Biology subjects

Schmid, S.

Publications and source records attributed to Schmid, S..

At least 19 recordsLinked to original sources

bioRxiv2026

Genomic structural variation in clownfish adaptive radiation

Clownfishes are a complex of 28 species that rapidly diversified after acquiring mutualism with host sea anemones around 15 million years ago. The genomic mechanisms behind this radiation are only beginning to emerge, and structural variants (SVs) have received little attention. Previous phylogenomic studies suggested two large inversions on chromosome 18, but their distribution across the clownfish phylogeny and their potential effects have not been formally explored. SVs can disrupt gene function and regulation or alter gene dosage, and they have been shown to play a central role in adaptive evolution and diversification across many taxa. Here, we characterized SVs across the clownfish radiation using long-read PacBio sequencing, generating high-quality genome assemblies for sixteen species spanning the main lineages of the genus. We identified and catalogued nearly 130,000 SVs spanning close to 570 Mb. Short insertions and deletions were the most numerous, but large inversions accounted for most of the affected sequence. No SV was consistently associated with host specialization. We nevertheless confirmed a single inversion of approximately 17 Mb on chromosome 18, clarifying earlier reports of two separate rearrangements at this locus, and identified an additional inversion on chromosome 9 whose distribution suggests a history of hybridization. This study provides the first genome-wide characterization of structural variation in clownfishes, revealing extensive SVs despite the group's rapid and recent radiation. It also delivers new, high-quality genomic resources that will support future research into this iconic group of coral reef fishes and their adaptation to sea anemones.

genomics↗

bioRxiv2026

Nanophotonic DyeCycling delivers single-molecule FRET beyond photobleaching to identify heterogenous dynamics in DNA and protein systems

With its unique spatiotemporal resolution at the single-molecule level, Forster resonance energy transfer (FRET) is a powerful tool for investigating biomolecular conformational dynamics and function. However, early photobleaching remains a key limitation restricting the achievable observation time and therefore the information gain and application range of single-molecule FRET. Here, we establish nanophotonic DyeCycling, which overcomes photobleaching by reversible fluorophore binding and efficient background suppression using zero-mode waveguides. Nanoscale conformational changes are sensitively resolved from milliseconds up to the hour range, enabling robust kinetic analyses at the single-molecule level. As a result, outlier molecules reflecting static heterogeneity and time-dependent kinetics within individual molecules reflecting dynamic heterogeneity are reliably resolved. The versatility of DyeCycling is demonstrated using DNA and protein systems. Altogether, nanophotonic DyeCycling extends smFRET observations beyond the conventional photobleaching limit, revealing previously inaccessible kinetic effects and providing deeper insight into biomolecular systems with multiple states and rates.

biophysics↗

bioRxiv2026

Cntnap2 deletion in mice causes developmentally transient alterations in auditory processing and persistent startle hyperreactivity

Autism spectrum disorder (ASD) is a neurodevelopmental condition often associated with auditory symptoms, including impairments in sound perception and hypersensitivity. These symptoms are thought to be partly due to the delayed development of the auditory brainstem, as evidenced through aberrant auditory brainstem responses (ABRs) and exaggerated startle responses in infants diagnosed with ASD. Loss-of-function mutations in CNTNAP2, a gene implicated in auditory processing and language development, are causally associated with ASD. Accordingly, knocking out Cntnap2 causes auditory brainstem impairments in rats; however, it is unknown if similar disruptions are observed in mice due to a possible conserved role of Cntnap2 in the auditory brainstem. To test this, we characterized the development of auditory processing, reactivity, and sensory filtering in juvenile and adult Cntnap2 knockout (KO) mice. We found that juvenile KO mice exhibited larger ABR wave III amplitudes and smaller wave IV widths, which normalized in adult mice, suggesting the possibility of transient hyperexcitability in the developing auditory brainstem. Additionally, our acoustic startle measurements revealed sex-specific phenotypes in which male KO mice exhibit an exaggerated startle response that persists into adulthood, while prepulse inhibition (PPI) remained generally intact in KO mice at both ages. These results demonstrate that loss of Cntnap2 in mice produces auditory brainstem abnormalities similar to rats, but causes species- and sex-specific effects on auditory reactivity, establishing the mouse model as a complementary animal model for investigating neural mechanisms underlying auditory dysfunction in ASD.

genetics↗

bioRxiv2026

Discovery and genomic characterization of a novel wild clownfish hybrid from the Philippines

Hybridization is widespread among marine fishes and can contribute to adaptation, diversification, and the generation of novel phenotypes. In clownfishes, only two wild hybrids Amphiprion leucokranos and A. thiellei have been described, yet those naturally occurring clownfish hybrids remain rarely documented. Both hybrids involve crosses with A. sandaracinos. During field surveys in the Philippines, we identified a previously undocumented clownfish individual with an unusual phenotype resembling both A. sandaracinos and A. perideraion. To characterize its origin, we combined genomic, mitochondrial, and phenotypic comparisons to previously described clownfish hybrid systems. Genome-wide PCA and admixture analyses supported mixed ancestry between A. sandaracinos and A. perideraion. Reconstruction of the mitochondrial genome placed the individual within the A. sandaracinos mitochondrial lineage. Together, these results support a hybrid origin and suggest predominant A. sandaracinos ancestry, consistent with a backcrossed descendant rather than a first-generation hybrid. Comparisons with the previously characterized hybrid A. leucokranos further revealed similarities in genomic composition and phenotype across independently derived clownfish hybrid systems. Our findings identify a previously undocumented natural clownfish hybrid and suggest that integrating genomic and field-based approaches may reveal additional cryptic hybrid systems and improve understanding of hybridization in clownfishes.

genomics↗

bioRxiv2025

Auditory Brainstem Development in Autism: From Childhood Hypo-Responsivity to Adult Hyper-Reactivity

BackgroundAutism Spectrum Disorder (ASD) is characterized by sensory disruptions, including auditory processing differences, which can significantly impact social, emotional, and cognitive development. This study investigates auditory brainstem development in Autistic children and adults using auditory brainstem responses (ABRs) and acoustic startle responses (ASRs), two key measures of auditory processing. We hypothesize that early hypo-responsivity in children, measured with ABRs, may lead to compensatory neural adaptations, resulting in hyper-reactivity in adulthood, measured by ASRs. MethodsThe study included 40 Autistic children, 57 non-Autistic children, 20 Autistic adults, and 21 non-Autistic adults. Participants underwent peripheral hearing screening, ABR testing at slow and fast click-rates, and ASR measurements. ABR wave and ASR amplitude were analyzed. Statistical analyses included mixed-model ANOVAs and Spearmans correlations to examine group differences and associations with age. ResultsAutistic participants showed trending differences in auditory brainstem timing relative to non-autistic participants, with no differences in brainstem amplitude at any wave or rate. Post hoc slope comparisons revealed that non-Autistic participants showed positive developmental trajectories in Wave I latency at both rates, while Autistic participants showed flat trajectories, a pattern directionally consistent with developmental convergence. A sex-specific group difference was observed at Wave I slow rate, with Autistic females showing longer latencies than non-Autistic females (d = 1.69), with no difference in males. In contrast, ASR amplitude showed diverging developmental trajectories between groups, with Autistic participants showing a positive age-related increase and non-Autistic participants showing a negative age-related decrease (slope contrast: t(99) = 2.16, p = .033, 2p = .05), consistent with a group difference emerging in adulthood. ABR amplitude was positively correlated with ASR amplitude in non-Autistic participants (Wave I: rho = +0.30; Wave V: rho = +0.25) but negatively correlated in Autistic participants (Wave I: rho = -0.19; Wave V: rho = -0.20), with the between-group difference in correlation direction surviving FDR correction for both waves (Fishers z padj = .035). ConclusionThe findings are consistent with the hypothesis that Autistic children experience auditory brainstem hypo-responsivity, which may normalize in adulthood but lead to maladaptive hyper-reactivity. These results highlight the role of early auditory disruptions in shaping long-term sensory processing and reactivity in Autism, emphasizing the need for further research into the neural mechanisms underlying these differences.

neuroscience↗

bioRxiv2024

Specialization into Host Sea Anemones Impacted Clownfish Demographic Responses to Pleistocene Sea Level Changes

Fluctuating sea levels during the Pleistocene led to habitat loss and fragmentation, impacting the evolutionary trajectories of reef fishes. Species with specialized ecological requirements or habitat preferences, like clownfishes (Amphiprioninae), may have been particularly vulnerable due to their intricate dependence on sea anemones. The diverse host specializations within this group likely contributed distinct responses to sea-level fluctuations, differentially shaping their recent evolutionary histories. Leveraging a comprehensive genomic dataset, we reveal demographic patterns and connectivity dynamics across multiple populations of ten clownfish species under different host specializations. Host-generalist species demonstrated strong resilience to habitat perturbations, while those specialized on single hosts suffered dramatic bottlenecks linked to sea-level fluctuations. Spatial analyses revealed the significant role of oceanic currents in shaping clownfish genetic diversity landscapes. Dispersal barriers were driven by environmental variables, with the Coral Triangle emerging as a hub of genetic diversity. Our results reveal how clownfish associative behavior influences their population dynamics, holding major implications for their conservation such as the need to consider their mutualism with sea anemones, particularly on host-specialists, to ensure their survival in the face of climate threats. These findings extend broader principles of conservation, improving our understanding of species responses to ecological constraints and environmental changes over evolutionary timescales.

genomics↗

bioRxiv2024

Host-use Drives Convergent Evolution in Clownfish and Disentangles the Mystery of an Iconic Adaptive Radiation

Clownfishes (Amphiprioninae) are a fascinating example of marine radiation. From a central Pacific ancestor, they quickly colonized the coral reefs of the Indo-Pacific and diversified independently on each side of the Indo-Australian Archipelago. Their association with venomous sea anemones is often thought to be the key innovation that enabled the clownfish radiation. However, this intuition has little empirical or theoretical support given our current knowledge of the clade. To date, no ecological variable has been identified that can explain clownfish niche partitioning, phenotypic evolution, species co-occurrence, and thus, the adaptive radiation of the group. Our synthetic work solves this long-standing mystery by testing the influence of sea anemone host use on phenotypic divergence. We provide the first major revision to the known clownfish-sea anemone host associations in over 30 years, accounting for host associations in a biologically relevant way. We gathered whole-genome data for all 28 clownfish species and reconstructed a fully supported species tree for the Amphiprioninae. Integrating this new data into comparative phylogenomic approaches, we demonstrate for the first time, that the host sea anemones are the drivers of convergent evolution in clownfish color pattern and morphology. During the adaptive radiation of this group, clownfishes in different regions that associate with the same hosts have evolved the same phenotypes. Comparative genomics also reveals several genes under convergent positive selection linked to host specialisation events. Our results identify the sea anemone host as the key ecological variable that disentangles the entire adaptive radiation. As one of the most recognizable animals on the planet and an emerging model organism in the biological sciences, our findings bear on the interpretation of dozens of prior studies on clownfishes and will radically reshape research agendas for these iconic organisms.

evolutionary biology↗

bioRxiv2024

Aggressive high-grade NF2 mutant meningiomas downregulate oncogenic YAP signaling via the upregulation of VGLL4 and FAT3/4.

Meningiomas are the most common primary brain tumors in adults. Although generally benign, a subset of meningiomas is of higher grade, shows aggressive growth behavior and recurs even after multiple surgeries. Around half of all meningiomas harbor inactivating mutations in NF2. While benign low-grade NF2 mutant meningiomas exhibit few genetic events in addition to NF2 inactivation, aggressive high-grade NF2 mutant meningiomas frequently harbor a highly aberrant genome. We and others have previously shown that NF2 inactivation leads to YAP1 activation and that YAP1 acts as the pivotal oncogenic driver in benign NF2 mutant meningiomas. Using bulk and single-cell RNA-Seq data from a large cohort of human meningiomas, we show that aggressive NF2 mutant meningiomas harbor decreased levels YAP1 activity compared to their benign counterparts. Decreased expression levels of YAP target genes are significantly associated with an increased risk of recurrence. We then identify the increased expression of the YAP1 competitor VGLL4 as well as the YAP1 upstream regulators FAT3/4 as a potential mechanism for the downregulation of YAP activity in aggressive NF2 mutant meningiomas. High expression of these genes is significantly associated with an increased risk of recurrence. In vitro, overexpression of VGLL4 resulted in the downregulation of YAP activity in benign NF2 mutant meningioma cells, confirming the direct link between VGLL4 expression and decreased levels of YAP activity observed in aggressive NF2 mutant meningiomas. Our results shed new insight on the biology of benign and aggressive NF2 mutant meningiomas and may have important implications for the efficacy of therapies targeting oncogenic YAP1 activity in NF2 mutant meningiomas.

molecular biology↗

bioRxiv2024

Ongoing hybridisation among clownfishes: the genomic architecture of the Kimbe Bay hybrid zone

Hybrid zones - locations where genetically distinct lineages interact and reproduce - are remarkable resources for exploring the evolutionary trajectory of species. Not only can we learn from hybrid zones about the mechanisms of speciation and how reproductive isolation is maintained, but we can also study their impact on evolutionary processes. Thanks to the advent of next-generation sequencing, we are now able to gain new insight into the structure of hybrid genomes and the factors influencing the outcome of hybridisation. Here, we focus on the Kimbe Bay hybrid zone, a narrow region in the Pacific Ocean where two species of clownfish - Amphiprion chrysopterus and A. sandaracinos - hybridise and give rise to the hybrid A. leucokranos. Based on whole-genome sequencing, we found that the hybrid zone is mainly composed of first-generation hybrids, the first evidence of F2 hybrids in the wild and early backcrosses with A. sandaracinos. The recurrent backcrossing with one of the parental species might lead to adaptive introgression, with few adaptive introgressed loci from A. chrysopterus integrated into the A. sandaracinos genomic background. This study builds upon the growing literature body relative to the evolutionary outcomes of hybridisation and its importance in the evolution of many species.

evolutionary biology↗

bioRxiv2024

Development of a series of genetically engineered NTRK fusion-driven pediatric-type high-grade glioma mouse models

Pediatric-type high-grade gliomas frequently harbor gene fusions involving receptor tyrosine kinase genes, including neurotrophic tyrosine kinase receptor (NTRK) fusions. Clinically, these tumors show high initial response rates to tyrosine kinase inhibition but ultimately recur due to the accumulation of additional resistance-conferring mutations. Here, we developed a series of genetically engineered mouse models of treatment-naive and -experienced NTRK1/2/3 fusion-driven gliomas. Both the TRK kinase domain and the N-terminal fusion partners influenced tumor histology and aggressiveness. Treatment with TRK kinase inhibitors significantly extended survival of NTRK fusion-driven glioma mice in a fusion- and inhibitor-dependent manner, but tumors ultimately recurred due to the presence of treatment-resistant persister cells. Finally, we show that ERK activation promotes resistance to TRK kinase inhibition and identify MEK inhibition as a potential combination therapy. These models will be invaluable tools for preclinical testing of novel inhibitors and to study the cellular responses of NTRK fusion-driven gliomas to therapy.

cancer biology↗

bioRxiv2023

Gene flow throughout the evolutionary history of a polymorphic and generalist clownfish

Even seemingly homogeneous on the surface, the oceans display high environmental heterogeneity across space and time. Indeed, different soft barriers structure the marine environment, which offers an appealing opportunity to study various evolutionary processes such as population differentiation and speciation. Here, we focus on Amphiprion clarkii (Actinopterygii; Perciformes), the most widespread of clownfishes that exhibits the highest colour polymorphism. Clownfishes can only disperse during a short pelagic larval phase before their sessile adult lifestyle, which might limit connectivity among populations, thus facilitating speciation events. Consequently, the taxonomic status of A. clarkii has been under debate. We used whole-genome resequencing data of 67 A. clarkii specimens spread across the Indian and Pacific Oceans to characterise the species population structure, demographic history, and colour polymorphism. We found that A. clarkii spread from the Indo-Pacific Ocean to the Pacific and Indian Oceans following a stepping-stone dispersal and that gene flow was pervasive throughout its demographic history. Moreover, edge populations exhibited more similar colouration patterns compared to central populations. However, we demonstrate that colour polymorphism is not associated with population structure, thus, colour phenotype is unreliable in assessing the taxonomic status of A. clarkii. Our study further highlights the power of whole-genome comparative studies to determine the taxonomy of geographically wide-ranging and phenotypically diverse species, supporting the status of A. clarkii as a single species.

evolutionary biology↗

bioRxiv2023

Nanopores reveal the stoichiometry of single oligo-adenylates produced by type III CRISPR-Cas

Cyclic oligoadenylates (cOAs) are small second messenger molecules produced by the type III CRISPR-Cas system as part of the prokaryotic immune response. The role of cOAs is to allosterically activate downstream effector proteins that induce dormancy or cell death, and thus abort viral spread through the population. Interestingly, different type III systems have been reported to utilize different cOA stoichiometries (with 3 to 6 adenylate monophosphates). However, so far, their characterization has only been possible in bulk and with sophisticated equipment, while a portable assay with single-molecule resolution has been lacking. Here, we demonstrate the label-free detection of single cOA molecules using a simple protein nanopore assay. It sensitively identifies the stoichiometry of individual cOA molecules and their mixtures from synthetic and enzymatic origin. To achieve this, we trained a convolutional neural network (CNN) and validated it with a series of experiments on mono- and polydisperse cOA samples. Ultimately, we determined the stoichiometric composition of cOAs produced enzymatically by the CRISPR type III-A and III-B variants of Thermus thermophilus. Interestingly, both variants produce cOAs of nearly identical composition, and we discuss the biological implications of this finding. The presented nanopore-CNN workflow with single-cOA resolution can be adapted to many other signaling molecules (including eukaryotic ones), and it may be integrated into portable handheld devices with potential point-of-care applications.

biophysics↗

bioRxiv2023

Molecular control of endurance training adaptation in mouse skeletal muscle

Skeletal muscle has an enormous plastic potential to adapt to various external and internal perturbations. While morphological changes in endurance-trained muscles are well-described, the molecular underpinnings of training adaptation are poorly understood. We aimed at defining the molecular signature of a trained muscle and unraveling the training statusdependent responses to an acute bout of exercise. Our results reveal that even though at baseline, the transcriptomes of trained and untrained muscles are very similar, training status substantially affects the transcriptional response to an acute challenge, both quantitatively and qualitatively, in part mediated by epigenetic modifications. Second, proteomic changes were elicited by different transcriptional modalities. Finally, transiently activated factors such as the peroxisome proliferator-activated receptor {gamma} coactivator 1 (PGC-1) are indispensable for normal training adaptation. Together, these results provide a molecular framework of the temporal and training status-dependent exercise response that defines muscle plasticity in training. HIGHLIGHTSO_LIVery few persistent transcriptional events define the trained muscle. C_LIO_LIThe training status determines the acute exercise response. C_LIO_LIEpigenetic changes shape the transcriptional specification of trained muscle. C_LIO_LIAbsence of the key regulator PGC-1 causes suboptimal training adaptations. C_LI

physiology↗

bioRxiv2022

Orientation-locked DNA origami for stable trapping of small proteins in the NEOtrap

Nanopores are versatile single-molecule sensors that offer a simple label-free readout with great sensitivity. We recently introduced the Nanopore Electro-Osmotic trap (NEOtrap) which can trap and sense single unmodified proteins for long times. The trapping is achieved by the electro-osmotic flow (EOF) generated from a DNA-origami sphere docked onto the pore, but thermal fluctuations of the origami limited the trapping of small proteins. Here, we use site-specific cholesterol functionalization of the origami sphere to firmly link it to the lipid-coated nanopore. We can lock the origami in either a vertical or horizontal orientation which strongly modulates the EOF. The optimized EOF greatly enhances the trapping capacity, yielding reduced noise, reduced measurement heterogeneity, an increased capture rate, and 100-fold extended observation times. We demonstrate the trapping of a variety of single proteins, including small ones down to a molecular mass of 14 kDa. The cholesterol functionalization significantly expands the application range of the NEOtrap technology.

biophysics↗

bioRxiv2022

Targeted insertion of reporter transgene into a gene safe harbor in human blood fluke, Schistosoma mansoni

The identification and characterization of genomic safe harbor sites (GSH) aims to facilitate consistent transgene activity without disruption to the host cell genome. We combined genome annotation and chromatin structure analysis by computational approach to predict the location of four GSHs in the human blood fluke, Schistosoma mansoni, a major infectious pathogen of the tropics. Introduction of a transgene into the egg of the parasite was accomplished using CRISPR/Cas-assisted homology-directed repair and overlapping guide RNAs. Gene editing efficiencies of 24% and transgene-encoded fluorescence of 75% of gene-edited schistosome eggs were observed. These outcomes advance functional genomics for schistosomes by providing a tractable path towards transgenic helminths using homology directed repair-catalyzed transgene insertion. This approach should be adaptable to helminths generally. MotivationFunctional genomics methods are needed in the arena of the Neglected Tropical Diseases, especially for helminth parasites, to facilitate basic and transformational studies to improve global public health. Gain-of-function phenotypes would be valuable in this context. Hence, the motivation for this investigation was to identify a genome safe harbor (GSH) site in the chromosomes of the human blood fluke, Schistosoma mansoni and, in a pilot approach, and to develop methods for transgene insertion and methods to characterize transgene performance following homology directed insertion at the schistosome GSH. The progress reported here can be expected to advance functional genomics for species of the Platyhelminthes - including model, free living species of planarians, and should be adaptable to helminths generally.

molecular biology↗

bioRxiv2022

Extensive hybridisation throughout clownfishes evolutionary history

The contribution of hybridisation in the generation of global species diversity has long been controversial among evolutionary biologists. However, it is now increasingly accepted that hybridisation has many impacts on the process of speciation. Notably, it is an important mechanism fostering adaptive radiation since it can generate new phenotypic combinations enabling the occupancy of new niches. Here, we focused on clownfish (Pomacentridae), a clade of 28 coral reef fishes displaying a mutualistic interaction with sea anemones. This behaviour is the key innovation that triggered adaptive radiation of clownfishes, as each species is able to occupy a different combination of host anemone species and habitat. Previous work suggested that hybridisation might be responsible for the extant diversity of clownfish species. To test this hypothesis, we analysed whole-genome datasets for each clownfish species. First, we reconstructed the phylogeny of the clade based on topology weighting methods, which enables the visualisation of the relationships between taxa across the genome. Then, we highlighted possible ancient hybridisation events based on a comparative genomic framework for detecting introgression in genomes. The resulting phylogeny is consistent with previous works based on a few mitochondrial and nuclear genes, and shallow nodes are now well supported in contrast to past studies. Furthermore, we detected multiple past hybridisation events throughout the evolutionary history of clownfishes, corroborating the potential role of hybridisation in the clownfish adaptive radiation. This study adds to the growing number of studies investigating the genomic mechanisms behind species diversification, drawing us closer to understanding how Earth biodiversity is generated.

evolutionary biology↗

bioRxiv2022

Cell-free Tumor Methylome Analysis of Small Cell Lung Cancer Patients Identifies Subgroups with Prognostic Associations

IntroductionSmall cell lung cancer (SCLC) is a highly aggressive type of cancer with a high risk of recurrence. The SCLC methylome may yield biologic insight but is understudied due to difficulty in acquiring primary patient tissue. Here, we comprehensively profile the SCLC methylome using cell-free methylated DNA immunoprecipitation sequencing (cfMeDIP-seq). MethodscfDNA was extracted from plasma samples collected from 74 SCLC patients prior to initiation of first-line treatment and from 20 non-cancer smoker participants. Genomic DNA (gDNA) was also extracted from paired peripheral blood leukocytes from the 74 SCLC patients and 7 accompanying circulating-tumour-cell patient-derived xenografts (CDX). cfDNA and gDNA were used as input for cfMeDIP-seq. We developed PeRIpheral blood leukocyte MEthylation (PRIME) subtraction as an algorithm to improve tumour specificity of cell-free methylome. ResultsSCLC total plasma cfDNA methylation profiles obtained using cfMeDIP-seq are representative of CDX tumour methylation. SCLC cfDNA methylation is distinct from non-cancer plasma. Using PRIME and k-means consensus clustering, we identified two SCLC methylome clusters with prognostic associations. These clusters had methylated biological pathways related to axon guidance, neuroactive ligand-receptor interaction, pluripotency of stem cells, and were differentially methylated at long noncoding RNA, LINEs, SINEs, retrotransposons, and other repeats features. ConclusionsWe have comprehensively profiled the SCLC methylome using cfMeDIP-seq in a large patient cohort and identified methylome clusters with prognostic associations. Our work demonstrates the potential of liquid biopsies in examining SCLC biology encoded in the methylome.

cancer biology↗

bioRxiv2022

The GEF-GAP pair Solo and DLC3 balances Rho activity during endocytic transport

The control of intracellular membrane trafficking by Rho GTPases is central to cellular homeostasis. How defined pairs of guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs) come together to locally balance GTPase activation cycles in this process is nevertheless largely unclear. By performing a microscopy-based RNAi screen we here identify the RhoGEF protein Solo as a counterpart of DLC3, a RhoGAP protein with established roles in membrane trafficking. Biochemical, imaging and optogenetics assays further uncover Solo as a novel regulator of endosomal RhoB. Remarkably, we find that the interplay between Solo and DLC3 controls not only the activity but also total protein levels of RhoB. Together, the results of our study uncover the first functionally connected RhoGAP-RhoGEF pair at endomembranes and place the Solo-DLC3 axis at the core of endocytic trafficking.

cell biology↗