טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentMaoz Eyla-Hagar
SubjectTargeting Glutamatergic Excitotoxic Damage and Mitochondria
by the Novel Multi-Target Neurorestorative Drug
HLA20
DepartmentDepartment of Medicine
Supervisors Professor Emeritus Moussa Youdim
Dr. Silvia Mandel
Full Thesis textFull thesis text - English Version


Abstract

The concept of chelation therapy as a valuable approach in neurological disorders lead our group to develop multi-target, non-toxic, brain permeable, neurorescue compounds with iron chelation and anti-apoptotic properties as a multifunctional therapeutic approach to neurodegenerative diseases (NDDs), such as Parkinson's disease (PD), Alzheimer's diseases (AD), and amyotrophic lateral sclerosis (ALS). HLA20 was identified as potential lead candidate for further studies.

Working hypothesis: The research premise underlying this study considers that the neurorestorative capacity of HLA20 will optimally target a number of the pathologies involved in hippocampal and cortical glutamatergic excitotoxicity- induced neurodegeneration. To test this assumption neuron-rich primary rat embryonic hippocampal and cortical cultures were employed as a research platform to determine the therapeutic efficacy of HLA20 against glutamatergic excitotoxicity induced by kainic acid (KA) and glutamate. This system comprises a heterogeneous population of cells (mainly neuronal) at different stages of differentiation, and as such, is better suited to estimate the potential of HLA20 to induce differentiation.

Results: This research work has clearly established a neuroprotective potential of HLA20 to counteract glutamatergic-mediated excitotoxicity in neuron-rich primary cultures from embryonic hippocampal and cortical tissues. The high effectiveness of HLA20 is reflected by the low, subnanomolar and nanomolar concentration profile at which maximal protection was achieved, predicting a high safety profile of the drug. Another major finding of this study is the differentiative action of HLA20 in both neuronal cultures, which may also contribute to the neuroprotective effect of the compound.

The  neuroprotective/differentiative actions are attributable, at least partly, to the following: (a) a capacity of HLA20 to induce differentiation, as evidenced by the percentage of newly generated post-mitotic neurons and the increase in the content of GAP-43 and neurotrophins; (b) downregulation of common apoptotic markers and inactivation of an apoptotic novel pathway involving the nuclear translocation of glyceraldehyde-3-phospate dehydrogenase and consequent elevation of monoamine oxidase-B gene transcription; (c) modulation of the iron-regulated transcription factor hypoxia-inducible factor 1 alpha and its target genes; and (d) activation of the, neuroprotectivedeacetylase, Sirtuin 1 and increased nuclear content of its downstream effector, the mitochondrial biogenesis-related peroxisome proliferator-activated receptor gamma coactivator 1-alpha.

Conclusion: Given that glutamate excitotoxicity, oxidative stress, and mitochondrial impairment have been implicated in the progression of many NDDs, such as PD, AD and ALS, the multi-target activities of HLA20 and its potent efficiency at low concentrations, may be of benefit towards some of the multiple pathologies associated with these disorders.