Meccanismi molecolari e aspetti comportamentali in modelli sperimentali di malattia di Parkinson

An increased activity of several classes of Ca2+ channels including L-type voltage-dependent and cyclic nucleotide- sensitive channels plays a key role in the pathogenesis of Parkinson's disease (PD), leading to an alteration of intracellular Ca2+ homeostasis. In addition, a dysregulation of Ca2+ ions in intracellular stores has been considered an important feature of neuronal degeneration in substantia nigra pars compacta. In this scenario, the Na+-Ca2+ exchanger (NCX), the major regulator of Ca2+ and Na+ influx and/or efflux, could assume a relevant role since it is involved in the maintainance of the intracellular homeostasis of the two cations. Interestingly, in the substantia nigra pars compacta, a brain region more affected in PD, a grater level of NCX1 expression has been detected in our laboratory. As in the brain NCX subfamily is composed of the three gene products NCX1, NCX2 and NCX3, by means of multidisciplinary approaches, from mice genetic and in situ hybridization to video-imaging and electrophysiology, our aims will be: (1) to study the distribution and the expression of each of the three NCX isoforms in substantia nigra pars compacta and striatum of mice transgenic for alpha-sinuclein and in wild type animals exposed to the neurotoxins mimicking PD including MPTP, rotenone, L-BMAA and 6-OHdopamina; (2) to study the progression of the neurodegenerative process of neurons involved in PD in mice overexpressing or lacking (KO) each NCX isoform exposed to the above mentioned neurotoxins; (3) to characterize the functional role played by each of the three NCX isoforms in the regulation of Ca2+ homeostasis in mesencephalic neurons and organotipic slices exposed to the neurotoxins, or dissected from animals transgenic for alpha-sinuclein; (4) to correlate the activity of the NCX isoforms with Ca2+ store dysregulation in cellular models of PD by means of the siRNA raised against NCX1, NCX2 or NCX3. This project will allow to dissect the role played by the three NCX proteins in the pathogenesis of Parkinson's disease in order to identify new potential molecular targets for the development of drugs useful in PD treatment.