1,3-and 1,4-linked polysaccharides uptake in intestinal cells relies on clathrin/dynamin 1/Rab5-dependent endocytosis

It is thought that polysaccharides cannot penetrate the intestinal mucosa into the circulatory system due to their high hydrophilicity and large molecular size. However, we show that different linked and charged polysaccharides can penetrate Caco-2 cell monolayers, and find β−1,3-linked glucan and α−1,4-linked glucan is detectable in rats (male) and mice plasma and liver after oral administration the isotope (99mTc, 3H) and fluorescein labeled polysaccharides. Using gene-knockdown strategies and inhibitors, we further show polysaccharide uptake requires clathrin heavy chain (CLTC) and its associated factors Rab5 and dynamin1 in intestinal cells. Strikingly, polysaccharide absorption is attenuated in both CLTC intestine deficient mice and RAB5A, DNM1conventional-knockout mice. Importantly, membrane receptors bone morphogenetic protein receptor type IA (BMPRIA), Dectin-1 and epidermal growth factor receptor (EGFR) are also critical for specific structural polysaccharide internalization. These findings provide novel insight to understand polysaccharide absorption mechanism and lay foundation for oral polysaccharide-based new drugs development. The study demonstrated that some exogenous natural polysaccharides could be absorbed in plasma with little degradation after orally administration. Polysaccharide uptake in the intestinal cells relied on clathrin/dynamin 1/Rab5-dependent endocytosis.