Neuraminidase-3 Is a Negative Regulator of LFA-1 Adhesion

Abstract

Within the plasma membrane environment, glycoconjugate-receptor interactions play an important role in the regulation of cell-cell interactions. We have investigated the mechanism and activity of the human neuraminidase (NEU) isoenzyme, NEU3, on T cell adhesion receptors. The enzyme is known to prefer glycolipid substrates, and we confirmed that exogenous enzyme altered the glycolipid composition of cells. NEU3 was able to modify the sialic acid content of purified LFA-1 in vitro. Enzymatic activity of NEU3 resulted in re-organization of LFA-1 into large clusters on the membrane. This change was facilitated by an increase in the lateral mobility of LFA-1 upon NEU3 treatment. Changes to the lateral mobility of LFA-1 were specific for NEU3 activity, and we observed no significant change in diffusion when cells were treated with a bacterial NEU (NanI). Furthermore, we found that NEU3 treatment of cells increased surface expression levels of LFA-1. We observed that NEU3-treated cells had suppressed LFA-1 adhesion to an ICAM-1 coated surface using an in vitro static adhesion assay. These results establish that NEU3 can modulate glycoconjugate composition and contribute to the regulation of integrin activity. We propose that NEU3 should be investigated to determine its role on LFA-1 within the inflammatory cascade.

The Janus-like role of neuraminidase isoenzymes in inflammation

“…(Wright & Cooper, 2014) Our previous work has suggested that NEU3 mediates desialylation of gangliosides and glycoproteins which may inhibit cis-interactions with β1 integrins (α4β1 and α5β1; also known as VLA4 and VLA5, respectively). (Howlader et al, 2019;Jia et al, 2016) Here, we confirmed that BMDM from Neu3 KO animals had increased in vitro chemotaxis through a FN-coated membrane, consistent with this isoenzyme acting as a negative regulator of cell migration in response to a chemoattractant (MCP-1/CCL2). In contrast, Neu1 KO animals showed reduced migration in vitro.…”

“…Activation epitopes of β2 integrins were reported to be unmasked by endogenous NEU activity, (Feng et al, 2011;Quinn et al, 2001) and NEU3 has been shown to alter LFA-1/ICAM-1 interactions. (Howlader et al, 2019) NEU enzymes can increase adhesion of polymorphonuclear leukocytes (PMN) to endothelium and also increase their migration through the endothelium to the site of inflammation. (Cross et al, 2003;Sakarya et al, 2004) NEU enzymes may unmask epitopes in β1 integrins VLA4 (CD49d/CD29) and VLA5 (CD49e/CD29), which are expressed on activated leukocytes and bind with VCAM-1 and fibronectin (FN).…”

The Mammalian Membrane Microenvironment Regulates the Sequential Attachment of Bacteria to Host Cells

“…We cultured HeLa GFP cells with a deglycosylating mix of enzymes, thereby promoting its degradation ( Fig. 4A ) ( 34 , 35 ). We confirmed specific enzymatic activity in mammalian medium by digesting fetuin, an N- and O-glycosylated control protein ( Fig.…”

The membrane microenvironment regulates the sequential attachment of bacteria to host cells

“…We cultured HeLa cells with a deglycosylating mix of enzymes, thereby promoting its degradation (Fig. 4A) 30,31 . We confirmed specific enzymatic activity in mammalian medium by digesting fetuin, a N- and O-glycosylated control protein (Fig.…”