Summary Beta-propeller protein-associated neurodegeneration (BPAN) is a rare neurological disease characterized by severe cognitive and motor impairments. BPAN is caused by de novo pathogenic variants in the WDR45 gene on the X chromosome. WDR45 gene encodes the protein WDR45/WIPI4, a known regulator of autophagy. A defective autophagy has been observed in cellular models of BPAN disease and is associated with neurological dysfunctions in WDR45 knockout (KO) mice. However, it remains unclear whether the autophagic defect directly contributes to all WDR45 loss-induced phenotypes or whether other WDR45-dependent cellular functions are involved. To investigate this, we generated a CRISPR/Cas9-mediated KO of CG11975 ( dwdr45 KO), the Drosophila homolog of WDR45 . Our analysis revealed that dwdr45 KO flies display BPAN-like phenotypes, including impaired locomotor function, autophagy dysregulation and iron dyshomeostasis. Additionally, dwdr45 KO flies exhibit shorten lifespan compared to control flies. These findings demonstrate that dwdr45 KO fly is a relevant model for investigating the key cellular and molecular mechanisms underlying BPAN-associated phenotypes. Notably, induction of autophagy in dwdr45 KO flies partially rescued the shortened lifespan, but did not restore locomotor function. This suggests that defective autophagy contributes to some, but not all, aspects of the phenotypes resulting from loss of dwdr45 function.

ABSTRACT Marchantia polymorpha oil bodies (OBs) are specialised cell structures housing a diverse array of C15-terpenes, called sesquiterpenes. These compounds are known for their roles as herbivore repellents, yet the enzymes responsible for the biosynthesis of their precursors (C5 isoprenoid units) remain poorly characterized. Discrepancies remain between enzyme localizations suggested by computational predictions and those observed in earlier experimental studies, complicating our understanding of terpene biosynthesis. We investigated the localization of isoprenoid biosynthetic enzymes using translational and transcriptional reporters, coupled with confocal microscopy. Most enzymes localized as predicted ( e.g ., cytosol, chloroplast and the endoplasmic reticulum), and OB cells were identified as the primary sites of terpene biosynthesis. To explore OBs as potential storage sites for terpenes, we attempted to produce exogenous but easily identifiable compounds in Marchantia , such as the diterpene taxadiene and the triterpene β-amyrin. Targeting to OB cells resulted in measurable amounts of these compounds, but their yields remained unaffected by the over-expression of key precursor genes, underscoring challenges in redirecting metabolic flux. To further investigate terpene accumulation in OBs, we focused on ABCG1, an ABC transporter previously reported to localize at the OB membrane. Overexpression of ABCG1 in OB cells, alongside an exogenous sesquiterpene synthase, only increased the levels of endogenous sesquiterpenes, while CRISPR-mediated disruption of ABCG1 resulted in a dramatic reduction in sesquiterpene accumulation. These findings establish ABCG1 as a critical factor for sesquiterpene retention within OBs and provide new insights into the mechanisms governing terpene metabolism and storage in Marchantia polymorpha .

Patient sex influences a wide range of cancer phenotypes, including prevalence, response to therapy and survival endpoints. Molecular sex differences have been identified at all levels of the central dogma. It is hypothesized that these molecular differences may drive the observed clinical sex differences. Yet despite a growing catalog of molecular sex differences in a range of cancer types, their specific functional consequences remain unclear. To directly assess how patient sex impacts cancer cell function, we evaluated 1,209 cell lines subjected to CRISPR knockout, RNAi knockdown or drug exposures. Despite limited statistical power, we identified pan- and per-cancer sex differences in gene essentiality in six sex-linked and fourteen autosomal genes, and in drug sensitivity for two compounds. These data fill a gap in our understanding of the link between sex-differential molecular effects and patient phenotypes. They call for much more careful and systematic consideration of sex-specific effects in mechanistic and functional studies.

SUMMARY CARD9 is an attractive target for therapeutic intervention because the human genetic data provides strong evidence for the causal role of CARD9 in both protection and susceptibility to autoimmune disease. Expression quantitative trait loci (eQTLs) link higher CARD9 expression to increased disease risk and lower CARD9 expression to protection. Additionally, a rare allele variant leading to a C-terminal truncation of CARD9 (CARD9Δ11) and subsequent loss-of-function is also protective for inflammatory bowel disease (IBD). The mechanism of CARD9-driven inflammation through scaffold assembly with BCL10 and MALT1 (CBM complex) suggests a durable inflammatory signal driven by increasing levels of CARD9. Therefore, CARD9 depletion is a desired therapeutic strategy for drug discovery, yet a difficult one due to the nature of CARD9 as an adaptor protein target and the limited number of chemical tools available to engage it. Here, we uncover through a protein homeostasis screen that casein kinase 2 (CK2/CSNK2) inhibition leads to cellular CARD9 depletion. Following up with arrayed CRISPR screening, we identify key casein kinase isoforms/subunits responsible for CARD9 depletion. We find that CK2 directly binds to CARD9 and phosphorylates S424/S425 as well as S483/S484. Orthosteric CK2 inhibition prevents CK2 binding to CARD9 and leads to CARD9 destabilization. We show that the interaction between CK2 and CARD9Δ11 is significantly attenuated and not sensitive to CK2-mediated protein stabilization. The CK2-driven CARD9 depletion mechanism is preserved outside of immortalized cell lines and conserved between primary, differentiated mouse and human dendritic cells. Finally, we demonstrate therapeutic proof of concept in vivo using CK2 inhibition to deplete CARD9 in murine whole blood, peritoneum, and colon. Our study expands the scope of cellular consequences dealt by kinase inhibition, offers an unconventional approach for engaging a therapeutically intractable target, and identifies a novel mechanism that could contribute to disease protection conferred by the CARD9Δ11 allele.

ABSTRACT Bacteria and archaea employ a rudimentary immune system, CRISPR-Cas, to protect against foreign genetic elements such as bacteriophage. CRISPR-Cas systems are found in Bombella apis, a microbe associated with honey bee queens, brood, and royal jelly. Unlike other honey bee microbiome members, B. apis does not colonize the worker bee midgut or hindgut and has therefore been understudied with regards to its importance in the honey bee colony. However, B. apis appears to play beneficial roles in the colony, by protecting developing brood from fungal pathogens and by bolstering their development under nutritional stress. Previously we identified CRISPR-Cas systems as being acquired by B. apis in its transition to bee association, as they are absent in a sister clade. Here we assess the variation and distribution of CRISPR-Cas types across B. apis strains. We found multiple CRISPR-Cas types, some of which have multiple arrays, within the same B. apis genomes and also in the honey bee queen gut metagenomes. We analyzed the spacers between strains to identify the history of mobile element interaction for each B. apis strain. Finally, we predict interactions between viral sequences and CRISPR systems from different honey bee microbiome members. Our analyses show that the B. apis CRISPR-Cas systems are dynamic, that microbes in the same niche have unique spacers which supports the functionality of these CRISPR-Cas systems, and that acquisition of new spacers may be occurring in multiple locations in the genome, allowing for a flexible antiviral arsenal for the microbe. IMPORTANCE Honey bee worker gut microbes have been implicated in everything from protection from pathogens to breakdown of complex polysaccharides in the diet. However, there are multiple niches within a honey bee colony that host a different group of microbes, including the acetic acid bacterium Bombella apis. B. apis is found in the colony food stores, in association with brood, in worker hypopharyngeal glands, and in the queen digestive tract. The roles that B. apis may serve in these environments are just beginning to be discovered and include production of a potent antifungal that protects developing bees and supplementation of dietary lysine to young larvae, bol-stering their nutrition. Niche specificity in B. apis may be affected by the pressures of bacteriophage and other mobile elements which may target different strains in each specific bee environment. Studying the interplay between B. apis and its mobile genetic elements (MGEs) may help us better understand microbial community dynamics within the colony and the potential ramifications for the honey bee host.

ABSTRACT The SARS-CoV-2 pandemic and the emergence of novel variants underscore the need to understand host-virus interactions and identify host factors that restrict viral infection. Here, we perform a genome-wide CRISPR knockout screen to identify host restriction factors for SARS-CoV-2, revealing DAZAP2 as a potent antiviral gene. DAZAP2, previously implicated in SARS-CoV-2 restriction, is found to inhibit viral entry by blocking virion fusion with both endolysosomal and plasma membranes. Additionally, DAZAP2 suppresses genomic RNA replication without affecting the primary translation of viral replicases. We demonstrate that DAZAP2 functions as a pan-coronavirus restriction factor across four genera of coronaviruses. Importantly, knockout of DAZAP2 enhances SARS-CoV-2 infection in mouse models and in human primary airway epithelial cells, confirming its physiological relevance. Mechanistically, antiviral activity of DAZAP2 appears to be indirect, potentially through the regulation of host gene expression, as it primarily localizes to the nucleus. Our findings provide new insights into the host defense system against coronaviruses and highlight DAZAP2 as a potential target for host-directed antiviral therapies. IMPORTANCE During viral infection, the host defense response is mediated by a variety of host factors through distinct mechanisms that have yet to be fully elucidated. Although DAZAP2 was previously implicated in SARS-CoV-2 restriction, its mechanisms of action and in vivo relevance remain unclear. In this study, we identify the DAZAP2 as a potent pan-coronavirus restriction factor that inhibits viral infection through dual mechanisms: blocking virion fusion with both endolysosomal and plasma membranes, and suppressing genomic RNA replication. We confirm its physiological relevance in host defense using mouse models and primary cell cultures. This study advances our understanding of host-pathogen interactions. Targeting DAZAP2 or its regulatory pathways could provide a new approach to enhance host defense against current and future coronavirus threats.

In maize, there are two meiotic drive systems that operate on large tandem repeat arrays called knobs that are found on chromosome arms. One meiotic drive haplotype, Abnormal chromosome 10 (Ab10), encodes two kinesin proteins that interact with two distinct tandem repeat arrays in a sequence-specific manner to confer meiotic drive. The kinesin KINDR associates with knob180 repeats while the kinesin TRKIN associates with TR-1 repeats. Prior data show that meiotic drive is conferred primarily by the KINDR/knob180 system, with the TRKIN/TR-1 system having little or no role. The second meiotic drive haplotype, K10L2, shows low levels of meiotic drive and only encodes the TRKIN/TR-1 system. Here we used long-read sequencing to assemble the K10L2 haplotype and showed that it has strong homology to an internal portion of the Ab10 haplotype. We also carried out CRISPR mutagenesis of Trkin to test the role of Trkin on Ab10 and K10L2. The data indicate that the Trkin gene on Ab10 does not improve drive or fitness but instead has a weak deleterious effect when paired with a normal chromosome 10. The deleterious effect is more severe when Ab10 is paired with K10L2: in this context functional Trkin on either chromosome nearly abolishes Ab10 drive. We modeled the effect of Trkin on Ab10 and found it should not persist in the population. We conclude that Trkin either confers an advantage to Ab10 in untested circumstances or that it is in the process of being purged from the Ab10 population.

An autosomal dominant GGGGCC repeat expansion in intron 1 of the C9orf72 gene is the most common genetic cause of both amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Here, we set out to engineer a gene targeted mouse model harbouring a pathogenic length humanised C9orf72 repeat expansion allele, in order to model pathological mechanisms in a physiological context. In human disease, pathogenic repeats typically range from the hundreds to thousands of units in length, representing a considerable challenge for cellular and in vivo model generation given the instability of GC rich and repetitive DNA sequences during molecular cloning. To overcome this challenge, we developed new methodology to synthetically and iteratively build pure GGGGCC repeats within a linear vector system, which we then seamlessly and scarlessly embedded within the native human genomic sequence. This created a gene targeting DNA vector for homologous recombination of the human sequence in mouse embryonic stem cells. We used this novel targeting vector to generate a new gene targeted mouse allele, C9orf72 h370 , that for the first time has mouse C9orf72 intron 1 scarlessly replaced with human intron 1 including a pure (GGGGCC) 370 hexanucleotide repeat expansion. We confirm that the mouse model expresses human intron 1-derived RNA and produces dipeptide repeat proteins derived from the GGGGCC repeat expansion. We now provide this model as a new freely available resource for the field. In addition, we demonstrate the utility of our cloning method for engineering diverse repeat expansion sequences for modelling other disorders, such as Fragile X Syndrome.

Parasitic weed infestations pose an increasing threat to agriculture worldwide, especially in the Mediterranean region. Phelipanche ramosa and P. aegyptiaca (broomrapes) cause severe damage to field-grown tomato ( Solanum lycopersicum L. ). Strigolactones (SLs), apocarotenoid phytohormones, play a critical role in plant physiology and development, and are also the primary signals that trigger the germination of parasitic weed seeds. We generated CRISPR/Cas9 tomato knock-out lines for the SlD27 gene, as well as three other key genes involved in SL biosynthesis ( SlCCD7 , SlCCD8 , SlMAX1 ), all within the same genetic background. The edited lines exhibited a marked reduction in SL content in root exudates, along with impaired broomrape seed germination. A comprehensive analysis of morphological, reproductive, and fruit-related traits revealed gene-specific effects on plant phenotype, including vegetative traits, fruit set, fruit development, and volatilome. Specifically, the knock-out of two CCDs and the MAX1 had a specific impact not only on plant development but also on the production of volatile organic compounds during fruit ripening. In contrast, the Sld27 lines, produced for the first time in this study, displayed a phenotype similar to the control non-edited plants, suggesting that the D27 gene holds promise as a breeding target for enhancing resistance to parasitic weeds in tomato. Highlight The characterization of tomato CRISPR/Cas9-edited lines for the four core genes involved in strigolactone biosynthesis revealed gene-specific effects on plant phenotype, with D27 emerging as a potential target for resistance to parasitic weeds.

ABSTRACT The first years of life are essential for the development of memory T cells, which rapidly populate the body’s diverse tissue sites during infancy. However, the degree to which tissue memory T cell responses in early life reflect those during adulthood is unclear. Here, we use single cell RNA-sequencing of resting and ex vivo activated T cells from lymphoid and mucosal tissues of infant (aged 2-9 months) and adult (aged 40-65 years) human organ donors to dissect the transcriptional programming of memory T cells over age. Infant memory T cells demonstrate a unique stem-like transcriptional profile and tissue adaptation program, yet exhibit reduced activation capacity and effector function relative to adults. Using CRISPR-Cas9 knockdown, we define Helios ( IKZF2 ) as a critical transcriptional regulator of the infant-specific tissue adaptation program and restricted effector state. Our findings reveal key transcriptional mechanisms that control tissue T cell fate and function in early life.

Bedaquiline is the cornerstone of a new regimen for the treatment of drug-resistant tuberculosis. However, its clinical use is threatened by the emergence of bedaquiline-resistant strains of Mycobacterium tuberculosis . Bedaquiline targets mycobacterial ATP synthase but the predominant route to clinical bedaquiline resistance is via upregulation of the MmpS5L5 efflux pump due to mutations that inactivate the transcriptional repressor Rv0678. Here, we show that the MmpS5L5 efflux pump reduces susceptibility to bedaquiline as well as its new, more potent derivative TBAJ-876 and other antimicrobial substrates, including clofazimine and the DprE1 inhibitors PBTZ-169 and OPC-167832. Furthermore, the increased resistance of Rv0678 mutants stems entirely from increased MmpS5L5 activity. These results highlight the potential of a pharmacological MmpS5L5 inhibitor to increase drug efficacy. Verapamil, primarily used as a calcium channel inhibitor, is known to inhibit diverse efflux pumps and to potentiate bedaquiline and clofazimine activity in M. tuberculosis . Here, we show that verapamil potentiates the activity of multiple diverse MmpS5L5 substrates. Using biochemical approaches, we demonstrate that verapamil does not exert this effect by acting as a disruptor of the protonmotive force used to power MmpS5L5, as previously proposed, suggesting that verapamil inhibits the function of the MmpS5L5 pump. Finally, norverapamil, the major verapamil metabolite, which has greatly reduced calcium channel activity, has equal potency in reducing resistance to MmpS5L5 substrates. Our findings highlight verapamil’s potential for enhancing bedaquiline TB treatment, for preventing acquired resistance to bedaquiline and other MmpS5L5 substrates, while also providing the impetus to identify additional MmpS5L5 inhibitors. Significance Statement Bedaquiline, an antitubercular drug targeting ATP synthase, forms the backbone of highly efficacious treatment regimens for drug-resistant tuberculosis. Bedaquiline resistance is emerging as a significant problem and is most commonly caused by mutations in Rv0678 that result in upregulation of the MmpS5L5 efflux pump. Here we define the contribution of the MmpS5L5 efflux pump to drug resistance in wild-type and Rv0678 mutant strains and show that the commonly used drug verapamil can inhibit MmpS5L5 activity. This suggests that this safe and inexpensive drug may be useful in enhancing bedaquiline treatment of TB and to help prevent bedaquiline acquired resistance.

Mitochondrial dysfunction is a key feature of many pathologies, including Parkinson’s disease. The selective vulnerability of dopaminergic neurons is thought to be influenced by mitochondrial dysfunction and mutations in the mitophagy regulating proteins PINK1 and Parkin that are known to cause early-onset Parkinsonism in an autosomal recessive manner. Augmentation of mitophagy through inhibition of USP30 may be a viable therapeutic strategy for a number of diseases including Parkinson’s. USP30 inhibition has been demonstrated to augment PINK1/PRKN mitophagy but also potentiate basal mitophagy to support the removal of dysfunctional mitochondria. Therefore, long-term de-regulation of mitophagy has been proposed to lead to mitochondrial depletion. We have used an integrated approach across cell lines, primary neurons and iPSC-derived dopaminergic neuronal cultures to assess the short and long-term effects of USP30 inhibition on mitochondrial health and neuronal activity. We investigated the dependence of USP30 inhibition phenotypes on the PINK1/Parkin pathway using genetic ablation and in iPSC-derived neurons from Parkinson’s patients with PINK1 or PRKN mutations. Loss of USP30 through CRISPRn-mediated knockout resulted in increased basal and depolarisation-induced mitophagy in SH-SY5Y cells. Loss of USP30 or pharmacological inhibition altered mitochondrial morphology and led to increases in membrane potential and ATP levels with decreased oxygen consumption, suggesting that USP30 loss results in a more efficient mitochondrial network. These changes in morphology were found to be independent of PINK1 or Parkin. Chronic pharmacological inhibition of USP30 or CRISPRi-mediated knockdown of USP30 did not impact dopaminergic neuronal activity, as assessed by electrophysiological profiling. These results support a dual role for USP30 in modulating the trigger threshold for mitophagy and regulating mitochondrial morphology without deleterious effects on dopaminergic neuronal activity.

Abstract Although several studies have highlighted the significant role of DMRTA2 in several cancers, its specific function and the underlying mechanisms in glioma remain unclear. CRISPR data was leveraged to identify DMRTA2 as a key candidate. We utilized bulk-tumor, single-cell, and spatial sequencing to explore the role of DMRTA2 in glioma malignancy and its possible mechanisms. Glioma specimens were used to assess DMRTA2 expression. In vitro and in vivo experiments were performed to validate the role of DMRTA2 in glioma malignancy and its possible mechanisms. Drug prediction and molecular docking were also conducted. We found that DMRTA2 was markedly upregulated and was identified as an independent prognostic marker. Moreover, single-cell and spatial sequencing analysis demonstrated that DMRTA2 was mainly localized in glioma cells. We constructed a malignant regulatory network for DMRTA2, with the JAK-STAT pathway as a central bridge. In vitro and in vivo experiments confirmed that DMRTA2 promoted the malignant behavior of glioma cells by activating the JAK2-STAT3 pathway. Additionally, DMRTA2 was significantly correlated with genomic mutation. Drugs potentially targeting DMRTA2 were screened and docked to DMRTA2. Taken together, DMRTA2 promotes the malignant progression of gliomas by activating the JAK2-STAT3 pathway and serves as a prognostic marker.

Summary The potential for using therapeutic antisense oligonucleotides (ASOs) has been hampered by lack of understanding of how they enter cells and subsequently access their targets. Endocytosis contributes to ASO uptake, but the machinery mediating subsequent ASO trafficking to permit suppression of their target mRNAs has not been described. Here, we show that ASO engagement with a scavenger receptor (CD44) activates the ERK-RSK axis to promote serine phosphorylation of a receptor tyrosine kinase (EPHA2). Serine phosphorylation of EPHA2 permits endocytosis, trafficking, and accumulation of ASOs in nuclear-adjacent endosomes. These endosomes then become leaky, allowing ASOs to escape and effectively suppress target mRNA expression. Inhibition of stress granule-mediated repair of leaky endosomes further enhances ASO effectiveness. These data identify an endocytic route to the nucleus which may be exploited to maximise effectiveness of ASO-mediated therapies.

Human homolog of Ariadne (HHARI) is a RING-between-RING ubiquitin E3 ligase which interacts with cullin-RING E3 ligase (CRL) complexes. HHARI has been implicated in the type-I interferon anti-viral response. However, how HHARI drives interferon signalling is not fully understood and the function of the unique, highly conserved acidic N-terminal domain of the protein is unknown. Here, we show that HHARI stimulates interferon-β secretion and autocrine type-I interferon signalling by directly targeting the viral RNA sensor RIG-I (Retinoic Acid-Inducible Gene I) in a neddylation-dependent manner. This suggests that neddylation inhibition could be used to treat interferonopathies and related diseases. Truncated HHARI containing only the N-terminal acidic/UBA-like domains retained the ability to induce interferon signalling in a neddylation-dependent mechanism. HHARI-mediated interferon-β secretion was enhanced by overexpression of cullins 1-5. The N-terminal acidic/UBA-like domain of HHARI is critical for RIG-I activation and interferon signalling, as removal of these domains inactivated the pro-interferon phenotype. We propose a mechanism by which the N-terminus of HHARI interacts with all neddylated cullins leading to endogenous HHARI activation. This suggests a model in which the N-terminus of HHARI ‘unlocks’ and activates neddylated cullins, which in turn are required for activation of HHARI itself. As cullins typically form modular cullin-RING ligase super-assemblies our findings imply that the HHARI N-terminus domain is a critical regulator of the versatile CRL system, which, through widespread protein ubiquitylation, controls many eukaryotic cell functions.

High-throughput phenotypic screening has historically relied on manually selected features, limiting our ability to capture complex cellular processes, particularly neuronal activity dynamics. While recent advances in self-supervised learning have revolutionized the ability to study cellular morphology and transcriptomics, dynamic cellular processes have remained challenging to phenotypically profile. To address this limitation, we developed Plexus, a novel self-supervised model specifically designed to capture and quantify network-level neuronal activity dynamics. Unlike existing phenotyping tools that focus on static readouts, Plexus leverages a novel network-level cell encoding method, which enables it to efficiently encode dynamic neuronal activity data into rich representational embeddings. In turn, Plexus achieves state of the art performance in detecting phenotypic changes in neuronal activity. We validated Plexus using a comprehensive GCaMP6m simulation framework and demonstrated its enhanced ability to classify distinct neuronal activity phenotypes compared to traditional signal-processing approaches. To enable practical application, we integrated Plexus with a scalable experimental system utilizing human iPSC-derived neurons equipped with the GCaMP6m calcium indicator and CRISPR interference machinery. This integrated platform successfully identified nearly twice as many distinct phenotypic changes in response to genetic perturbations compared to conventional methods, as demonstrated in a 52-gene CRISPRi screen across multiple iPSC lines. Using this framework, we identified potential genetic modifiers of aberrant neuronal activity in frontotemporal dementia, illustrating its utility for understanding complex neurological disorders.

ABSTRACT Zebrafish serve as a valuable model organism for studying human genetic diseases. While generating knockout lines is relatively straightforward, introducing precise disease-specific genetic variants by knock-in (KI) remains challenging. KI lines, however, enable more accurate studies of molecular and physiological consequences of genetic diseases. Their generation is often hampered by low editing efficiencies (EE) and potential off-target effects. In this study, we optimized conventional CRISPR/Cas9-mediated homology-directed repair (HDR) strategies for precise KI of genetic variants in zebrafish and compared their efficacy with prime editing (PE), a recently developed technique that is not yet commonly used. Using next-generation sequencing (NGS), we determined KI EE by HDR for six unique base-pair substitutions in three different zebrafish genes. We assessed the effect of 1) varying Cas9 amounts, 2) HDR templates with chemical modifications to improve integration efficiency, 3) different micro-injection procedures, and 4) synonymous guide-blocking variants in the protospacer sequence. Increasing Cas9 amounts augmented KI EE, with optimal injected amounts of Cas9 between 200 and 800 pg. The use of Alt-R™ HDR templates (IDT) further increased KI EE, while guide-blocking modifications did not. Injecting components directly into the cell was not superior to injections into the yolk. PE, however, increased EE up to fourfold and expanded the F0 founder pool for four targets when compared to conventional HDR editing, with fewer off-target effects. Therefore, PE is a very promising methodology for improving the creation of precise genomic edits in zebrafish, facilitating the modeling of human diseases.

Advances in single-cell sequencing and CRISPR technologies have enabled detailed case-control comparisons and experimental perturbations at single-cell resolution. However, uncovering causal relationships in observational genomic data remains challenging due to selection bias and inadequate adjustment for unmeasured confounders, particularly in heterogeneous datasets. To address these challenges, we introduce causarray, a doubly robust causal inference framework for analyzing array-based genomic data at both bulk-cell and single-cell levels. causarray integrates a generalized confounder adjustment method to account for unmeasured confounders and employs semiparametric inference with flexible machine learning techniques to ensure robust statistical estimation of treatment effects. Benchmarking results show that causarray robustly separates treatment effects from confounders while preserving biological signals across diverse settings. We also apply causarray to two single-cell genomic studies: (1) an in vivo Perturb-seq study of autism risk genes in developing mouse brains and (2) a casecontrol study of Alzheimer’s disease using three human brain transcriptomic datasets. In these applications, causarray identifies clustered causal effects of multiple autism risk genes and consistent causally affected genes across Alzheimer’s disease datasets, uncovering biologically relevant pathways directly linked to neuronal development and synaptic functions that are critical for understanding disease pathology.

The detection of cytosolic dsDNA is tightly regulated to avoid pathological inflammatory responses. A major pathway involved in their detection relies on the cyclic GMP-AMP synthase (cGAS) that triggers activation of the Stimulator of interferon genes (STING) which subsequently drives the expression of inflammatory genes and type I Interferons (IFNs). Here, we show that the methyl-CpG-binding protein 2 (MECP2), a major transcriptional regulator, controls dsDNA-associated inflammatory responses. We show that the presence of cytosolic dsDNA promotes MECP2 export from the nucleus to the cytosol where it interacts with dsDNA, dampening cGAS activation. Our data also indicate that MECP2 export from the nucleus partially phenocopies MECP2 deficiency, leading to the expression of inflammatory and interferon stimulated genes, enforcing an antiviral state. Finally, we also show that MECP2 displacement from the nucleus following dsDNA stimulation is sufficient to disrupt its canonical function, leading to the reactivation of otherwise repressed genes, such endogenous retroelements of the Long interspersed nuclear element-1 (LINE-1) family. Re-expression of the latter led to the accumulation of DNA species feeding cGAS-dependent signaling and can be dampened by reverse transcriptase inhibitors. We thus establish a previously unforeseen direct role of MECP2 in the regulation of the breadth and nature of dsDNA-associated inflammatory responses. Furthermore, our results suggest that targeting dsDNA-associated pathways or pharmacological inhibition of LINE-1 may bear therapeutic hopes for Rett syndrome (RTT) patients that present with MECP2 deficiency.

Summary Base editing stands at the forefront of genetic engineering, heralding precise genetic modifications with broad implications. While CRISPR-based DNA and RNA base editing systems capitalize on sgRNA-guided specificity and diverse deaminase functionalities, the pursuit of efficient C-to-U RNA editing has been hampered by the inherent constraints of cytidine deaminases. Here, we report an RNA base editing platform by refining cytidine deaminases, termed professional APOBECs (ProAPOBECs), through systematic enhancements and AI-driven protein engineering. ProAPOBECs demonstrate unprecedented catalytic versatility, particularly fused with RNA-recognizing Pumilio and FBF (PUF) proteins. We present the first effective use of RNA base editing in the brain with ProAPOBECs in Mef2c mutant mice, a model for autism. The AAV-mediated RNA base editing via ProAPOBEC not only corrects genetic mutation in mRNAs but significantly alleviates autistic-like behaviors in the mice. This work introduces a pioneering collection of RNA base editing instruments, emphasizing their therapeutic potential in combatting genetic disorders.

Recent advances in functional genomics tools have ushered in a new era of genetic editing to identify molecular pathways relevant to developmental and disease biology. However, limited model systems are available that adequately mimic cell states and phenotypes associated with human disease pathways. Here, we quantitatively analyzed the founder population bottleneck effect and demonstrated how the population changes from induced pluripotent stem cells (iPSCs) to hematopoietic stem cells and to the final induced macrophage population. We then engineered SAMHD1 knockout (KO) iPSC and characterized the iPSC line with RNA Seq, and induced macrophages from two distinct protocols with functional analysis. We then generated SAMHD1 KO CRISPR-dCAS9 KRAB iPSC through lenti-viral transduction aiming to increase the efficiency of lentiviral mediated gene transfer. We demonstrated increased lenti-viral transduction efficiency in induced macrophage, as well as microglia induced with two distinct protocols. This model allows for efficient gene knock down, as well as large-scale functional genomics screens in mature iPSC-derived macrophages or microglia with applications in innate immunity and chronic inflammatory disease biology. These experiments highlight the broad applicability of this platform for disease-relevant target identification and may improve our ability to run large-scale screens in iPSC-derived myeloid model systems.

Centromeres are chromosomal loci that ensure proper chromosome segregation by providing a platform for kinetochore assembly and spindle force transduction during cell division. Human centromeres are defined primarily by a unique chromatin domain featuring the histone H3 variant, Centromere Protein A (CENP-A), that marks a single active centromere locus per chromosome. CENP-A chromatin typically occupies a small subregion of low DNA methylation within multi-megabase arrays of hypermethylated alpha-satellite repeats and constitutive pericentric heterochromatin. However, the mechanisms defining and maintaining precise centromere position and domain size, and the role of the underlying alpha satellite DNA sequence, are poorly characterised. Using an experimentally-induced neocentromere in RPE1 cells, we discovered that the SUV39H1 and H2 methyltransferases tri-methylate H3K9 at neocentromere boundaries to maintain CENP-A domain size independent of DNA methylation or satellite sequences. Furthermore, we found that the CENP-A domain at canonical alpha-satellite-based centromeres is characterized by local depletion of H3K9me3-mediated heterochromatin, coinciding with the DNA methylation dip region. We identified the SETDB1 methyltransferase as key to maintaining H3K9me3 within flanking active higher order alpha satellite arrays while SUV39s and SUZ12 contribute to globally heterochromatinize both alpha satellites and neighbouring repeats. Loss of this heterochromatin boundary results in the progressive expansion of the primary CENP-A domain, erosion of DNA methylation, and the nucleation of new centromeres across alpha satellite sequences. Our study identifies the functional specialization of different H3K9 methyltransferases across centromeric and pericentric domains, crucial for maintaining centromere domain size and number.

Drug discovery requires a deep understanding of disease mechanisms, making the integration and analysis of diverse, multi-modal data types essential. These data types, spanning omics types, disease- associated, and biological pathway information, often originate from disparate sources and must be combined to uncover critical insights. We have developed iPANDDA ( in-silico Pipeline for Agnostic Network-based Drug Discovery Analysis ), a computational pipeline that integrates multi-modal data through a network-based approach to predict candidate drug target proteins for specific diseases. We applied iPANDDA to lung squamous cell carcinoma (LUSC), a subtype of non-small cell lung cancer (NSCLC) that accounts for approximately 25% of all lung cancer cases globally. Despite advances in cancer therapeutics, targeted therapies specifically approved for LUSC remain lacking, exacerbated by the shortage of robust models for studying LUSC carcinogenesis and therapeutic responses. The SOX2 gene, amplified in about 50% of LUSC patients, plays a critical role in driving and maintaining the cancer phenotype. Using iPANDDA, we identified relevant therapeutic targets for SOX2-dependent LUSC. Selected candidate drug targets were validated in vitro using cell-based models. We conducted target inhibition studies in both SOX2-dependent and non-SOX2-dependent cell lines, evaluating the effects of inhibition and knockout through cell viability assays. Our findings confirmed key monotherapy and combination therapy targets for SOX2-focused models. Specifically, we validated the AKT and mTOR complexes as promising therapeutic targets for LUSC. Additionally, we identified potential pathways for developing novel combination therapies targeting SOX2-dependent LUSC. iPANDDA offers a robust approach to refining and focusing therapeutic strategies for diseases with unmet clinical needs.

Transfer RNA molecules have been recently recognized as widespread targets of bacterial immune systems. Translation inhibition through tRNA cleavage or modification inhibits phage propagation, thereby protecting the bacterial population. To counteract this, some viruses encode their own tRNA molecules, allowing infection to take place. The AriB effector of the PARIS defence system is a Toprim nuclease previously shown to target the E. coli tRNA Lys(UUU) , but not a tRNA Lys(UUU) variant encoded by bacteriophage T5. We demonstrate here that the T5-tRNA Lys(UUU) is required but not sufficient to bypass PARIS immunity. Combining tRNA-sequencing, genetics, phage infection and in vitro biochemical data, we reveal that the E. coli tRNA Thr(UGU) , is another prime target of AriB and tRNA Asn(GUU) represents a secondary, yet biologically relevant, target of the PARIS effector. Activated AriB protein cleaves these targets in vitro , and the cleavage reaction is not dependent on the presence of specific tRNA modifications. We show that the overexpression of phage T5 tRNA Lys(UUU) , tRNA Thr(UGU) and tRNA Asn(GUU) variants is sufficient to inhibit PARIS anti-viral defence. Finally, we propose a model for tRNA recognition by the AriB dimer and provide molecular details of its nuclease activity and specificity.

Commander is an endosome associated sixteen protein assembly that associates with the sorting nexin 17 (SNX17) cargo adaptor to regulate cell surface recycling of internalised integral membrane proteins including integrins and lipoprotein receptors. Mutations in Commander are causative for Ritscher-Schinzel syndrome (RSS), a multiorgan developmental disease associated with a core triad of cerebellar-cardiac-craniofacial malformation. Here, using unbiased proteomics and computational modelling, we identify leucine rich melanocyte differentiation associated (LRMDA) as a novel Commander binding protein. Using recombinant protein reconstitution, we show that LRMDA simultaneously associates with Commander and active RAB32, and, by revealing that LRMDA and SNX17 share a common mechanism of Commander association, establish the mutually exclusive nature of RAB32-LRMDA-Commander and SNX17-Commander assemblies. From functional analysis in human melanocytes, we establish an essential role for RAB32-LRMDA-Commander in melanosome biogenesis and pigmentation and reveal a distinct functional role for SNX17-Commander in this organelle biogenesis pathway. We reveal how LRMDA mutations, causative for oculocutaneous albinism type 7 (OCA7), a hypopigmentation disorder accompanied by poor visual acuity, uncouple RAB32 and Commander binding thereby establishing the mechanistic basis of this disease. Our discovery and characterisation of this alternative Commander assembly establishes an unrecognised plasticity of Commander function within a highly complex organelle biogenesis pathway. This extends Commander function beyond the confines of SNX17-mediated cell surface recycling into RAB32-family mediated biogenesis of lysosome-related organelles and, potentially, other RAB32 regulated pathways including host-pathogen defence mechanisms. Our work also extends the breath of Commander pathway dysfunction for human disease.