Biology subjects

Zaoralova, M.

Publications and source records attributed to Zaoralova, M..

5 recordsLinked to original sources

bioRxiv2026

Cryo-ET reveals nanoscale thick filamentdisorganization in MYH7 P710R hypertrophiccardiomyopathy cardiomyocytes

Hypertrophic cardiomyopathy (HCM) is the most common monogenic inherited heart disease and is a major cause of sudden death in individuals under 35 years of age. HCM is associated with progressive tissue-level disarray and subcellular disorganization in individual cardiomyocytes. Mutations in {beta}-cardiac myosin (MYH7), the second most common genetic cause of HCM, commonly result in changes in sarcomeric force production, but how this leads to altered cell- and tissue-level organization is unclear. Here, we use cryo-electron tomography (cryo-ET) to bridge the molecular and cellular scales by visualizing the nanoscale organization of individual myosin-containing thick filaments within sarcomeres of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Compared to isogenic wild-type controls, hiPSC-CMs expressing P710R MYH7 exhibit pronounced disruption of the hexagonal packing of thick filaments within individual sarcomeres, which would be difficult to visualize using conventional light microscopy or even room-temperature electron microscopy. We also observe ribosome infiltration into areas of sarcomeric disorder for both wild-type and P710R MYH7 hiPSC-CMs, suggesting that disordered regions may be sites of local proteostasis or remodeling. Together, these data illuminate how altered myosin activity can propagate to yield dramatic changes in sarcomeric organization in HCM.

cell biology↗

bioRxiv2026

Nup42 safeguards heat-induced mRNAs from nuclear condensation tosupport chaperone synthesis

Cells exposed to acute stress selectively express stress-adaptive genes while repressing growth-related genes. Upon heat shock, most pre-existing mRNAs localize to translationally repressed biomolecular condensates. How heat-induced mRNAs evade condensation and remain translationally competent remains unclear. Here, we show that ribosomal protein-coding transcripts preferentially accumulate in condensates during heat shock, whereas heat-induced chaperone mRNAs are selectively excluded and preferentially translated. Using a whole-genome CRISPRi screening platform, Fractionation of Reporter-Seq (FRep-Seq), we identify the nucleoporin Nup42 as the strongest suppressor of heat-induced mRNA condensation. Loss of Nup42 triggers temperature- and transcription-dependent nuclear condensation of chaperone mRNAs, which are exported but remain translationally incompetent, leading to impaired chaperone production and thermosensitivity. Co-transcriptional mRNP packaging is a critical determinant of condensation in the absence of Nup42. Together, our findings reveal a nuclear, translation-independent layer of mRNP solubility control that enables heat shock gene expression.

molecular biology↗

bioRxiv2024

Optical Interference for the Guidance of Cryogenic Focused Ion Beam Milling Beyond the Axial Diffraction Limit

Using a tri-coincident cryogenic FIB-SEM-LM system, we identify an interferometric optical response that can be used for targeting lamella production to fluorescently labelled structures with accuracy beyond the diffraction limit. We demonstrate the approach using synthetic samples of fluorescent beads embedded in micron-scale droplets of water. We then apply the approach to capture virions inside host cells. Successful targeting is confirmed by cryogenic electron tomography revealing clusters of virions in intracellular vesicles.

biophysics↗

bioRxiv2023

Extracellular filaments revealed by affinity capture cryo-electron tomography of lymphocytes

Cryogenic-electron tomography (cryo-ET) has provided an unprecedented glimpse into the nanoscale architecture of cells by combining cryogenic preservation of biological structures with electron tomography. Micropatterning of extracellular matrix proteins is increasingly used as a method to prepare adherent cell types for cryo-ET as it promotes optimal positioning of cells and subcellular regions of interest for vitrification, cryo-focused ion beam (cryo-FIB) milling, and data acquisition. Here we demonstrate a micropatterning workflow for capturing minimally adherent cell types, human T-cells and Jurkat cells, for cryo-FIB and cryo-ET. Our affinity capture system facilitated the nanoscale imaging of Jurkat cells, revealing extracellular filamentous structures. It improved workflow efficiency by consistently producing grids with a sufficient number of well positioned cells for an entire cryo-FIB session. Affinity capture can be extended to facilitate high resolution imaging of other adherent and non-adherent cell types with cryo-ET.

cell biology↗

bioRxiv2022

Optimizing Cryo-FIB Lamellas for sub-5 Angstrom in situ Structural Biology

We here present a method based on metallic platinum sputtering that can substantially enhance the quality of subtomogram averages from lamellas and thereby reduce the number of particles needed for high-resolution subtomogram averaging. We provide evidence for the physical background of this improvement and demonstrate its usefulness by producing sub-5[A] ribosome averages from yeast.

molecular biology↗