Biology subjects

Mayer, A.

Publications and source records attributed to Mayer, A..

At least 19 recordsLinked to original sources

bioRxiv2026

ELOF1 is a core component of the promoter-proximal paused RNA polymerase II complex

Metazoan RNA polymerase II is prone to pause in the promoter-proximal region of genes. This pausing involves DRB Sensitivity-Inducing Factor (DSIF) and Negative Elongation Factor (NELF). DSIF and NELF, however, are insufficient to fully reconstitute the degree of promoter-proximal pausing observed in cells. Their negative effects are counteracted by transcription initiation factor TFIIF or by physiological nucleotide concentrations, indicating an additional factor is required. Here, we report that Elongation Factor Homolog 1 (ELOF1) is this missing factor. ELOF1 is enriched in the promoter-proximal region of genes, and its rapid degradation reduces pause duration in cells. In reconstituted assays, ELOF1 potently enhances pausing induced by DSIF and NELF at physiological nucleotide concentrations. Cryo-EM structures reveal that DSIF-NELF-ELOF1 sterically clashes with the position of TFIIF on RNA polymerase II. Accordingly, RNA polymerase II-DSIF-NELF-ELOF1, but not RNA polymerase II-DSIF-NELF, counteracts the positive effects of TFIIF. Our results establish ELOF1 as a core component of promoter-proximal paused RNA polymerase II.

molecular biology↗

bioRxiv2026

Nucleolus transformation and Pol1 activity pattern dual transcriptomes of neuronal subtype identity

Gene expression directs neuronal fate during development with multiple RNA polymerases in the nucleus. mRNA transcribed by Pol2 ultimately depends on the rRNA transcribed by Pol1 in the nucleolus, which generates a ribosome pool to control mRNA translation. How Pol1 activity is synchronized with the Pol2 transcriptome to direct gene expression and neuronal fate is unknown. By creating a high-resolution map of nucleoli in the developing neocortex, we discover that the nucleolus is restructured in neuronal lineages with distinct Pol1 activity. With a new method for rRNA and mRNA dual-transcriptome sequencing in single-cells, we reveal that rRNA transcription is neuronal subtype and stage specific. Rather than a general feature of neural progenitor differentiation, rRNA production peaks transiently in post-mitotic subcortical projection neurons, which have atypical nucleoli containing a single, large cavity. Pol1 inactivation redirects these neurons towards a distinct fate that expresses a hybrid of subcortical and intracortical projection neuron markers. Thus, nucleolar architecture and Pol1 activity pattern dual rRNA-mRNA transcriptome signatures of neuronal subtype identity.

neuroscience↗

bioRxiv2026

The GTPase activating protein Gyp6 binds Retromer and inactivates Rab7/Ypt7 to coordinate the formation of endosomal carriers

The Retromer coat is conserved in all eukaryotes and is crucial for the correct intracellular sorting of many transmembrane receptors and lysosomal hydrolases. Retromer is an effector of the late endosomal small GTPase RAB7 and is also implicated in its inactivation required for proper endosomal maturation. Here, we explore the role of controlled GTP hydrolysis by the RAB7 ortholog Ypt7 in the formation of Retromer-coated membrane carriers in yeast. Proximity labelling and genetic ablation identify the GTPase Activating Protein (GAP) Gyp6 as a critical regulator of Ypt7 activity in the context or Retromer. Structural studies show that Retromer recruits Gyp6 through its Vps29 subunit, which recognises a specific PL motif and a secondary binding site in the C-terminal domain of Gyp6. This interaction does not occur with other yeast GAPs. Ablation of the Gyp6-Retromer interface or the catalytic activity of Gyp6 leads to the accumulation of tubular structures on endo-lysosomal compartments and to increased association of Ypt7 with Retromer and its cargo Vps10. These results support a model in which Gyp6 controls the switch from Ypt7-dependent Retromer coat assembly and cargo collection to the departure of the carrier through membrane fission and uncoating.

cell biology↗

bioRxiv2025

Modeling patient tissues at molecular resolution with Eva

Tissue structure is essential to function and homeostasis in all organs, and disruptions to structure usually indicate disease. Modeling relationships between structural, molecular, and clinical aspects of tissues could advance new diagnostics and treatment strategies. Although profiling techniques like spatial proteomics can capture these relationships, the data remain challenging to extract insight from. Here, we present Eva, a foundation model for tissue imaging data that learns multi-scale spatial representations of tissues at the molecular, cellular, and sample level. Eva uses a novel vision transformer architecture and is pre-trained on masked reconstruction of over 40 million matched spatial proteomics and histopathology images. We show that Eva excels at a variety of tasks, including cross-modal inference from H&E to proteomics stains, quality control, data annotation, zero-shot retrieval, survival modeling, and patient stratification. Extensive evaluations on held-out validation data demonstrate the versatility and generalizability of the learned embeddings. We anticipate that Eva will accelerate translational science by bridging basic research and clinical practice.

bioinformatics↗

bioRxiv2025

Temporal Dynamics of Antigen-Specific T Cell Expansion in Primary SARS-CoV-2 Infection

Quantifying T cell response during primary infection in humans is crucial for understanding adaptive immunity. Leveraging a controlled human challenge to SARS-CoV-2, we characterized antigen-specific T cell response within and across individuals. Notably, individual clones reached similar maximum frequencies despite differences in the timing of their peak expansion. Mathematical modeling showed that this observation is consistent with precursor frequency, but not TCR signal strength, as the source of inter-clonal variability. Single-cell profiling revealed distinct temporal programs for CD4+ and CD8+ T cells, with CD4+ cells expanding earlier but contracting to a lower frequency. Clones with similar receptors, likely recognizing the same antigen, expanded at similar times. Together, these findings highlight how clone-intrinsic properties such as precursor frequency and lineage shape T cell clonal kinetics. These insights provide a quantitative framework for understanding T cell response in humans, with implications for vaccine design.

biophysics↗

bioRxiv2025

CROP2, a Retriever-PROPPIN Complex Mediating Protein Export from Endosomes to the Plasma Membrane

Endosomes generate tubulo-vesicular carriers to redistribute proteins between plasma membrane, Golgi, and lysosomes. These transport routes employ distinct combinations of sorting nexins with complexes such as Retromer or Retriever. We now show that, while Retromer associates with the PROPPIN WIPI1 to form the previously described CROP complex, Retriever associates with WIPI2, forming CROP2. WIPI2 integrates into Retriever-dependent coat complexes, since it interacts both with the Commander subunit CCDC93 and its cognate sorting nexin SNX17. CROP and CROP2 are exclusive in their physical associations and pathway selective. Whereas CROP2 is required for endosomal exit of {beta}1-Integrin, it does not affect CROP-dependent cargos, such as EGFR or GLUT1. Vice versa, CROP is not required for {beta}1-Integrin trafficking. WIPI1 and WIPI2 rely on similar molecular features. Their activity depends on the same FSSS motif to integrate into Retromer and Retriever complexes, respectively, and on an amphipathic membrane-inserting -helix, which conveys membrane fission activity to PROPPINs. This suggests that Retromer and Retriever coats integrate distinct PROPPIN isoforms to promote fission of the respective endosomal carriers formed by them.

cell biology↗

bioRxiv2025

Hybrid endosomal coats containing different classes of sorting nexins

Endosomes are protein sorting stations where multiple coats form tubulovesicular carriers exporting proteins to the Golgi, the plasma membrane, or endo-lysosomal compartments. Distinct classes of sorting nexins are assumed to form distinct homogeneous coats that define the endosomal sorting routes and their cargos. Snx3 and the SNX-BARs Vps5-Vps17 belong to different sorting nexin classes. They form homogeneous Retromer-dependent coats that differ in structure and their modes of membrane association and cargo recognition. Here, we show the formation of hybrid coats between purified SNX-BARs, Snx3 and their cargos. Hybrid coats assemble at variable subunit ratios and diameters and show greater membrane scaffolding activity than homogeneous coats. In vivo, Snx3 and SNX-BARs colocalise and mutually impact the sorting of their respective cargos. Although simultaneous binding of Snx3- and SNX-BARs to Retromer is sterically prohibited, hybrid coats incorporate both SNXs in a common complex, probably linked by Retromer oligomerisation. We hence propose that SNX-BARs and Snx3 form Retromer-mediated hybrid coats in novel, stoichiometrically adaptable configurations that allow to adjust endosomal carriers for transporting varying ratios of cargo.

cell biology↗

bioRxiv2025

Acidocalcisome-like vacuoles constitute a feedback-controlled phosphate buffering system for the cytosol

Cells experience strong variations in the consumption and availability of inorganic phosphate (Pi). Since Pi is an essential macronutrient but excess Pi has negative impacts on nucleotide hydrolysis and metabolism, its concentration must be maintained in a suitable range. Conserved storage organelles, acidocalcisomes, provide this buffering function. We used acidocalcisome-like yeast vacuoles to study how such organelles are set up to for this task. Our combined in vitro and in vivo analyses revealed that their ATP-driven polyphosphate polymerase VTC converts cytosolic Pi into inorganic polyphosphates (polyP), which it transfers into the vacuole lumen. Luminal polyphosphatases immediately hydrolyse this polyP to establish a growing reservoir of vacuolar Pi. Product inhibition by this Pi pool silences the polyphosphatases, caps Pi accumulation, and favours vacuolar polyP storage. Upon cytosolic Pi scarcity, the declining inositol pyrophosphate levels activate the vacuolar Pi exporter Pho91 to replenish cytosolic Pi. In this way, acidocalcisome-like vacuoles constitute a feedback-regulated buffering system for cytosolic Pi, which the cells can switch between Pi accumulation, Pi release, and high-capacity phosphate storage through polyP.

cell biology↗

bioRxiv2025

Crossing effects in the tactile temporal order judgment task: A meta-analysis

The tactile temporal order judgment (TOJ) task is widely used in multisensory neuroscience. Participants judge which of two tactile stimuli, one on each hand, came first. A key finding is that TOJ performance declines when the arms are crossed, likely due to interactions between tactile, proprioceptive, and visual information. The TOJ crossing effect has been widely reported. However, studies have used different analysis methods, leaving open whether the choice of method influences the effects magnitude. Some studies have also reported that the crossing effect is modulated by moderators such as the analysis method, availability of visual information, response modality, or speeded response requirements. Through a systematic, exhaustive literature search, we identified 85 experiments in 51 publications that investigated the TOJ crossing effect, of which 39 experiments from 29 publications reported sufficient information for inclusion in a meta-analysis and fit the focus of our study. This analysis estimated the crossing effects size at approximately 1.45. Checks for potential publication bias indicated that this estimate may be inflated, with a corrected estimate of 0.97 using a regression-based adjustment for small-study effects (Ruckers method), and 1.4 based on p-curve analysis of the reported p-values. Although analysis method and response mode were identified as significant moderators, most moderators and specific contrasts were not statistically significant, likely because too few studies were available to achieve adequate statistical power. The large effect size supports the TOJ tasks use in other research, e.g. developmental and clinical. However, the lack of significant moderation suggests caution when applying the task to questions beyond the crossing effect itself. Public Significance StatementWe provide an effect size estimate of a well-known tactile-spatial measure, the tactile temporal order judgment crossing effect, based on a PRISMA-guided literature review. This measure will help planning for sufficient power in future studies.

neuroscience↗

bioRxiv2025

The break in the cycle: Inositol pyrophosphate fluxomics disentangled via mathematical modelling

This study investigates the metabolic pathways of inositol pyrophosphates (IPPs) in the yeast cell line {Delta}SPX and the human tumor cell line HCT116. Utilizing pulse-labelling experiments with 18O water and ordinary differential equation (ODE) models, we explore the synthesis and turnover of the highly phosphorylated IPP, 1,5-InsP8. Our findings challenge the notion that 1,5-InsP8 can be synthesized through distinct routes, revealing a linear reaction sequence in both systems. Employing model reduction via the profile likelihood method, we achieved statistically concise identifiability analysis that led to significant biological insights. In yeast, we determined that 1,5-InsP8 production primarily occurs through the phosphorylation of 5-InsP7, with the pathway involving 1-InsP7 deemed unnecessary as its removal did not compromise model accuracy. In HCT116 cells, 1,5-InsP8 synthesis is mainly driven by 1-InsP7, with variations observed across different experimental conditions. These results underscore the utility of model reduction in enhancing our understanding of metabolic pathways, challenging traditional views of IPP metabolism, and providing a framework for future investigations into the regulation and implications of linear IPP pathways in eukaryotic cells.

molecular biology↗

bioRxiv2024

Halfpipe: a tool for analyzing metabolic labeling RNA-seq data to quantify RNA half-lives

We introduce Halfpipe, a tool for analyzing RNA-seq data from metabolic RNA labeling experiments. Its main features are the absolute quantification of 4sU-labeling-induced T>C conversions in the data as generated by SLAM-seq, calculating the proportion of newly synthesized transcripts, and estimating subcellular RNA half-lives. Halfpipe excels at correcting critical biases caused by typically low labeling efficiency. We measure and compare the RNA metabolism in the G1 phase and during the mitosis of synchronized human cells. We find that RNA half-lives of constantly expressed RNAs are similar in mitosis and G1 phase, suggesting that RNA stability of those genes is constant throughout the cell cycle. Our estimates correlate well with literature values and with known RNA sequence features. Halfpipe is freely available at https://github.com/IMSBCompBio/Halfpipe

bioinformatics↗

bioRxiv2024

The role of liprin-α1 phosphorylation in its liquid-liquid phase separation: regulation by PPP2R5D/PP2A holoenzyme

Liprin-1 is a widely expressed scaffolding protein responsible for regulating cellular processes such as focal adhesion, cell motility, and synaptic transmission. Liprin-1 interacts with many proteins including ELKS, GIT1, liprin-{beta}, and LAR-family receptor tyrosine protein phosphatase. Through these protein-protein interactions, liprin-1 assembles large higher-order molecular complexes; however, the regulation of this complex assembly/disassembly is unknown. Liquid-liquid phase separation (LLPS) is a process that concentrates proteins within cellular nano-domains to facilitate efficient spatiotemporal signaling in response to signaling cascades. While there is no report that liprin-1 spontaneously undergoes LLPS, we found that GFP-liprin-1 expressed in HEK293 cells occasionally forms droplet-like condensates. MS-based interactomics identified Protein Phosphatase 2A (PP2A)/B56{delta} (PPP2R5D) trimers as specific interaction partners of liprin-1 through a canonical Short Linear Interaction Motif (SLiM) in its N-terminal dimerization domain. Mutation of this SLiM nearly abolished PP2A interaction, and resulted in significantly increased LLPS. GFP-liprin-1 showed significantly increased droplet formation in HEK293 cells devoid of B56{delta} (PPP2R5D knockout), suggesting that PPP2R5D/PP2A holoenzyme inhibits liprin-1 LLPS. Guided by reported liprin-1 Ser/Thr phosphorylation sites, we found liprin-1 phospho-mimetic mutant at serine 763 (S763E) is sufficient to drive its LLPS. Domain mapping studies of liprin-1 indicated that the intrinsically disordered region, the N-terminal dimerization domain, and the SAM domains are all necessary for liprin-1 LLPS. Finally, expression of p.E420K, a human PPP2R5D variant causing Houge-Janssens Syndrome type 1 (also known as Jordans Syndrome), significantly compromised suppression of liprin-1 LLPS. Our work identified B56{delta}-PP2A holoenzyme as an inhibitor of liprin-1 LLPS via regulation at multiple phosphorylation sites.

neuroscience↗

bioRxiv2024

Pools of independently cycling inositol phosphates revealed by pulse labeling with 18O-water

Inositol phosphates control many central processes in eukaryotic cells, including nutrient availability, growth, and motility. Kinetic resolution of a key modulator of their signaling functions, the turnover of the phosphate groups on the inositol ring, has been hampered by slow uptake, high dilution, and constraining growth conditions in radioactive pulse-labeling approaches. Here, we demonstrate rapid (seconds to minutes), non-radioactive labeling of inositol polyphosphates through 18O-water in yeast, amoeba and human cells, which can be applied in any media. In combination with capillary electrophoresis and mass spectrometry, 18O-water labeling simultaneously dissects the in vivo phosphate group dynamics of a broad spectrum of even rare inositol phosphates. The improved temporal resolution allowed us to discover vigorous phosphate group exchanges in some inositol poly- and pyrophosphates, whereas others remain remarkably inert. Our observations support a model in which the biosynthetic pathway of inositol poly- and pyrophosphates is organized in distinct, kinetically separated pools. While transfer of compounds between those pools is slow, each pool undergoes rapid internal phosphate cycling. This might enable the pools to perform distinct signaling functions while being metabolically connected.

biochemistry↗

bioRxiv2024

Molecular basis for the assembly of the Vps5-Vps17 SNX-BAR proteins with Retromer

Retromer mediates endosomal retrieval of transmembrane proteins in all eukaryotes and was first discovered in yeast in complex with the Vps5 and Vps17 sorting nexins (SNXs). Cryoelectron tomography (cryoET) studies of Retromer-Vps5 revealed a pseudo-helical coat on membrane tubules where dimers of the Vps26 subunit bind Vps5 membrane-proximal domains. However, the Vps29 subunit is also required for Vps5-Vps17 association despite being far from the membrane. Here, we show that Vps5 binds both Vps29 and Vps35 subunits through its unstructured N-terminal domain. A Pro-Leu (PL) motif in Vps5 binds Vps29 and is required for association with Retromer on membrane tubules in vitro, and for the proper recycling of the Vps10 cargo in Saccharomyces cerevisiae. CryoET of Retromer tubules with Vps5-Vps17 heterodimers show a similar architecture to the coat with Vps5-Vps5 homodimers, however, the spatial relationship between Retromer units is highly restricted, likely due to more limited orientations for docking. These results provide new mechanistic insights into how Retromer and SNX-BAR association has evolved across species.

cell biology↗

bioRxiv2023

Spatial proteomics of human diabetic kidney disease, from health to class III

Aims/HypothesisDiabetic kidney disease (DKD) remains a significant cause of morbidity and mortality in people with diabetes. Though animal models have taught us much about the molecular mechanisms of DKD, translating these findings to human disease requires greater knowledge of the molecular changes caused by diabetes in human kidneys. Establishing this knowledge base requires building carefully curated, reliable, and complete repositories of human kidney tissue, as well as tissue proteomics platforms capable of simultaneous, spatially resolved examination of multiple proteins. MethodsWe used the multiplexed immunofluorescence platform CO-Detection by indexing (CODEX) to image and analyze the expression of 21 proteins in 23 tissue sections from 12 individuals with diabetes and healthy kidneys (DM, 5 individuals), DKD classes IIA, and IIB (2 individuals per class), IIA-B intermediate (2 individuals), and III (one individual). ResultsAnalysis of the 21-plex immunofluorescence images revealed 18 cellular clusters, corresponding to 10 known kidney compartments and cell types, including proximal tubules, distal nephron, podocytes, glomerular endothelial and peritubular capillaries, blood vessels, including endothelial cells and vascular smooth muscle cells, macrophages, cells of the myeloid lineage, broad CD45+ inflammatory cells and the basement membrane. DKD progression was associated with co-localized increase in collagen IV deposition and infiltration of inflammatory cells, as well as loss of native proteins of each nephron segment at variable rates. Compartment-specific cellular changes corroborated this general theme, with compartment-specific variations. Cell type frequency and cell-to-cell adjacency highlighted (statistically) significant increase in inflammatory cells and their adjacency to tubular and SMA+ cells in DKD kidneys. Finally, DKD progression was marked by substantial regional variability within single tissue sections, as well as variability across patients within the same DKD class. The sizable intra-personal variability in DKD severity impacts pathologic classifications, and the attendant clinical decisions, which are usually based on small tissue biopsies. Conclusions/InterpretationsHigh-plex immunofluorescence images revealed changes in protein expression corresponding to differences in cellular phenotypic composition and microenvironment structure with DKD progression. This initial dataset demonstrates the combined power of curated human kidney tissues, multiplexed immunofluorescence and powerful analysis tools in revealing pathophysiology of human DKD.

molecular biology↗

bioRxiv2023

Inositol pyrophosphate dynamics in yeast reveals control of the PHO starvation program through 1,5-IP8 and the SPX domain of the CDK inhibitor Pho81

Eukaryotic cells control inorganic phosphate to balance its role as essential macronutrient with its negative bioenergetic impact on reactions liberating phosphate. Phosphate homeostasis depends on the conserved INPHORS signaling pathway that utilizes inositol pyrophosphates (IPPs) and SPX receptor domains. Since cells synthesize various IPPs and SPX domains bind them promiscuously, it is unclear whether a specific IPP regulates SPX domains in vivo, or whether multiple IPPs act as a pool. In contrast to previous models, which postulated that phosphate starvation is signaled by increased production of the IPP 1-IP7, we now show that the levels of all detectable IPPs of yeast, 1-IP7, 5-IP7 and 1,5-IP8, strongly decline upon phosphate starvation. Among these, specifically the decline of 1,5-IP8 triggers the transcriptional phosphate starvation response, the PHO pathway. 1,5-IP8 inactivates the cyclin-dependent kinase inhibitor Pho81 through its SPX domain. This stimulates the cyclin-dependent kinase Pho85-Pho80 to phosphorylate the transcription factor Pho4 and repress the PHO pathway. Combining our results with observations from other systems we propose a unified model where 1,5-IP8 signals cytosolic phosphate abundance to SPX proteins in fungi, plants, and mammals. Its absence triggers starvation responses. Significance statementCytosolic Pi is of prime importance for cellular bioenergetics because Pi influences free energy of nucleotide hydrolysis and the metabolite fluxes through glycolysis and oxidative phosphorylation. Eukaryotic cells use the INPHORS pathway to signal Pi via SPX domains and their ligands, inositol pyrophosphates (IP7, IP8), which control Pi homeostasis through a network of target proteins that import, export, store or detoxify Pi. Studies with different systems failed to yield a coherent model on this regulation. We performed the first time-resolved profiling of the full isomer spectrum of inositol pyrophosphates in yeast and dissected the isomer that is relevant to intracellular Pi signaling. Our results can be combined with existing observations from plants, mammals, and other fungi to support a unified model of Pi signaling across all eukaryotic kingdoms, which is in accord with the fundamental importance of Pi management for metabolism.

cell biology↗

bioRxiv2023

Genetic investigation of honeybee populations in Kazakhstan

Beekeeping as a staple of agriculture in Kazakhstan is believed to have emerged when external bee specimens were introduced into the country. The Central Russian bee (Apis mellifera mellifera) has been present throughout Kazakhstanian apiaries for a long time since its import into Eastern Kazakhstan at the end of the 18th century. To date, six subspecies have been distributed across the country (A.m. sossimai, A.m. carpatica, A.m. mellifera, A.m. ligustica, [A].m. caucasica, and A.m. carnica). According to mitochondrial haplotype analysis based on DraI mtDNA COI-COII (DmCC) test, local samples were represented by C2 (316), C1 (99), and M4 (7) haplotypes. The results of simple sequence repeats (SSR) genotyping revealed a large polymorphism at nine microsatellite loci, with the number of alleles amounting to 35 (AP55), 32 (AP43), 25 (A124), 18 (A113), 13 (A88), 12 (A43), 11 (A007), 7 (A28), and 5 (A24). Relative to the expected heterozygosity (He), the observed heterozygosity (Ho) was slightly higher for most markers considering both the overall samples and individual populations. The inbreeding coefficient confirmed the excess outbreeding for the geographical populations of car-Shym-T (-0,105), car-zham-A (-0,114), Zhet-Alakol (-0,008), and Zhet-Ushbulak (-0,028). The admixture of honeybee local populations was confirmed by the research presented here.The differentiation of populations was only possible by geographical location according to clustering analysis. A considerable degree of genetic admixtures among subspecies was identified in every population. The subspecies were not separated from each other. None of the groups formed by the neighbor-joining tree based on Neis genetic distance included a precise subspecies or population. All groups represented an admixture of subspecies from different populations. Unregulated cross-breeding for the past 50 years has laid the foundation for the promiscuous genetic nature of honeybee populations in Kazakhstan. It could be concluded that some samples were the result of cross-breeding with endemic bee Apis mellifera pomonella since most apiaries were located in areas of endemic bee distribution.

genetics↗

bioRxiv2023

PP1β opposes classic PP1 function, inhibiting spine maturation and promoting LTP

Protein phosphatase 1 (PP1) regulates synaptic plasticity and has been described as a molecular constraint on learning and memory. There are three neuronal isoforms, PP1, PP1{beta}, and PP1{gamma}, but little is known about their individual functions. PP1 and PP1{gamma} are assumed to mediate the effects of PP1 on learning and memory based on their enrichment at dendritic spines and their preferential binding to neurabin and spinophilin, major PP1 synaptic scaffolding proteins. However, it was recently discovered that human de novo PP1{beta} mutations cause intellectual disability, suggesting an important but ill-defined role for PP1{beta}. In this study, we investigated the functions of each PP1 isoform in hippocampal synaptic physiology using conditional CA1-specific knockout mice. In stark contrast to classic PP1 function, we found that PP1{beta} promotes synaptic plasticity as well as spatial memory. These changes in synaptic plasticity and memory are accompanied by changes in GluA1 phosphorylation, GluN2A levels, and dendritic spine density and morphology, including silent synapse number. These functions of PP1{beta} reveal a previously unidentified signaling pathway regulating spine maturation and plasticity, broadening our understanding of the complex role of PP1 in synaptic physiology.

neuroscience↗