Insights into O-GlcNAc-mediated regulation of galectin expression and secretion in promyelocytic HL-60 cells
Abstract
Galectins are a family of -galactoside-binding proteins involved in cell stress responses and differentiation. Galectins are multifunctional proteins widely studied in many cell models including acute myeloid leukemia HL-60 cells where they mediate numerous intra- and extracellular functions in response to many stress-inducing stimuli. O-GlcNAcylation is a dynamic post-translational modification implicated in the regulation of many cellular diseases including cancers. The O-GlcNAc mediated expression and secretion of galectins during neutrophilic differentiation was examined in HL-60 cells. Galectin gene (LGALS), galectin protein expression, and galectin secretion were determined by RT-qPCR, immunoblotting, and ELISA, respectively. Inhibition of O-GlcNAcylation induced markers of differentiation namely growth arrest, segmented nuclear morphology, and H2O2 production by NADPH oxidase comparable to ATRA-induced differentiation. The reduction of O-GlcNAcylation modified galectin expression, and increased galectin secretion in a manner similar to ATRA. This study confirms that inhibition of O-GlcNAcylation is one of the important mechanisms regulating expression and secretion of galectins and cellular differentiation.