Biology subjects

Grau-Perales, A.

Publications and source records attributed to Grau-Perales, A..

3 recordsLinked to original sources

bioRxiv2025

PKMζ-PKC{iota}/{lambda} double-knockout reveals the atypical PKCs are crucial for hippocampal late-LTP and spatial long-term memory

PKM{zeta}, a persistently active atypical PKC (aPKC) isoform, is thought to maintain late-phase long-term potentiation (late-LTP) and long-term memory. However, PKM{zeta}-knockout mice still exhibit hippocampal LTP and spatial memory while lacking neocortical LTP, questioning whether this kinase is fundamental to enduring synaptic potentiation and memory. Tsokas et al. (2016) showed the other aPKC, PKC{iota}/{lambda}, likely compensates for PKM{zeta} during maintenance in the hippocampus of PKM{zeta}-null mice. In wild-type mice, PKC{iota}/{lambda} drives early-LTP and short-term memory, while PKM{zeta} compensates for PKC{iota}/{lambda} knockout by supporting both early- and late-phase processes. Here we show PKC{iota}/{lambda} persistently increases during maintenance in two mouse models: PKM{zeta}-conditional knockout (cKO) mice, and double-knockout mice carrying both conditional deletion of PKC{iota}/{lambda} and constitutive loss of PKM{zeta}. In the double-knockout mice, PKC{iota}/{lambda} was measured while the kinase was still present, prior to its inducible ablation, to characterize its compensatory upregulation in late-LTP before removal. To test whether this compensation was functional, we ablated PKC{iota}/{lambda} in the hippocampus of the double-knockout mice. The double-knockout eliminated late-LTP, whereas individual knockout of either aPKC alone showed normal-appearing LTP. Double-knockout also abolished spatial long-term memory without affecting short-term memory. Thus, when PKM{zeta} is absent, PKC{iota}/{lambda} persists to maintain hippocampal late-LTP and long-term memory.

neuroscience↗

bioRxiv2025

Persistently increased expression of PKMzeta and unbiased gene expression profiles identify hippocampal molecular traces of a long-term active place avoidance memory and 'shadow' proteins

Long-term memory formation transiently activates Ca2+-calmodulin kinase II and atypical protein kinase C isoform iota/lambda, whereas persistent activation of the other atypical PKC, protein kinase M zeta (PKM{zeta}), together with its interacting partner, the scaffolding-protein KIBRA (Wwc1), are necessary for maintaining potentiated synapses and memory. Here, we use immediate-early gene (IEG) Arc activation during active place avoidance memory expression to tag memory-activated neurons with EYFP-ChR2. PKM{zeta} immunohistochemistry identified which hippocampal synaptic pathways are persistently altered. EYFP-PKM{zeta} colocalization persistently increases in the hippocampal trisynaptic pathway (dentate gyrus [DG][->]CA3[->]CA1) tracing a one-month-old PKM{zeta} engram. DG, CA3, and CA1 transcriptional profiling identifies that memory persistence correlates with upregulated immediate-early-genes Arc, Fos, and NPas4 in DG, but not with PKM{zeta} or most genes known to be crucial for LTP and memory. This rules out strong memory-related transcriptional regulation, but not regulation of mRNA translation or altered stability of "shadow proteins" like PKM{zeta} that, despite being crucial for memory maintenance, evade detection by unbiased transcriptome profiling. In contrast, our method Correlation Signal Co-cluster Reduction (C-SCoRe) incorporates weak linear and non-linear gene correlations and highlights network interaction changes predicting memory, and related IEG and Prkcz/Wwc1 expression. Manifold transcriptional relationships can reveal shadow molecular components of long-term memory.

neuroscience↗

bioRxiv2023

A Photoactivated Protein Degrader for Optical Control of Synaptic Function

Hundreds of proteins determine the function of synapses, and synapses define the neuronal circuits that subserve myriad brain, cognitive, and behavioral functions. It is thus necessary to precisely manipulate specific proteins at specific sub-cellular locations and times to elucidate the roles of particular proteins and synapses in brain function. We developed PHOtochemically TArgeting Chimeras (PHOTACs) as a strategy to optically degrade specific proteins with high spatial and temporal precision. PHOTACs are small molecules that, upon wavelength-selective illumination, catalyze ubiquitylation and degradation of target proteins through endogenous proteasomes. Here we describe the design and chemical properties of a PHOTAC that targets Ca2+/calmodulin-dependent protein kinase II alpha (CaMKII), which is abundant and crucial for baseline synaptic function of excitatory neurons. We validate the PHOTAC strategy, showing that the CaMKII-PHOTAC is effective in mouse brain tissue. Light activation of CaMKII-PHOTAC removed CaMKII from regions of the mouse hippocampus only within 25 m of the illuminated brain surface. The optically-controlled degradation decreases synaptic function within minutes of light activation, measured by the light-initiated attenuation of evoked field excitatory postsynaptic potential (fEPSP) responses to physiological stimulation. The PHOTACs methodology should be broadly applicable to other key proteins implicated in synaptic function, especially for evaluating their precise roles in the maintenance of long-term potentiation and memory within subcellular dendritic domains.

neuroscience↗