We recently described mitochondrial pathology in neurons of transgenic mice with genes associated with Parkinson's disease (PD). Now we describe severe mitochondrial damage in glial cells of the mesencephalon in mice carrying a targeted deletion of parkin (PaKO) or overexpressing doubly mutated human alpha-synuclein (asyn). The number of mitochondria with altered morphology in glial cells is cell type-dependent, but always higher than in neurons. Interestingly, mitochondrial damage also occurs in mesencephalic glia of mice carrying mutated asyn controlled by the tyrosine hydroxylase promoter. Such mice do not show glial expression of the transgene, but show expression in neighboring neurons. However, we found strong overexpression of endogenous asyn in mesencephalic astrocytes from these mice. Cortical astrocytes neither display enhanced asyn expression nor mitochondrial damage. Cultivated mesencephalic astrocytes from newborn transgenic mice display various functional defects along with the morphological damage of mitochondria. First, the mitochondrial Ca(2+)-storage capacity is reduced in asyn transgenic mesencephalic astrocytes, but not in astrocytes from PaKO. Second, the expression of the mitochondrial protein PTEN-induced putative kinase is constitutively increased in asyn transgenic mice, while in PaKO it reacts to oxidative stress by overexpressing this protein along with other mitochondria-related proteins. Third, the neurotrophic effects exerted by control astrocytes, stimulating cortical neurons from healthy mice to develop longer processes and larger neuronal areas, are lacking in co-cultures with transgenic mesencephalic astrocytes. In summary, glial mitochondria from transgenic mice display morphological and functional alterations. Such transgenic astrocytes fail to influence neuronal differentiation, reflecting an important role that glia may play in PD pathogenesis.
Accumulation of α-synuclein is observed in neurodegenerative diseases like Parkinson's disease and Multiple System Atrophy. In previous studies with transgenic C57BL/6 mice overexpressing α-synuclein carrying the mutations A53T and A30P found in Parkinson's disease or with a parkin-null background, we reported severe mitochondrial impairments in neurons and to a larger extent in glial cells of the mesencephalon. Neuron death was not observed in the brain. Here we show that the mice show severe motor impairments in behavioral tests. In addition, these mice exhibit astrocytic cell death in the spinal cord, accompanied by extensive gliosis and microglial activation. This is shown by cell death staining and immunohistochemistry. Ultrastructural analyses revealed severe mitochondrial impairments not only in astrocytes, but also in oligodendrocytes and, to a small extent, in neurons.
Thus, the transgenic mice show a profound pathology in glial cells of the spinal cord.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.