Biology subjects

Lapios, P.

Publications and source records attributed to Lapios, P..

2 recordsLinked to original sources

bioRxiv2025

Cryo-correlative light and electron tomography of dopaminergic axonal varicosities reveals non-synaptic modulation of cortico-striatal synapses

Dopamine is an essential brain neuromodulator involved in reward and motor control. Dopaminergic (DA) neurons project to most brain areas, with particularly dense innervation in the striatum. DA varicosities bind to target striatal synapses and form dopamine hub synapses (DHS). However, the basic features of dopamine release sites are still largely unknown. Here we studied the ultrastructure of fluorescent DA and glutamatergic (GLU) synaptosomes isolated from the striatum of adult mice with cryo-correlative light and electron microscopy and cryo-electron tomography. We observed that DA synaptosomes display [~]10 times fewer vesicles than GLU ones. DA vesicles are bigger and less round. Vesicle organization at single nanometer scale indicates that most GLU synaptosomes have tethered and primed vesicles, indicative of a readily releasable pool, while only 39 % of DA synaptosomes have tethered vesicles, which appear not to be primed. In addition, GLU terminals contacted by DA terminals in DHS have more primed vesicles than others. While DA varicosities do not form genuine synapses, their adhesion to cortico-striatal synapses may convey a local regulation of synaptic release properties.

neuroscience↗

bioRxiv2020

Novel proteostasis reporter mouse reveals different effects of cytoplasmic and nuclear aggregates on protein quality control in neurons

The cellular protein quality control machinery is important for preventing protein misfolding and aggregation, and decline in protein homeostasis (proteostasis) is believed to play a crucial role in age-related neurodegenerative disorders. However, how proteostasis capacity of neurons changes in different diseases is not yet sufficiently understood, and progress in this area has been hampered by the lack of tools to monitor proteostasis in mammalian models. Here, we have developed reporter mice for in vivo analysis of neuronal proteostasis. The mice express EGFP-fused firefly luciferase (Fluc), a conformationally unstable protein that requires chaperones for proper folding and sensitively reacts to proteotoxic stress by formation of intracellular Fluc-EGFP foci and by reduced luciferase activity. Using these mice, we provide evidence for proteostasis decline in the aging brain. Moreover, we find a marked impairment in proteostasis in tauopathy mice, but not in Huntingtons disease mice. Mechanistic investigations in primary neuronal cultures demonstrate that cytoplasmic, but not nuclear, aggregates cause defects of cellular protein quality control. Thus, the Fluc-EGFP reporter mice enable new insights into proteostasis alterations in different diseases.

neuroscience↗