Design Parameters for a Mass Cytometry Detectable HaloTag Ligand.

Mass cytometry permits the high dimensional analysis of complex biological samples; however, some techniques are not yet integrated into the mass cytometry workflow due to reagent availability. The use of self-labeling protein systems, such as HaloTag, are one such application. Here, we describe the design and implementation of the first mass cytometry ligands for use with HaloTag. "Click"-amenable HaloTag warheads were first conjugated onto poly(l-lysine) or poly(acrylic acid) polymers that were then functionalized with diethylenetriaminepentaacetic acid (DTPA) lutetium metal chelates. Kinetic analysis of the HaloTag labeling rates demonstrated that the structure appended to the 1-chlorohexyl warhead was key to success. A construct with a diethylene glycol spacer appended to a benzamide gave similar rates (kobs ∼ 102 M-1 s-1), regardless of the nature of the polymer. Comparison of the polymer with a small molecule chelate having rapid HaloTag labeling kinetics (kobs ∼ 104 M-1 s-1) suggests the polymers significantly reduced the HaloTag labeling rate. HEK293T cells expressing surface-exposed GFP-HaloTag fusions were labeled with the polymeric constructs and 175Lu content measured by cytometry by time-of-flight (CyTOF). Robust labeling was observed; however, significant nonspecific binding of the constructs to cells was also present. Heavily pegylated polymers demonstrated that nonspecific binding could be reduced to allow cells bearing the HaloTag protein to be distinguished from nonexpressing cells.

Metabolic Usage and Glycan Destinations of GlcNAz in E. coli.

Bacteria use a diverse range of carbohydrates to generate a profusion of glycans, with amino sugars, such as N-acetylglucosamine (GlcNAc), being prevalent in the cell wall and in many exopolysaccharides. The primary substrate for GlcNAc-containing glycans, UDP-GlcNAc, is the product of the bacterial hexosamine pathway and a key target for bacterial metabolic glycan engineering. Using the strategy of expressing NahK, to circumvent the hexosamine pathway, it is possible to directly feed the analogue of GlcNAc, N-azidoacetylglucosamine (GlcNAz), for metabolic labeling in Escherichia coli. The cytosolic production of UDP-GlcNAz was confirmed by using fluorescence-assisted polyacrylamide gel electrophoresis. The key question of where GlcNAz is incorporated was interrogated by analyzing potential sites including peptidoglycan (PGN), the biofilm-related exopolysaccharide poly-ß-1,6-N-acetylglucosamine (PNAG), lipopolysaccharide (LPS), and the enterobacterial common antigen (ECA). The highest levels of incorporation were observed in PGN with lower levels in PNAG and no observable incorporation in LPS or ECA. The promiscuity of the PNAG synthase (PgaCD) toward UDP-GlcNAz in vitro and the lack of undecaprenyl-pyrophosphoryl-GlcNAz intermediates generated in vivo confirmed the incorporation preferences. The results of this work will guide the future development of carbohydrate-based probes and metabolic engineering strategies.

Characterization of an N-Allylglyoxylamide-Based Bioorthogonal Nitrone Trap.

Aldehydes are attractive bioorthogonal coupling partners. The ease of manipulation of aldehydes and their orthogonality to other classes of bioorthogonal reactions have inspired the exploration of chemistries, which generate irreversible conjugates. Similarly, nitrones have been shown to be potent 1,3-dipoles in bioorthogonal reactions when paired with strained alkynes. Here, we combine the reactivity of nitrones with the simplicity of aldehydes using an N-allylglyoxylamide, in a cascade reaction with an N-alkylhydroxylamine to produce a bicyclic isoxazolidine. The reaction is found to be catalyzed by 5-methoxyanthranilic acid and proceeds at pH 7 with favorable kinetics. Using the HaloTag7 protein bearing an N-alkylhydroxylamine, we show the reaction to be bioorthogonal in a complex cell lysate and to proceed well at the surface of a HEK293 cell. Furthermore, the reaction is compatible with a typical strain-promoted alkyne-azide click reaction. The characteristics of this reaction suggest it will be a useful addition to the pallet of bioorthogonal reactions that have revolutionized chemical biology.

The Metabolic Usage and Glycan Destinations of GlcNAz in E. coli.

Bacteria use a diverse range of carbohydrates to generate a profusion of glycans, with amino sugars such as N-acetylglucosamine (GlcNAc) being prevalent in the cell wall and in many exopolysaccharides. The primary substrate for GlcNAc-containing glycans, UDP-GlcNAc, is the product of the bacterial hexosamine pathway, and a key target for bacterial metabolic glycan engineering. Using the strategy of expressing NahK, to circumvent the hexosamine pathway, it is possible to directly feed the analogue of GlcNAc, N-azidoacetylglucosamine (GlcNAz), for metabolic labelling in E. coli. The cytosolic production of UDP-GlcNAz was confirmed using fluorescence assisted polyacrylamide gel electrophoresis. The key question of where GlcNAz is incorporated, was interrogated by analyzing potential sites including: peptidoglycan (PGN), the biofilm-related exopolysaccharide poly-ß-1,6-N-acetylglucosamine (PNAG), lipopolysaccharide (LPS) and the enterobacterial common antigen (ECA). The highest levels of incorporation were observed in PGN with lower levels in PNAG and no observable incorporation in LPS or ECA. The promiscuity of the PNAG synthase (PgaCD) towards UDP-GlcNAz in vitro and lack of undecaprenyl-pyrophosphoryl-GlcNAz intermediates generated in vivo confirmed the incorporation preferences. The results of this work will guide the future development of carbohydrate-based probes and metabolic engineering strategies.

Small Molecule Inhibition of an Exopolysaccharide Modification Enzyme is a Viable Strategy To Block Pseudomonas aeruginosa Pel Biofilm Formation.

Biosynthesis of the Pel exopolysaccharide in Pseudomonas aeruginosa requires all seven genes of the pelABCDEFG operon. The periplasmic modification enzyme PelA contains a C-terminal deacetylase domain that is necessary for Pel-dependent biofilm formation. Herein, we show that extracellular Pel is not produced by a P. aeruginosa PelA deacetylase mutant. This positions PelA deacetylase activity as an attractive target to prevent Pel-dependent biofilm formation. Using a high-throughput screen (n = 69,360), we identified 56 compounds that potentially inhibit PelA esterase activity, the first enzymatic step in the deacetylase reaction. A secondary biofilm inhibition assay identified methyl 2-(2-pyridinylmethylene) hydrazinecarbodithioate (SK-017154-O) as a specific Pel-dependent biofilm inhibitor. Structure-activity relationship studies identified the thiocarbazate as a necessary functional group and that the pyridyl ring could be replaced with a phenyl substituent (compound 1). Both SK-017154-O and compound 1 inhibit Pel-dependent biofilm formation in Bacillus cereus ATCC 10987, which has a predicted extracellular PelA deacetylase in its pel operon. Michaelis-Menten kinetics determined SK-017154-O to be a noncompetitive inhibitor of PelA, while compound 1 did not directly inhibit PelA esterase activity. Cytotoxicity assays using human lung fibroblast cells showed that compound 1 is less cytotoxic than SK-017154-O. This work provides proof of concept that biofilm exopolysaccharide modification enzymes are important for biofilm formation and can serve as useful antibiofilm targets. IMPORTANCE Present in more than 500 diverse Gram-negative and 900 Gram-positive organisms, the Pel polysaccharide is one of the most phylogenetically widespread biofilm matrix determinants found to date. Partial de-N-acetylation of this α-1,4 linked N-acetylgalactosamine polymer by the carbohydrate modification enzyme PelA is required for Pel-dependent biofilm formation in Pseudomonas aeruginosa and Bacillus cereus. Given this and our observation that extracellular Pel is not produced by a P. aeruginosa PelA deactylase mutant, we developed an enzyme-based high-throughput screen and identified methyl 2-(2-pyridinylmethylene) hydrazinecarbodithioate (SK-017154-O) and its phenyl derivative as specific Pel-dependent biofilm inhibitors. Michaelis-Menten kinetics revealed SK-017154-O is a noncompetitive inhibitor and that its noncytotoxic, phenyl derivative does not directly inhibit P. aeruginosa PelA esterase activity. We provide proof of concept that exopolysaccharide modification enzymes can be targeted with small molecule inhibitors to block Pel-dependent biofilm development in both Gram-negative and Gram-positive bacteria.

Reagents for Mass Cytometry.

Mass cytometry (cytometry by time-of-flight detection [CyTOF]) is a bioanalytical technique that enables the identification and quantification of diverse features of cellular systems with single-cell resolution. In suspension mass cytometry, cells are stained with stable heavy-atom isotope-tagged reagents, and then the cells are nebulized into an inductively coupled plasma time-of-flight mass spectrometry (ICP-TOF-MS) instrument. In imaging mass cytometry, a pulsed laser is used to ablate ca. 1 µm2 spots of a tissue section. The plume is then transferred to the CyTOF, generating an image of biomarker expression. Similar measurements are possible with multiplexed ion bean imaging (MIBI). The unit mass resolution of the ICP-TOF-MS detector allows for multiparametric analysis of (in principle) up to 130 different parameters. Currently available reagents, however, allow simultaneous measurement of up to 50 biomarkers. As new reagents are developed, the scope of information that can be obtained by mass cytometry continues to increase, particularly due to the development of new small molecule reagents which enable monitoring of active biochemistry at the cellular level. This review summarizes the history and current state of mass cytometry reagent development and elaborates on areas where there is a need for new reagents. Additionally, this review provides guidelines on how new reagents should be tested and how the data should be presented to make them most meaningful to the mass cytometry user community.

Attenuation of Polysialic Acid Biosynthesis in Cells by the Small Molecule Inhibitor 8-Keto-sialic acid.

Sialic acids are key mediators of cell function, particularly with regard to cellular interactions with the surrounding environment. Reagents that modulate the display of specific sialyl glycoforms at the cell surface would be useful biochemical tools and potentially allow for therapeutic intervention in numerous challenging chronic diseases. While multiple strategies are being explored for the control of cell surface sialosides, none that shows high selectivity between sialyltransferases or that targets a specific sialyl glycoform has yet to emerge. Here, we describe a strategy to block the formation of α2,8-linked sialic acid chains (oligo- and polysialic acid) through the use of 8-keto-sialic acid as a chain-terminating metabolic inhibitor that, if incorporated, cannot be elongated. 8-Keto-sialic acid is nontoxic at effective concentrations and serves to block polysialic acid synthesis in cancer cell lines and primary immune cells, with minimal effects on other sialyl glycoforms.

An Engineered Paper-Based 3D Coculture Model of Pancreatic Cancer to Study the Impact of Tissue Architecture and Microenvironmental Gradients on Cell Phenotype.

The spatial configuration of cells in the tumor microenvironment (TME) affects both cancer and fibroblast cell phenotypes contributing to the clinical challenge of tumor heterogeneity and therapeutic resistance. This is a particular challenge in stroma-rich pancreatic ductal adenocarcinoma (PDAC). Here, a versatile system is described to study the impact of tissue architecture on cell phenotype using PDAC as a model system. This fully human system encompassing both primary pancreatic stellate cells and primary organoid cells using the TRACER platform to allow the creation of user-defined TME architectures that have been inferred from clinical PDAC samples and are analyzed by CyTOF to characterize cells extracted from the system. High dimensional characterization using CyTOF demonstrates that tissue architecture leads to distinct hypoxia and proliferation gradients. Furthermore, phenotypic markers for both cell types are also graded in ways that cannot be explained by either hypoxia or coculture alone. This demonstrates the importance of using complex models encompassing cancer cells, stromal cells, and allowing control over architecture to explore the impact of tissue architecture on cell phenotype. It is anticipated that this model will help decipher how tissue architecture and cell interactions regulate cell phenotype and hence cellular and tissue heterogeneity.

Using a high-throughput, whole-cell hydrogenase assay to identify potential small molecule inhibitors of [NiFe]-hydrogenase.

[NiFe]-hydrogenases are used by several human pathogens to catalyze the reversible conversion between molecular hydrogen and protons and electrons. Hydrogenases provide an increased metabolic flexibility for pathogens, such as Escherichia coli and Helicobacter pylori, by allowing the use of molecular hydrogen as an energy source to promote survival in anaerobic environments. With the rise of antimicrobial resistance and the desire for novel therapeutics, the [NiFe]-hydrogenases are alluring targets. Inhibiting the nickel insertion pathway of [NiFe]-hydrogenases is attractive as this pathway is required for the generation of functional enzymes and is orthogonal to human biochemistry. In this work, nickel availability for the production and function of E. coli [NiFe]-hydrogenase was explored through immunoblot and activity assays. Whole-cell hydrogenase activities were assayed in high throughput against a small molecule library of known bioactives. Iodoquinol was identified as a potential inhibitor of the nickel biosynthetic pathway of [NiFe]-hydrogenase through a two-step screening process, but further studies with immunoblot assays showed confounding effects dependent on the cell growth phase. This study highlights the significance of considering the growth phenotype for whole-cell based assays overall and its effects on various cellular processes influenced by metal trafficking and homeostasis.

The TPR domain of PgaA is a multifunctional scaffold that binds PNAG and modulates PgaB-dependent polymer processing.

The synthesis of exopolysaccharides as biofilm matrix components by pathogens is a crucial factor for chronic infections and antibiotic resistance. Many periplasmic proteins involved in polymer processing and secretion in Gram-negative synthase dependent exopolysaccharide biosynthetic systems have been individually characterized. The operons responsible for the production of PNAG, alginate, cellulose and the Pel polysaccharide each contain a gene that encodes an outer membrane associated tetratricopeptide repeat (TPR) domain containing protein. While the TPR domain has been shown to bind other periplasmic proteins, the functional consequences of these interactions for the polymer remain poorly understood. Herein, we show that the C-terminal TPR region of PgaA interacts with the de-N-acetylase domain of PgaB, and increases its deacetylase activity. Additionally, we found that when the two proteins form a complex, the glycoside hydrolase activity of PgaB is also increased. To better understand structure-function relationships we determined the crystal structure of a stable TPR module, which has a conserved groove formed by three repeat motifs. Tryptophan quenching, mass spectrometry analysis and molecular dynamics simulation studies suggest that the crystallized TPR module can bind PNAG/dPNAG via its electronegative groove on the concave surface, and potentially guide the polymer through the periplasm towards the porin for export. Our results suggest a scaffolding role for the TPR domain that combines PNAG/dPNAG translocation with the modulation of its chemical structure by PgaB.

Tellurophene-Tagging of Teniposide Facilitates Monitoring by Mass Cytometry.

Target engagement and the biodistribution of exogenously administered small molecules is rarely homogenous. Methods to determine the biodistribution at the cellular level are limited by the ability to detect the small molecule and simultaneously identify the cell types or tissue structures with which it is associated. The highly multiplexed nature of mass cytometry could facilitate these studies provided a heavy isotope label was available in the molecule of interest. Here we show it is possible to append a tellurophene to a known chemotherapeutic, teniposide, to follow this molecule in vivo. A semi-synthetic approach offers an efficient route to the teniposide analogue which is found to have similar characteristics when compared with the parent teniposide in vitro. Using mass cytometry we find the teniposide analogue has significant nonspecific binding to cells. In vivo the tellurium bearing teniposide produces the expected DNA damage in a PANC-1 xenograft model. The distribution of Te in the tissue is near the limits of detection and further work will be required to characterize the localization of this analogue with respect to cell type distributions.

Applications of an inactive Dispersin B probe to monitor biofilm polysaccharide production.

Bacterial biofilms consist of surface-attached communities that secrete polymeric substances to form a biofilm matrix, generating a local microenvironment which helps protect from external factors. One such matrix component produced by a diverse list of microorganisms is the polysaccharide poly-ß-1,6-N-acetylglucosamine (PNAG). Dispersin B is a PNAG-specific glycosyl hydrolase, which by leveraging its unique specificity, can be used to design a macromolecular fluorescent PNAG binding probe. An active site mutant of Dispersin B was fused to a fluorescent protein, to generate a probe that bound PNAG but did not hydrolyze its polysaccharide target. The ease and versatility of this strategy has made it possible to study PNAG in the context of maturing biofilms, as the probe tends to sequester in regions of high PNAG density. In this chapter, typical workflows from probe construction to cell-binding and imaging experiments are described.

Termination of Poly-N-acetylglucosamine (PNAG) Polymerization with N-Acetylglucosamine Analogues.

Bacteria require polysaccharides for structure, survival, and virulence. Despite their central role in microbiology, few tools are available to manipulate their production. In E. coli, the glycosyltransferase complex PgaCD produces poly-N-acetylglucosamine (PNAG), an extracellular matrix polysaccharide required for biofilm formation. We report that C6-substituted (H, F, N3, SH, NH2) UDP-GlcNAc substrate analogues are inhibitors of PgaCD. In vitro, the inhibitors cause PNAG chain termination, consistent with the mechanism of PNAG polymerization from the nonreducing terminus. In vivo, expression of the GlcNAc-1-kinase NahK in E. coli provided a non-native GlcNAc salvage pathway that produced the UDP-GlcNAc analogue inhibitors in situ. The 6-fluoro and 6-deoxy derivatives were potent inhibitors of biofilm formation in the transformed strain, providing a tool to manipulate this key exopolysaccharide. Characterization of the UDP-GlcNAc pool and quantification of PNAG generation support PNAG termination as the primary in vivo mechanism of biofilm inhibition by 6-fluoro UDP-GlcNAc.

Allosteric modulation of the adenosine A2A receptor by cholesterol.

Cholesterol is a major component of the cell membrane and commonly regulates membrane protein function. Here, we investigate how cholesterol modulates the conformational equilibria and signaling of the adenosine A2A receptor (A2AR) in reconstituted phospholipid nanodiscs. This model system conveniently excludes possible effects arising from cholesterol-induced phase separation or receptor oligomerization and focuses on the question of allostery. GTP hydrolysis assays show that cholesterol weakly enhances the basal signaling of A2AR while decreasing the agonist EC50. Fluorine nuclear magnetic resonance (19F NMR) spectroscopy shows that this enhancement arises from an increase in the receptor's active state population and a G-protein-bound precoupled state. 19F NMR of fluorinated cholesterol analogs reveals transient interactions with A2AR, indicating a lack of high-affinity binding or direct allosteric modulation. The combined results suggest that the observed allosteric effects are largely indirect and originate from cholesterol-mediated changes in membrane properties, as shown by membrane fluidity measurements and high-pressure NMR.

Multiplexed single-cell analysis of organoid signaling networks.

Organoids are biomimetic tissue models comprising multiple cell types and cell states. Post-translational modification (PTM) signaling networks control cellular phenotypes and are frequently dysregulated in diseases such as cancer. Although signaling networks vary across cell types, there are limited techniques to study cell type-specific PTMs in heterocellular organoids. Here, we present a multiplexed mass cytometry (MC) protocol for single-cell analysis of PTM signaling and cell states in organoids and organoids co-cultured with fibroblasts and leukocytes. We describe how thiol-reactive organoid barcoding in situ (TOBis) enables 35-plex and 126-plex single-cell comparison of organoid cultures and provide a cytometry by time of flight (CyTOF) signaling analysis pipeline (CyGNAL) for computing cell type-specific PTM signaling networks. The TOBis MC protocol takes ~3 d from organoid fixation to data acquisition and can generate single-cell data for >40 antibodies from millions of cells across 126 organoid cultures in a single MC run.

Incorporation of TePhe into Expressed Proteins is Minimally Perturbing.

Tellurium is a versatile heavy chalcogen with numerous applications in chemical biology, providing valuable probes in mass cytometry, fluorescence imaging and structural biology. L-Tellurienylalanine (TePhe) is an analogue of the proteinogenic amino acid L-phenylalanine (Phe) in which the phenyl side chain has been replaced by a 5-membered tellurophene moiety. High incorporation level of TePhe in expressed proteins at defined sites is expected to facilitate studies in proteomics, protein NMR spectroscopy, and structure elucidation. As a model we chose immunoglobulin-binding Protein G, B1 domain (GB1) to validate TePhe as a suitable structural analogue for Phe. We demonstrate that approximately 1 in 2 of all Phe sites within GB1 can be substituted with TePhe through expression in standard non-Phe-auxotrophic E. coli in Phe-deficient media containing glyphosate, an inhibitor of aromatic amino acid biosynthesis. The TePhe content of the GB1 sample can be further increased to 85 % through HPLC. Using NMR and CD spectroscopy, we confirm that the Phe-to-TePhe substitution has negligible impact on the global structure and stability of GB1.

An Iodinated DAPI-Based Reagent for Mass Cytometry.

Multiparametric single-cell analysis has seen dramatic improvements with the introduction of mass cytometry (MC) and imaging mass cytometry (IMC™ ). These technologies expanded the number of biomarkers that can be identified simultaneously by using heavy-isotope-tagged antibody reagents. Small-molecule probes bearing heavy isotopes are emerging as additional useful functional reporters of cellular features. Realizing this, we explored the iodination of DAPI to produce a heavy-atom-substituted derivative of the commonly used fluorescent DNA stain. Although exhibiting a drastically reduced fluorescence emission profile, I-DAPI retains strong binding affinity for DNA. I-DAPI was used to detect cellular DNA in MC and IMC™ assays with comparable efficiency to known Ir-containing DNA intercalators. This work suggests repurposing well-known colorimetric stains through simple reactions could be an effective strategy to develop new, functional MC and IMC™ reagents.

Synthesis of C6-substituted UDP-GlcNAc derivatives.

UDP-sugar analogs are useful for the study of glycosyltransferases and the production of unnatural glycans. The preparation of five UDP-GlcNAc derivatives is reported with 6-deoxy, 6-azido, 6-amino, 6-mercapto, or 6-fluoro substitutions. A concise chemoenzymatic synthesis was developed using the kinase NahK (B. longum JCM1217) and the uridyl transferase GlmU (E. coli K12).

PelX is a UDP-N-acetylglucosamine C4-epimerase involved in Pel polysaccharide-dependent biofilm formation.

Pel is a GalNAc-rich bacterial polysaccharide that contributes to the structure and function of Pseudomonas aeruginosa biofilms. The pelABCDEFG operon is highly conserved among diverse bacterial species, and Pel may therefore be a widespread biofilm determinant. Previous annotation of pel gene clusters has helped us identify an additional gene, pelX, that is present adjacent to pelABCDEFG in >100 different bacterial species. The pelX gene is predicted to encode a member of the short-chain dehydrogenase/reductase (SDR) superfamily, but its potential role in Pel-dependent biofilm formation is unknown. Herein, we have used Pseudomonas protegens Pf-5 as a model to elucidate PelX function as Pseudomonas aeruginosa lacks a pelX homologue in its pel gene cluster. We found that P. protegens forms Pel-dependent biofilms; however, despite expression of pelX under these conditions, biofilm formation was unaffected in a ΔpelX strain. This observation led us to identify a pelX paralogue, PFL_5533, which we designate here PgnE, that appears to be functionally redundant to pelX In line with this, a ΔpelX ΔpgnE double mutant was substantially impaired in its ability to form Pel-dependent biofilms. To understand the molecular basis for this observation, we determined the structure of PelX to 2.1 Å resolution. The structure revealed that PelX resembles UDP-GlcNAc C4-epimerases. Using 1H NMR analysis, we show that PelX catalyzes the epimerization between UDP-GlcNAc and UDP-GalNAc. Our results indicate that Pel-dependent biofilm formation requires a UDP-GlcNAc C4-epimerase that generates the UDP-GalNAc precursors required by the Pel synthase machinery for polymer production.

SCO-Spondin Defects and Neuroinflammation Are Conserved Mechanisms Driving Spinal Deformity across Genetic Models of Idiopathic Scoliosis.

Adolescent idiopathic scoliosis (AIS) affects 3% to 4% of children between the ages of 11 and 18 [1, 2]. This disorder, characterized by abnormal three-dimensional spinal curvatures that typically develop during periods of rapid growth, occurs in the absence of congenital vertebral malformations or neuromuscular defects [1]. Genetic heterogeneity [3] and a historical lack of appropriate animal models [4] have confounded basic understanding of AIS biology; thus, treatment options remain limited [5, 6]. Recently, genetic studies using zebrafish have linked idiopathic-like scoliosis to irregularities in motile cilia-mediated cerebrospinal fluid flow [7-9]. However, because loss of cilia motility in human primary ciliary dyskinesia patients is not fully associated with scoliosis [10, 11], other pathogenic mechanisms remain to be determined. Here, we demonstrate that zebrafish scospondin (sspo) mutants develop late-onset idiopathic-like spinal curvatures in the absence of obvious cilia motility defects. Sspo is a large secreted glycoprotein functionally associated with the subcommissural organ and Reissner's fiber [12]-ancient and enigmatic organs of the brain ventricular system reported to govern cerebrospinal fluid homeostasis [13, 14], neurogenesis [12, 15-18], and embryonic morphogenesis [19]. We demonstrate that irregular deposition of Sspo within brain ventricles is associated with idiopathic-like scoliosis across diverse genetic models. Furthermore, Sspo defects are sufficient to induce oxidative stress and neuroinflammatory responses implicated in AIS pathogenesis [9]. Through screening for chemical suppressors of sspo mutant phenotypes, we also identify potent agents capable of blocking severe juvenile spine deformity. Our work thus defines a new preclinical model of AIS and provides tools to realize novel therapeutic strategies.