Overexpression of Muscle Glycogen Phosphorylase in Cultured Human Muscle Fibers Causes Increased Glucose Consumption and Nonoxidative Disposal

Control of glycogen synthesis by glucose, glycogen, and insulin in cultured human muscle cells.

A key feature of type 2 diabetes is impairment in the stimulation of glycogen synthesis in skeletal muscle by insulin. Glycogen synthesis and the activity of the enzyme glycogen synthase (GS) have been studied in human myoblasts in culture under a variety of experimental conditions. Incubation in the absence of glucose for up to 6 h caused an approximately 50% decrease in glycogen content, whic...

Glycogen depletion rather than glucose 6- P increments controls early glycogen recovery in human cultured muscle.

In glycogen-containing muscle, glycogenesis appears to be controlled by glucose 6-phosphate (6- P) provision, but after glycogen depletion, an autoinhibitory control of glycogen could be a determinant. We analyzed in cultured human muscle the contribution of glycogen depletion versus glucose 6- P in the control of glycogen recovery. Acute deglycogenation was achieved by engineering cells to ove...

McArdle's disease-muscle glycogen phosphorylase deficiency.

Control of glycogen synthesis is shared between glucose transport and glycogen synthase in skeletal muscle fibers.

The effects of transgenic overexpression of glycogen synthase in different types of fast-twitch muscle fibers were investigated in individual fibers from the anterior tibialis muscle. Glycogen synthase was severalfold higher in all transgenic fibers, although the extent of overexpression was twofold greater in type IIB fibers. Effects of the transgene on increasing glycogen and phosphorylase an...

Expression of muscle-gene-specific isozymes of phosphorylase and creatine kinase in innervated cultured human muscle

Isozymes of creatine kinase and glycogen phosphorylase are excellent markers of skeletal muscle maturation. In adult innervated muscle only the muscle-gene-specific isozymes are present, whereas aneurally cultured human muscle has predominantly the fetal pattern of isozymes. We have studied the isozyme pattern of human muscle cultured in monolayer and innervated by rat embryo spinal cord explan...