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[Preprint]. 2023 Aug 22:2023.08.21.554214. [Version 2] doi: 10.1101/2023.08.21.554214

Figure 1. Microglia upregulate and NEU3 and active Neu3 is necessary for secreted sialidase activity.

Figure 1.

(A, B) Primary mouse hippocampal neurons were treated with conditioned media from resting or LPS-activated BV-2 microglia in the presence or absence of zanamivir. Representative scheme and images (A) and quantification of fluorescence (B) reveal that LPS-activation causes 3-fold increase in PNA signal compared to resting (+LPS vs. -LPS, p=0.045), an effect abrogated by pharmacological sialidase inhibition (-LPS vs. +LPS +zan, p=0.90; +LPS vs. +LPS +zan, p=0.042). Hypothesis testing performed with hierarchical permutation test, n=3 coverslips/condition, avg. 20 neurons/condition. (C) Quantification of transcript levels of NEU1, NEU3, and NEU4 by qPCR in resting and LPS-activated BV-2 microglia (NEU1, p=0.11; NEU3, p=0.041; NEU4, p=0.90). (D) Neurons were treated with conditioned media from wild-type (WT) or NEU3 knockout (NEU3 KO) BV-2 microglia, with or without deoxy-2,3-anhydroneuraminic acid (DANA), and stained with peanut agglutinin (PNA). Media from activated WT microglia produced a 3-fold increase in desialylation compared to resting (-LPS vs. +LPS, p=0.043; +LPS vs. +LPS+zan, p=0.042) but media from NEU3 KO microglia exhibited no significant change in desialylation in response to LPS or zanamivir (-LPS vs. +LPS, p=0.74; +LPS vs. +LPS+zan, p=0.12). n=3 coverslips/condition, 60 total WT cells, 48 total NEU3 KO cells. Hypothesis tests performed with hierarchical permutation test.