Ciencia Puerto Rico

Proyect 1: Studies of congenital myasthenic syndrome (CMS) revealed mutations in acetylcholine receptor (AChR) subunit genes. These alterations either reduce expression or alter the receptor kinetic profile to decrease or increase the response to acetylcholine (ACh). Mutations that increase response to ACh and prolong activation are known to cause slow channel CMS (SCCMS). Those mutations that underlie SCCMS have been identified in different acetylcholine receptor (AChR) subunits, and in different domains of the subunits, provoking AChR channelopaties, at neuromuscular junction level. Furthermore, neuromuscular transmission is compromised because of cationic overloading after ACh binding. SCCMS is characterized by weakness and fatigability of the voluntary muscles as a result of this impaired neuromuscular transmission. Using wildtype models, several reports have demonstrated that alcohol interacts with nicotinic AChR (nAChR) (Murrell et al., 1991; Sterz et al., 1981), and produce alterations at neuromuscular junction in rats (Wali and Hayter, 1988), and frog preparations (Bradley et al., 1980). Moreover, in vitro studies demonstrated that chronic exposure to ethanol affects mRNA levels of nicotinic nAChR subunits expressed in M10 and SH-SY5Y cell lines in a receptor-dependent composition manner (Gorbounova et al., 1998). Also, recombinant human neuronal nicotinic receptors expressed in oocytes suggest that the ethanol effect depends on the receptor subunit composition (Cardoso et al., 1999). Although ethanol modulation of the nicotinic receptor at the neuromuscular junction is well documented, the very limited reports concerning the direct action of ethanol on CMS still unknown. Anecdotic evidence suggests that there is increased alcohol consumption in CMS patients. The presence of slow channels mutations related to CMS in these patients led us to question the possible effect of the mutations on the receptor in response to alcohol. Using transgenic mice models of SCCMS, electrophysiological, molecular and confocal microscopy approaches, we are investigating the role of alcohol in aV249F, a mutation that cause SCCMS. The long term goal of this project is to determine the effects of alcohol in a dissimilar panel of SCCMS, both in vivo and in vitro. The overall results from this study will provide a new insight in understanding the role of alcohol in CMS pathogenesis progression and the tools to develop prevention strategies.