TSENG-NING TSAI2026-10-162026-10-162005-12-01Pure ID: 15020645Pure UUID: e0540852-f40d-444e-83c5-e3853a94de6e10.1016/j.biocel.2005.07.002https://www.scopus.com/pages/publications/25844494985https://scholars.csmu.edu.tw/handle/123456789/24433This study explored the effects of inhibition of endoplasmic reticulum (ER) Ca2+-ATPase on lipopolysaccharide (LPS)-induced protein kinase C (PKC) activation, nuclear factor-κB (NF-κB) translocation, inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) production in RAW 264.7 macrophages. Thapsigargin (TG) irreversibly inhibits ER Ca 2+-ATPase and LPS-induced NO production is reduced even after washout. TG also attenuated LPS-stimulated iNOS expression by using immunoblot analysis. However, another distinct fully reversible ER Ca2+-ATPase inhibitor, 2,5-di-tert-butylhydroquinone (DBHQ), ionophore A23187 and ionomycin could exert a similar effect to TG in increasing intracellular calcium concentration; however, these agents could not mimic TG in reducing iNOS expression and NO production. LPS increased PKC-α and -β activation, and TG pretreatment attenuated LPS-stimulated PKC activation. Not did pretreatment with DBHQ, A23187 and ionomycin reduce LPS-stimulated PKC activation. Furthermore, NF-κB-specific DNA-protein-binding activity in the nuclear extracts was enhanced by treatment with LPS, and TG pretreatment attenuated LPS-stimulated NF-κB activation. None of DBHQ, A23187 and ionomycin pretreatment reduced LPS-stimulated NF-κB activation. These data suggest that persistent inhibition of ER Ca2+-ATPase by TG would influence calcium release from ER Ca2+ pools that was stimulated by the LPS activated signal processes, and might be the main mechanism for attenuating PKC and NF-κB activation that induces iNOS expression and NO production.12enjournal article