ERK inhibition aids IFN-β promoter activation during EV71 infection by blocking CRYAB degradation in SH-SY5Y cells

Enterovirus 71 (EV71) can cause severe hand-foot-and-mouth disease with neurological complications. It has evolved multiple mechanisms to compromise the host type I interferon (IFN-I) response. In neuronal cells, EV71-mediated IFN-I antagonism may be associated with neural precursor cell-expressed developmentally downregulated 4-like (Nedd4L), the E3 ubiquitin ligase that can interact with alphaB-crystallin (CRYAB) in the regulation of Nav1.5 stability. Here, we investigated the effect of CRYAB stability on IFN-β promoter activity in neuronal SH-SY5Y cells infected with EV71, and its relations to Nedd4 L and extracellular signal-regulated kinases (ERK). Results showed that EV71 infection significantly caused CRYAB degradation via the Nedd4L-proteasome pathway, which required ERK-mediated phosphorylation of Serine 45 in CRYAB. Subsequently, it was observed that siRNA- or EV71-mediated CRYAB reduction limited Poly(dAT)-activated IFN-β promoter, and CRYAB stabilisation by U0126-mediated inhibition of ERK activation remarkably enhanced the activity of IFN-β promoter upon EV71 challenge. Collectively, we elucidate a novel mechanism by which ERK activation contributes to EV71 immune escape via CRYAB/IFN-β axis in SH-SY5Y cells, indicating that perturbing ERK activation is desirable for anti-EV71 therapy.