Biology subjects

Parra-Bueno, P.

Publications and source records attributed to Parra-Bueno, P..

4 recordsLinked to original sources

bioRxiv2024

Formation of long-term memory without short-term memory by CaMKII inhibition

Most of the current models of long-term memory consolidation require prior establishment of short-term memory. Here, we show that optogenetic or genetic inhibition of CaMKII, a kinase important for synaptic plasticity, in an inhibitory avoidance task impairs short-term memory at 1 h but not long-term memory at 1 d. Similarly, cortico-amygdala synaptic potentiation was more sensitive to CaMKII inhibition at 1 h but not at 1 d. These results strongly suggest that long-term memory does not require the prior formation of short-term memory and that CaMKII-dependent synaptic plasticity specifically regulates short-term memory, but not long-term memory, for avoidance memory.

neuroscience↗

bioRxiv2022

Disinhibition of Rab10 gates AMPAR insertion and spine enlargement during long-term potentiation

Rab-dependent membrane trafficking is critical for changing the structure and function of dendritic spines during synaptic plasticity. Here, we developed highly sensitive sensors to monitor Rab protein activity in single dendritic spines undergoing structural long-term potentiation (sLTP) in rodent organotypic hippocampal slices. During sLTP, Rab10 was persistently inactivated (>30 min) in the stimulated spines, whereas Rab4 was transiently activated over [~]5 min. Inhibiting or deleting Rab10 enhanced sLTP, electrophysiological LTP and AMPA receptor (AMPAR) trafficking during sLTP. In contrast, disrupting Rab4 impaired sLTP only in the first few minutes, and decreased AMPAR trafficking during sLTP. Thus, our results suggest that Rab10 and Rab4 oppositely regulate AMPAR trafficking during sLTP, and inactivation of Rab10 signaling facilitates the induction of LTP and associated spine structural plasticity.

neuroscience↗

bioRxiv2021

Dual regulation of spine-specific and synapse-to-nucleus signaling by PKCδ during plasticity

The activity-dependent plasticity of synapses is believed to be the cellular basis of learning. These synaptic changes are mediated through the coordination of local biochemical reactions in synapses and changes in gene transcription in the nucleus to modulate neuronal circuits and behavior. The protein kinase C (PKC) family of isozymes has long been established as critical for synaptic plasticity. However, due to a lack of suitable isozyme-specific tools, the role of the novel subfamily of PKC isozymes is largely unknown. Here, through the development of FLIM-FRET activity sensors, we investigate novel PKC isozymes in synaptic plasticity in mouse CA1 pyramidal neurons. We find that PKC{delta} is activated downstream of TrkB and that the spatiotemporal nature of its activation depends on the plasticity stimulation. In response to single spine plasticity, PKC{delta} is activated primarily in the stimulated spine and is required for local expression of plasticity. However, in response to multi-spine stimulation, a long-lasting and spreading activation of PKC{delta} scales with the number of spines stimulated and, by regulating CREB activity, couples spine plasticity to transcription in the nucleus. Thus, PKC{delta} plays a dual functional role in facilitating synaptic plasticity.

neuroscience↗

bioRxiv2018

RGS14 restricts plasticity in hippocampal CA2 by limiting postsynaptic calcium signaling

Pyramidal neurons in hippocampal area CA2 are distinct from neighboring CA1 in that they resist synaptic long-term potentiation (LTP) at CA3 Schaffer Collateral synapses. Regulator of G Protein Signaling 14 (RGS14) is a complex scaffolding protein enriched in CA2 dendritic spines that naturally blocks CA2 synaptic plasticity and hippocampus-dependent learning, but the cellular mechanisms by which RGS14 gates LTP are largely unexplored. A previous study has attributed the lack of plasticity to higher rates of calcium (Ca2+) buffering and extrusion in CA2 spines. Additionally, a recent proteomics study revealed that RGS14 interacts with two key Ca2+-activated proteins in CA2 neurons: calcium/calmodulin, and CaMKII. Here, we investigate whether RGS14 regulates Ca2+ signaling in its host CA2 neurons. We find the nascent LTP of CA2 synapses due to genetic knockout (KO) of RGS14 in mice requires Ca2+-dependent postsynaptic signaling through NMDA receptors, CaMK, and PKA, revealing similar mechanisms to those in CA1. We report RGS14 negatively regulates the long-term structural plasticity of dendritic spines of CA2 neurons. We further show that wild-type (WT) CA2 neurons display significantly attenuated spine Ca2+ transients during structural plasticity induction compared with the Ca2+ transients from CA2 spines of RGS14 KO mice and CA1 controls. Finally, we demonstrate that acute overexpression of RGS14 is sufficient to block spine plasticity, and elevating extracellular Ca2+ levels restores plasticity to RGS14-expressing neurons. Together, these results demonstrate for the first time that RGS14 regulates plasticity in hippocampal area CA2 by restricting Ca2+ elevations in CA2 spines and downstream signaling pathways.\n\nSignificance StatementRecent studies of hippocampal area CA2 have provided strong evidence in support of a clear role for this apparently plasticity-resistant subregion of the hippocampus in social, spatial, and temporal aspects of memory. Regulator of G Protein Signaling 14 (RGS14) is a critical factor that inhibits synaptic plasticity in CA2, but the molecular mechanisms by which RGS14 limits LTP remained unknown. Here we provide new evidence that RGS14 restricts spine calcium (Ca2+) in CA2 neurons and that key downstream Ca2+-activated signaling pathways are required for CA2 plasticity in mice lacking RGS14. These results define a previously unrecognized role for RGS14 as a natural inhibitor of postsynaptic Ca2+ signaling in hippocampal area CA2.

neuroscience↗