Biology subjects

Renner, M.

Publications and source records attributed to Renner, M..

10 recordsLinked to original sources

bioRxiv2026

Conserved dimerization architecture in C-type lectins from virus-vector mosquitoes

C-type lectins (CTLs) play key roles in innate immunity and microbial carbohydrate recognition. In the disease vector mosquito Aedes aegypti, the CTLD-S family comprises 34 soluble CTLs whose members are implicated in flavivirus dissemination and microbial homeostasis, yet their structure and organization remain uncharacterized. Here, we combine X-ray crystallography, small-angle X-ray scattering (SAXS), molecular dynamics, and machine learning-based structure prediction to characterize CTLs in Aedes aegypti. We determined the crystal structures of four representative CTLD-S proteins: mosGCTL-1, -3, -6, and -20. All crystals featured mosGCTL proteins in an identical homodimer arrangement, positioning both carbohydrate-binding sites on the same molecular face. Dimerization was confirmed in solution and AlphaFold predictions across the entire CTLD-S family indicated that dimer formation may be a unifying feature of mosquito CTLD-S proteins. For one mosGCTL structure, paucimannose glycans bound at a Ca2+-dependent site, demonstrating bi-dentate glycan-binding through one dimer. Finally, machine learning based predictions indicated hundreds of possible CTLD-S heterodimers may be viable, with wide-ranging implications for preferred glycan binding through one dimer. Our findings reveal a conserved dimeric arrangement among mosquito lectins that may underpin carbohydrate recognition relevant to vector-pathogen interactions.

biochemistry↗

bioRxiv2025

Open and closed forms of assembled henipavirus nucleoprotein suggest structural basis of genome access

Henipaviruses, such as Nipah virus, can cause deadly illness and constitute WHO blueprint priorities due to their pandemic potential. Their genomes are packaged within a nucleocapsid consisting of viral nucleoproteins (N). Currently, it is unclear how the encapsidated genome is released from N to allow the viral polymerase to read its sequence. Here, we present the first high-resolution cryo-EM structure of a helical N-RNA filament from Langya henipavirus (LayV), allowing us to identify vertical interactions crucial for assembly. We show that assembly eficiency is sequence-dependent and prefers 5-genomic sequences. Further, we solve the structure of an RNA-free assembly of LayV N. Structural comparison of the RNA-bound and RNA-free LayV N shows a conformational opening and closing, even within the assembled state. Our data suggest that N within nucleocapsids may undergo local conformational changes, switching between closed and open states, to temporarily allow access to the encapsidated RNA without nucleocapsid disruption.

microbiology↗

bioRxiv2023

Cell type-focused compound screen in human organoids reveals molecules and pathways controlling cone photoreceptor death

Human organoids that mirror their corresponding organs in cell-type diversity present an opportunity to perform large-scale screens for compounds that protect disease-affected or damage healthy cell types. However, such screens have not yet been performed. Here, we generated 20,000 human retinal organoids with GFP-labeled cone photoreceptors. Since degeneration of cones is a leading cause of blindness, we induced cone death and screened 2,707 compounds with known targets, for those that saved cones or those that further damaged cones. We identified inhibitors of CK1 or MAPK11 that protected cones, HSP90 inhibitors that saved cones in the short term but damaged them in the longer term, and broad HDAC inhibition by many compounds that significantly damaged cones. This work provides a database for cone-damaging compounds and describes compounds that can be starting points to develop neuroprotection for cones in diseases such as macular degeneration.

neuroscience↗

bioRxiv2023

Structure of the N-RNA/P interface reveals mode of L/P attachment to the nucleocapsid of human metapneumovirus

Human metapneumovirus (HMPV) is a major cause of respiratory illness in young children. The polymerase complex of HMPV consists of two obligate components, the L polymerase and its cofactor, the phosphoprotein P. During replication and transcription, the L/P complex traverses the viral RNA genome, which is encapsidated within multimerized N nucleoproteins. An essential interaction between N and a C-terminal region of P is required for tethering of the L/P polymerase to the RNA template. This N-P interaction is also involved in the formation of cytoplasmic viral factories in infected cells, called inclusion bodies. To define how L/P recognizes N-encapsidated RNA (N-RNA) we employed cryogenic electron microscopy (cryo-EM) and molecular dynamics simulations, coupled to polymerase activity assays and imaging of inclusion bodies in transfected cells. We report a 2.9 [A] resolution structure of a triple-complex between multimeric N, bound to both RNA and the C-terminal region of P. Furthermore, we also present cryo-EM structures of assembled N in different oligomeric states, highlighting the plasticity of N. Combined with our functional assays, these structural data delineate in molecular detail how P attaches to N-RNA whilst retaining substantial conformational dynamics. Moreover, the N-RNA-P triple complex structure provides a molecular blueprint for the design of therapeutics to potentially disrupt the attachment of L/P to its template.

microbiology↗

bioRxiv2023

High-efficiency base editing for Stargardt disease in mice, non-human primates, and human retina tissue

Stargardt disease is a currently untreatable, inherited neurodegenerative disease that leads to macular degeneration and blindness due to loss-of-function mutations in the ABCA4 gene. We have designed a dual adeno-associated viral vector split-intein adenine base-editing strategy to correct the most common mutation in ABCA4 (c.5882G>A, p.G1961E). We optimized ABCA4 base editing in human models, including retinal organoids, iPSC-derived retinal pigment epithelial (RPE) cells, as well as adult human retinal- and RPE/choroid explants in vitro. The resulting gene therapy vectors achieved high levels of gene correction in mutation-carrying mice and in non-human primates, with an average editing of 37% of photoreceptors and 73% of RPE cells in vivo. The high editing rates in primates make way for precise and efficient gene editing in other neurodegenerative ocular diseases.

neuroscience↗

bioRxiv2022

Multimodal spatiotemporal phenotyping of human organoid development

Organoids generated from human pluripotent stem cells (PSCs) provide experimental systems to study development and disease. However, we lack quantitative spatiotemporal descriptions of organoid development that incorporate measurements across different molecular modalities. Here we focus on the retina and use a single-cell multimodal approach to reconstruct human retinal organoid development. We establish an experimental and computational pipeline to generate multiplexed spatial protein maps over a retinal organoid time course and primary adult human retina, registering protein expression features at the population, cellular, and subcellular levels. We develop an analytical toolkit to segment nuclei, identify local and global tissue units, infer morphology trajectories, and analyze cell neighborhoods from multiplexed imaging data. We use this toolkit to visualize progenitor and neuron location, the spatial arrangements of extracellular and subcellular components, and global patterning in each organoid and primary tissue. In addition, we generate a single-cell transcriptome and chromatin accessibility time course dataset and infer a gene regulatory network underlying organoid development. We then integrate genomic data with spatially segmented nuclei into a multi-modal atlas enabling virtual exploration of retinal organoid development. We visualize molecular, cellular, and regulatory dynamics during organoid lamination, and identify regulons associated with neuronal differentiation and maintenance. We use the integrated atlas to explore retinal ganglion cell (RGC) spatial neighborhoods, highlighting pathways involved in RGC cell death. Finally, we show that mosaic CRISPR/Cas genetic perturbations in retinal organoids provide insight into cell fate regulation. Altogether, our work is a major advance toward a virtual human retinal organoid, and provides new directions for how to approach disorders of the visual system. More broadly, our approaches can be adapted to many organoid systems.

systems biology↗

bioRxiv2020

A high resolution view of an adolescent flavivirus

Mosquito-transmitted flaviviruses, such as Dengue virus (DENV) or Zika virus (ZIKV), are responsible for significant economic damage and human misery. In infected cells, flaviviruses first assemble into an immature form within the endoplasmatic reticulum (ER), and then undergo further processing by furin protease in the trans-Golgi. Despite substantial efforts, previous cryogenic electron microscopy (cryo-EM) studies of immature flaviviruses were restricted to low to medium resolutions, limiting our understanding of maturation. To better grasp the process of maturation, we have carried out cryo-EM reconstructions of immature Spondweni virus (SPOV), an emerging human flavivirus belonging to the same serogroup as ZIKV (~75% amino acid identity). By combining localized reconstruction and focused refinement, we were able to improve the resolution to 3.8 [A], yielding unprecedented insight into the immature form. The structure elucidates how, at neutral pH, polar interactions conceal the furin recognition site within trimeric envelope (E) protein spikes. Furthermore, we identify how a strictly conserved pH sensor anchors the precursor membrane (prM) protein to immature E. We reconstructed mature forms of SPONV and DENV to 2.6[A] and 3.1[A], respectively. Comparison with immature virus shows a conserved binding pocket for a lipid headgroup, which forms as a consequence of the rearrangement of amphipathic stem-helices of E. We propose a structural role for the pocket and suggest it stabilizes mature E. Taken together, our data suggest a compelling rationale for low-pH triggered conformational rearrangement in the Golgi, which occurs during flavivirus maturation.

microbiology↗

bioRxiv2019

Expanded huntingtin CAG repeats disrupt the balance between neural progenitor expansion and differentiation in human cerebral organoids

Huntington disease (HD) manifests in both adult and juvenile forms. Mutant HTT gene carriers are thought to undergo normal brain development followed by a degenerative phase, resulting in progressive clinical manifestations. However, recent studies in children and prodromal individuals at risk for HD have raised the possibility of abnormal neurodevelopment. Although key findings in rodent models support this notion, direct evidence in the context of human physiology remains lacking. Using a panel of isogenic HD human embryonic pluripotent stem cells and cerebral organoids, we investigated the impact of mutant HTT on early neurodevelopment. We find that ventricular zone-like neuroepithelial progenitor layer expansion is blunted in an HTT CAG repeat length-dependent manner due to premature neurogenesis in HD cerebral organoids, driven by cell intrinsic processes. Transcriptional profiling and imaging analysis revealed impaired cell cycle regulatory processes, increased G1 length, and increased asymmetric division of apical progenitors, collectively contributing to premature neuronal differentiation. We demonstrate increased activity of the ATM-p53 pathway, an up-stream regulator of cell cycle processes, and show that treatment with ATM antagonists partially rescues the blunted neuroepithelial progenitor expansion in HD organoids. Our findings suggest that CAG repeat length regulates the balance between neural progenitor expansion and differentiation during early neurodevelopment. Our results further support the view that HD, at least in its early-onset forms, may not be a purely neurodegenerative disorder, and that abnormal neurodevelopment may be a component of HD pathophysiology.

developmental biology↗

bioRxiv2019

Cell types of the human retina and its organoids at single-cell resolution: developmental convergence, transcriptomic identity, and disease map

How closely human organoids recapitulate cell-type diversity and cell-type maturation of their target organs is not well understood. We developed human retinal organoids with multiple nuclear and synaptic layers. We sequenced the RNA of 158,844 single cells from these organoids at six developmental time points and from the periphery, fovea, pigment epithelium and choroid of light-responsive adult human retinas, and performed histochemistry. Cell types in organoids matured in vitro to a stable developed state at a rate similar to human retina development in vivo and the transcriptomes of organoid cell types converged towards the transcriptomes of adult peripheral retinal cell types. The expression of disease-associated genes was significantly cell-type specific in adult retina and cell-type specificity was retained in organoids. We implicate unexpected cell types in diseases such as macular degeneration. This resource identifies cellular targets for studying disease mechanisms in organoids and for targeted repair in adult human retinas.

neuroscience↗

bioRxiv2018

Topographical cues control the morphology and dynamics of migrating cortical interneurons

In mammalian embryos, cortical interneurons travel long distances among complex three-dimensional tissues before integrating into cortical circuits. Several molecular guiding cues involved in this migration process have been identified, but the influence of physical parameters remains poorly understood. In the present study, we have investigated in vitro the influence of the topography of the microenvironment on the migration of primary cortical interneurons released from mouse embryonic explants.\n\nWe found that arrays of 10 m-sized PDMS micro-pillars, either round or square, influenced both the morphology and the migratory behavior of interneurons. Strikingly, most interneurons exhibited a single and long leading process oriented along the diagonals of the square pillared array, whereas leading processes of interneurons migrating in-between round pillars were shorter, often branched and oriented in all available directions. Accordingly, dynamic studies revealed that growth cone divisions were twice more frequent in round than in square pillars. Both soma and leading process tips presented forward directed movements within square pillars, contrasting with the erratic trajectories and more dynamic movements observed among round pillars. In support of these observations, long interneurons migrating in square pillars displayed tight bundles of stable microtubules aligned in the direction of migration.\n\nOverall, our results show that micron-sized topography provides global spatial constraints promoting the establishment of two different morphological and migratory states. Remarkably, both states belong to the natural range of migratory behaviors of cortical interneurons, highlighting the potential importance of topographical cues in the guidance of these embryonic neurons, and more generally in brain development.

cell biology↗