Carbon Monoxide Produced by Heme Oxygenase-1 in Response to Nitrosative Stress Induces Expression of Glutamate-Cysteine Ligase in PC12 Cells via Activation of Phosphatidylinositol 3-Kinase and Nrf2 Signaling

Abstract

Induction of heme oxygenase-1 (HO-1) expression has been associated with adaptive cytoprotection against a wide array of toxic insults, but the underlying molecular mechanisms remain largely unresolved. In this study, we investigated the potential role of carbon monoxide (CO), one of the by-products of the HO-1 reaction, in the adaptive survival response to peroxynitrite-induced PC12 cell death. Upon treatment of rat pheochromocytoma (PC12) cells with the peroxynitrite generator 3-morpholinosydnonimine hydrochloride (SIN-1), the cellular GSH level decreased initially, but was gradually restored to the basal level. This was accompanied by increased expression of the catalytic subunit of glutamate-cysteine ligase (GCLC), the rate-limiting enzyme in GSH biosynthesis. The SIN-1-induced GCLC up-regulation was preceded by induction of HO-1 and subsequent CO production. Inhibition of HO activity by zinc protoporphyrin IX or knockdown of HO-1 gene expression by small interfering RNA abrogated the up-regulation of GCLC expression and the subsequent GSH restoration induced by SIN-1. In contrast, additional exposure to the CO-releasing molecule (CO-RM) restored the GSH level previously reduced by inhibition of CO production using zinc protoporphyrin IX. Furthermore, CO-RM treatment up-regulated GCLC expression through activation of Nrf2. The CO-RM-induced activation of Nrf2 was under the control of the phosphatidylinositol 3-kinase/Akt signaling pathway. In conclusion, CO produced by HO-1 rescues PC12 cells from nitrosative stress through induction of GCLC, which is mediated by activation of phosphatidylinositol 3-kinase/Akt and subsequently Nrf2 signaling. Heme oxygenase (HO)2 is the rate-limiting enzyme involved in the oxidative degradation of free heme and produces biliverdin/bilirubin, free iron, and carbon monoxide (CO) (1). Of the two known isoforms of HO (i.e. HO-1 and HO-2), the expression of only HO-1 is induced in response to external stresses. Formerly known as the stress response protein HSP32 in rats, HO-1 confers cytoprotection against oxidative and inflammatory injuries caused by a wide array of noxious or pathogenic insults (2-4). In a previous study, we observed that up-regulation of HO-1 prevents the rat pheochromocytoma (PC12) cells from apoptotic death caused by peroxynitrite (5). CO produced by elevated HO activity has been found to be responsible, at least in part, for the anti-apoptotic function of up-regulated HO-1 (6 -8). However, the underlying mechanisms by which CO exerts the cytoprotective effects against peroxynitrite-induced cell death remain largely unresolved.CO is reported to increase the production of cGMP and to exert vasodilatory and anti-apoptotic effects (9). Liu et al. (7) reported that the anti-apoptotic function of CO is partially dependent on the activation of soluble guanylate cyclase in vascular smooth muscle cells. Furthermore, a recent study has revealed that the anti-apoptotic effect of CO is associated with activation of p38 mitogen-activated protein kinase (MAPK) (10). In t...

Gliopreventive effects of guanosine against glucose deprivation in vitro

“…This protein acts as a scavenger of NO and has been associated with adaptive cytoprotection against a wide array of toxic insults by modulating antioxidant defenses, such as GSH system and thioredoxin [92,93]. Resveratrol is another antioxidant that modulates glial functions [43] and induces HO1 expression, thereby, under experimental conditions, protecting against stroke, which is a condition associated with glucose deprivation [94].…”

Нозоспецифічні Особливості Редокс-Процесів При Бронхіальній Астмі Та Хронічній Обструктивній Хворобі Легень

“…По сравнению с контролируемой БА более тяже-лые ее формы сопровождаются значительным по-вышением уровня концентрации NO 3 -и нитротиро-зинов в выдыхаемом воздухе. Уже через несколько минут после индукции аллергеном у больных БА наблюдаются достоверное повышение концентра-ции NO 3 -и тенденциозное снижение концентрации NO…”

“…Уже через несколько минут после индукции аллергеном у больных БА наблюдаются достоверное повышение концентра-ции NO 3 -и тенденциозное снижение концентрации NO…”

“…, обусловливающей появление пероксинитрита, который в последующем распадается с образовани-ем NO 3 -или участвует в формировании нитротиро-зинов. Содержание нитротирозинов у больных с тя-желой формой БА на порядок выше, чем у здоровых людей (рис.…”

“…Основным источником GSH в организме че-ловека является печень, а оксидантный стресс при заболеваниях органов дыхания сопряжен с повыше-нием активности γ-глутамилтрансферазы (gammaglutamyltransferase -GGT) в гепатоцитах [32]. Так-же одним из важнейших компонентом системы, регулирующей уровень концентрации GSH, являет-ся окись углерода (СО), которая индуцирует актив-ность глутаматцистеинлигазы (glutamate-cysteine ligase -GCL) [3]. Снижение уровня концентрации GSH способствует продукции провоспалительных цитокинов.…”