Glucosamine prevents polarization of cytotoxic granules in NK-92 cells by disturbing FOXO1/ERK/paxillin phosphorylation

Abstract

Glucosamine (GlcN) is a naturally occurring derivative of glucose and an over-the-counter food additive. However, the mechanism underlying GlcN action on cells is unknown. In this study, we investigated the effect of GlcN on natural killer (NK) cells. We demonstrate that GlcN affects NK-92 cell cytotoxicity by altering the distribution of cathepsin C, a cysteine protease required for granzyme processing in cytotoxic granules. The relocation of cathepsin C due to GlcN was shown to be accompanied by a decrease in the intracellular enzyme activity and its extracellular secretion. Similarly, the relocation of endosomal aspartic cathepsin E was observed. Furthermore, we elucidated that repositioning of cathepsin C is a consequence of altered signaling pathways of cytotoxic granule movement. The inhibition of phosphorylation upstream and downstream of ERK by GlcN disturbed the polarized release of cytotoxic vesicles. Considerable changes in the ERK phosphorylation dynamics, but not in those of p38 kinase or JNK, were observed in the IL2-activated NK-92 cells. We found decreased phosphorylation of the transcription factor FOXO1 and simultaneous prolonged phosphorylation of ERK as well as its nuclear translocation. Additionally, a protein downstream of the ERK phosphorylation cascade, paxillin, was less phosphorylated, resulting in a diffuse distribution of cytotoxic granules. Taken together, our results suggest that dietary GlcN affects signaling pathway activation of NK-92 immune cells.

Glucosamine Interferes With Myelopoiesis and Enhances the Immunosuppressive Activity of Myeloid-Derived Suppressor Cells

“…While, we could not rule out the possibility that GlcN might activate ERK1/2 and STAT3 pathways to enhance MDSC production in mice. Similar to our results about GlcN-mediated enhancement of MDSC immunosuppressive activity on cytotoxic T cells via ERK1/2 pathway, GlcN prolongs ERK1/2 phosphorylation to suppress the cytotoxic activity of NK-92 natural killer (NK) cells ( 36 ). Accumulating data has highlighted the interaction between immune cells, such as MDSCs and NK cells, and cancer cells within the tumor microenvironment to promote cancer progression ( 37 ).…”

O-GlcNAcylation in Viral Infections: The Sweet and Sour

“…This is supported by data that shows reduced O-GlcNAcylation following the induction of cytotoxicity in NK cells [110,111]. Furthermore, increasing O-GlcNAcylation by administering glucosamine in NK cells alters the localization of cathepsin and causes the polarization of lytic granules [110]. Despite this, O-GlcNAcylation regulates the development, maturation, and function of NK cells by controlling the modification of a histone methyltransferase protein, enhancer of zeste homologs 2 (EZH2) [112,113].…”

“…Natural killer (NK) cells: O-GlcNAcylation has been associated with the reduction of cytotoxicity in natural killer (NK) cells by increasing the activity of MEK and ERK [109]. This is supported by data that shows reduced O-GlcNAcylation following the induction of cytotoxicity in NK cells [110,111]. Furthermore, increasing O-GlcNAcylation by administering glucosamine in NK cells alters the localization of cathepsin and causes the polarization of lytic granules [110].…”

O-GlcNAcylation and Its Role in Cancer-Associated Inflammation

“…Cathepsin C can activate granzymes by proteolytic cleavage and granzymes can enter the target cell to induce apoptosis through various signaling pathways (125). Studies revealed Glucosamine (GlcN), an intermediate fluxing into HBP pathway to increase O-GlcNAcylation, could reduce NK cell cytotoxicity by altering the distribution of cathepsin C and E, indicating O-GlcNAcylation might play a role in regulating the cytotoxic activity of NK cells (126).…”