes was 40% (P < 0.005) higher. No difference in GS immunoreactive protein abundance was found between the groups. PFK activity and protein levels were respectively 15% (P < 0.05) and 20% (P < 0.02) lower in athletes, whereas no differences was found in the level of PFK mRNA. After 4 h of hyperinsulinemia, total glucose disposal rate (P < 0.005) and both nonoxidative (P < 0.02) and oxidative (P < 0.03) glucose metabolism were significantly higher in athletes. In parallel, after hyperinsulinemia, the relative activation of GS by G-6-P was significantly higher in athletes, whereas total activity and gene expression of both GS and PFK were unaffected by insulin. We conclude that athletes have increased whole body insulin-stimulated nonoxidative glucose metabolism associated with both pretranslational (mRNA) and posttranslational (enzyme activity) upregulation of GS. However, the immunoreactive mass of GS is normal, emphasizing that posttranslational regulation of the GS protein activity is important for the increased glycogen synthesis rate of muscle in endurance-trained individuals.
KW - Adult
KW - Glucose
KW - Glucose Clamp Technique
KW - Glycogen Synthase
KW - Humans
KW - Hyperinsulinism
KW - Lipid Metabolism
KW - Male
KW - Muscles
KW - Phosphofructokinase-1
KW - Protein Processing, Post-Translational
KW - RNA, Messenger
KW - Sports
KW - Up-Regulation
M3 - Journal article
C2 - 8304448
VL - 266
SP - E92-101
JO - American Journal of Physiology - Cell Physiology
JF - American Journal of Physiology - Cell Physiology
SN - 0363-6143
IS - 1 Pt 1
ER -
ID: 150332793