Sialidases are glycosidases responsible for the removal of sialic acid residues (desialylation) from glycan portions of either glycoproteins or glycolipids. In vertebrates, the sialidase family comprises four different forms in different subcellular localizations: the lysosomal sialidase Neu1, the soluble or cytosolic sialidase Neu2, the membrane-associated sialidase Neu3 and lysosomal or mitochondrial membrane associated sialidase Neu4. Each sialidase (Neu1, Neu2, Neu3 or Neu4) also has substrate specificity, suggesting different biological functions. Neu1 is typically located in the lysosome, but also could relocate to plasma membrane upon stimulation, where it impacts receptor activation and signaling in a variety of cell types, including immune cells. In this report, we profiled Neu1 and Neu3 sialidase expression, relocation and secretion of THP-1 monocytes and THP-1 macrophages. Briefly, we examined sialidase activity of Neu1 and Neu3 in cell lysates, cell plasma membranes and cell culture media of THP-1 monocytes upon LPS stimulation and differentiation to THP-1 macrophages with the artificial substrates, respectively. Also, Neu1 and Neu3 activity in cell lysates, cell plasma membranes and cell culture media of THP-1 macrophages upon LPS stimulation were measured. In addition, western blot analysis of Neu1 and Neu3 proteins in cell lysates, cell plasma membranes and cell culture media of the cells above were investigated, respectively. Finally, cell surface Neu1 and Neu3 were examined by flow cytometry, respectively. Overall, we found that Neu1 are highly expressed and relocate to cell surface in monocytes upon LPS stimulation and differentiation to macrophages. This presentation will discuss the detailed results about sialidase Neu1 and Neu3 expression, relocation and secretion of monocytes upon LPS stimulation and differentiation and macrophages upon LPS stimulation.

Profiling sialidase expression: Relocation and secretion of monocytes and macrophages

ACS Spring Meeting 2021

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