Biology subjects

Bina, L.

Publications and source records attributed to Bina, L..

3 recordsLinked to original sources

bioRxiv2025

ATXN2 polyglutamine expansion impairs QKI-dependent alternative splicing and oligodendrocyte maintenance

BackgroundPolyglutamine (polyQ) tract expansion mutations in Ataxin-2 gene (ATXN2) are associated with neurodegenerative diseases spinocerebellar ataxia type 2 (SCA2) and amyotrophic lateral sclerosis (ALS), while the therapeutic reduction of ATXN2 confers strong health-/lifespan extension in models of both disorders. Although the involvement of ATXN2 in peripheral lipid metabolism has been elaborated in Atxn2 knock-out mice, its impact on nervous system lipid maintenance and a potential influence on oligodendrocytes remains unexplored. MethodsWe examine the nervous tissue of an authentic ATXN2 polyQ expansion mouse model in terms of (i) gross morphology of the brain and differential glial affection via immunohistochemical analyses, (ii) spinocerebellar proteome profile via label-free mass spectroscopy and (iii) alternative splicing patterns of oligodendroglial transcripts via quantitative RT-PCR. Finally, electrophysiological recording of sensory response in cerebellar Purkinje cells was performed as a phenotypic measure of demyelination. ResultsWe demonstrate a massive impairment in myelin maintenance due to ATXN2 polyQ expansion, affecting key oligodendroglial proteins accompanied by their splicing anomalies much earlier than disease manifestation. Oligodendroglial ATXN2 aggregates were documented for the first time in cerebellum, which sequestrated the RNA splicing factor Quaking (QKI). As an outcome of demyelination, our SCA2 model showed a significant delay in response to sensory stimuli. ConclusionsOverall, we provide pioneer evidence of oligodendroglial proteotoxicity leading to myelin maintenance defects in an authentic mouse model of SCA2. Our findings suggest that not only neuronal metabolism, but also that of oligodendroglia depends on ATXN2 and is affected during the disease course. This novel aspect of ATXN2 pathomechanism sheds light on potential outcomes of its therapeutic manipulation, and makes it relevant also for demyelination syndromes next to SCA2 and other polyQ disorders.

neuroscience↗

bioRxiv2024

Cerebellar control of targeted tongue movements

The cerebellum is critical for coordinating movements related to eating, drinking and swallowing. Cerebellar Purkinje cell activity has been shown to encode ongoing tongue movements, but it is unclear how this activity can alter the trajectory of the tongue. To elucidate the impact of Purkinje cells on goal-directed tongue movements, we recorded their activity in the vermis and hemispheres during spontaneous licking from a stationary or moving water spout. Some Purkinje cells encode rhythmic tongue movements with their complex spikes, others with their simple spikes or a combination of both. Complex spikes predominantly marked the start and end of a licking bout, and thus encoded behavioural state changes, while simple spike firing was more related to individual licks. In addition, complex spikes reported unexpected changes in the position of the water spout and subsequent modulation of simple spike firing caused bending of the tongue, reaching out for the new target position. Using machine learning, we demonstrated that it is possible to predict licking activity based on the spiking patterns of individual Purkinje cells. Using optogenetic stimulation of Purkinje cells, we could experimentally replicate the impact of modulated simple spike firing, suggesting that increased simple spike activity indeed causes ipsilateral bending of the tongue during goal-directed movements. Our data highlight that directional control of movements is paramount in cerebellar function and that complex spike and simple spike modulation complement each other during sensorimotor coordination. These results bring us closer to understanding clinical implications of cerebellar disorders during eating, drinking and swallowing. Key pointsO_LIWhen drinking, mice make rhythmic tongue movements directed towards the water source. C_LIO_LICerebellar Purkinje cells can fire rhythmically in tune with the tongue movements. C_LIO_LIPurkinje cells encode changes in the position of the water source with complex spikes. C_LIO_LIPurkinje cell simple spike firing affects the direction of tongue movements. C_LIO_LIPurkinje cells that report changes in the position of the target can also adjust movements in the right direction. C_LI

neuroscience↗

bioRxiv2020

Complex spike firing adapts to saliency of inputsand engages readiness to act

The cerebellum is involved in cognition next to motor coordination. During complex tasks, climbing fiber input to the cerebellum can deliver seemingly opposite signals, covering both motor and non-motor functions. To elucidate this ambiguity, we hypothesized that climbing fiber activity represents the saliency of inputs leading to action-readiness. We addressed this hypothesis by recording Purkinje cell activity in lateral cerebellum of awake mice learning go/no-go decisions based on entrained saliency of different sensory stimuli. As training progressed, the timing of climbing fiber signals switched in a coordinated fashion with that of Purkinje cell simple spikes towards the moment of occurrence of the salient stimulus that required action. Trial-by-trial analysis indicated that emerging climbing fiber activity is not linked to individual motor responses or rewards per se, but rather reflects the saliency of a particular sensory stimulus that engages a general readiness to act, bridging the non-motor with the motor functions. In brief O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=199 SRC="FIGDIR/small/314534v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@c319edorg.highwire.dtl.DTLVardef@db527eorg.highwire.dtl.DTLVardef@104e94eorg.highwire.dtl.DTLVardef@17115f2_HPS_FORMAT_FIGEXP M_FIG C_FIG Mice were trained to identify the saliency of different sensory inputs in that they had to learn to ignore a prominent sound cue and respond to a light tactile cue in a Go/No-Go licking task. As the mice learned to discriminate the two inputs and respond to the proper signal, the Purkinje cells in the lateral cerebellum switched their climbing fiber activity (i.e., complex spike activity) towards the moment of occurrence of the salient stimulus that required a response, while concomitantly shifting the phase of their simple spike modulation. Trial-by-trial analysis indicates that the emerging climbing fiber activity is not linked to the occurrence of the motor response or reward per se, but rather reflects the saliency of a particular sensory stimulus engaging a general readiness to act.

neuroscience↗