Biology subjects

Guhathakurta, D.

Publications and source records attributed to Guhathakurta, D..

3 recordsLinked to original sources

bioRxiv2026

Bassoon is required for adult ocular dominance plasticity and experience-induced changes in synapsin phosphorylation in visual cortex

Sensory stimulation enables experience-dependent fine tuning of brain circuits for optimal perception. In juvenile mice, brief closure of the contralateral eye reduces primary visual cortex (V1) activation through the deprived eye. In contrast, in adult animals, eye closure induces potentiated V1-responses to non-deprived eye visual stimulation. While considerable knowledge exists about postsynaptic mechanisms underlying this ocular dominance (OD) plasticity, little is known about contributing presynaptic molecules. Here we report that constitutive deletion of the presynaptic scaffolding protein bassoon (Bsn{Delta}Ex4/5) disrupted OD-plasticity in V1 of adult mice leaving juvenile OD-plasticity unaffected. Notably, in mice with a conditional deletion of Bsn only from cortical glutamatergic neurons (BsnEmx1), adult OD-plasticity was also impaired indicating that normal presynaptic plasticity of glutamatergic cortical synapses is selectively required in this process. While spatial vision was severely compromised in Bsn{Delta}Ex4/5 mice, it was preserved in BsnEmx1 mice, consistent with normal Bsn expression in subcortical circuit in these mice. Parallel experiments in cultured neurons revealed that deletion of Bsn left the inactivity-induced postsynaptic scaling of AMPA-responses mediated by increased AMPA receptor trafficking unchanged. However, presynaptic scaling was completely abolished as assessed by both electrophysiology and live-cell imaging of evoked synaptic vesicle fusion in cultured primary cortical neurons. Finally, monocular deprivation induced enhanced phosphorylation of synaptic vesicle-associated synapsin in contralateral V1 that was absent in BsnEmx1 mice. Overall, our data indicate that adult OD-plasticity requires Bsn-dependent presynaptic plasticity, involving experience-induced changes in synapsin phosphorylation. In contrast, juvenile OD-plasticity does not appear to be dependent on Bsn.

neuroscience↗

bioRxiv2023

Developmental effect of RASopathy mutations on neuronal network activity on a chip

RASopathies are a group of genetic disorders caused by mutations in genes encoding components and regulators of the RAS/MAPK signaling pathway, resulting in overactivation of signaling. RASopathy patients exhibit distinctive facial features, cardiopathies, growth and skeletal abnormalities, and varying degrees of developmental delay, neurocognitive impairment, intellectual disabilities, and attention deficits. At present, it is unclear how RASopathy mutations cause neurocognitive impairment and what their neuron-specific cellular and network phenotypes are. Such knowledge would be crucial for the development of specific therapies, which are still lacking for the treatment of the neurocognitive and behavioral symptoms in RASopathies. Here, we investigated the effect of RASopathy mutations on the establishment and functional maturation of neuronal networks. We isolated cortical neurons from RASopathy mouse models and cultured them for several weeks in multiwell plates with implanted multielectrode arrays. The arrays were used for longitudinal recordings of spontaneous activity in developing networks as well as for recordings of evoked responses in mature neurons. To facilitate the analysis of large and complex data sets resulting from long-term multielectrode recordings, we developed MATLAB-based tools for data processing, analysis and statistical evaluation. Longitudinal analysis of spontaneous network activity revealed a convergent developmental phenotype in neurons carrying the gain-of-function RASopathy mutations Ptpn11D61Y and KrasV14l. The phenotype was more pronounced at early time points and faded out over time, suggesting compensatory effects during network maturation. Nevertheless, persistent differences in excitatory/inhibitory balance and network excitability were observed in mature networks. This study improves the understanding of the complex relationship between genetic mutations and clinical manifestations in RASopathies by adding insights into functional network processes as an additional piece of the puzzle.

neuroscience↗

bioRxiv2021

Bassoon controls synaptic vesicle pools via regulation of presynaptic phosphorylation and cAMP homeostasis

Neuronal presynaptic terminals contain hundreds of neurotransmitter-filled synaptic vesicles (SVs). The morphologically uniform SVs differ in their release competence segregating into functional pools that differentially contribute to neurotransmission. The presynaptic scaffold bassoon is required for neurotransmission, but the underlying molecular mechanisms are unknown. We report that glutamatergic synapses lacking bassoon featured a decreased SV release competence and increased resting pool of SV as observed by imaging of SV release in cultured neurons. Further analyses in vitro and in vivo revealed a dysregulation of CDK5/calcineurin and cAMP/PKA presynaptic signalling resulting in an aberrant phosphorylation of their downstream effectors synapsin 1 and SNAP25, which are well-known regulators of SV release competence. An acute pharmacological restoration of physiological CDK5 and cAMP/PKA activity fully normalised the SV pools in neurons lacking bassoon. Finally, we demonstrated that CDK5-dependent regulation of PDE4 activity controls SV release competence by interaction with cAMP/PKA signalling. These data reveal that bassoon organises SV pools via regulation of presynaptic phosphorylation and indicate an involvement of PDE4 in the control of neurotransmitter release.

neuroscience↗