Cells were pretreated for 1 h with -secretase inhibitors (2.5 M DAPT) and then exposed to 25 M Cd for 6 h. inhibitor also inhibited the CSE and Cd-mediated increase in the expression of COX-2. Furthermore, recombinant overexpression of Notch1 intracellular domain name resulted in an increase in the expression TAK-063 of COX-2. Notch signaling induced by CSE and Cd induced apoptosis in C6 cells. Our results demonstrate that CSE exposure activated the p38 MAPK and CREB-mediated induction in COX-2 expression in astrocytes via -secretase-mediated Notch1 signaling. Our data provides novel insights into the potential mechanism of pro-inflammatory response activated by exposure to cigarette smoke. Introduction Cigarette smoke is usually reportedly a major risk factor for stroke and vascular diseases [1]. Several environmental pollutants including heavy metals are associated with neurological disorders, such as ischemic stroke and learning disabilities in children [2C4]. Cadmium (Cd), a potent mediator of oxidative stress and inflammation, is an environmental pollutant present in cigarettes and contaminated food. Cd is also one of major components of air flow particulate matters that associated with acute changes in cardiovascular or respiratory physiology [5]. A few studies report a significant correlation between the increased risk for stroke and Cd or cigarette smoke extract (CSE) exposure [6, 7]. Brain ischemia triggers an inflammatory reaction that contributes to the TAK-063 progression of brain diseases [8]. Astrocytes, a major type of glial cells in the TAK-063 brain, play an important role in stroke and are involved in the regulation of the brain microenvironment and maintenance of the blood-brain barrier [9]. Astrocytes also regulate the cerebral blood flow (CBF) [10]. Production of inflammatory cytokines and harmful mediators by astrocytes has been reported to be associated with stroke pathology [11]. Cyclooxygenase-2 (COX-2), an enzyme mediating the progression of inflammation, plays a critical role in the progression of cerebral ischemic damage. Increased COX-2 expression is usually observed in rodents and patients with ischemic stroke [12]. Substantial evidence supports the potential effect of cigarette smoke on COX-2 and its downstream metabolites such as prostaglandin E2 (PGE2) [13] and COX-2 knock-out mice are guarded against brain ischemia [14]. Cyclic AMP response element-binding protein (CREB) and activating transcription factor 1 (ATF1) are the major proteins that regulate COX-2 expression [15] and cigarette smoke, in turn, reportedly induces CREB phosphorylation [16]. Since Cd induces COX-2 upregulation via -secretase [17], it can be speculated that CREB phosphorylation is usually involved in -secretase-mediated COX-2 upregulation induced by Cd. Presenilin (PS), also called -secretase, is recognized as one of the causes for Alzheimers diseases. -secretase is usually a multi-protein complex composed of four proteins, presenilin 1 (PS1) and 2 (PS2), nicastrin, APH-1 (anterior pharynx-defective 1), and PEN-2 (presenilin enhancer 2) [18]. Several proteins, such as amyloid precursor protein (APP), Notch-1, and N-cadherin are substrates for -secretase-dependent protein processing [19, 20]. Notch1 is usually abundantly expressed in neurons and astrocytes and is involved in the mitogen-activated protein kinase (MAPK) signaling cascades to modulate inflammation [21]. Although Notch1 has been shown to worsen stroke end result through glial cell-mediated inflammatory responses, the molecular mechanisms of -secretase dependent association of Notch1 processing with hazardous outcomes of cigarette smoke exposure remain elusive. TAK-063 Here, we investigated the transmission transduction pathways by which Cd or cigarette smoke induce COX-2 expression and apoptosis. Since the COX-2 promoter contains a cyclic AMP response element (CRE), we wondered if p38 MAPK/CREB signaling cascades play a role in mediating the induction of COX-2 via -secretase. We show that Cd or cigarette smoke exposure to C6 astrocytes is usually accompanied by -secretase-mediated Notch1 intracellular domain name (NICD) production and activation of p38 MAPK signaling and its downstream target CREB, thereby inducing the expression of COX-2. Notch1 signaling induced by cigarette smoke and Cd induces EGF apoptosis in C6 astrocytes. Together, our data suggest that COX-2 overexpression induced by Cd or cigarette smoke in astrocytes entails the activation of.