Alginate oligomer induces nitric oxide (NO) production in RAW264.7 cells: elucidation of the underlying intracellular signaling mechanism. Issue 11 (2nd November 2015) - Ueno, Mikinori
Abstract: Alginate is an acidic linear polysaccharide with immune-modulating activities. In this study, we found that enzymatically digested alginate oligomer (AO) with various degrees of polymerization (DP; 2–5) induced a higher level of nitric oxide (NO) production in RAW264.7 cells than undigested alginate polymer (AP). Reverse transcription-polymerase chain reaction and western blot analyses revealed that the expression level of inducible NO synthase in AO-treated RAW264.7 cells was higher than that in AP-treated cells. AO induced nuclear translocation of nuclear factor (NF)-κB p65 subunit in RAW264.7 cells to a greater extent than AP. Although AO and AP induced similar extents of phosphorylation in three mitogen-activated protein (MAP) kinases, c-Jun N-terminal kinase inhibitor exhibited the most potent inhibitory effect on NO induction in AO- and AP-treated RAW264.7 cells, among three MAP kinase inhibitors that were tested. Graphical abstract: : Alginate is composed of two forms of uronic acids, α-L-guluronate (G) and β-D-mannuronate (M), which in turn form three types of polymer blocks: G-block, M-block, and random block.