Biology subjects

Barak, T.

Publications and source records attributed to Barak, T..

5 recordsLinked to original sources

bioRxiv2026

Multicellular Spatial Programs Define the Histopathological Architecture of Meningioma

Tumors are often described by cell types or gradients, but the organizing units of tumor tissue remain unclear. Using meningiomas, which show marked morphologic diversity despite constrained and recurrent genetics, we identify reproducible multicellular spatial molecular programs (SMPs) characterized by recurring cell-type mixtures that combine in different proportions across tumors. We built a multi-omic atlas of 147 human meningiomas (1.6 million cells/spots), integrating scRNA-seq, Visium, CosMx-RNA, and CosMx-Protein. Across platforms, SMPs mapped onto canonical whorl-lobule architecture and defined a structured ecological landscape linking hypoxic, immune-evasive states to vascularized, matrix-remodeling, and mineralization-rich states. For translation, we developed MeningNet, a hybrid ConvNeXt-Vision Transformer that infers SMPs directly from hematoxylin-and-eosin sections. MeningNet generalized across an internal replication cohort and 465 external whole-slide images, recovering cross-platform inference and showing significant association with CNS-WHO grade. These findings establish meningioma architecture as a reproducible histopathological framework for inferring spatial molecular state from routine pathology.

Cancer Biology↗

bioRxiv2026

Plant pathogens cleave 2′cADPR to suppress TIR immune signaling

Small molecules produced by TIR (Toll-interleukin-1 receptor) domains are essential for plant immune signaling. A central TIR-derived signal is 2'cADPR, a cyclic ADP-ribose (ADPR) molecule that is generated by plant TIR-domain proteins upon sensing pathogen infection. Here we show that XopQ, a virulence protein widespread in plant pathogenic bacteria, cleaves 2'cADPR and converts it into an inactive, linear ADPR molecule. Steady-state kinetic analyses revealed that XopQ is a highly efficient enzyme that hydrolyzes 2'cADPR with near diffusion-limited catalytic efficiency, while displaying high specificity and no detectable activity toward closely related molecules such as 3'cADPR. We show that XopQ eliminates 2'cADPR in planta and prevents accumulation of pRib-AMP, a derivative of 2'cADPR that activates the downstream immune complex EDS1-PAD4. Our data demonstrate that XopQ inhibits PAD4-dependent plant immunity and can promote pathogen virulence even when the pathogen carries an avirulence effector that triggers TIR-mediated immune signaling. Finally, we show that XopQ can also inhibit type VI Thoeris, a bacterial anti-phage defense system that relies on 2'cADPR signaling, possibly explaining why XopQ and type VI Thoeris are not observed co-occurring in bacterial genomes. Our findings uncover a widespread and conserved strategy used by plant pathogens to directly target host TIR signaling.

Plant Biology↗

bioRxiv2026

A mitochondrial program encodes brain vascular reserve

Brain resilience depends on collateral vessels whose geometries preserve blood flow when primary arteries are perturbed. How these protective vascular architectures are developmentally established remains unknown. Using longitudinal in vivo imaging in zebrafish, we show that mitochondrial state in embryonic angiogenic tip cells encodes the topology of basal and surface brain collateral networks. Mechanistically, microRNA-125a establishes the bioenergetic and redox balance of endothelial tip-cell mitochondria through conserved repression of the metabolic regulator PGC1a. Disruption of the microRNA-125a-PGC1a axis uncouples mitochondrial capacity from redox buffering in developing brain tip cells, redirecting their migration toward sparse, incompletely connected collateral network topologies and increasing adult cerebrovascular vulnerability. Consistent with this mechanism, humans with subclinical cerebrovascular injury exhibit reduced circulating microRNA-125a levels associated with incomplete basal collateral configurations. Together, these findings identify mitochondrial state as an instructive and conserved developmental program that encodes brain vascular reserve.

developmental biology↗

bioRxiv2025

Non-invasive approach for endoluminal biopsy coupled with single-cell proteomics allows for immune characterization of intracranial aneurysms

The immune regulatory mechanisms driving the stability, growth, and rupture of intracranial aneurysms (IAs) remain incompletely understood. In this study, we employ endoluminal biopsy with single-cell proteomics to comprehensively profile the immune landscape of IAs across their pathologic states. Our findings reveal distinct immune signatures associated with aneurysm states. Stable, i.e. non-growing unruptured, IAs exhibit a balanced immune cell composition. Ruptured IAs are marked by significant neutrophil predominance. Notably, we highlight key immune markers in aneurysm instability, offering new insights into immune drivers of aneurysm progression. These findings provide a foundation for immune-targeted, non-invasive therapeutic strategies aimed at targeting IAs and preventing rupture.

physiology↗

bioRxiv2022

spARC Recovers Human Glioma Spatial SignalingNetworks with Graph Filtering

Biological networks operate within architectural frameworks that influence the state and function of cells through niche-specific factors such as exposure to nutrients and metabolites, soluble signaling molecules, and direct cognate cell-cell communication. Spatial omics technologies incorporate environmental information into the study of biological systems, where the spatial coordinates of cells may directly or indirectly encode these micro-anatomical features. However, they suffer from technical artifacts, such as dropout, that impede biological discovery. Current methods that attempt to correct for this fail to adequately integrate highly informative spatial information when recovering gene expression and modelling cell-cell dynamics in situ. To address this oversight, we developed spatial Affinity-graph Recovery of Counts (spARC), a data diffusion-based filtration method that shares information between neighboring cells in tissue and related cells in expression space, to recover gene dynamics and simulate signalling interactions in spatial transcriptomics data. Following validation, we applied spARC to 10 IDH-mutant surgically resected human gliomas across WHO grades II-IV in order to study signaling networks across disease progression. This analysis revealed co-expressed genes that border the interface between tumor and tumor-infiltrated brain, allowing us to characterize global and local structure of glioma. By simulating paracrine signaling in silico, we identified an Osteopontin-CD44 interaction enriched in grade IV relative to grade II and grade III astrocytomas, and validated the clinical relevance of this signaling axis using TCGA.

bioinformatics↗