Hydrogen peroxide down-regulates inositol 1,4,5-trisphosphate receptor content through proteasome activation

• Published in: Free radical biology & medicine 2009-11, Vol.47 (10), p.1362-1370
• Main Authors: Martín-Garrido, A., Boyano-Adánez, M.C., Alique, M., Calleros, L., Serrano, I., Griera, M., Rodríguez-Puyol, D., Griendling, K.K., Rodríguez-Puyol, M.
• Format: Article
• Language: English
• Subjects: Angiotensin II; Angiotensin II - pharmacology; Animals; Cells, Cultured; Down-Regulation - drug effects; Enzyme Activation - drug effects; Free radicals; Hydrogen peroxide; Hydrogen Peroxide - pharmacology; Inositol 1,4,5-trisphosphate receptor; Inositol 1,4,5-Trisphosphate Receptors - biosynthesis; Inositol 1,4,5-Trisphosphate Receptors - genetics; Muscle, Smooth, Vascular - cytology; Muscle, Smooth, Vascular - metabolism; Proteasome Endopeptidase Complex - metabolism; Rats; Rats, Wistar; Reactive oxygen species; Reactive Oxygen Species - metabolism; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; RNA, Messenger - metabolism; Vascular smooth muscle cells
• ISSN: 0891-5849; 1873-4596
• DOI: 10.1016/j.freeradbiomed.2009.07.006

Hydrogen peroxide (H 2O 2) is implicated in the regulation of signaling pathways leading to changes in vascular smooth muscle function. Contractile effects produced by H 2O 2 are due to the phosphorylation of myosin light chain kinase triggered by increases in intracellular calcium (Ca 2+) from intracellular stores or influx of extracellular Ca 2+. One mechanism for mobilizing such stores involves the phosphoinositide pathway. Inositol 1,4,5-trisphosphate (IP 3) mobilizes intracellular Ca 2+ by binding to a family of receptors (IP 3Rs) on the endoplasmic–sarcoplasmic reticulum that act as ligand-gated Ca 2+ channels. IP 3Rs can be rapidly ubiquitinated and degraded by the proteasome, causing a decrease in cellular IP 3R content. In this study we show that IP 3R 1 and IP 3R 3 are down-regulated when vascular smooth muscle cells (VSMC) are stimulated by H 2O 2, through an increase in proteasome activity. Moreover, we demonstrate that the decrease in IP 3R by H 2O 2 is accompanied by a reduction in calcium efflux induced by IP 3 in VSMC. Also, we observed that angiotensin II (ANGII) induces a decrease in IP 3R by activation of NADPH oxidase and that preincubation with H 2O 2 decreases ANGII-mediated calcium efflux and planar cell surface area in VSMC. The decreased IP 3 receptor content observed in cells was also found in aortic rings, which exhibited a decreased ANGII-dependent contraction after treatment with H 2O 2. Altogether, these results suggest that H 2O 2 mediates IP 3R down-regulation via proteasome activity.