Biology subjects

Schuh, M.

Publications and source records attributed to Schuh, M..

4 recordsLinked to original sources

bioRxiv2026

Restoring Shugoshin 1 reduces chromosome errors in human eggs

Aneuploidy in human eggs, which rises sharply with age, is a leading cause of infertility, IVF failure, and miscarriage. This age-related aneuploidy is primarily driven by premature sister chromatid separation (PSSC), resulting from loss of the cohesin complex that holds chromatids together. How cohesin is destabilized in the long-lived mammalian oocyte is poorly understood. Here, we show that in mouse oocytes, pericentromeric transcription is essential for maintaining the cohesion protector Shugoshin 1 (SGO1) and PP2A at centromeres, which together safeguard the cohesin subunit REC8. With age, mouse oocytes lose pericentromeric transcription, SGO1, and PP2A, leading to destabilized cohesion and increased PSSC. Supplementing aged mouse oocytes with Sgo1 restores centromeric protection, and reduces PSSC to youthful levels. Aged human oocytes also show reduced SGO1, and SGO1 supplementation reduces the fraction of human eggs with PSSC by approximately half. These findings establish SGO1 supplementation as a potential strategy to preserve chromatid cohesion in aging oocytes.

cell biology↗

bioRxiv2025

Governed by surface amino acid composition: HIV capsid passage through the NPC barrier

Nuclear transport receptors (NTRs) carry cargo across the permeability barrier of nuclear pore complexes (NPCs) - an FG phase condensed from disordered but cohesive FG repeats. This phase repels normal macromolecules but allows NTR passage. When HIV infects non-dividing cells, its capsid is transported into nuclei not like cargo but crosses NPCs like NTRs. We now uncovered the molecular determinants of the capsids NTR behavior: The FG-binding pocket is insufficient. Hexameric and pentameric capsomers contribute. The highly exposed outer capsid surface is key. It lacks FG-repulsive charged residues (K,D,E) that are very abundant on normal protein surfaces. FG-attractive residues dominate the capsid surface. Introducing FG-repulsive ones impedes FG phase-partitioning, NPC-targeting and NPC-passage of assembled capsids. Capsids are thus made FG phase-soluble by myriads of transient FG-attractive interactions originating from individual surface sidechains. We discuss that CPSF6 releases the capsid from NPCs by switching its surface from FG-attractive to FG-repulsive.

cell biology↗

bioRxiv2025

Direct mechanical communication of cellular to nuclear shape in oocytes

The mechanical properties of the cytoplasm and nucleoplasm are crucial for the correct and robust functioning of a cell and play a key role in understanding how mechanical signals are transferred to the nucleus. Here, we demonstrate remarkable shape mimicry between the cellular and nuclear shape of oocytes, following the externally applied deformation without direct contact between the cell cortex and the nucleus. This effect arises from a surprisingly soft and fluid-like nucleoplasm that is barely resisting any external strain, while the viscoelastic cytoplasm drives shape transmission. Comparative studies in jellyfish, starfish, and mouse oocytes reveal that lower cytoplasmic elasticity in jellyfish leads to reduced nuclear shape mimicry, highlighting the role of cytoplasmic mechanics in nuclear deformation. Significance StatementMechanosensing of the nucleus is, in addition to chemical signalling, an important factor in gene expression. Although nuclei are often thought to be rigid inclusions in the cytoplasm of a cell, we show that in oocytes nuclei are much more deformable. Using a combination of intranuclear, intracellular and extracellular measurements, we attribute our findings to a fine balance between the soft nucleoplasm surrounded by an elastic shell and the viscoelastic properties of the cytoplasm.

biophysics↗

bioRxiv2020

Parental genome unification is highly erroneous in mammalian embryos

The vast majority of human embryos are aneuploid. Aneuploidy frequently arises during the early mitotic divisions of the embryo, but the origin of this remains elusive. Using bovine embryos as a model for human embryos, we identify an error-prone mechanism of parental genome unification which often results in aneuploidy. Surprisingly, genome unification initiates hours before breakdown of the two pronuclei that encapsulate the parental genomes. While still within intact pronuclei, the parental genomes polarize towards each other, in a process driven by centrosomes, dynein, and microtubules. The maternal and paternal chromosomes eventually cluster at the pronuclear interface, in direct proximity to each other. Parental genome clustering often fails however, leading to massive chromosome segregation errors, incompatible with healthy embryo development. Nucleoli, which associate with chromatin, also cluster at the pronuclear interface in human zygotes. Defects in nucleolar clustering correlate with failure in human embryo development, suggesting a conserved mechanism.

developmental biology↗