Expression analysis of genes of ubiquitin-proteasome protein degradation system in MPTP-induced mice models of early stages of Parkinson's disease.

Parkinson's disease (PD) is the second most common severe neurodegenerative disorder that is characterized by progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc) region of the brain. However, causes and mechanisms of the development of this disorder are still not fully understood. At the same time, it is well known that dysfunction of the ubiquitin-proteasome protein degradation system (UPPDS) is one of the major mechanisms of the pathogenesis of PD. In this study we have investigated alterations in expression of Uchl3, Ubr7, Ube3c, Usp19, Usp39, Ube2k, Ube2d3, Ube2m, Ube2g1 genes, which are directly involved in the functioning of the UPPDS, using the real-time PCR in mice with the MPTP-induced pre-symptomatic and early symptomatic stages of PD. We have revealed reduction of expression of all genes studied in the striatum of brain in mice with the MPTP-induced pre-symptomatic and early symptomatic stages of PD and the majority of genes in the substantia nigra: Uchl3, Ubr7, Ube3c, Usp39, Ube2k, Ube2d3, Ube2g1 at pre-symptomatic stage and Uchl3, Ube3c, Usp39, Ube2k, Ube2m at early symptomatic stage of PD. Decreasing transcript levels of the genes studied may indicate decrease in the efficiency of the UPPDS on the whole which in turn may lead to the accumulation of abnormal proteins and toxic protein aggregates and subsequent death of the neurons. Thus, our findings appear to indicate that a violation of this system can play an important role in the development of pathogenic processes that occur at the earliest stages of the disease.