Neuroprotection and neuronal differentiation studies using substantia nigra dopaminergic cells derived from transgenic mouse embryos

The major pathological lesion of Parkinson's disease (PD) is the selective cell death of dopaminergic (DA) neurons in substantia nigra (SN). Although the initial cause and subsequent molecular signaling mechanisms leading to DA cell death underlying the PD process remain elusive, brain-derived neuro trophic factor (BDNF) is thought to exert neuroprotective as well as neurot rophic roles for the survival and differentiation of DA neurons in SN, Addr essing molecular mechanisms of BDNF action in both primary embryonic mesenc ephalic cultures and in vivo animal models has been technically difficult b ecause DA neurons in SN are relatively rare and present with many heterogen eous cell populations in midbrain. We have developed and characterized a DA neuronal cell line of embryonic SN origin that is more accessible to molec ular analysis and can be used as an in vitro model system for studying SN D A neurons. A clonal SN DA neuronal progenitor cell line SN4741, arrested at an early DA developmental stage, was established from transgenic mouse emb ryos containing the targeted expression of the thermolabile SV40Tag in SN D A neurons. The phenotypic and morphological differentiation of the SN4741 c ells could be manipulated by environmental cues in vitro. Exogenous BDNF tr eatment produced significant neuroprotection against 1-methyl-4-phenylpyrid inium, glutamate, and nitric oxide-induced neurotoxicity in the SN4741 cell s. Simultaneous phosphorylation of receptor tyrosine kinase B accompanied t he neuroprotection, This SN DA neuronal cell line provides a unique model s ystem to circumvent the limitations associated with primary mesencephalic c ultures for the elucidation of molecular mechanisms of BDNF action on DA ne urons of the SN.