While the etiology of Parkinsons disease (PD) remains elusive, perturbations in astrocyte function and induction of constitutively expressed neuronal nitric oxide synthase (NOS1) has emerged as a key components of both human PD and the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyradine model of the disease in rodents. Preliminary data generated by our laboratory have demonstrated selective induction of NOS1 in primary astrocytes exposed to a treatment paradigm designed to simulate early stage inflammatry insult, such as that which may occur in PD. Furthermore, our data have demonstrated suppression of this event through modulation of the orphan receptor peroxisome proliferator-activated receptor-gamma (PPAR- gamma) using a novel high-affinity diindolylmethane (DIM) analogue. It is the objective of this research to characterize the molecular mechanisms by which NOS1 is selectively induced in astrocytes and suppressed through modulation of this receptor. Because PD is currently incurable, it is anticipated that this research will reveal novel targets for more effectively treating PD. The research proposed here entails treating isolated astrocytes with low (e.g. suboptimal) concentrations of both MPTP and the inflammatory cytokines TNF-alpha and IFN-gamma, which has been shown to selectively induce NOS1.
The specific aims proposed by this application have been designed to test the hypothesis that modulation of NOS1 expression in astrocytes by PPAR-gamma occurs through suppression of NF-kB activity by influencing critical protein- protein interactions at the NOS1 promoter, and are based on additional preliminary data generated by our laboratory. Briefly, it is postulated that putative NF-kappa B elements found in the 5' untranslated region flanking exon 1 is involved in the induction of NOS1 by this stimulus. It is also postulated that suppression of NOS1 occurs in the same region due to SUMOylation, translocation to, and stabilization of a nuclear corepressor complex by PPAR-gamma. Interactions between these proteins will be measured through co- immunoprecipitation, while interaction with the promoter of exon 1 will be measured through chromatin immunoprecipitation. Finally, siRNA knockdown experiments are proposed to test the role for NCoR in the observed suppression by the high-affinity PPAR-gamma ligand. Parkinsons disease is a severely debilitating movement disorder, and is currently incurable. However, recent advances in understanding the etiology of this disorder have revealed a critical progressive role for the enzyme neuronal nitric oxie synthase. It is anticipated that the this work here will benefit public health by revealing therapeutic targets which can be explioted to more effectively treat this devastating disease. ? ?
| Carbone, David L; Popichak, Katriana A; Moreno, Julie A et al. (2009) Suppression of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced nitric-oxide synthase 2 expression in astrocytes by a novel diindolylmethane analog protects striatal neurons against apoptosis. Mol Pharmacol 75:35-43 |
