Biology subjects

Chakravarti, A.

Publications and source records attributed to Chakravarti, A..

At least 19 recordsLinked to original sources

bioRxiv2026

Oxidized TRX1 and DPP8/9 stabilize the MIA40-AIFM1 complex during intrinsic apoptosis

Mammalian cells execute diverse death programs with distinct immunological consequences. Mitochondrial outer membrane permeabilization (MOMP) drives typically immunologically silent intrinsic apoptosis by releasing cytochrome c and other proapoptotic proteins into the cytosol. Here, we show that MOMP also engages two established repressors of the pyroptosis-inducing NLRP1 inflammasome, oxidized thioredoxin-1 (oxTRX1) and catalytically active DPP8/9, in a coordinated redox and proteostasis program. Immediately after MOMP, oxTRX1 forms a disulfide with MIA40 Cys4 at the MIA40-AIFM1 interface. Subsequently, DPP8/9 cleave AK2, targeting this competing AIFM1 ligand for degradation. Biochemical reconstitution and cryo-EM reveal that oxTRX1 promotes AIFM1 dimerization and preferentially stabilizes MIA40-AIFM1 over AK2-AIFM1. Thus, redox-dependent complex assembly and selective proteolysis converge to favor MIA40-bound AIFM1 after MOMP. These findings suggest how post-MOMP remodeling could reinforce NLRP1 restraint during apoptosis and how disruption of this program could trigger pyroptosis.

cell biology↗

bioRxiv2026

Cyclase-generated 3,5-cGMP activates PucsarTIR antiphage defense through a stepwise zig-zag aligned filament assembly

Bacteria use nucleotide second messengers to couple phage recognition to antiviral effector activation. Here, we identify Pucsar, an ofshoot of the Pycsar-related antiphage family, whose cyclases generate 3,5-cGMP from GTP, that are associated with Toll/Interleukin-1 receptor (TIR) and transmembrane (TM) effectors. In the PucsarTIR system, cGMP produced by cyclase PucC, selectively activates the cognate PucTIR NADase. X-ray crystallography shows that PucC adopts a dimeric cyclase scaffold with a guanine-compatible base-recognition pocket. Cryo-EM and mutational analyses revealed that apo-PucTIR, composed of cyclic nucleotide binding and TIR domains, is self-sequestered as an inactive tetramer, in which TIR domains are proximal but misoriented. Sequential cGMP binding remodels this assembly through partially occupied intermediates and stabilizes a fully cGMP-bound dimer, that polymerizes into a zig-zag aligned filament, creating composite NAD+-binding pockets required for efficient NADase activity. These findings establish 3',5'-cGMP as an antiphage second messenger and reveal how cyclic purine signaling converts self-sequestered TIR effectors into a NADase-competent filament.

microbiology↗

bioRxiv2026

BxbI-mediated insertion of a 77kb human RET sensitive haplotype into the mouse genome to generate a humanized model of Hirschsprung disease

Hirschsprung disease (HSCR) is a complex developmental disorder of the enteric nervous system, primarily driven by regulatory variants within enhancer elements of the RET gene. To investigate how these variants lead to aganglionosis, we developed a humanized mouse model by inserting an intact 77kb human RET genomic locus into the Rosa26 safe-harbor locus. Utilizing "big DNA" synthetic biology and Bxb1-mediated recombination, we integrated the complete human locus including all exons, introns, and upstream regulatory elements which we validated via nanopore and short-read sequencing. Functional analysis confirmed in vivo human RET expression; however, our initial HSCR-associated "sensitive" haplotype expressed at only 21% of wild-type levels. This significant reduction proved insufficient to rescue the viability when endogenous mouse Ret was deleted. We identified that this deficiency is partially driven by five risk SNPs within established enhancers. Specifically, using CRISPR/Cas9 to restore a conserved Sox10 binding site (converting a sensitive SNP to a protective one) increased RET expression by 1.9-fold and restored transcription factor binding. This study provides a robust framework for modeling human-specific regulatory disorders and demonstrates the critical impact of non-coding variation on disease pathogenesis.

synthetic biology↗

bioRxiv2026

Radiosensitization of Glioblastoma by the K-ras Inhibitor RMC-6236

PurposeGlioblastoma (GBM) is characterized by poor clinical outcomes and marked resistance to radiotherapy. Because effective radiosensitizing strategies for GBM remain limited, we investigated whether inhibition of KRAS/RAS signaling could enhance radiation response in GBM. In particular, we evaluated the radiosensitizing potential of RMC-6236, an RAS(ON) multiselective inhibitor that suppresses active RAS signaling across multiple RAS-dependent states. Experimental DesignHuman GBM cell lines (U251, LN-18, ACPK1, and OSU61) were treated with radiation, with or without genetic or pharmacological KRAS inhibition. KRAS signaling was suppressed by siRNA-mediated knockdown or RMC-6236 treatment. Radiation-induced KRAS activation and downstream MAPK signaling were assessed by Raf-RBD pull-down assays and immunoblotting. Radiosensitivity was evaluated using clonogenic survival assay. DNA damage persistence, cell cycle distribution, and mitotic catastrophe were analyzed by {gamma}H2AX immunofluorescence, flow cytometry, and nuclear morphology assessment, respectively. In vivo therapeutic efficacy was examined in an orthotopic U251 xenograft model. ResultsRadiation-induced transient activation and increased KRAS protein expression of KRAS, accompanied by activation of ERK, JNK, and p38 signaling in GBM cells. siKRAS suppressed radiation-induced KRAS and MAPK activation, and significantly enhanced radiosensitivity in all four GBM cell lines. Similarly, RMC-6236 inhibited radiation-induced KRAS activation and attenuated downstream MAPK signaling without reducing the total KRAS protein expression. RMC-6236 significantly increased the radiosensitivity across all GBM cell lines, with dose enhancement factors ranging from 1.33 1.46. Mechanistically, combined treatment with RMC-6236 and radiation increased persistent {gamma}H2AX foci and enhanced mitotic catastrophe without producing consistent redistribution of cells into radiosensitive cell cycle phases. In an orthotopic GBM model, the combination of RMC-6236 and radiation significantly prolonged survival compared to that of the control and radiation alone. ConclusionsThese findings indicate that radiation-induced KRAS signaling is a functionally important mediator of radioresistance in GBM and demonstrate that inhibition of KRAS/RAS signaling enhances the radiation response in vitro and in vivo. RMC-6236 may represent a promising radiosensitizing strategy for GBM by suppressing adaptive RAS/MAPK signaling and promoting persistent DNA damage and mitotic catastrophe following irradiation. However, clinical trials of this combination are warranted.

neuroscience↗

bioRxiv2026

Sex Steroid Hormone Signaling Tunes Metabolic and Neuronal Programs in Human Cortical Development

Autism spectrum disorder (ASD) exhibits a profound male biased sex ratio. While numerous genes have been implicated in ASD, the functional basis of this sex difference is unclear. One enticing hypothesis is genome-wide transcriptional regulation through estrogens and androgens. While hormone-mediated transcription is well-studied in reproductive tissues, its role in cortical development is poorly defined. Thus, we profiled androgen (AR) and estrogen (ESR1/ESR2) receptor expression in primary human cortex and developmental stage-matched organoid models by single-cell RNA-seq. AR was primarily expressed in radial glia and intermediate progenitors while ESR1/ESR2 was more broadly distributed across multiple cell types of the developing cortex, although with the highest expression in radial glia. To study their genetic effects, we exposed iNeurons and cortical organoids to physiological levels of dihydro-testosterone (DHT) and estradiol (E2). DHT consistently up-regulated oxidative metabolism programs enriched in progenitor cells and down-regulated neuronal maturation pathways, while E2 exhibited a much more attenuated effect. The presence of DHT reduced NTRK2 (TrkB) expression, correlating with expression in developing cortex where NTRK2 had significantly higher expression in progenitor cells of the female cortex, which is also reflected in the increased expression of AR in radial glia. Together, these data indicate that in developing human cortical lineages, sex hormones act as selective, cell-state- dependent modulators that tune metabolic and maturation programs rather than broadly reprogramming the genome. Thus, the effects of variation in transcriptional regulation through estrogens and androgens are likely to be minor, but not absent, in ASD.

genomics↗

bioRxiv2026

A massively parallel reporter assay of MECP2 cis-regulatory elements reveals genetic candidates for male-biased autism

Autism affects males four times more often than females, yet the basis of this sex bias remains unclear. One hypothesis is that hypomorphic variants in X-linked genes--genes where loss-of-function alleles cause syndromic neurodevelopmental disorders (NDDs) predominantly in females--produce milder, non-syndromic phenotypes in hemizygous males. We tested this by investigating cis-regulatory elements (CREs) of MECP2, a dosage-sensitive X-linked gene. Using a massively parallel reporter assay in human neurons, we mapped transcription factor binding sites within MECP2 CREs and tested autism-associated variants for functional impact. We identified two noncoding variants that change CRE activity, each with a male-biased phenotype. One of these, a promoter variant, disrupts NFY binding and reduces MECP2 expression by [~]30%, a magnitude that produces autism-like phenotypes in mice. These findings suggest noncoding MECP2 variants can cause non-syndromic, male-biased autism, and provide a framework for uncovering regulatory variants in other X-linked NDD genes that may contribute to autisms missing heritability.

genetics↗

bioRxiv2026

Sod1 trisomy causes ENS developmental defects and susceptibility to Hirschsprung disease via neuronal Ret suppression and glial remodeling

Down syndrome (DS; trisomy 21) confers a [~]100-fold increased risk of Hirschsprung disease (HSCR), yet the causal contributions of specific chromosome 21 genes remain unresolved. Here we show that increased dosage of SOD1 alone is sufficient to perturb enteric nervous system (ENS) development. We engineered a humanized SOD1 trisomic mouse line by inserting a 28 kb human SOD1 locus into ROSA26 and genetically profiled the distal colon at postnatal day 0 using single-cell RNA-seq and immunofluorescence. Sod1/SOD1 was elevated [~]1.5X in the ENS but varied by cell type, with transcriptionally active progenitors showing the greatest increase. Cell composition shifted toward transcriptionally active cells and glia, with concomitant loss of excitatory and inhibitory motor neurons and interneurons. Genetically, Sod1/SOD1 trisomy downregulated synaptic and neuronal communication programs but upregulated DNA replication/cell-cycle and genome maintenance pathways, especially within glia. Consequently, key HSCR genes were dysregulated: Ret, Ednrb, and Sema3c were decreased, while Sema3a ,a negative guidance cue, was increased. Ret was selectively reduced in inhibitory and excitatory motor neurons and progenitors, unchanged in glia, and reduced at the protein level in vivo. Within glia, Sod1/SOD1 was particularly elevated in proliferating/active glia with a glia-specific bias toward endogenous mouse Sod1 expression. Taken together, these data support a dual mechanism whereby increased Sod1/SOD1 dosage suppresses RET-dependent neurogenesis while independently promoting reactive/proliferative glial states. Thus, SOD1 is sufficient to alter ENS development significantly and provide the susceptibility substrate for HSCR with further reductions in RET gene expression leading to aganglionosis.

genomics↗

bioRxiv2026

A methylome-derived m6-dAMP trigger assembles a PUA-Cal-HAD immune filament that depletes dNTPs to abort phage infection

Bacteria must distinguish phage attack from normal homeostatic processes, yet the danger signals that trigger many defence systems remain unknown. Here, we show that a PUA-Calcineurin-CE-HAD module from Escherichia coli ECOR28 confers broad anti-phage protection by binding Dam-methylated deoxyadenosine monophosphate (m6-dAMP) generated during phage-induced chromosome degradation. Ligand binding converts a preassembled PUA-Calcineurin-CE hexamer loaded with six HAD phosphatases into a polymerising filament. The filament acts as a high-flux dNTP sink through a two-enzyme cascade: HAD first dephosphorylates dATP to dADP, and Calcineurin-CE then converts dADP to dAMP. dNTP collapse halts phage replication and enforces abortive infection. Multiple mobile-element DNA mimic proteins block filament assembly, revealing a direct phage counter-defence. More broadly, our findings extend a conserved, cross-kingdom paradigm of immune filament assembly to nucleotide-depletion antiviral defence and suggest modified-nucleotide sensing by related PUA-Calcineurin-CE modules as a widespread, underappreciated bacterial strategy.

microbiology↗

bioRxiv2025

Molecular basis for thermoresponsive protein condensation in plants

Plants continuously experience temperature fluctuations that shape their physiology, development, and survival. Yet, how plants sense and adapt to elevated temperatures at the molecular level remains only partially understood. Here, we uncover a sequence-encoded mechanism by which plant proteins directly sense temperature through phase separation. Focusing on prion-like low-complexity domains (PLCDs) in Arabidopsis thaliana, we combine cellular imaging, quantitative biophysics, and coarse-grained molecular dynamics simulations to show that numerous PLCDs undergo reversible lower critical solution temperature (LCST)-type transitions. We find that PLCDs that are sufficient and necessary for phase separation confer thermoresponsive variability to full-length proteins. Sequence analysis and simulations reveal that thermoresponsiveness is encoded in compositional heuristics, with sufficient PLCDs enriched in aliphatic and aromatic residues, enabling accurate prediction and rational tuning of condensation thresholds. Engineered variants with altered sequence composition exhibit predictable shifts in thermoresponsive behavior, confirming a direct, sequence-level encoding of temperature sensitivity. Our findings establish LCST-driven phase separation as a fundamental mechanism of thermoresponsiveness in plants and provide a molecular framework for designing synthetic biomolecules with programmable temperature responses.

biophysics↗

bioRxiv2025

Sex differences in the developing human cortex intersect with genetic risk of neurodevelopmental disorders

Autism is highly heritable and diagnosed more frequently in males than females. To identify neurodevelopmental processes that might present sex-biased vulnerability, we generated transcriptomic and epigenomic profiles of cell types present in the prenatally developing human cerebral cortex of 27 males and 21 females. By intersecting sex-biased molecular signatures and genes with de novo mutations in male and female autistic probands, we reveal two points of vulnerability contributing to the sex-biased penetrance in neurodevelopmental disorders (NDDs). First, we show that NDD risk genes are biased towards higher expression in females, identifying the NDD gene MEF2C as a critical transcription factor for female-biased expression. Second, we identify a significant contribution of X chromosome genes to NDD pathobiology. We construct a gene regulatory map of X-linked risk genes to enable functional studies of genetic variants that likely disrupt gene expression in the developing brains of autistic males. Together, these results point towards an outsized contribution of the X-chromosome to both the origin of sex differences in the developing human cortex and NDD vulnerability. We propose a model where female-biased vulnerability is driven by coding variation within genes while male-biased vulnerability is driven by noncoding variation in regulatory elements that affect gene expression.

neuroscience↗

bioRxiv2025

Structural basis for Lamassu-based antiviral immunity and its evolution from DNA repair machinery

Bacterial immune systems exhibit remarkable diversity and modularity, as a consequence of the continuous selective pressures imposed by phage predation. Despite recent mechanistic advances, the evolutionary origins of many antiphage immune systems remain elusive, especially for those that encode homologs of the Structural Maintenance of Chromosomes (SMC) superfamily, which are essential for chromosome maintenance and DNA repair across domains of life. Here, we elucidate the structural basis and evolutionary emergence of Lamassu, a bacterial immune system family featuring diverse effectors but a core conserved SMC-like sensor. Using cryo-EM, we determined structures of the Vibrio cholerae Lamassu complex in both apo- and dsDNA-bound states, revealing unexpected stoichiometry and topological architectures. We further demonstrate how Lamassu specifically senses dsDNA in vitro and phage replication origins in vivo, thereby triggering the formation of LmuA tetramers that activate the Cap4 nuclease domain. Our findings reveal that Lamassu evolved via exaptation of the bacterial Rad50-Mre11 DNA repair system to form a compact, modular sensor for viral replication, exemplifying how cellular machinery can be co-opted for novel immune functions.

microbiology↗

bioRxiv2025

Massively parallel reporter assays identify functional enhancer variants at QT interval GWAS loci

Genome-wide association studies (GWAS) have identified >30 loci with multiple common noncoding variants explaining interindividual electrocardiographic QT interval (QTi) variation. Of the many types of noncoding functional elements, here we sought to identify transcriptional enhancers with sequence variation and their cognate transcription factors (TFs) that alter the expression of proximal cardiac genes to affect QTi variation. We used massively parallel reporter assays (MPRA) in mouse cardiomyocyte HL-1 cells to screen for functional enhancer variants among 1,018 QTi-associated GWAS variants that overlap candidate cardiac enhancers across 31 loci. We identified 445 GWAS variant-containing enhancers of which 79 showed significant allelic difference in enhancer activity across 21 GWAS loci, with multiple enhancer variants per locus. Of these, we predicted differential binding by cardiac TFs, including AP-1, ATF-1, GATA2, MEF2, NKX2.5, SRF and TBX5 which are known to play key roles in development and homeostasis, at 49 enhancer variants. Finally, we used expression quantitative trait locus mapping and predicted promoter-enhancer contacts to identify 14 candidate target genes through analyses of 36 enhancer variants at 16 loci. This study provides strong evidence for 14 cardiac genes, 10 of them novel, impacting on QTi variation, beyond explaining observed genetic associations.

genetics↗

bioRxiv2025

Joint disruption of Ret and Ednrb transcription drives cell fate reversal in the Enteric Nervous System in Hirschsprung disease

Despite extensive genetic heterogeneity, 72% of pathogenic alleles for Hirschsprung disease (HSCR) arise from coding and regulatory variants in genes of the RET and EDNRB gene regulatory network (GRN) in the enteric nervous system (ENS). Reduced signaling of these two receptors below a threshold in enteric neural crest-derived cells (ENCDCs) leads to a molecular tipping point at which otherwise lesser cellular defects result in aganglionosis. To elucidate the mechanisms leading to enteric neuronal loss from these genetic defects, we generated four strains of mice carrying reduced function alleles at Ret or Ednrb or both, along with their wildtype alleles. ENS tissue- and single-cell gene expression profiling of the developing and postnatal gastrointestinal tract in five mouse models, with various combinations of mutant alleles, revealed 3 major insights: (i) Ret and Ednrb deficiency, rather than complete loss, is sufficient to induce HSCR, (ii) Ret and Ednrb demonstrate strong trans interactions, and (3) disruption of this interaction leads to cellular fate changes to compensate for neuronal loss. This study of targeted mouse models of a multifactorial disorder reveals how increasing dosage of genetic defects within a GRN leads to quantifiably increasing dysregulation from genotype to gene expression to cellular identity to function. Importantly, our studies establish that aganglionosis results only with severely reduced gene expression at both receptor genes and their consequent disruption of normal and compensatory cell fate trajectories.

genetics↗

bioRxiv2025

Accurate prediction of thermoresponsive phase behavior of disordered proteins

Protein responses to environmental stress, particularly temperature fluctuations, have long been a subject of investigation, with a focus on how proteins maintain homeostasis and exhibit thermoresponsive properties. While UCST-type (upper critical solution temperature) phase behavior has been studied extensively and can now be predicted reliably using computational models, LCST-type (lower critical solution temperature) phase transitions remain less explored, with a lack of computational models capable of accurate prediction. This gap limits our ability to probe fully how proteins undergo phase transitions in response to temperature changes. Here, we introduce Mpipi-T, a residue-level coarse-grained model designed to predict LCST-type phase behavior of proteins. Parametrized using both atomistic simulations and experimental data, Mpipi-T accounts for entropically driven protein phase separation that occurs upon heating. Accordingly, Mpipi-T predicts temperature-driven protein behavior quantitatively in both single- and multi-chain systems. Beyond its predictive capabilities, we demonstrate that Mpipi-T provides a framework for uncovering the molecular mechanisms underlying heat stress responses, offering new insights into how proteins sense and adapt to thermal changes in biological systems.

biophysics↗

bioRxiv2025

Synergistic effects of Ret coding and enhancer loss-of-function alleles cause progressive loss of inhibitory motor neurons in the enteric nervous system

Hirschsprung disease (HSCR) is a congenital enteric neuropathy caused by disrupted development of enteric neural crest-derived cells (ENCDCs). Although pathogenic coding variants in RET account for many cases, the largest genetic contribution to HSCR risk arises from a common non-coding variant (rs2435357) within a SOX10-bound RET enhancer (MCS+9.7) that reduces RET gene expression in vivo and triggers expression changes in other ENS genes in the human fetal gut. However, the ENS cell types affected by this enhancer and the mechanisms by which these transcriptional changes lead to HSCR remain unknown. Here, we investigated the role of this enhancer by generating mice carrying a deletion of the orthologous Ret mcs+9.7 enhancer ({Delta}mcs+9.7). Single-cell RNA sequencing of E14.5 embryonic gut demonstrated that enhancer deletion reduced Ret expression by 8% without altering ENS cell composition. However, reduced Ret expression was restricted to differentiating neurons and inhibitory motor neuron lineages, revealing cell type-specific enhancer activity. To determine the functional consequences of further reducing Ret dosage, we generated compound heterozygous mice carrying both the enhancer deletion and a Ret coding null allele (+/{Delta}mcs+9.7;+/CFP). These mice exhibited additive reductions in Ret expression, altered Sox10 expression, dysregulation of cell-cycle and neuronal differentiation programs, and selective depletion of developing inhibitory motor neuron lineages. These findings establish a cell type-specific role for the mcs+9.7 enhancer in modulating Ret dosage and reveal how subtle enhancer perturbations alter neural subtype specification without overt hypoganglionosis, suggesting that HSCR arises from a cascade of cellular defects triggered by >50% loss of Ret function.

genetics↗

bioRxiv2024

Finding Salient Multi-Omic Interactomes Relevant to Multiple Biomedical Outcomes using Graph Ensemble Neural Networks

Although multi-omics integration relevant to patient outcome is typically characterized by an analyte interactome, current multi-omic integration methods either (1) model outcome without directly including associations between analytes, (2) model the interactome without directly evaluating the saliency of the model in the context of outcome, or (3) model outcome in a high-dimensional parameter space not suitable for small sample sizes (which are common in multi-omics studies). We introduce Graph Ensemble Neural Network (GENN), a methodology that learns the interactome most predictive of outcome in a low-dimensional parameter space built on complementary attributes for all possible analyte associations (metafeatures). We show that GENN is robust to noise in measurements using a theoretical model, outperforms the predictive performance of existing methods when evaluated on Tegafur drug response in NCI-60 cancer cell line data, and uncovers potentially novel multi-omic mechanisms driving total serum IgE levels in pediatric asthma and patient survival in glioblastomas.

bioinformatics↗

bioRxiv2024

Variability in proliferative and migratory defects in Hirschsprung disease-associated RET pathogenic variants

Despite the extensive genetic heterogeneity of Hirschsprung disease (HSCR; congenital colonic aganglionosis) 72% of patients harbor pathogenic variants in 10 genes that form a gene regulatory network (GRN) controlling the development of the enteric nervous system (ENS). Among these genes, the receptor tyrosine kinase gene RET is the most significant contributor, accounting for pathogenic variants in 12%-50% of patients depending on phenotype. RET plays a critical role in the proliferation and migration of ENS precursors, and defects in these processes lead to HSCR. However, despite the genes importance in HSCR, the functional consequences of RET pathogenic variants and their mechanism of disease remain poorly understood. To address this, we investigated the proliferative and migratory phenotypes in a RET-dependent neural crest-derived cell line harboring one of five missense (L56M, E178Q, Y791F, S922Y, F998L) or three nonsense (Y204X, R770X, Y981X) pathogenic heterozygous variants. Using a combination of cDNA-based and CRISPR-based PRIME editing coupled with quantitative proliferation and migration assays, we detected significant losses in cell proliferation and migration in three missense (E178Q, S922Y, F998L) and all nonsense variants. Our data suggests that the Y791F variant, whose pathogenicity has been debated, is likely not pathogenic. Importantly, the severity of migration loss did not consistently correlate with proliferation defects, and the phenotypic severity of nonsense variants was independent of their position within the RET protein. This study highlights the necessity and feasibility of targeted functional assays to accurately assess the pathogenicity of HSCR-associated variants, rather than relying solely on machine learning predictions, which could themselves be refined by incorporating such functional data.

genetics↗

bioRxiv2022

Cardiac muscle-restricted partial loss of Nos1ap expression has limited impact on electro- and echo-cardiographic features

Genome-wide association studies (GWAS) of QT interval variation have identified common noncoding variants at the NOS1AP gene as the most common genetic regulators of trait variation in the general population. Invoking a cis-regulatory mechanistic hypothesis, we have reported identification of a functional enhancer variant underlying the GWAS signal that influenced human cardiac NOS1AP expression. Functional studies based on in vitro overexpression in murine cardiomyocytes and ex vivo knockdown in zebrafish embryonic hearts, by us and others, have demonstrated that NOS1AP expression levels can alter cellular electrophysiology. Here, to explore the role of NOS1AP in cardiac electrophysiology at an organismal level, we generated and characterized constitutive and heart muscle-restricted Nos1ap knockout mice to assess whether NOS1AP disruption alters the QT interval in vivo. Constitutive loss of Nos1ap led to genetic background-dependent variable lethality at or right before birth. Heart muscle-restricted Nos1ap knockouts generated using cardiac specific alpha-myosin heavy chain promoter-driven tamoxifen-inducible Cre resulted in tissue-level Nos1ap expression reduced by half. This partial loss of expression had no detectable effect on the QT interval, but led to a small yet significant reduction in the QRS interval. Given that challenges associated with defining the end of T wave on murine electrocardiogram can limit identification of subtle effects on QT interval, and that common noncoding NOS1AP variants are also associated with QRS interval, our findings support the role of NOS1AP in regulation of the cardiac electrical cycle.

genetics↗