Nicotine Modulation of Caspases in Non-Neuronal Cells

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DESCRIPTION (provided by applicant): While nicotine effects on the central nervous system (CNS) are believed to underlie the molecular mechanisms that ultimately lead to addiction, in terms of effects on peripheral systems, nicotine has long been considered to be one of the less dangerous components of tobacco. Herein we propose to re-examine this issue by determining the effects of nicotine on caspase activation in peripheral cells. We have recently found (Meyer, Gahring and Rogers, JBC, 2002, in press) that pre-conditioning cells with nicotine, as occurs in chronic abusers of tobacco products, alters caspase8 or caspase8-1ike protease activation. This suggests the possibility that this basic mechanism underlies how nicotine modulates immune and inflammatory responses working through its 'neuronal' nicotinic acetylcholine receptors (nAChR) that are expressed by peripheral cells including lung epithelia, keratinocytes and lymphocytes. The hypothesis proposed is: Nicotine preconditioning of cells that express nAChRs, as occurs in a chronic smoker, alters signaling by the pro-inflammatory and pro-apoptotic cytokine, TNFalpha, through disrupting caspase8 activation. Three Specific Aims will address this hypothesis: SPECIFIC AIM 1. Does the expression of a specific combinations of nAChR subtypes by cell lines of peripheral cell origin impart nicotine regulation of cytokine-induced caspase activity? SPECIFIC AIM 2. Does nicotine pre-conditioning delay TNFalpha-mediated Caspase8 activation in peripheral cells? We will determine whether nicotine pre-conditioning of peripheral cells alters the expression/assembly of TNFR1 or auxiliary proteins important for pro-caspase8 aggregation and activation. SPECIFIC AIM 3. Does nicotine pre-conditioning alter cell cycle progression or impede entry into cytokine-signaled apoptosis? The implications of these studies will be to define a testable model with regard to the cellular and molecular mechanisms through which nicotine exerts its pleiotropic systemic effects on cell susceptibility to death in the milieu of an inflammatory environment.