Biology subjects

Lendl, T.

Publications and source records attributed to Lendl, T..

9 recordsLinked to original sources

bioRxiv2026

Minimal essential requirements for neural tube self-organisation

The reliable generation of diverse cell types in precise proportions is essential for the formation of functional tissues during embryonic development. Three-dimensional organoid models derived from pluripotent stem cells (PSCs) provide powerful systems for identifying principles governing tissue self-organisation. Neural tube organoids (NTOs), initiated from single PSCs with a pulse of retinoic acid (RA), self-organise into structures containing floorplate cells that secrete SHH morphogen to pattern adjacent neural tissue. Yet, how the initial cellular diversity arises and how appropriate cell-type proportions are allocated has remained unclear. Here, using time-resolved single-cell transcriptomics, quantitative immunofluorescence, and dynamical systems modelling we show that RA triggers a transient co-expression state of the transcription factors PAX6 and FOXA2 from which cells asynchronously resolve into two opposing fates: PAX6 neural precursors and FOXA2 floorplate precursors. PAX6 and FOXA2 are both necessary and sufficient to reconstitute self-organisation, establishing these transcription factors as key determinants of emergent tissue pattern. Rather than operating as a simple feed-forward system in which cells are guided solely by RA, feedback between the alternative cell fates, mediated by BMP signalling from floorplate precursors, determines cell type proportions and ensures reproducible cell-type diversity in each NTO. This dual expression state was also identified in mouse embryos, demonstrating how in vitro models inform in vivo biology. These findings establish a general design strategy - symmetry breaking through opposing fate determinants coupled to proportioning via signal feedback control - that may operate broadly across developmental contexts to generate tissues with predictable cellular compositions.

developmental biology↗

bioRxiv2025

AXL governs axolotl cardiac regeneration and directs mammalian cardiomyocyte dedifferentiation

Cardiac injury outcomes vary widely across species, from complete regeneration to irreversible scarring. Using single-nucleus multiomics and spatial transcriptomics, we generated a spatially resolved atlas of axolotl heart regeneration following injury, identifying a distinct border-zone cardiomyocyte population with a pro-regenerative transcriptional program. Ligand-receptor analysis of the border zone niche identified enrichment of the receptor tyrosine kinase AXL in injury-responsive cardiomyocytes and its ligand Gas6 in endothelial cells. Functional perturbation demonstrated AXL requirement for border-zone cardiomyocyte activation and axolotl heart regeneration. In murine cardiomyocytes, AXL overexpression induced sarcomere disassembly, metabolic rewiring, and immature gene expression without triggering proliferation. These findings show that AXL signaling induces cardiomyocyte dedifferentiation and uncouples dedifferentiation from cell cycle re-entry, providing mechanistic insight into cellular plasticity during heart regeneration.

cell biology↗

bioRxiv2024

A journey towards developing a new cleavable crosslinker reagent for in-cell crosslinking

Crosslinking mass spectrometry (XL-MS) is a powerful technology that recently emerged as an essential complementary tool for elucidating protein structures and mapping interactions within a protein network. Crosslinkers which are amenable to post-linking backbone cleavage simplify peptide identification, aid in 3D structure determination and enable system-wide studies of protein-protein interactions (PPIs) in cellular environments. However, state-of-the-art cleavable linkers are fraught with practical limitations, including extensive evaluation of fragmentation energies and fragmentation behaviour of the crosslinker backbone. We herein introduce DiSPASO as a lysine-selective, MS-cleavable cross-linker with an alkyne handle for affinity enrichment. DiSPASO was designed and developed for efficient cell membrane permeability and crosslinking while securing low cellular perturbation. We tested DiSPASO employing three different copper-based enrichment strategies using model systems with increasing complexity (Cas9-Halo, purified ribosomes, live cells). Fluorescence microscopy in-cell crosslinking experiments revealed a rapid uptake of DiSPASO into HEK 293 cells within 5 minutes. While DiSPASO represents progress in cellular PPI analysis, its limitations and low crosslinking yield in cellular environments require careful optimisation of the crosslinker design, highlighting the complexity of developing effective XL-MS tools and the importance of continuous innovation in accurately mapping PPI networks within dynamic cellular environments. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=60 SRC="FIGDIR/small/621843v2_ufig1.gif" ALT="Figure 1"> View larger version (13K): org.highwire.dtl.DTLVardef@1821ed4org.highwire.dtl.DTLVardef@1b6180dorg.highwire.dtl.DTLVardef@1e50aaborg.highwire.dtl.DTLVardef@1f6185_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2024

Increase in ER-mitochondria contacts and mitochondrial fusion are hallmarks of mitochondrial activation during embryogenesis

Mitochondrial ATP production is essential for development, yet the mechanisms underlying the continuous increase in mitochondrial activity during embryogenesis remain elusive. Using zebrafish as a model system for vertebrate development, we comprehensively profile mitochondrial activity, morphology, metabolome, proteome and phospho-proteome as well as respiratory chain enzymatic activity. Our data show that the increase in mitochondrial activity during embryogenesis does not require mitochondrial biogenesis, is not limited by metabolic substrates at early stages, and occurs without an increase in the abundance of respiratory chain complexes or their in vitro activity. Our analyses pinpoint a previously unexplored increase in mitochondrial-ER association during early stages in combination with changes in mitochondrial morphology at later stages as possible contributors to the rise in mitochondrial activity during embryogenesis. Overall, our systematic profiling of the molecular and morphological changes to mitochondria during embryogenesis provides a valuable resource for further studying mitochondrial function during embryogenesis.

developmental biology↗

bioRxiv2023

ARID1B controls transcriptional programs of axon projection in the human corpus callosum

Mutations in ARID1B, a member of the mSWI/SNF complex, cause severe neurodevelopmental phenotypes with elusive mechanisms in humans. The most common structural abnormality in the brain of ARID1B patients is agenesis of the corpus callosum (ACC). This condition is characterized by a partial or complete absence of the corpus callosum (CC), an interhemispheric white matter tract that connects distant cortical regions. Using human neural organoids, we identify a vulnerability of callosal projection neurons (CPNs) to ARID1B haploinsufficiency, resulting in abnormal maturation trajectories and dysregulation of transcriptional programs of CC development. Through a novel in vitro model of the CC tract, we demonstrate that ARID1B mutations reduce the proportion of CPNs capable of forming long-range projections, leading to structural underconnectivity phenotypes. Our study uncovers new functions of the mSWI/SNF during human corticogenesis, identifying cell-autonomous defects in axonogenesis as a cause of ACC in ARID1B patients. O_FIG O_LINKSMALLFIG WIDTH=193 HEIGHT=200 SRC="FIGDIR/small/539362v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@dd4e9aorg.highwire.dtl.DTLVardef@153a081org.highwire.dtl.DTLVardef@14e884corg.highwire.dtl.DTLVardef@d64081_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstractC_FLOATNO Human callosal projection neurons are vulnerable to ARID1B haploinsufficiency. (Top) During healthy development, callosal projection neurons (CPNs) project long interhemispheric axons, forming the corpus callosum (CC) tract, which can be modeled in vitro. (Bottom) In ARID1B patients, transcriptional dysregulation of genetic programs of CC development reduces the formation of long-range projections from CPNs, causing CC agenesis in vivo and underconnectivity phenotypes in vitro. C_FIG

neuroscience↗

bioRxiv2022

A hormone-activated mobile RNAi pathway defends plant stem cells from virus infection

Stem cells are essential for the development and organ regeneration of multicellular organisms, so their infection by pathogenic viruses must be prevented. Accordingly, mammalian stem cells are highly resistant to viral infection due to dedicated antiviral pathways including RNA interference (RNAi) (1, 2). In plants, a small group of stem cells harbored within the shoot apical meristem (SAM) generates all postembryonic above-ground tissues, including the germline cells. Many viruses do not proliferate in these cells, yet the molecular bases of this exclusion remain only partially understood (3, 4). Here we show that a plant-encoded RNA-dependent RNA polymerase, after activation by the plant hormone salicylic acid, amplifies antiviral RNAi in infected tissues. This provides stem cells with RNA-based virus sequence information, which prevents virus proliferation. Furthermore, we find RNAi to be necessary for stem cell exclusion of several unrelated RNA viruses, despite their ability to efficiently suppress RNAi in the rest of the plant. This work elucidates a molecular pathway of great biological and economic relevance and lays the foundations for our future understanding of the unique systems underlying stem cell immunity.

plant biology↗

bioRxiv2022

Shuffled ATG8 interacting motifs form an ancestral bridge between UFMylation and C53-mediated autophagy

UFMylation mediates the covalent modification of substrate proteins with UFM1 (Ubiquitin-fold modifier 1) and regulates the selective degradation of endoplasmic reticulum (ER) via autophagy (ER-phagy) to maintain ER homeostasis. Specifically, collisions of the ER-bound ribosomes trigger ribosome UFMylation, which in turn activates C53-mediated autophagy that clears the toxic incomplete polypeptides. C53 has evolved non-canonical shuffled ATG8 interacting motifs (sAIMs) that are essential for ATG8 interaction and autophagy initiation. Why these non-canonical motifs were selected during evolution, instead of canonical ATG8 interacting motifs remains unknown. Here, using a phylogenomics approach, we show that UFMylation is conserved across the eukaryotes and secondarily lost in fungi and some other species. Further biochemical assays have confirmed those results and showed that the unicellular algae, Chlamydomonas reinhardtii has a functional UFMylation machinery, overturning the assumption that this process is linked to multicellularity. Our conservation analysis also revealed that UFM1 co-evolves with the sAIMs in C53, reflecting a functional link between UFM1 and the sAIMs. Using biochemical and structural approaches, we confirmed the interaction of UFM1 with the C53 sAIMs and found that UFM1 and ATG8 bound to the sAIMs in a different mode. Conversion of sAIMs into canonical AIMs prevented binding of UFM1 to C53, while strengthening ATG8 interaction. This led to the autoactivation of the C53 pathway and sensitized Arabidopsis thaliana to ER stress. Altogether, our findings reveal an ancestral toggle switch embodied in the sAIMs that regulates C53-mediated autophagy to maintain ER homeostasis.

plant biology↗

bioRxiv2020

A deeply conserved miR-1 dependent regulon supports muscle cell physiology

Muscles are not only essential for force generation but are also key regulators of systemic energy homeostasis1. Both these roles rely heavily on mitochondria and lysosome function as providers of energy and building blocks, but also as metabolic sensors2-4. Perturbations in these organelles or their crosstalk lead to a wide range of pathologies5. Here, we uncover a deeply conserved regulon of mitochondria and lysosome homeostasis under control of the muscle-specific microRNA miR-1. Animals lacking miR-1 display a diverse range of muscle cell defects that have been attributed to numerous different targets6. Guided by the striking conservation of miR-1 and some of its predicted targets, we identified a set of direct targets that can explain the pleiotropic function of miR-1. miR-1-mediated repression of multiple subunits of the vacuolar ATPase (V-ATPase) complex, a key player in the acidification of internal compartments and a hub for metabolic signaling7,8, and of DCT-1/BNIP3, a mitochondrial protein involved in mitophagy and apoptosis9,10, accounts for the function of this miRNA in C. elegans. Surprisingly, although multiple V-ATPase subunits are upregulated in the absence of miR-1, this causes a loss-of-function of V-ATPase due to altered levels or stoichiometry, which negatively impact complex assembly. Finally, we demonstrate the conservation of the functional relationship between miR-1 and the V-ATPase complex in Drosophila.

cell biology↗

bioRxiv2019

A heterochromatin-specific RNA export pathway facilitates piRNA production

PIWI-interacting RNAs (piRNAs) guide transposon silencing in animals. The 22-30nt piRNAs are processed in the cytoplasm from long non-coding RNAs. How piRNA precursors, which often lack RNA processing hallmarks of export-competent transcripts, achieve nuclear export is unknown. Here, we uncover the RNA export pathway specific for piRNA precursors in the Drosophila germline. This pathway requires Nxf3-Nxt1, a variant of the hetero-dimeric mRNA export receptor Nxf1-Nxt1. Nxf3 interacts with UAP56, a nuclear RNA helicase essential for mRNA export, and CG13741/Bootlegger, which recruits Nxf3-Nxt1 and UAP56 to heterochromatic piRNA source loci. Upon RNA cargo binding, Nxf3 achieves nuclear export via the exportin Crm1, and accumulates together with Bootlegger in peri-nuclear nuage, suggesting that after export, Nxf3-Bootlegger delivers precursor transcripts to the piRNA processing sites. Our findings indicate that the piRNA pathway bypasses nuclear RNA surveillance systems to achieve export of heterochromatic, unprocessed transcripts to the cytoplasm, a strategy also exploited by retroviruses.

molecular biology↗