Antioxidants, vitamin C and dithiothreitol, activate membrane-bound guanylate cyclase in PC12 cells

Abstract

Antioxidants and antioxidant enzymes are known to protect against cell death induced by reactive oxygen species. However, apart from directly quenching free radicals, little is known about the effect of antioxidants on hormone-activated second messenger systems. We previously found that antioxidants such as 17-beta estradiol and resveratrol activate membrane-bound guanylate cyclase GC-A, the receptor for atrial natriuretic factor (ANF), in PC12 cells. It is possible that other antioxidants may also activate membrane-bound guanylate cyclase GC-A. The aim of this study was to determine if dithiothreitol (DTT), vitamin C, and vitamin E activate membrane-bound guanylate cyclase GC-A in PC12 cells. The results showed that both DTT and vitamin C increased cGMP levels in PC12 cells, whereas vitamin E had no effect. DTT and vitamin C inhibited membrane-bound guanylate cyclase activity stimulated by ANF in PC12 cells. In contrast, DTT and vitamin C had no effect on soluble guanylate cyclase activity stimulated by substance P. Furthermore, NO synthase inhibitors L-NAME and aminoguanidine did not affect DTT- and vitamin C-stimulated guanylate cyclase activity. The results indicate that DTT and vitamin C, but not vitamin E, activate membrane-bound guanylate cyclase GC-A in PC12 cells.

Resveratrol: Preventing properties against vascular alterations and ageing

“…Resveratrol activates membrane-bound guanylate cyclase GC-A, the receptor for atrial natriuretic factor (ANF) [95]. At molecular level, the cGMP/kinase-G is an antiproliferative signaling in SMCs and it dilates blood vessels through the reduction of intracellular calcium.…”

Protective Effect of Chronic Vitamin C Treatment on Endothelial Function of Apolipoprotein E-Deficient Mouse Carotid Artery

“…However, it was surprising that vitamin C reduced relaxations to acetylcholine and DEA-NONOate in C57BL/6J mice. Measurements of cGMP levels in arterial wall indicated that vitamin C significantly increased concentration of nitric oxide second messenger (Chen et al, 2001). This effect was selective for cGMP because cAMP levels were not affected.…”

Quercetin, a phytoestrogen and dietary flavonoid, activates different membrane-bound guanylate cyclase isoforms in LLC-PK1 and PC12 cells

“…The cell extracts were scraped and centrifuged for 15 min at 2000 g, and the supernatant fractions were extracted with water-saturated ether to remove trichloroacetic acid. The cGMP levels in the supernatants were determined by radioimmunoassay (Chang & Song 1993;Chen et al 1998Chen et al , 2000Chen et al , 2001a.…”

“…Reactions were initiated by the addition of LLC-PK1 cell membranes, incubated for 10 min and terminated by the addition of 0.5 mL 50 mM chilled sodium acetate, pH 4.0. Generated cGMP was quantified by the radioimmunoassay as previously described (Chang & Song 1993;Chen et al 1998Chen et al , 2000Chen et al , 2001a.…”

“…Membrane-bound guanylate cyclase GC-A and GC-B are activated by ANF and CNP, respectively (for review, see Wedel & Garbers 2001). Recently, we have found that antioxidants such as 17 -estradiol, resveratrol (a phytoestrogen), dithiothreitol and vitamin C activate GC-A in PC12 cells (Chen et al 1998(Chen et al , 2000(Chen et al , 2001a. Since quercetin is a potent antioxidant (Soleas et al 1997, Wiseman 1999, Jovanovic & Simic 2000, Lamson & Brignall 2000, and expresses oestrogen-like (Piantelli et al 1995;Caltagirone et al 1997) or anti-oestrogen properties (Miodini et al 1999), we examined whether quercetin affects the activation of GC-A or GC-B.…”