NEU1 sialidase controls gene expression and secretion of IL-6 and MCP-1 through NF-&kgr;B pathway in 3T3-L1 adipocytes

Abstract

A sialidase NEU1 that removes sialic acids from glycoconjugates has been implicated in diverse cellular functions. Aberrant NEU1 activity is associated with various pathologies including lysosomal storage disorder sialidosis, autoimmune diseases and the malignancy and metastasis of cancer cells. We recently reported that NEU1 activity increases during 3T3-L1 adipogenesis and that it is higher in the epididymal fat of obese and diabetic mice. However, the precise functions of NEU1 in adipocytes have not been elucidated. Knockdown of NEU1 using siRNA transfection in 3T3-L1 adipocytes significantly decreased the mRNA expression and protein secretion of IL-6 and MCP-1 induced by LPS. The promoter activities of both IL-6 and MCP-1 as well as nuclear factor-kappa B (NF-κB) nuclear translocation were reduced in adipocytes transfected with an siRNA sequence that targets NEU1(siNEU1). NEU1 suppression using siNEU1 affected TLR4 sialylation. These findings suggest that NEU1 is involved in the production of IL-6 and MCP-1 in adipocytes possibly through TLR4/NF-κB signalling.