Glucose stockpile in the intestinal apical brush border in C. elegans

Abstract

Since understanding the mechanisms of glucose transport is a crucial approach for pathological diseases induced by glucose toxicities such as diabetes, numerous studies have unveiled molecular functions involved in glucose transport in the nematode Caenorhabditis elegans, a commonly used model organism. However, physicochemical behaviors of glucose in intestinal lumen-to-cell are still elusive. To address that, we here evaluated a diffusion coefficient of glucose in the intestinal apical brush border in C. elegans by fluorescence recovery after photobleaching (FRAP) with fluorescent glucose. Our results indicate that the fluorescent glucose is accumulated in the intestinal brush border, where the diffusion coefficient of glucose is [~]10-8 cm2/s, two orders of magnitude slower than that in bulk. Namely, the intestinal brush border is considered to be a highly viscous layer composed of intestinal microvilli and more dominantly glycocalyx. These findings imply that this high concentration of glucose in the viscous layer acts as a stockpile.