Biology subjects

Gookin, S. E.

Publications and source records attributed to Gookin, S. E..

3 recordsLinked to original sources

bioRxiv2026

AKAP-CaN-NFATc3 signaling drives persistent inhibitory long-term potentiation

GABAergic inhibitory synaptic plasticity has critical roles in neuronal function, synaptic plasticity, and cognition. Activity-dependent alterations in gene expression are essential for generating long-term changes in inhibitory postsynaptic strength, yet the signaling mechanisms that drive inhibitory postsynaptic plasticity are not well understood. During an important form of inhibitory long-term potentiation (iLTP), NMDA receptor (NMDAR) activity promotes de novo synthesis of GABAA receptors (GABAARs) and the inhibitory scaffold, gephyrin, leading to persistent strengthening of inhibition. However, it remains unclear what activity-dependent signaling mechanisms control these changes in gene expression to maintain iLTP. In this study, we identify that activation of the transcription factor, nuclear-factor of activated T-cells (NFAT), and anchoring of the phosphatase, calcineurin (CaN), to A-kinase anchoring protein (AKAP79/150) are crucial in regulating long-term structural and functional GABAergic postsynaptic plasticity. Using short hairpin RNA (shRNA) to knock-down hippocampal NFAT isoform, NFATc3, we demonstrate its requirement for the synthesis of new inhibitory synaptic proteins, inhibitory synapse growth, and strengthening of synaptic currents during persistent iLTP. Additionally, using a knock-in mouse line containing a mutation in the CaN binding region of AKAP, we find that AKAP-CaN signaling lies upstream of NFATc3 activation and is required for increased inhibitory synapse clustering and synapse strengthening during iLTP via regulation of miRNA transcriptional activity and protein synthesis. Thus, we have identified an excitation-transcription coupling pathway that rapidly controls the synthesis of new inhibitory synaptic proteins and maintains persistent inhibitory synaptic plasticity, an essential process for memory formation and cognition in the brain.

neuroscience↗

bioRxiv2026

Distinct nanoscale architectures of GABAergic inhibitory synapses predict diverse synaptic output

GABAergic synaptic inhibition is heterogenous across neuronal compartments, and plays a critical role in shaping local, cellular and circuit excitability. In pyramidal neurons, inhibition is mediated by GABAA receptors (GABAARs) clustered at the inhibitory postsynaptic domain (iPSD). Synaptic strength depends not only on the number of GABAARs within the iPSD, but also on their precise nanoscale organization into discrete sub-synaptic domains (SSDs). These SSDs often align with presynaptic GABA release sites to form nanocolumn structures that enhance synaptic efficacy. While nanocolumn organization is increasingly recognized as a key determinant of synaptic function, most studies of GABAergic synapses have focused on archetypal dendritic synapses, which control the plasticity and integration of excitatory inputs. Nonetheless, it remains unclear whether somatic synapses - which deliver and provide robust inhibition to suppress neuronal output - share a similar nanoscale organization. Here, we used complementary super-resolution imaging approaches to directly compare inhibitory synapses in somatic and dendritic compartments. We found that somatic synapses are larger and exhibit greater structural diversity and nanoscale complexity than dendritic synapses. Dendritic synapses display relatively compact architectures with GABAAR SSDs frequently arranged into nanocolumns. In contrast, somatic synapses show a broader range of organizations, including aligned nanocolumns as well as more disorganized configurations with additional misaligned release sites or receptor SSDs. Computational modeling revealed that these structural differences produce distinct functional outcomes, including increased IPSC amplitude and altered kinetics at somatic synapses. Together, our findings demonstrate that nanoscale organization differentially shapes inhibitory strength and signaling properties across neuronal compartments. SIGNIFICANCE STATEMENTDiverse GABAergic synaptic inhibition is crucial to control brain excitability and its efficacy is influenced by the nanoscale trans-synaptic alignment of GABAARs and GABA release sites. Although GABAAR nano-architecture is defined at dendritic synapses, the extent to which this organization is conserved across GABAergic synapses with distinct synaptic properties is unknown. Using super-resolution imaging methods, we report that inhibitory synapses in the soma are larger and more structurally diverse than dendritic synapses, exhibiting both aligned and more disorganized configurations. Combined with computational modeling indicating distinct nanoarchitectures can create heterogeneous inhibitory currents, these findings suggest a key role for nanoscale organization in the generation of diverse synaptic outputs across the neuron, which could serve distinct circuit functions.

neuroscience↗

bioRxiv2023

miRNA-mediated control of gephyrin synthesis drives sustained inhibitory synaptic plasticity

Activity-dependent protein synthesis is crucial for many long-lasting forms of synaptic plasticity. However, our understanding of the translational mechanisms controlling inhibitory synapses is limited. One distinct form of inhibitory long-term potentiation (iLTP) enhances postsynaptic clusters of GABAARs and the primary inhibitory scaffold, gephyrin, to promote sustained synaptic strengthening. While we previously found that persistent iLTP requires mRNA translation, the precise mechanisms controlling gephyrin translation during this process remain unknown. Here, we identify miR153 as a novel regulator of Gphn mRNA translation which controls gephyrin protein levels and synaptic clustering, ultimately impacting GABAergic synaptic structure and function. We find that iLTP induction downregulates miR153, reversing its translational suppression of Gphn mRNA and allowing for increased de novo gephyrin protein synthesis and synaptic clustering during iLTP. Finally, we find that reduced miR153 expression during iLTP is driven by an excitation-transcription coupling pathway involving calcineurin, NFAT and HDACs, which also controls the miRNA-dependent upregulation of GABAARs. Overall, this work delineates a miRNA-dependent post-transcriptional mechanism that controls the expression of the key synaptic scaffold, gephyrin, and may converge with parallel miRNA pathways to coordinate gene upregulation to maintain inhibitory synaptic plasticity.

neuroscience↗