Biology subjects

Beschauner, T.

Publications and source records attributed to Beschauner, T..

3 recordsLinked to original sources

bioRxiv2026

Localized heme sensing through a ternary molecular glue

Molecular glues are an emerging class of therapeutics that stabilize binary interactions and there-by rewire disease-relevant protein networks. Whether glues can integrate additional information to orchestrate signaling beyond initial complex formation is unknown. Here, we report that cells use an endogenous glue strategy to sense heme, an essential metabolite with deleterious pro-oxidant properties. Distinct from other glues, heme bridges three polypeptides to trigger degradation of the transcriptional repressor BACH1 through cytoplasmic, but not mitochondrial, CUL2FEM1B. This mechanism allows cells to eliminate toxic heme in the cytoplasm by inducing expression of the heme-degrading oxygenase HMOX1, yet ignore mitochondrial heme destined for function in the electron transport chain. While protective in healthy cells, ternary glue signaling creates a therapeutic vulnerability for Acute Myeloid Leukemias dependent on high rates of ETC assembly. Molecular glues can therefore drive assembly of higher-order complexes to establish localized signaling, which offers unexplored opportunities for induced proximity therapeutics.

biochemistry↗

bioRxiv2026

Multi-omics profiling reveals MAGEL2-driven defects in human corticogenesis shared across Prader-Willi and Schaaf-Yang syndromes.

The human cortex acquires its advanced cognitive capacity through tightly regulated developmental programs, disruption of which underlies neurodevelopmental disorders such as Schaaf-Yang syndrome (SYS) and Prader-Willi syndrome (PWS). While SYS results from pathogenic variants in the imprinted gene MAGEL2, PWS arises from chromosomal deletions, imprinting defects or uniparental disomy encompassing the MAGEL2 locus. However, the contribution of MAGEL2 to disease pathogenesis and human corticogenesis is not fully understood. Here, we performed integrated transcriptomic, proteomic, and ubiquitinomic profiling of cortical neurons derived from CRISPR/Cas9-engineered isogenic human pluripotent stem cells (hiPSC) modeling SYS and PWS. Beyond PWS-specific signatures including dysregulated ribosomal processes, we identified MAGEL2-dependent defects shared across both disorders. These include reduced progenitor proliferation, accelerated neuronal maturation, impaired migration and adhesion, as well as abnormal synaptic development, collectively linking PWS and SYS at the level of cortical development. Notably, these phenotypes partially overlap with those observed in other neurodevelopmental disorders, suggesting that MAGEL2 governs core pathways broadly vulnerable in disease. Together, our findings establish MAGEL2 as a key regulator of human cortical development, provide a unifying mechanistic framework for SYS and PWS, accessible via a web-based platform.

neuroscience↗

bioRxiv2024

The molecular basis of integrated stress response silencing

Chronic stress response activation impairs cell survival and causes devastating degenerative diseases. To counteract this, cells deploy dedicated silencing factors, such as the E3 ligase SIFI that terminates the mitochondrial stress response. How a single enzyme can sense stress across cells and elicit timely stress response inactivation is poorly understood. Here, we report the structure of human SIFI, which revealed how this 1.3MDa complex can target hundreds of proteins for accurate stress response silencing. SIFI attaches the first ubiquitin to substrates using flexible domains within an easily accessible scaffold, yet builds linkage-specific ubiquitin chains at distinct, sterically restricted elongation modules in its periphery. Ubiquitin handover via a ubiquitin-like domain couples versatile substrate modification to precise chain elongation. Stress response silencing therefore exploits a catalytic mechanism that is geared to process many diverse proteins and hence allows a single enzyme to monitor and, if appropriate, modulate a complex cellular state.

biochemistry↗