The α-
synuclein has been implicated in the pathophysiology of
Parkinson's disease (PD), because mutations in the
alpha-synuclein gene cause autosomal-dominant hereditary PD and fibrillary aggregates of
alpha-synuclein are the major component of Lewy bodies. Since presynaptic accumulation of α-
synuclein aggregates may trigger synaptic dysfunction and degeneration, we have analyzed alterations in synaptosomal
proteins in early symptomatic α-synuclein(A30P)-transgenic mice by two-dimensional differential gel electrophoresis. Moreover, we carried out
microRNA expression profiling using microfluidic chips, as
microRNA have recently been shown to regulate synaptic plasticity in rodents and to modulate
polyglutamine-induced
protein aggregation and neurodegeneration in flies. Differentially expressed
proteins in α-synuclein(A30P)-transgenic mice point to alterations in mitochondrial function, actin dynamics,
iron transport, and vesicle exocytosis, thus partially resembling findings in PD patients. Oxygen consumption of isolated brain mitochondria, however, was not reduced in mutant mice. Levels of several
microRNA (miR-10a, -10b, -212, -132, -495) were significantly altered. One of them (miR-132) has been reported to be highly inducible by
growth factors and to be a key regulator of neurite outgrowth. Moreover, miR-132-recognition sequences were detected in the
mRNA transcripts of two differentially expressed
proteins.
MicroRNA may thus represent novel
biomarkers for neuronal malfunction and potential therapeutic targets for human
neurodegenerative diseases.