Biology subjects

Lechner, S.

Publications and source records attributed to Lechner, S..

5 recordsLinked to original sources

bioRxiv2026

Chemoproteomics identifies a pyrimidopyrimidine analogue as a tubulin-tyrosine ligase binder

Small-molecule drug discovery relies on identifying compounds that modulate specific protein targets, a process often hindered by cellular complexity. Through phenotypic screening of a kinase-focused diazaquinazoline library, we serendipitously identified CEM198 as the first high-affinity ligand of tubulin-tyrosine ligase (TTL). Functional assays combining live-cell TTL inhibition, microtubule polymerization, cell cycle analysis, and proteomics revealed that CEM198 acts through a dual mechanism: directly binding to TTL and altering /{beta}-tubulin conformation. This interaction restricts -tubulin tyrosination and disrupts tubulin polymerization, leading to microtubule destabilization. The differential effects observed between SH-SY5Y and HEK293T cells indicate that effective TTL inhibition depends on both direct binding and structural modulation of the tubulin heterodimer. These findings introduce CEM198 as a chemical probe for investigating the tubulin tyrosination-detyrosination and demonstrate the potential of chemoproteomics to uncover novel modulators of microtubule dynamics.

biochemistry↗

bioRxiv2026

Leveraging the BAF chromatin remodeling complex for targeted transcriptional rewiring in cancer

Chromatin accessibility is essential for maintaining the fidelity of gene regulation and is dynamically regulated by epigenetic enzymes that are often dysregulated in cancer. The most commonly mutated regulator is the modular, multi-subunit Brahma-associated factor (BAF) chromatin remodeling complex. Previous attempts to exploit BAF complex mutations as potential tumor vulnerabilities using loss-of-function approaches have shown limited clinical success. Here, we instead propose a gain-of-function (GOF) strategy and establish Transcriptional/Remodeling chemical Inducers of Proximity (TRIPs), a class of neomorphic molecules that recruit active BAF complexes to rewire an oncogenic repressor, B-cell lymphoma 6 (BCL6). TRIPs potently induce transcriptional de-repression and apoptosis in Diffuse Large B-cell Lymphoma (DLBCL), enabled by ternary complex formation between BCL6 and BAF. CRISPR knockout screening identifies the PBAF complex as an essential contributor to cellular TRIP efficacy. Finally, we demonstrate that TRIP induces chromatin enrichment of BAF at BCL6-bound sites, resulting in ATPase-dependent eviction of BCL6, and de-repression of pro-apoptotic BCL6 target genes. We establish BAF recruitment for targeted chromatin remodeling as a viable GOF pharmacological strategy for tackling diseases driven by aberrant gene repression.

cancer biology↗

bioRxiv2026

Inhibition of V-ATPase function drives apoptosis via GCN1/GCN2 kinase signaling

Natural products are a rich source of bioactive molecules that have served both as templates for drug discovery and as tools to uncover fundamental biological processes. While characterizing the pro-apoptotic activity of the cyanobacterial metabolite Nostatin A, we identified vacuolar-type H-ATPase (V-ATPase) as its molecular target and uncovered an unexpected signalling response preceding cell death initiation. V-ATPase inhibition rapidly activates the integrated stress response (ISR) through engagement of the GCN1/GCN2 kinase module, indicative of ribosomal collisions and translational shutdown. This response is conserved across established V-ATPase inhibitors, including bafilomycin A1, but not with compounds disrupting lysosomal function by other means. Mechanistically, V-ATPase inhibition depletes the pro-survival protein MCL-1 resulting in BAX/BAK-dependent mitochondrial apoptosis. Loss of MCL-1 creates a vulnerability that renders cells dependent on co-expressed BCL-2 family proteins, enabling potent synergy with the BH3 mimetics ABT-737 or venetoclax. Taken together, our results reveal a therapeutically exploitable vulnerability in V-ATPase-reliant or MCL-1 dependent cancers.

cell biology↗

bioRxiv2023

Targeting LC3/GABARAP for degrader development and autophagy modulation

Recent successes in developing small-molecule degraders that act through the ubiquitin system have spurred efforts to extend this technology to other mechanisms, including the autophagosomal-lysosomal pathway. Therefore, reports of autophagosome tethering compounds (ATTECs) have received considerable attention from the drug development community. ATTECs are based on the target recruitment to LC3/GABARAP, a family of membrane-bound proteins that tether autophagy receptors to the autophagosome. In order to validate the existing ligands, we rigorously tested target engagement of reported ATTEC ligands and handles. Surprisingly, using various biophysical methods, most available ligands did not interact with their designated target LC3. Intrigued by the idea of developing ATTECs, we evaluated the druggability of LC3/GABARAP by in silico docking and large scale crystallographic fragment screening. The data revealed that most fragments bound to the HP2, but not the HP1 pocket of the LC3-interacting region (LIR) docking site, suggesting favorable druggability of this binding pocket. Here, we present diverse comprehensively validated ligands for future ATTEC development.

biochemistry↗

bioRxiv2023

A region-resolved proteomic map of the human brain enabled by high-throughput proteomics

Substantial efforts are underway that aim to deepen our understanding of human brain morphology, structure and function using high-resolution imaging as well has high-content molecular profiling technologies. The current work adds to these efforts by providing a comprehensive and quantitative protein expression map of 13 anatomically distinct brain regions covering more than 10,000 proteins. This was enabled by the optimization, characterization and implementation of a high-sensitivity and high-throughput micro-flow liquid chromatography timsTOF tandem mass spectrometry system (LC-MS/MS) capable of analyzing >2,000 consecutive samples prepared from formalin fixed paraffin embedded (FFPE) material. Analysis of this proteomic resource highlighted e.g. brain region-enriched protein expression patterns and functional protein classes, protein localization differences between brain regions and individual protein markers for specific brain regions. To facilitate access to and ease further mining of the data by the scientific community, all data can be explored online in a purpose-built Shiny App (https://brain-region-atlas.proteomics.ls.tum.de).

neuroscience↗