Synaptic responses adapt on millisecond-to-second timescales through short-term plasticity (STP), a key process that filters and transforms neuronal information. While STP is classically ascribed to presynaptic release mechanisms, postsynaptic receptor properties-particularly desensitization and surface diffusion-also shape synaptic responses. Here, we dissect pre- and postsynaptic contributions to synaptic adaptation using molecular tools to visualize glutamate release and manipulate AMPA receptor (AMPAR) diffusion in intact circuits. We find that synaptic gain during STP is tuned by synapse-specific regulation of AMPAR biophysics and diffusion-trapping. These features are determined constitutively by auxiliary subunit profiles and dynamically by activity-dependent signaling engaged during long-term plasticity. With modeling, we quantified how short-term synaptic dynamics are impacted by postsynaptic regulation of filtering properties, which broadened heterogeneity of filtering timescales to refine temporal selectivity in synaptic networks. By augmenting desensitization-mediated synaptic depression, AMPAR diffusion-trapping emerges as a fundamental regulatory mechanism of postsynaptic integration and circuit-level information processing.

To meet the constantly improving spatial resolution offered by advanced microscopy techniques to study sub-cellular structures in biology, there is a need for small, monovalent probes that label proteins of interest with high specificity and minimal distance to the target, and are compatible with various imaging modalities. In this direction, we designed a strategy to generate minimal-size probes composed of a controlled 1:1 conjugate between a small domain binder and a 1.4 nm-gold nanoparticle with direct access to fluorescent labelling for dual light-electron microscopy. Our approach was applied to the widely used single-domain antibody against GFP (GBP). The modified GBP-gold conjugate retained normal binding to purified GFP in vitro, specifically labelled COS-7 cells and neurons expressing GFP-tagged synaptic membrane proteins, and penetrated readily into tight cell-cell contacts including neuronal synapses. The optional fluorescence labelling with a second ALFA nanobody allowed dSTORM imaging, while the silver-enhanced nanogold particle detected in TEM was used to characterize the number and nanoscale organization of individual proteins in the synaptic cleft. We counted a small number of endogenous neurexins in the pre-synapse and a larger number of AMPA receptors in the post-synapse, often aligned in nanodomains. This GBP-gold probe thus emerges as a potent tool to label an ever-increasing repertoire of GFP-tagged proteins in numerous biological organisms and models. ### Competing Interest Statement The authors have declared no competing interest. Agence Nationale de la Recherche, https://ror.org/00rbzpz17, ANR-20-CE11-0006-01, ANR-21-CE11-0019-01, ANR-21-CE44-0013, ANR-23-CE11-0007, ANR-10-INBS-04-0

A scarcity of live, paralog-specific tools has limited analysis of PSD-MAGUKs at excitatory synapses. To address this gap, we engineered small, 10FN3-derived binders that selectively recognize PSD-93 and SAP102 -alongside an enhanced PSD-95 reagent- and converted them into regulated, gene-encoded intrabodies for endogenous imaging. Through sequence-guided selection and targeted optimization, we obtained high-specificity reagents that label their native targets in neurons with minimal perturbation and support multiplexed live-cell and advanced imaging modalities. This toolkit enables differential visualization of MAGUK paralogs at native levels and provides a practical route to dissect their distinct contributions to synapse organization and plasticity. ### Competing Interest Statement The authors have declared no competing interest. Agence Nationale de la Recherche, https://ror.org/00rbzpz17, ANR-21-CE44-0013, ANR-16-CE16-0026, ANR-10-INBS-04, ANR-10-LABX-43

Synaptic responses adapt to fast repetitive inputs during bursts of neuronal network activity over timescales of milliseconds to seconds, either transiently facilitating or depressing. This high-frequency stimulus-dependent short-term synaptic plasticity (HF-STP) relies on a number of molecular processes that collectively endow synapses with filtering properties for information processing, optimized for the transmission of certain input frequencies and patterns in distinct circuits [1][1]–[3][2]. Changes in HF-STP are traditionally thought to stem from changes in pre-synaptic transmitter release [1][1],[2][3], but post-synaptic modifications in receptor biophysical properties or surface diffusion also regulate HF-STP [4][4]–[11][5]. A major challenge in understanding synapse function is to decipher how pre- and post-synaptic mechanisms synergistically tune synaptic transmission efficacy during HF-STP, and to determine how neuronal activity modifies post-synaptic signal computation and integration to diversify neuronal circuit function. Here, taking advantage of new molecular tools to directly visualize glutamate release [12][6] and specifically manipulate the surface diffusion of endogenous AMPAR in intact circuits [13][7], we define the respective contributions of pre-synaptic glutamate release, AMPAR desensitization and surface mobility to frequency-dependent synaptic adaptation. We demonstrate that post-synaptic gain control and signal integration capacity in synaptic networks is influenced by synapse-specific differences in AMPAR desensitization and diffusion-trapping characteristics that are shaped by molecular signaling events recruited during LTP. ### Competing Interest Statement The authors have declared no competing interest. [1]: #ref-1 [2]: #ref-3 [3]: #ref-2 [4]: #ref-4 [5]: #ref-11 [6]: #ref-12 [7]: #ref-13

Supplementary Figures S1-S3 from Localization of Fas/CD95 into the Lipid Rafts on Down-Modulation of the Phosphatidylinositol 3-Kinase Signaling Pathway

Cancer stem cells are a subpopulation of tumor cells characterized by their ability to self-renew, induce tumors upon engraftment in animals and exhibit strong resistance to chemotherapy and radiotherapy. These cells exhibit numerous characteristics in common with embryonic stem cells, expressing some of their markers, typically absent in non-pathological adult differentiated cells. The aim of this study was to investigate the potential of conditioned media from cancer stem cells to modulate the fate of Leukemia Inhibitory Factor (LIF)-dependent murine embryonic stem cells (mESCs) as a way to obtain a direct readout of the secretome of cancer cells. A functional assay, "the StemDif sensor test", was developed with two types of cancer stem cells derived from grade IV glioblastoma (adult and pediatric) or from gastric adenocarcinoma. We show that conditioned media from the selection of adult but not pediatric Glioma-Inducing Cells (GICs) maintain mESCs' pluripotency in correlation with LIF secretion and activation of STAT3 protein. In contrast, conditioned media from gastric adenocarcinoma cells display LIF-independent stemness and differentiation activities on mESC. Our test stands out for its user-friendly procedures, affordability and straightforward output, positioning it as a pioneering tool for in-depth exploration of cancer stem cell secretome characteristics.

Supplementary Figures 1-2 from Dominant-Negative Fas Mutation Is Reversed by Down-expression of c-FLIP

MDGA molecules can bind neuroligins and interfere with trans-synaptic interactions to neurexins, thereby impairing synapse development. However, the subcellular localization and dynamics of MDGAs, or their specific action mode in neurons remain unclear. Here, surface immunostaining of endogenous MDGAs and single molecule tracking of recombinant MDGAs in dissociated hippocampal neurons reveal that MDGAs are homogeneously distributed and exhibit fast membrane diffusion, with a small reduction in mobility across neuronal maturation. Knocking-down/out MDGAs using shRNAs and CRISPR/Cas9 strategies increases the density of excitatory synapses, the membrane confinement of neuroligin-1, and the phosphotyrosine level of neuroligins associated with excitatory post-synaptic differentiation. Finally, MDGA silencing reduces the mobility of AMPA receptors, increases the frequency of miniature EPSCs (but not IPSCs), and selectively enhances evoked AMPA-receptor-mediated EPSCs in CA1 pyramidal neurons. Overall, our results support a mechanism by which interactions between MDGAs and neuroligin-1 delays the assembly of functional excitatory synapses containing AMPA receptors.

Regulation of synaptic neurotransmitter receptor content is a fundamental mechanism for tuning synaptic efficacy during experience-dependent plasticity and behavioral adaptation. However, experimental approaches to track and modify receptor movements in integrated experimental systems are limited. Exploiting AMPA-type glutamate receptors (AMPARs) as a model, we generated a knock-in mouse expressing the biotin acceptor peptide (AP) tag on the GluA2 extracellular N-terminal. Cell-specific introduction of biotin ligase allows the use of monovalent or tetravalent avidin variants to respectively monitor or manipulate the surface mobility of endogenous AMPAR containing biotinylated AP–GluA2 in neuronal subsets. AMPAR immobilization precluded the expression of long-term potentiation and formation of contextual fear memory, allowing target-specific control of the expression of synaptic plasticity and animal behavior. The AP tag knock-in model offers unprecedented access to resolve and control the spatiotemporal dynamics of endogenous receptors, and opens new avenues to study the molecular mechanisms of synaptic plasticity and learning.

The editors are publishing this note to alert readers to concerns about [this article][1] ([1][2]). The same Western blot analysis image was used for Jurkat-R cells in Fig. 4A and for Jurkat parental cells in Fig. 1B of another article previously published by the authors ([2][3]). In addition, lane

Impaired hippocampal synaptic plasticity is increasingly considered to play an important role in cognitive impairment in Huntington’s disease (HD). However, the molecular basis of synaptic plasticity defects is not fully understood. Combining live-cell nanoparticle tracking and super-resolution imaging, we show that dysregulation of AMPA receptors (AMPARs) surface diffusion represents a molecular basis underlying the aberrant hippocampal synaptic plasticity during HD. AMPARs surface diffusion is increased in various HD neuronal models, which results in the failure of AMPARs surface stabilization after long-term potentiation (LTP) stimuli. This appears to result from a defective brain-derived neurotrophic factor (BDNF) - tyrosine receptor kinase B (TrkB) - Ca2+/calmodulin-dependent protein kinase II (CaMKII) signaling pathway that impacts the interaction between the AMPAR auxiliary subunit stargazin and postsynaptic density protein 95 (PSD-95). Notably, the disturbed AMPAR surface diffusion is rescued, via BDNF signaling pathway and by the antidepressant tianeptine. Tianeptine also restores the impaired LTP and hippocampus-dependent memory as well as anxiety/depression-like behavior in different HD mouse models. We thus unveil a mechanistic framework underlying hippocampal synaptic and memory dysfunction and propose a new perspective in HD treatment by targeting AMPAR surface diffusion.

Differential expression of inflammasome gene modules and inflammasome-activating metabolites correlates with interleukin-1β expression, hypertension, arterial stiffness and longevity in older individuals. Low-grade, chronic inflammation has been associated with many diseases of aging, but the mechanisms responsible for producing this inflammation remain unclear. Inflammasomes can drive chronic inflammation in the context of an infectious disease or cellular stress, and they trigger the maturation of interleukin-1β (IL-1β). Here we find that the expression of specific inflammasome gene modules stratifies older individuals into two extremes: those with constitutive expression of IL-1β, nucleotide metabolism dysfunction, elevated oxidative stress, high rates of hypertension and arterial stiffness; and those without constitutive expression of IL-1β, who lack these characteristics. Adenine and N4-acetylcytidine, nucleotide-derived metabolites that are detectable in the blood of the former group, prime and activate the NLRC4 inflammasome, induce the production of IL-1β, activate platelets and neutrophils and elevate blood pressure in mice. In individuals over 85 years of age, the elevated expression of inflammasome gene modules was associated with all-cause mortality. Thus, targeting inflammasome components may ameliorate chronic inflammation and various other age-associated conditions.

Umbilical cord blood transplantation (UCBT) is an alternative in the absence of related or unrelated HLA-matched donor. Defects in the mechanisms of immuno-surveillance, due to the absence of antigen-experienced lymphoid subsets transferred in the cord blood unit (CBU), render recipients more prone to viral infections. Our center conducted a clinical trial testing the benefit of ex vivo amplification of the CD34+ fraction (using SCF, FLT3L, TPO and GCSF) enriched from one CBU on hematopoietic reconstitution, while the CD34- fraction was infused at the same time as the expanded fraction (NCT01034449). We intended to simultaneously evaluate the potential impact of such a procedure on the immune reconstitution following freeze-thaw cycle for the CD34- fraction and on the expansion potential of lymphoid progenitors from CD34+ fraction.

Human γδ T cells contribute to tissue homeostasis under normal conditions and participate in lymphoid stress surveillance against infection and tumors. However, the molecular mechanisms underlying the recognition of complex cell stress signatures by γδ T cells are still unclear. Tumor cells and human cytomegalovirus (HCMV)-infected cells are known targets of γδ T cells. We show here that many tumor and CMV-infected cells express caspase-1 inflammasomes and release interleukin (IL)-18. Engagement of the T-cell receptor (TCR) on Vδ2neg γδ T cells controlled the direct innate immune sensing of IL-18 that enhanced cytotoxicity and interferon gamma (IFNγ) production. This TCR-dependent sensitization to IL-18 was mediated by the upregulation of the innate IL-18 receptor β chain (IL-18Rβ) expression. These findings shed light on inflammasomes as a unified stress signal of tumor and infected cells to alert γδ T cells. Moreover, uncovering the TCR-mediated sensitization of γδ T cells to inflammatory mediators establishes a molecular link between the innate and adaptive immune functions of γδ T cells that could fine tune the commitment of antigen-experienced γδ T cells to inflammatory responses.

Background. Anti-human leukocyte antigen (HLA) antibody detection in solid-phase flow beads assays can be quenched by complement activation, but the precise mechanism of this interference is not fully elucidated yet.Methods. Using the Luminex flow beads screening assay for detection of anti-HLA antibodies, we analyzed the binding of high concentrations of the pan class I anti-HLA monoclonal antibody W6/32 in neat normal, ethylenediaminetetraacetic acid-treated normal and complement factors C1q, C4/C3, C2, C3, factor B or C5-depleted human sera, using anti-mouse immunoglobulin G as the detection antibody. Complement activation and binding to beads were revealed using anti-human C1q, C4d, and C3d antibodies. To translate our findings to the human setting, we used the class I and class II HLA single-antigen flow beads assays and sera from four patients with high titers of antibodies.Results. Detection of W6/32 did not suffer any interference with C1q and C4/C3-depleted sera. A partial quenching was observed with C2, C3, and factor B-depleted sera, but was more pronounced with the factor B-depleted serum. W6/32 was undetectable in presence of C5-depleted serum. The binding of activation products derived from C3 principally, and also from C4, impaired immunoglobulin G and C1q detection. Accordingly, C4d detection was hindered by deposition of activated C3. Similar findings were obtained with patients' sera.Conclusion. Binding of C4 and C3 activation products is the main responsible for complement interference in flow beads assays. A complete quenching requires complement activation through C3 cleavage and its amplification by the alternative pathway.