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Kramer, E.

Publications and source records attributed to Kramer, E..

6 recordsLinked to original sources

ModCRE-NN: Interpretable Deep Learning Harnesses Structural and Evolutionary Synergy to Predict Transcription Factor Binding Specificity

We present ModCRE-NN, a machine-learning framework and server for predicting transcription-factor (TF) DNA-binding motifs through the integration of structural and evolutionary information. The method combines structure-derived Position Weight Matrices (PWMs) together with PWMs of homologous spanning multiple evolutionary sequence-identity intervals, which are integrated into a unified 20-channel tensor representation. Benchmark datasets were constructed on experimental databases of TF motifs, showing DNA binding specificity, while redundancy reduction and strict train/test partitioning minimized homology leakage. Prediction quality was evaluated on an independent separated set of TFs using the similarity analysis of profiles. Three complementary architectures were implemented and evaluated: an interpretable regression-based model, a convolutional neural network (CNN), and a Transformer-based architecture using self-attention mechanisms. The regression model achieved strong performance in high-homology regimes dominated by closely related PWMs, whereas CNN and Transformer architectures showed superior robustness under low evolutionary similarity and increased structural uncertainty. Importantly, AI-generated motifs consistently improved the similarity-scores while reducing prediction variance relative to the original structural and evolutionary input motifs, indicating that the models effectively denoise heterogeneous motif assemblies and reconstruct stable consensus DNA-binding representations rather than simply transferring PWMs from the nearest homolog. The CNN model exhibited the most balanced attribution profile, suggesting enhanced ability to combine weak structural and evolutionary signals into coherent motif representations. Additionally, we implemented a prediction-reliability framework combining Random Forest regression, exponential interpolation, and hybrid residual-corrected modeling to estimate the quality and uncertainty of the PWMs as functions of evolutionary similarity, motif-cluster consistency, and TF-family context. Overall, our results demonstrate that integrating structural information with deep learning provides a robust framework for large-scale TF-binding specificity prediction under conditions of substantial evolutionary divergence and motif uncertainty.

bioinformatics↗

ExoFILT: Transfer learning for robust and accelerated analysis of exocytosis single-particle tracking data

MotivationUnderstanding constitutive exocytosis at the molecular level requires quantitative characterization of protein dynamics during the process. Single-particle tracking allows the measurement of protein dynamics in living cells. However, identifying bona fide exocytic events requires extensive manual annotation, limiting throughput and introducing personal biases that affect reproducibility. ResultsWe present ExoFILT, a deep learning-based classifier designed to identify exocytic events in single-particle tracking data, using the exocyst complex as a reference. Trained via transfer learning on simulated and experimental data, ExoFILT reduces the time required for manual annotation by ten-fold while improving measurement consistency across researchers. When applied to simultaneous dual-color time-lapse movies, ExoFILT enabled the systematic quantification of temporal relationships between exocytic proteins. The increased throughput uncovered distinct subpopulations of exocytic events with differential molecular composition (e.g., events with and without detectable levels of Sec1), underscoring the potential of ExoFILT to reveal mechanistic insights into exocytosis.

bioinformatics↗

Continuum architecture dynamics of vesicle tethering in exocytosis

Essential for eukaryotic organisms, multiple copies of the exocyst complex tether each secretory vesicle to the plasma membrane (PM) in constitutive exocytosis. The exocyst higher-order structure (ExHOS) that coordinates the action of these multiple exocysts remains unexplored. We integrated particle-tracking, super-resolution microscopy and cryo-electron tomography in a model that time-resolves the continuum conformational landscape of the ExHOS and functionally annotates its different conformations. We found that 7 exocysts form flexible ring-shaped ExHOS that tether vesicles at <45 nm from the PM. The ExHOS, initially 19 nm in radius, rapidly expands while it pulls the vesicle towards the PM. Subsequently, the ExHOS stabilizes, securing the vesicle at [~]4 nm from the PM. After fusion, Sec18 mediates the ExHOS disassembly when its radius is 38 nm. By resolving the fundamental biophysical principles of tethering we bridged the gap between static isolated structures and the dynamic and multimeric nature of exocytosis.

cell biology↗

Paper-based Sensing of Fucosylated Biological Compounds

Advances in sensing technology have enabled rapid analysis of various biomolecules including complex carbohydrates. However, glycan analysis is limited by the throughput and complexity of assays for quantifying them. We describe a simple, low-cost enzymatic assay for the rapid analysis of fucosylation, down to linkage specificity, and its application to high-throughput screening of biologically relevant fucosylated compounds, to facilitate simple and straightforward analytical techniques. Paper-based devices integrate biosensor platforms and other diagnostic assays by fusing them with wax printing technology, making their fabrication even more inexpensive and simple. The specificity of the assay is established by linkage-specific glycosidic enzymes and the colorimetric output is visible to the naked eye, with costs that are lower than fluorescence/luminescence-based assays ($0.02/reaction). This platform was further improved by enhancing storage stability to retain analytical performance over time using desiccation and freeze-drying techniques. The assay platform allows analysis of hundreds of samples in minutes and we anticipate that this rapid and simple analytical method will be extended towards developing a universal glyco-barcoding platform for high throughput screening of glycosylation.

biochemistry↗

Associations between Processing Speed and Psychopathology in a Transdiagnostic, Pediatric Sample

ObjectiveThe present study sought to examine the relationships between processing speed (PS), mental health disorders, and learning disorders. Prior work has tended to explore relationships between PS deficits and individual diagnoses (i.e., anxiety, autism, ADHD, depressive) in isolation of one another, often relying on relatively modest sample sizes. In contrast, the present work simultaneously investigated associations between PS deficits and these diagnoses, along with specific learning disabilities (i.e., reading, math), in a large-scale, transdiagnostic, community self-referred sample.\n\nMethodA total of 843 children, ages 8-16 were included from the Healthy Brain Network (HBN) Biobank. Given the presence of four PS tasks in HBN, principal component analysis (PCA) was employed to create a composite measure that represented the shared variance of the four PS tasks, referred to as PC1. Intraclass correlation coefficient (ICC) between the four PS measures, as well as PC1, were calculated to assess reliability. We then used multiple linear regression models to assess specific relationships between PS deficits and psychiatric diagnoses.\n\nResultsICCs were moderate between WISC-V tasks (0.663), and relatively modest between NIH Toolbox Pattern Comparison and other PS scales (0.14-0.27). Regression analyses revealed specific significant relationships between PS and reading and math disabilities, ADHD-inattentive type (ADHD-I), and ADHD-combined type (ADHD-C). Secondary analyses accounting for inattention dimensionally diminished associations with ADHD-C, but not ADHD-I or specific learning disability subtypes. The present study did not find a significant relationship with Autism Spectrum Disorder after accounting for inattentive symptoms. Consistent with prior work, demographic variables, including sex, socioeconomic status, and motor control exhibited independent relationships with PC1 as well.\n\nDiscussionThis study provided a comprehensive examination of PS, mental health disorders, and learning disabilities through a transdiagnostic approach. Implications for understanding how PS interacts with a highly heterogeneous childhood sample, as well as the need for increased focus on detection of affected populations are discussed.

developmental biology↗

The Healthy Brain Network Biobank: An open resource for transdiagnostic research in pediatric mental health and learning disorders

Technological and methodological innovations are equipping researchers with unprecedented capabilities for detecting and characterizing pathologic processes in the developing human brain. As a result, ambitions to achieve clinically useful tools to assist in the diagnosis and management of mental health and learning disorders are gaining momentum. To this end, it is critical to accrue large-scale multimodal datasets that capture a broad range of commonly encountered clinical psychopathology. The Child Mind Institute has launched the Healthy Brain Network (HBN), an ongoing initiative focused on creating and sharing a biobank of data from 10,000 New York area participants (ages 5-21). The HBN Biobank houses data about psychiatric, behavioral, cognitive, and lifestyle phenotypes, as well as multimodal brain imaging (resting and naturalistic viewing fMRI, diffusion MRI, morphometric MRI), electroencephalography, eye-tracking, voice and video recordings, genetics, and actigraphy. Here, we present the rationale, design and implementation of HBN protocols. We describe the first data release (n = 664) and the potential of the biobank to advance related areas (e.g., biophysical modeling, voice analysis).

neuroscience↗