Excess phosphate promotes SARS‑CoV‑2 N protein‑induced NLRP3 inflammasome activation via the SCAP‑SREBP2 signaling pathway

Abstract

Hyperphosphatemia or severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) infection can promote cardiovascular adverse events in patients with chronic kidney disease. Hyperphosphatemia is associated with elevated inflammation and sterol regulatory element binding protein 2 (SREBP2) activation, but the underlying mechanisms in SARS‑CoV‑2 that are related to cardiovascular disease remain unclear. The present study aimed to elucidate the role of excess inorganic phosphate (PI) in SARS‑CoV‑2 N protein‑induced NLRP3 inflammasome activation and the underlying mechanisms in vascular smooth muscle cells (VSMCs). The expression levels of SARS‑CoV‑2 N protein, SREBP cleavage‑activating protein (SCAP), mature N‑terminal SREBP2, NLRP3, procaspase‑1, cleaved caspase‑1, IL‑1β and IL‑18 were examined by western blotting. The expression levels of SREBP2, HMG‑CoA reductase, HMGCS1, low density lipo‑ protein receptor, proprotein convertase subtilisin/kexin type 9 (PCSK9), SREBP1c, fatty acid synthase, stearyl coenzyme A desaturase 1, acetyl‑CoA carboxylase α and ATP‑citrate lyase were determined by reverse transcription‑quantitative PCR. The translocation of SCAP or NLRP3 from the endoplasmic reticulum to the Golgi was detected by confocal microscopy. The results showed that excess PI promoted SCAP‑SREBP.