Biology subjects

James, R.

Publications and source records attributed to James, R..

At least 19 recordsLinked to original sources

bioRxiv2026

Zebrafish Functional Screening of FDA-Approved Drugs for Autosomal Dominant Retinitis Pigmentosa Caused by RHODOPSIN Q344X Mutation

Retinitis Pigmentosa (RP) is a group of inherited retinal degenerations for which most subtypes lack effective drug treatments. This challenge is particularly critical for autosomal dominant (ad) RP, which is often unsuitable for gene replacement therapy. To address this challenge, we screened an FDA-approved compound library using a zebrafish adRP model expressing a human RHODOPSIN transgene with the Q344X mutation. The screen evaluated drug effects on larval visual behavior by assessing the visual-motor response (VMR). Four compounds significantly improved VMR in Q344X zebrafish: amitriptyline, difluprednate, maprotiline, and prednisolone. Further characterization revealed that these hits act through distinct mechanisms, including reducing rod death, promoting rod neogenesis, and enhancing the function of extraocular photoreceptors. Together, these findings demonstrate the potential to repurpose these drugs for adRP caused by the RHO Q344X mutation, providing preclinical candidates and revealing potential targets for future drug development.

neuroscience↗

bioRxiv2026

A look inside the net: freshwater turtles assort with conspecifics in feeding aggregations

Non-avian reptiles have been assumed to be non-social for many years, yet recent studies show diverse social behaviours in squamates, crocodilians, and turtles. Here, we investigate social structure within feeding aggregations of three freshwater turtle species caught in baited traps in a coastal marsh over 12 years. In 488 instances in which traps contained turtles, 45% contained multiple individuals, and these aggregations were strongly positively assorted by species. midland painted turtles (Chrysemys picta) and Blandings turtles (Emydoidea blandingii) were captured with conspecifics more often than expected in a non-social null model. Snapping turtles (Chelydra serpentina), the largest species in this study, were caught with conspecifics at rates consistent with the non-social null model, and were avoided by heterospecifics. This suggests that species differences play a role in how feeding aggregations are structured, with painted and Blandings turtles driving positive species assortment while avoiding snapping turtles around food sources. We did not detect significant intraspecific sex assortment in any of the three species, nor did turtle body size strongly affect the probability of aggregating with conspecifics at the perceived food source in the traps. Our study illustrates how long-term monitoring data can be used to investigate social structure in wild populations, an approach that may be valuable for species of conservation concern. Significance StatementReptile sociality has been historically overlooked, but recent work has revealed intriguing social behaviours in non-avian reptiles. We investigated associations among three species of freshwater turtle, captured in baited traps over 12 years of trapping. Turtles in these feeding aggregations grouped with their own species more often than expected by chance. This result was driven by the two smaller-bodied species (midland painted turtle and Blandings turtle), which were more likely to be caught with conspecifics than with other species. In contrast, the largest species (snapping turtle) showed no evidence of attraction to other snapping turtles, and midland painted turtles and Blandings turtles showed avoidance of the larger snapping turtles. Our analyses illustrate how long-term monitoring data can be used to uncover previously unrecognized social behaviour in turtles and other species in which behaviour is difficult to observe directly.

animal behavior and cognition↗

bioRxiv2026

Characterising retinal function with optomotor visual performance in P23H rodent models of retinitis pigmentosa

Rhodopsin (RHO) P23H is one of the most common mutations causing autosomal dominant retinitis pigmentosa (adRP), yet the relationship between retinal electrophysiology, structure and visually guided behaviour in rodent models remains unclear. We characterised changes in heterozygous P23H (Sakami line) mice and P23H line 3 (P23H-3) rats using full-field electroretinography (ERG), optomotor response (OMR) assays and, in rats, optical coherence tomography (OCT). ERG assessed rod- and cone-mediated responses relative to wild-type controls, whereas OMR under scotopic and photopic conditions quantified contrast sensitivity and visual acuity. In P23H mice, scotopic ERG responses were significantly reduced from postnatal day 16 and declined further from 4 months. Scotopic OMR contrast sensitivity remained largely preserved until 2 months, and photopic acuity was comparable to wild-type up to 6 months. In 13-week-old P23H-3 rats, ERG amplitudes were significantly reduced, and OCT revealed retinal thinning. OMR showed a decline in contrast sensitivity at 7 and 15 weeks, whereas photopic acuity was maintained. Thus, in both models, electrophysiological and structural abnormalities precede detectable OMR deficits, with implications for the selection of outcome measures in preclinical studies. Summary StatementThis study compares electrical and behavioural measures of vision in rodent models of inherited blindness, revealing that retinal dysfunction appears well before measurable vision loss.

animal behavior and cognition↗

bioRxiv2026

REMAG: recovery of eukaryotic genomes from metagenomic data using contrastive learning

Metagenome-assembled genomes (MAGs) are central to exploring microbial communities. Yet, despite the relevance of protists and fungi to diverse ecosystems, eukaryotic MAG recovery lags behind that of prokaryotes. A major bottleneck is that most state-of-the-art binning pipelines exclusively rely on prokaryotic single-copy core gene reference databases and are optimized for smaller genomes. To address this gap, we present REMAG (Recovery of Eukaryotic MAGs), a tool designed to recover high-quality eukaryotic genomes suited for longread metagenomic data. REMAG leverages finetuned HyenaDNA genomic foundation models to efficiently filter eukaryotic contigs. It then employs a dual-encoder Siamese network trained with Barlow Twins contrastive loss to learn a shared embedding space by integrating contig composition and differential coverage. Finally, high-quality bins are extracted using greedy iterative Leiden clustering optimized with eukaryotic single-copy core gene constraints. In benchmarks based on simulated mixed prokaryotic/eukaryotic communities and real datasets of varying sizes and origin, we demonstrate REMAGs ability to recover more near-complete eukaryotic genomes than existing state-of-the-art tools, which often produce highly fragmented eukaryotic bins. REMAG provides an automated eukaryotic binning method that scales effectively with the increasing size and sequencing depth of metagenomic datasets.

bioinformatics↗

bioRxiv2025

Phenologically Explicit Robustness Metric Reveals Increased Vulnerabilities in Temporal Plant-Pollinator Networks

Robustness is a useful metric in evaluating the ability of an ecosystem to resist further extinction after species loss. This measure is straightforward to calculate from empirical interaction data, however doing so typically requires a static network of time-aggregated interactions, ignoring the finer-scale variation imposed by species phenologies. Although the analysis of time-aggregated ecological networks has been successful in capturing their overall structure, it often leads to the loss of information of the within-season variation that ecosystems typically exhibit. We demonstrate how this approach can also dramatically overestimate robustness by assuming all interactions are concurrent. Here, we develop a new measure of temporal robustness that incorporates the time-varying nature of species interactions. We apply our measure to plant-pollinator systems using both simulated and empirical networks, and obtain analytical predictions for the temporal robustness of randomly generated networks. In each case, our analysis reveals a substantial loss of information in the established static-network robustness measure, which obscures the crucial role of phenology in determining the vulnerability of pollinators to species loss. We find that pollinators active over long time periods appear more robust after time-aggregation, but typically have a much lower temporal robustness, indicating that long-lived pollinators may be more vulnerable to plant loss than previously thought.

ecology↗

bioRxiv2025

Pre-clinical validation of a novel AAV-mediated gene therapy for KCNV2 retinopathy improves visual function in a mouse model and expression in patient organoids

Voltage-gated (Kv) potassium channels are critical for neuronal physiology, and their dysfunction can lead to serious consequences. For example, mutations in the silent modulatory Kv8.2 subunit are known to cause irreversible inherited blindness (KCNV2 retinopathy). This is a currently incurable condition that causes lifelong visual loss, reduced visual acuity, photoaversion, night blindness and abnormal colour vision, alongside a distinctive supernormal electrophysiological (ERG) retinal response to light. In this study, we demonstrate that AAV-mediated gene replacement therapy delivering a codon-optimised human KCNV2 gene subretinally into Kv8.2 knock-out mice significantly restores retinal function. Treated mice exhibited improved ERG responses and correct expression of KCNV2 and its encoded Kv8.2 protein in photoreceptors. Recovery of visually guided scotopic and photopic optomotor responses to wildtype levels was achieved at lower vector doses, highlighting dose-dependent efficacy. Furthermore, treatment of human retinal organoids derived from a KCNV2 patient iPSC line resulted in substantial Kv8.2 protein rescue. This work provides the first preclinical proof-of-concept for the safety and therapeutic potential of gene therapy for KCNV2 retinopathy, laying a strong foundation for future clinical trials.

neuroscience↗

bioRxiv2025

Optimizing storage, high-molecular weight DNA extraction and genome reconstructions from human faecal samples.

Metagenomic sequencing has become an essential tool for assessing the composition and functional potential of microbial communities. However, established metagenomic DNA extraction protocols are limited by trade-offs between universal taxonomic representation, DNA quality, quantity and molecule length, making them mostly unsuitable for 3rd generation sequencing. MethodsWe assessed the effectiveness of high molecular weight (HMW) DNA workflows from faecal samples, using different combinations of collection, storage and extraction kits. Faecal samples were either immediately processed, frozen at -80{degrees}C or stored in DNA/RNA Shield, GutAlive or OMNIgeneGUT and then subjected to three different DNA isolation kits, each modified for mechanical, chemical and enzymatic cell lysis steps, totalling 32 evaluated combinations. Isolated DNA was assessed for its quality and quantity, while taxonomic consistency was evaluated using metataxonomics and validated with metagenomic sequencing. ResultsThe yield of HMW DNA differed substantially between storage and DNA extraction protocols. Specifically, storage protocol had the highest impact on HMW DNA recovery, with DNA/RNA Shield storage yielding on average 51% more HMW DNA >30kb. Similarly, the sample storage had independently the effect size of R2 = 26.9% on the microbiome composition, and since the DNA extraction protocol in our study inherently combines both DNA extraction kit and lysis type, the latter had the largest effect size (R2 = 12.8%). While all kits had specific dis/advantages and biases, DNA/RNA Shield and Maxwell RSC PureFood GMO and Authentication kit performed best overall for long-read metagenomics. The protocol was validated on a) isolate genomes and b) 4 faecal samples, demonstrating both increased DNA yield at >30kb molecule length. Using the MG-TK pipeline these metagenomes yielded genomes on average, per sample, 48 Pacific Biosciences (PacBio) and 55 Oxford Nanopore Technologies (ONT) circular bacterial metagenomic assembled genomes. ConclusionThe current gold-standard of freezing faecal samples was surprisingly inconsistent and inefficient for long-read metagenomics, necessitating rethinking gut microbial study designs. We provide a simple and cheap protocol that preserves both taxonomic composition and HMW DNA quality, while our bioinformatics workflow allows for complete bacterial genome reconstruction.

molecular biology↗

bioRxiv2025

Sealable capped nanovials for high-throughput screening of cell growth and function

Millions of modular nanoliter-scale compartments that isolate functionally rich single-cell and cell-to-cell communication data can scale biological discovery for the age of AI. Here, we introduce capped nanovials--suspendable, sealable microscale compartments formed by the docking of hydrogel capping particles into bowl-shaped nanovials--as a versatile system for culturing, analyzing, and sorting single cells and small colonies. This two-particle architecture enables localized confinement of cells and secreted products while maintaining compatibility with standard laboratory workflows such as wash and reagent exchange steps, fluorescence microscopy, and flow cytometry. Crucially, these compartments are formed via simple pipetting and centrifugation steps, making the platform highly democratized. We demonstrate the ability of capped nanovials to compartmentalize single mammalian, bacterial, and yeast cells and support growth into colonies, enabling selection based on proliferation and bioproduction. We further show that capped nanovials enhance single-cell secretion assays by reducing molecular crosstalk and increasing signal-to-noise ratios. Importantly, we demonstrate functional co-culture assays by permitting stable confinement of cell pairs, enabling detection and enrichment of antibody-secreting cells based on the ability of their secreted antibodies to activate co-encapsulated reporter T cells, achieving a signal-to-noise ratio of >30 and up to 100% selection purity. By combining the simplicity of standard lab handling with the resolution and throughput of traditional microfluidic compartmentalization approaches, capped nanovials provide a new class of scalable, accessible test tubes for modern single-cell biology.

bioengineering↗

bioRxiv2025

High-quality metagenome assembly from nanopore reads with nanoMDBG

Third-generation long-read sequencing technologies, have been shown to significantly enhance the quality of metagenome assemblies. The results obtained using the highly accurate reads generated by PacBio HiFi have been particularly notable yielding hundreds of circularized, complete genomes as metagenome-assembled genomes (MAGs) without manual intervention. Oxford Nanopore Technologies (ONT) has recently improved the accuracy of its sequencing reads, achieving a per-base error rate of approximately 1-2%. Given the high-throughput, convenience and low-cost of ONT sequencing this could accelerate the uptake of long read metagenomics. However, current metagenome assemblers are optimized for PacBio HiFi data and underperform on the latest ONT data and do not scale to the large data sets that it enables. We present nanoMDBG, an evolution of the metaMDBG HiFi assembler, designed to support newer ONT sequencing data through a novel pre-processing step that performs fast and accurate error correction in minimizer-space. Across a range of ONT datasets, including a large 400 Gbp soil sample sequenced specifically for this study, nanoMDBG reconstructs up to twice as many high-quality MAGs as the next best ONT assembler, metaFlye, while requiring a third of the CPU time and memory. As a result of these advances, we show that the latest ONT technology can now produce results comparable to those obtained using PacBio HiFi sequencing at the same sequencing depth.

bioinformatics↗

bioRxiv2024

Multi-reactive hydrogel nanovials for temporal control of secretion capture from antibody-secreting cells

Antibody discovery can benefit from techniques to screen antibody-secreting cells (ASCs) at scale for the binding and functionality of a diverse set of secreted antibodies. Previously, we demonstrated the use of cavity-containing hydrogel microparticles (nanovials) coated with a single affinity agent, biotin, to capture and identify ASCs secreting antibodies against a recombinant antigen bound to the nanovial through biotin-streptavidin linkages. However, rapidly secreted antibodies from unbound cells or cells in adjacent nanovials can cause crosstalk leading to background signal. Earlier efforts address this by localizing capture sites to the nanovial cavity, emulsifying nanovials, or short secretion times to limit secreted antibodies from binding to neighboring nanovials. Here, we demonstrate a method to functionalize nanovials with moieties that impart orthogonal reactivity, enabling conjugation of cell capture antibodies and antigens at different times. We show that by using a strained alkyne moiety to attach cell-capture antibodies via click chemistry to nanovials, we can capture cells and subsequently quantify secretions via biotin-streptavidin linkages. By delaying the loading of antigens onto the nanovials until after cell capture, we were able to ensure high purity (>95%) isolation of hybridoma secreting an antigen-specific antibody in a background of other hybridoma. This approach allows tight temporal control of the secretion measurement, which is independent of the cell loading time, and requires less convective transfer steps. Click chemistry-based coupling further improved cell loading into nanovials by 58% compared to biotin-streptavidin-biotin coupling and caused no reduction in cell viability. We demonstrate an implementation of this system to improve antigen-specific hybridoma screening, yielding an 8-fold improvement in hybridoma enrichment while maintaining a similar workflow complexity. Hybridomas on nanovials sorted into well plates regrew into colonies following sorting using standard fluorescence-activated cell sorting and maintained secretion of antigen-specific antibodies with high purity ([~]90%), as validated via standard enzyme-linked immunosorbent assays. This lab-on-a-particle approach can be applied more generally to decouple cell loading, treatment, or activation, from secretion measurements for single-cell functional assays.

bioengineering↗

bioRxiv2024

A blended genome and exome sequencing method captures genetic variation in an unbiased, high-quality, and cost-effective manner

We deployed the Blended Genome Exome (BGE), a DNA library blending approach that generates low pass whole genome (1-4x mean depth) and deep whole exome (30-40x mean depth) data in a single sequencing run. This technology is cost-effective, empowers most genomic discoveries possible with deep whole genome sequencing, and provides an unbiased method to capture the diversity of common SNP variation across the globe. To evaluate this new technology at scale, we applied BGE to sequence >53,000 samples from the Populations Underrepresented in Mental Illness Associations Studies (PUMAS) Project, which included participants across African, African American, and Latin American populations. We evaluated the accuracy of BGE imputed genotypes against raw genotype calls from the Illumina Global Screening Array. All PUMAS cohorts had R2 concordance [≥]95% among SNPs with MAF[≥]1%, and never fell below [≥]90% R2 for SNPs with MAF<1%. Furthermore, concordance rates among local ancestries within two recently admixed cohorts were consistent among SNPs with MAF[≥]1%, with only minor deviations in SNPs with MAF<1%. We also benchmarked the discovery capacity of BGE to access protein-coding copy number variants (CNVs) against deep whole genome data, finding that deletions and duplications spanning at least 3 exons had a positive predicted value of [~]90%. Our results demonstrate BGE scalability and efficacy in capturing SNPs, indels, and CNVs in the human genome at 28% of the cost of deep whole-genome sequencing. BGE is poised to enhance access to genomic testing and empower genomic discoveries, particularly in underrepresented populations.

genomics↗

bioRxiv2024

Patient-specific responses to SMN2 splice-modifying treatments in spinal muscular atrophy fibroblasts

The availability of three therapies for the neuromuscular disease spinal muscular atrophy (SMA) highlights the need to match patients to the optimal treatment. Two of these treatments (nusinersen and risdiplam) target splicing of SMN2, but treatment outcomes vary from patient to patient. An incomplete understanding of the complex interactions between SMA genetics, SMN protein and mRNA levels, and gene-targeting treatments, limits our ability to explain this variability and identify optimal treatment strategies for individual patients. To address this, we analyzed responses to nusinersen and risdiplam in 45 primary fibroblast cell lines. Pre-treatment SMN2-FL, SMN2{Delta}7 mRNA, and SMN protein levels were influenced by SMN2 copy number, age, and sex. After treatment, SMN and mRNA levels were more heterogeneous. In 43% of patients, response to both therapies was similar, but in 57% one treatment led to a significantly higher SMN increase than the other treatment. Younger age, higher SMN2 copy number, and higher SMN levels before treatment predicted better in vitro efficacy. These findings showcase patient-derived fibroblasts as a tool for identifying molecular predictors for personalized treatment.

molecular biology↗

bioRxiv2024

3D quantification of viral transduction efficiency in living human retinal organoids

The development of therapeutics builds on testing their efficiency in vitro. To optimize gene therapies, for example, fluorescent reporters expressed by treated cells are typically utilized as readouts. Traditionally, their global fluorescence signal has been used as an estimate of transduction efficiency. However, analysis in individual cells within a living 3D tissue remains a challenge. Readout on a single-cell level can be realized via fluorescence-based flow cytometry at the cost of tissue dissociation and loss of spatial information. Complementary, spatial information is accessible via immunofluorescence of fixed samples. Both approaches impede time-dependent studies on the delivery of the vector to the cells. Here, quantitative 3D characterization of viral transduction efficiencies in living retinal organoids is introduced. The approach combines quantified gene delivery efficiency in space and time, leveraging human retinal organoids, engineered adeno-associated virus (AAV) vectors, confocal live imaging, and deep learning-based image segmentation. The integration of these tools in an organoid imaging and analysis pipeline allows quantitative testing of future treatments and other gene delivery methods. It has the potential to guide the development of therapies in biomedical applications.

neuroscience↗

bioRxiv2023

Efficient High-Quality Metagenome Assembly from Long Accurate Reads using Minimizer-space de Bruijn Graphs

We introduce a novel metagenomics assembler for high-accuracy long reads. Our approach, implemented as metaMDBG, combines highly efficient de Bruijn graph assembly in minimizer space, with both a multi-k' approach for dealing with variations in genome coverage depth and an abundance-based filtering strategy for simplifying strain complexity. The resulting algorithm is more efficient than the state-of-the-art but with better assembly results. metaMDBG was 1.5 to 12 times faster than competing assemblers and requires between one-tenth and one-thirtieth of the memory across a range of data sets. We obtained up to twice as many high-quality circularised prokaryotic metagenome assembled genomes (MAGs) on the most complex communities, and a better recovery of viruses and plasmids. metaMDBG performs particularly well for abundant organisms whilst being robust to the presence of strain diversity. The result is that for the first time it is possible to efficiently reconstruct the majority of complex communities by abundance as nearcomplete MAGs.

bioinformatics↗

bioRxiv2021

Transcriptomic analysis of pathways associated with alpha(v) integrin-related non-canonical autophagy in human B cells

Autophagy proteins have been linked with development of immune-mediated diseases including lupus, but the mechanisms for this are unclear. We have previously shown that non-canonical autophagy induced by v-integrins regulates B cell activation by viral and self-antigens in mice. Here we investigated the involvement of this pathway in B cells from human tissue. Our data revealed that autophagy is specifically induced in germinal-center and memory B cell sub-populations from human tonsil and spleen. Transcriptomic analysis showed that induction of autophagy is related to unique aspects of activated B cells such as mitochondrial metabolism. To understand the function of non-canonical autophagy in B cells, we used CRISPR-mediated knockdown of autophagy genes. Integrating data from primary B cells and knockout cells we found that v-integrin-related non-canonical autophagy limits activation of specific pathways while promoting others. These data provide new mechanistic links for autophagy and immune dysregulation in diseases such as lupus.

immunology↗

bioRxiv2021

TNF-mediated neuroinflammation is linked to neuronal necroptosis in Alzheimer's disease hippocampus

The pathogenetic mechanisms underlying neuronal death and dysfunction in Alzheimers disease (AD) remain unclear. However, chronic neuroinflammation has been implicated in stimulating or exacerbating neuronal damage. The tumor necrosis factor (TNF) superfamily of cytokines are involved in many systemic chronic inflammatory and degenerative conditions and are amongst the key mediators of neuroinflammation. TNF binds to the TNFR1 and TNFR2 receptors to activate diverse cellular responses that can be either neuroprotective or neurodegenerative. In particular, TNF can induce programmed necrosis or necroptosis in an inflammatory environment. Although activation of necroptosis has recently been demonstrated in the AD brain, its significance in AD neuron loss and the role of TNF signaling is unclear. We demonstrate an increase in expression of multiple proteins in the TNF/TNF receptor-1-mediated necroptosis pathway in the AD post-mortem brain, as indicated by the phosphorylation of RIPK3 and MLKL, predominantly observed in the CA1 pyramidal neurons. The density of phosphoRIPK3+ and phosphoMLKL+ neurons correlated inversely with total neuron density and showed significant sexual dimorphism within the AD cohort. In addition, apoptotic signaling was not significantly activated in the AD brain compared to the control brain. Exposure of human iPSC-derived glutamatergic neurons to TNF increased necroptotic cell death when apoptosis was inhibited, which was significantly reversed by small molecule inhibitors of RIPK1, RIPK3, and MLKL. In the post-mortem AD brain and in human iPSC neurons to TNF, we show evidence of altered expression of proteins of the ESCRT III complex, which has been recently suggested as an antagonist of necroptosis and a possible mechanism by which cells can survive after necroptosis has been triggered. Taken together, our results suggest that neuronal loss in AD is due to TNF-mediated necroptosis rather than apoptosis, which is amenable to therapeutic intervention at several points in the signaling pathway.

neuroscience↗

bioRxiv2021

Genetic structure correlates with ethnolinguistic diversity in eastern and southern Africa

African populations are the most diverse in the world yet are sorely underrepresented in medical genetics research. Here, we examine the structure of African populations using genetic and comprehensive multigenerational ethnolinguistic data from the Neuropsychiatric Genetics of African Populations-Psychosis study (NeuroGAP-Psychosis) consisting of 900 individuals from Ethiopia, Kenya, South Africa, and Uganda. We find that self-reported language classifications meaningfully tag underlying genetic variation that would be missed with consideration of geography alone, highlighting the importance of culture in shaping genetic diversity. Leveraging our uniquely rich multi-generational ethnolinguistic metadata, we track language transmission through the pedigree, observing the disappearance of several languages in our cohort as well as notable shifts in frequency over three generations. We find suggestive evidence for the rate of language transmission in matrilineal groups having been higher than that for patrilineal ones. We highlight both the diversity of variation within the African continent, as well as how within-Africa variation can be informative for broader variant interpretation; many variants appearing rare elsewhere are common in parts of Africa. The work presented here improves the understanding of the spectrum of genetic variation in African populations and highlights the enormous and complex genetic and ethnolinguistic diversity within Africa.

genomics↗

bioRxiv2020

Deletion of Gremlin-2 alters estrous cyclicity and disrupts female fertility in mice

Members of the differential screening-selected gene aberrative in neuroblastoma (DAN) protein family are developmentally conserved extracellular binding proteins that antagonize bone morphogenetic protein (BMP) signaling. This protein family includes the Gremlin proteins, GREM1 and GREM2, which are known to have key functions during embryogenesis and adult physiology. While BMPs play essential roles in adult female reproductive physiology, the role of the DAN family in ovarian function is less understood. We generated mice null for Grem2 to study its role in female fertility in addition to screening patients with primary ovarian insufficiency for variants in GREM2. Grem2-/- mice are viable and female Grem2-/- mice have diminished fecundity and irregular estrous cycles. This is accompanied by reduced serum levels of anti-Mullerian hormone, a marker of the ovarian reserve, in adult mice. Alterations in ovarian expression of inhibin and activin subunit genes, which are required for regulation of the hypothalamic-pituitary-ovarian (HPO) axis, were identified. While Grem2 mRNA transcript was not detected in the pituitary, Grem2 was expressed in the hypothalami of wild type female mice. Additionally, screening 106 women with primary ovarian insufficiency identified one individual with a heterozygous variant in GREM2 that lies within the predicted BMP-GREM2 interface. In total, these data suggest that Grem2 is necessary for female fecundity by playing a novel role in regulating the HPO axis and possibly contributing to female reproductive disease.

physiology↗