Changes in Glycogen Structure over Feeding Cycle Sheds New Light on Blood-Glucose Control

摘要

Liver glycogen, a highly branched polymer of glucose, is important for maintaining blood-glucose homeostasis. It was recently shown that, db/db mice, a model for Type 2 diabetes, are unable to form the large composite glycogen a particles present in normal, healthy mice. In this study, the structure of healthy mouse-liver glycogen over the diurnal cycle was characterized using size exclusion chromatography and transmission electron microscopy. Glycogen was found to be formed as smaller β particles, and then only assembled into large a particles, with a broad size distribution, Significantly after the time when glycogen content had reached a maximum. This pathway, missing in diabetic animals, is likely to give optimal blood-glucose control during the daily feeding cycle. Lack of this control may contribute to, or result from, diabetes. This discovery suggests novel approaches to diabetes management.