Molecular Pathogenesis Of Cell Death In Neurodegenerativ

Neurological Disorders And Stroke

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Abstract

The goal of this project is to elucidate the molecular mechanisms by which nerve cells degenerate in Parkinson's disease and related neurodegenerative disorders, identify transcription control mechanisms that contribute to the pathogenesis of these diseases, and develop improved therapies. Parkinson's disease (PD) is characterized by progressive loss of dopaminergic neurons in the substantia nigra. A leading hypothesis of the neurodegeneration in Parkinson and other related disorders is protein misfolding and aggregation. Alpha-synuclein is mutated in few families with dominantly inherited PD and is a major fibrillar component of Lewy bodies. We found that this neuronal protein is a substrate for the cross-linking activity of transglutaminase-2. This process can be prevented but not reversed by the transglutamianse inhibitor cystamine. Further, we demonstrated that the Lewy bodies in the brains of patients with Parkinson and with dementia with Lewy bodies have isodipeptide cross-linked alpha-synuclein. These findings provide a potential therapeutic lead for synucleinopathies. We also found that alpha-synuclein overexpression is associated with abarrent activation of cell cycle proteins including cyclin B. The latter was also present in the Lewy bodies on postmortem examination. We found that these changes occur through activation of the ERK pathway and propose that this contributes to apoptosis due to over-expression of alpha-synuclein. Towards our goal to develop novel therapeutic strategies for central nervous system disorders, we previously found that the bone marrow contains cellular elements capable of seeding the brain and homing preferentially into injured tissue. We also demonstrated that these cells can be exploited as vehicles to deliver the gene encoding for the neurotrophic factor Glial Cell Line Derived Neurotrophic Factor (GDNF) and can protect mice against the dopaminergic neurotoxin MPTP. We now confirmed the ability of bone marrow cells to deliver additional gene products of therapeutic value in brain diseases, namely BDNF and interferon-beta. Further refinements in this technology are underway. A second approach to deliver a therapeutic gene that we have tested is the delviery of the use of polymer encapsulated cells engineered with GDNF and translanted in the putement of MPTP lesioned non-human primates. This approach proved to be indequate due to intense inflammatory response to the implants and consequent poor transgene delivery.