Glycogen Shunt Activity and Glycolytic Supercompensation in Astrocytes May Be Distinctly Mediated via the Muscle Form of Glycogen Phosphorylase

Neurochemical Research
Emil JakobsenHelle S Waagepetersen

Abstract

Glycogen is the main storage form of glucose in the brain. In contrast with previous beliefs, brain glycogen has recently been shown to play important roles in several brain functions. A fraction of metabolized glucose molecules are being shunted through glycogen before reentering the glycolytic pathway, a phenomenon known as the glycogen shunt. The significance of glycogen in astrocyte energetics is underlined by high activity of the glycogen shunt and the finding that inhibition of glycogen degradation, under some conditions leads to a disproportional increase in glycolytic activity, so-called glycolytic supercompensation. Glycogen phosphorylase, the key enzyme in glycogen degradation, is expressed in two different isoforms in brain, the muscle and the brain isoform. Recent studies have illustrated how these are differently regulated. In the present study, we investigate the role of the two isoforms in glycolytic supercompensation in cultured astrocytes with the expression of either one of the isoforms silenced by siRNA knockdown. When reintroducing glucose to glucose-starved astrocytes, glycolytic activity increased dramatically. Interestingly, the increase was 30% higher in astrocytes not expressing the muscle isoform of gl...Continue Reading

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Citations

Feb 28, 2018·The Journal of Biological Chemistry·Clara PratsJane Shearer
Mar 25, 2018·The Journal of Biological Chemistry·Lasse K BakHelle S Waagepetersen
Aug 31, 2018·PLoS Computational Biology·Jay S CogganPierre J Magistretti
Nov 30, 2019·International Journal of Molecular Sciences·Francisco LlaveroJosé Luis Zugaza
Feb 8, 2020·Brain Research·Kelly StarichaSusan Cohen
May 1, 2021·Cells·Marta Migocka-Patrzałek, Magdalena Elias

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