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Expression and glycogenic effect of glycogen-targeting protein phosphatase 1 regulatory subunit GL in cultured human muscle.

Publication ,  Journal Article
Montori-Grau, M; Guitart, M; Lerin, C; Andreu, AL; Newgard, CB; García-Martínez, C; Gómez-Foix, AM
Published in: Biochem J
July 1, 2007

Glycogen-targeting PP1 (protein phosphatase 1) subunit G(L) (coded for by the PPP1R3B gene) is expressed in human, but not rodent, skeletal muscle. Its effects on muscle glycogen metabolism are unknown. We show that G(L) mRNA levels in primary cultured human myotubes are similar to those in freshly excised muscle, unlike subunits G(M) (gene PPP1R3A) or PTG (protein targeting to glycogen; gene PPP1R3C), which decrease strikingly. In cultured myotubes, expression of the genes coding for G(L), G(M) and PTG is not regulated by glucose or insulin. Overexpression of G(L) activates myotube GS (glycogen synthase), glycogenesis in glucose-replete and -depleted cells and glycogen accumulation. Compared with overexpressed G(M), G(L) has a more potent activating effect on glycogenesis, while marked enhancement of their combined action is only observed in glucose-replete cells. G(L) does not affect GP (glycogen phosphorylase) activity, while co-overexpression with muscle GP impairs G(L) activation of GS in glucose-replete cells. G(L) enhances long-term glycogenesis additively to glucose depletion and insulin, although G(L) does not change the phosphorylation of GSK3 (GS kinase 3) on Ser9 or its upstream regulator kinase Akt/protein kinase B on Ser473, nor its response to insulin. In conclusion, in cultured human myotubes, the G(L) gene is expressed as in muscle tissue and is unresponsive to glucose or insulin, as are G(M) and PTG genes. G(L) activates GS regardless of glucose, does not regulate GP and stimulates glycogenesis in combination with insulin and glucose depletion.

Duke Scholars

Published In

Biochem J

DOI

EISSN

1470-8728

Publication Date

July 1, 2007

Volume

405

Issue

1

Start / End Page

107 / 113

Location

England

Related Subject Headings

  • Rats
  • Protein Subunits
  • Protein Phosphatase 1
  • Phosphoprotein Phosphatases
  • Muscle, Skeletal
  • Muscle Fibers, Skeletal
  • Isoenzymes
  • Insulin
  • Humans
  • Glycogen
 

Citation

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Montori-Grau, M., Guitart, M., Lerin, C., Andreu, A. L., Newgard, C. B., García-Martínez, C., & Gómez-Foix, A. M. (2007). Expression and glycogenic effect of glycogen-targeting protein phosphatase 1 regulatory subunit GL in cultured human muscle. Biochem J, 405(1), 107–113. https://doi.org/10.1042/BJ20061572
Montori-Grau, Marta, Maria Guitart, Carles Lerin, Antonio L. Andreu, Christopher B. Newgard, Cèlia García-Martínez, and Anna M. Gómez-Foix. “Expression and glycogenic effect of glycogen-targeting protein phosphatase 1 regulatory subunit GL in cultured human muscle.Biochem J 405, no. 1 (July 1, 2007): 107–13. https://doi.org/10.1042/BJ20061572.
Montori-Grau M, Guitart M, Lerin C, Andreu AL, Newgard CB, García-Martínez C, et al. Expression and glycogenic effect of glycogen-targeting protein phosphatase 1 regulatory subunit GL in cultured human muscle. Biochem J. 2007 Jul 1;405(1):107–13.
Montori-Grau, Marta, et al. “Expression and glycogenic effect of glycogen-targeting protein phosphatase 1 regulatory subunit GL in cultured human muscle.Biochem J, vol. 405, no. 1, July 2007, pp. 107–13. Pubmed, doi:10.1042/BJ20061572.
Montori-Grau M, Guitart M, Lerin C, Andreu AL, Newgard CB, García-Martínez C, Gómez-Foix AM. Expression and glycogenic effect of glycogen-targeting protein phosphatase 1 regulatory subunit GL in cultured human muscle. Biochem J. 2007 Jul 1;405(1):107–113.

Published In

Biochem J

DOI

EISSN

1470-8728

Publication Date

July 1, 2007

Volume

405

Issue

1

Start / End Page

107 / 113

Location

England

Related Subject Headings

  • Rats
  • Protein Subunits
  • Protein Phosphatase 1
  • Phosphoprotein Phosphatases
  • Muscle, Skeletal
  • Muscle Fibers, Skeletal
  • Isoenzymes
  • Insulin
  • Humans
  • Glycogen