Ketogenic diet administration later in life improves memory by modifying the synaptic cortical proteome via the PKA signaling pathway in aging mice.

Aging compromises brain function leading to cognitive decline. A cyclic ketogenic diet (KD) improves memory in aged mice after long-term administration; however, short-term effects later in life and the molecular mechanisms that govern such changes remain unclear. Here, we explore the impact of a short-term KD treatment starting at elderly stage on brain function of aged mice. Behavioral testing and long-term potentiation (LTP) recordings reveal that KD improves working memory and hippocampal LTP. Furthermore, the synaptosome proteome of aged mice fed a KD long-term evidence changes predominantly at the presynaptic compartment associated to the protein kinase A (PKA) signaling pathway. These findings were corroborated in vivo by western blot analysis, with high BDNF abundance and PKA substrate phosphorylation. Overall, we show that a KD modifies brain function even when it is administered later in life and recapitulates molecular features of long-term administration, including the PKA signaling pathway, thus promoting synaptic plasticity at advanced age.

Role of the CaV1.2 distal carboxy terminus in the regulation of L-type current.

L-type calcium channels are essential for the excitation-contraction coupling in cardiac muscle. The CaV1.2 channel is the most predominant isoform in the ventricle which consists of a multi-subunit membrane complex that includes the CaV1.2 pore-forming subunit and auxiliary subunits like CaVα2δ and CaVß2b. The CaV1.2 channel's C-terminus undergoes proteolytic cleavage, and the distal C-terminal domain (DCtermD) associates with the channel core through two domains known as proximal and distal C-terminal regulatory domain (PCRD and DCRD, respectively). The interaction between the DCtermD and the remaining C-terminus reduces the channel activity and modifies voltage- and calcium-dependent inactivation mechanisms, leading to an autoinhibitory effect. In this study, we investigate how the interaction between DCRD and PCRD affects the inactivation processes and CaV1.2 activity. We expressed a 14-amino acid peptide miming the DCRD-PCRD interaction sequence in both heterologous systems and cardiomyocytes. Our results show that overexpression of this small peptide can displace the DCtermD and replicate the effects of the entire DCtermD on voltage-dependent inactivation and channel inhibition. However, the effect on calcium-dependent inactivation requires the full DCtermD and is prevented by overexpression of calmodulin. In conclusion, our results suggest that the interaction between DCRD and PCRD is sufficient to bring about the current inhibition and alter the voltage-dependent inactivation, possibly in an allosteric manner. Additionally, our data suggest that the DCtermD competitively modifies the calcium-dependent mechanism. The identified peptide sequence provides a valuable tool for further dissecting the molecular mechanisms that regulate L-type calcium channels' basal activity in cardiomyocytes.

Deletion of VPS50 protein in mice brain impairs synaptic function and behavior.

VPS50, is an accessory protein, involved in the synaptic and dense core vesicle acidification and its alterations produce behavioral changes in C.elegans. Here, we produce the mosaic knock out (mKO) of VPS50 using CRISPR/Cas9 system in both cortical cultured neurons and whole animals to evaluate the effect of VPS50 in regulating mammalian brain function and behavior. While mKO of VPS50 does not change the number of synaptic vesicles, it produces a mislocalization of the V-ATPase pump that likely impact in vesicle acidification and vesicle content to impair synaptic and neuronal activity in cultured neurons. In mice, mKO of VPS50 in the hippocampus, alter synaptic transmission and plasticity, and generated robust cognitive impairments associate to memory formation. We propose that VPS50 is an accessory protein that aids the correct recruitment of the V-ATPase pump to synaptic vesicles, thus having a crucial role controlling synaptic vesicle acidification and hence synaptic transmission.

Abriendo espacios de participación virtual multimodal a jóvenes durante la pandemia covid-19 / Opening multimodal virtual participation spaces for young students during the COVID-19 pandemic / Abrindo espaços virtuais multimodais de participação para estudantes durante a pandemia Covid-19

Resumen (analítico) Las y los estudiantes carecen de espacios para valorar sus experiencias de inclusión/exclusión escolar. La crisis sanitaria obligó a vincularnos virtualmente, sin conocer las posibilidades para el intercambio de significados digitales, representación de experiencias y movilización de relaciones interpersonales. Desde una perspectiva pedagógica, semiótica y social, este estudio analiza una sesión de un taller virtual con nueve estudiantes secundarios de tres escuelas chilenas, preguntándose sobre cómo se materializó la participación de las y los jóvenes. Con herramientas de la multimodalidad se analiza un corpus audiovisual de una cartografía virtual de espacios educativos. Se visibilizan los recursos disponibles para la participación virtual y las maneras en que fueron usados para compartir significados individuales y generar solidaridad co-construyendo relatos de inclusión/exclusión escolar.

Abstract (analytical) Students lack spaces that evaluate their experiences of inclusion/exclusion in school. The health cri-sis forced us to interact online and at first we were not aware of the resources available for the ex-change of digital meanings, representation of experiences and formation of interpersonal relation-ships. Using a pedagogical, semiotic and social approach, this study analyzes the results of an online workshop attended by nine secondary students from three Chilean schools. The aim was to identify the means and resources that facilitated student participation in online environments. Using multi-modal tools, an audiovisual corpus consisting of an Online Cartography of Educational Spaces is explored by the authors. The resources available for online participation were shared by participants. In addition, the article describes semiotic mechanisms for sharing individual meanings and developing solidarity by co-constructing stories about inclusion/exclusion in the classroom.

Resumo (analítico) Os alunos e alunas não têm espaços para avaliar suas experiências de inclusão/exclusão escolar. A crise de saúde pela Covid-19 obrigou as pessoas a termos uma interação virtual, sem conhecer os recursos disponíveis para a troca de significados digitais, a representação de experiências e o desenvolvimento das relações interpessoais. Do ponto de vista pedagógico, semiótico e social, este estudo analisa uma sessão de oficina virtual com nove alunos e alunas do ensino médio de três es-colas chilenas. A pesquisa foca em identificar os significados y recursos que auxiliam a participação dos e das estudantes. Utilizando ferramentas multimodais, foi analisado um corpus audiovisual de uma Cartografia Virtual de Espaços Educacionais. Assim, este estudo mostra os recursos disponíveis para a participação virtual e as formas como foram utilizados para compartilhar significados desde a experiência pessoal, além de promover a solidariedade através da co-construção de relatos de inclusão/exclusão escolar.

Heterogeneous CaMKII-Dependent Synaptic Compensations in CA1 Pyramidal Neurons From Acute Hippocampal Slices.

Prolonged changes in neural activity trigger homeostatic synaptic plasticity (HSP) allowing neuronal networks to operate within functional ranges. Cell-wide or input-specific adaptations can be induced by pharmacological or genetic manipulations of activity, and by sensory deprivation. Reactive functional changes caused by deafferentation may partially share mechanisms with HSP. Acute hippocampal slices are a suitable model to investigate relatively rapid (hours) modifications occurring after denervation and explore the underlying mechanisms. As during slicing many afferents are cut, we conducted whole-cell recordings of miniature excitatory postsynaptic currents (mEPSCs) in CA1 pyramidal neurons to evaluate changes over the following 12 h. As Schaffer collaterals constitute a major glutamatergic input to these neurons, we also dissected CA3. We observed an average increment in mEPSCs amplitude and a decrease in decay time, suggesting synaptic AMPA receptor upregulation and subunit content modifications. Sorting mEPSC by rise time, a correlate of synapse location along dendrites, revealed amplitude raises at two separate domains. A specific frequency increase was observed in the same domains and was accompanied by a global, unspecific raise. Amplitude and frequency increments were lower at sites initially more active, consistent with local compensatory processes. Transient preincubation with a specific Ca2+/calmodulin-dependent kinase II (CaMKII) inhibitor either blocked or occluded amplitude and frequency upregulation in different synapse populations. Results are consistent with the concurrent development of different known CaMKII-dependent HSP processes. Our observations support that deafferentation causes rapid and diverse compensations resembling classical slow forms of adaptation to inactivity. These results may contribute to understand fast-developing homeostatic or pathological events after brain injury.