Biology subjects

Khan, H.

Publications and source records attributed to Khan, H..

At least 19 recordsLinked to original sources

bioRxiv2026

Folic acid polyglutamylation triggers MAP2K5 signaling to induce adipocyte lipid catabolism

Adipocyte signaling adaptively responds to macronutrients, but how essential micronutrients impact lipid homeostasis remains poorly understood. Here, we demonstrate that folate polyglutamylation, the sequential conjugation of glutamate residues to folate, serves as a dynamic biochemical process regulating metabolic signaling. Using our folate metabolomics platform, we show that polyglutamylated folic acid accumulates in healthy adipose tissue, but is depleted in obesity across mice and humans, independent of circulating folate levels. Genetic ablation of the polyglutamylation enzyme folylpolyglutamate synthase (Fpgs) in adipocytes suppresses lipid catabolism to induce cell-autonomous lipid accumulation, operating independently of canonical adipogenesis or downstream one-carbon flux. Target-engagement proteomics identifies monoglutamylated folic acid as a Map2k5-interacting molecule that inhibits Map2k5 activity, whereas Fpgs-mediated folic acid polyglutamylation acts as a chemical switch that disrupts this interaction to promote lipolysis. In vivo, whole-body inhibition of Map2k5 or adipose-targeted genetic depletion of Fpgs increases body fat mass in the absence of dietary obesogenic triggers. Furthermore, single-cell and single-nuclear transcriptomic analyses establish the Fpgs-Map2k5 pathway as a core transcriptional signature of mouse and human adipose tissues. These findings uncover a non-canonical signaling role for folate that regulates adipocyte lipid homeostasis.

biochemistry↗

bioRxiv2026

Complement Dysregulation During the Early Phases of Synucleinopathy

Parkinsons disease (PD) is characterized by progressive degeneration of nigrostriatal dopamine neurons and synucleinopathy, which is the accumulation of aggregated -synuclein (-syn). Increasing evidence implicates -syn-associated neuroinflammation as a contributor to PD pathogenesis; however, immune mechanisms linking synucleinopathy to neurodegeneration remain incompletely defined. Activation of the complement cascade occurs in PD and other neurodegenerative disorders, but most studies report complement activation after overt neurodegeneration, making it difficult to conclude if complement is directly activated by pathological -syn or secondarily following neurodegeneration. We used the rat -syn preformed fibril (PFF) mode, in vitro complement assays and human postmortem PD tissue to test whether pathological -syn directly activates complement prior to overt neurodegeneration. The -syn PFF model exhibits a protracted pathological time course and distinct temporal separation between peak -syn aggregation and nigrostriatal degeneration; thus we quantified complement expression, activation, and regulation during the aggregation phase. Synucleinopathy induced complement activation prior to nigrostriatal degeneration, including upregulation of components of both the classical (C1qa, C1r, C4b) and alternative (Cfd, Cfb) pathways, the anaphylatoxin (C3aR, C5aR) and phagocytic (CR3) complement receptors, and activation of complement C3. During early synucleinopathy, microglia upregulated C3 which significantly correlated with synucleinopathy burden across several brain regions, including the substantia nigra pars compacta (SNc) and cortex. Concurrently, complement regulatory proteins, including CD55, CD59, neuronal pentraxin-1 (Nptx1), and the neuronal pentraxin receptor were downregulated in the synucleinopathy-affected SNc. Importantly, increased levels of C1q and iC3b along with downregulation of CD55 and NPTX1 were also observed in human postmortem PD SNc, supporting the translational relevance of our findings. Mechanistically, we demonstrate that aggregated, but not monomeric, -syn directly binds C1q and activates the complement cascade in a C1q-dpendent manner. These data provide the first in vivo evidence that synucleinopathy triggers complement activation and dysregulation prior to neurodegeneration.

neuroscience↗

bioRxiv2026

Comparing Random and Natural RNA Boltzmann Ensembles

A morphospace is an abstract space of theoretically possible biological traits, shapes, or property values. It is interesting to explore which parts of a morphospace life occupies, as compared to those parts which could be occupied, but are not. Comparing random and natural non-coding (nc) RNA secondary structures is an established approach to studying morphospace occupation for RNA structures. Most earlier studies have focused on the minimum free energy (MFE) structure, while relatively few have looked at the Boltzmann distribution, describing the ensemble of energetically suboptimal RNA folds. These suboptimal structures may have important roles and functions, and hence should be examined carefully. Here we compare random and natural ncRNA in terms of their Boltzmann distributions, finding that natural RNA tend to have very similar profiles to random RNA, with the main difference being that natural RNA are slightly more energetically stable, except for very short sequences (20 to 30 nucleotides) which appear to be equally or slightly less stable. We infer that natural ncRNA and random RNA occupy similar parts of the morphospace, indicating that the biophysics of the genotype-phenotype map largely determines the ensemble properties of ncRNA.

biophysics↗

bioRxiv2026

The pyruvate branch point controls lymphoid cancer cell dissemination

Cancer cell dissemination critically determines clinical prognosis, yet metabolic dependencies and corresponding therapeutic targets during spread of lymphoid malignancies remain poorly understood. Here we show that the pyruvate branch point operates as a metabolic checkpoint for lymphoid cancer cell migration and disease dissemination through mitochondrial ROS (mROS)/HIF-1a signaling. Isolation of highly migratory mROShi cells led us to identify selective metabolic requirements of malignant lymphocyte migration and disease dissemination. Highly migratory cells show a reprogrammed metabolic profile characterized by increased glucose uptake and reduced glucose-carbon entry into the TCA cycle. Reprogramming of the TCA cycle with downregulation of citrate synthase provide the mechanistic basis for decreased pyruvate oxidation leading to increased migration and disease dissemination through mROS/HIF-1a signaling. Our findings connect central carbon metabolism and migratory capacity of lymphoid cancer cells and identify the pyruvate branch point as a metabolic switch and potential therapeutic target in lymphoid cancer cell dissemination.

cancer biology↗

bioRxiv2025

BNIP3-mTOR Signaling Mediates Resistance to MET Inhibition in Glioblastoma

Glioblastoma (GBM) is an aggressive primary brain malignancy with poor prognosis due to rapid progression, extensive invasiveness, and intrinsic resistance to standard therapies. Aberrant activation of receptor tyrosine kinases (RTKs), particularly MET, drives tumor proliferation, invasion, and therapy resistance. Here, we show that MET inhibition with crizotinib induces senescence and mitochondrial dysfunction in glioma-initiating cells (GICs), in part via downregulation of the mitochondrial protein BNIP3. However, BNIP3 downregulation activates mTOR signaling, enabling adaptive resistance. Targeting mTOR with everolimus in combination with crizotinib synergistically enhances anti-tumor effects, inducing apoptosis, senescence, and necroptosis, and significantly reducing cell viability and sphere-forming capacity. In orthotopic GBM xenograft models, this combination, particularly in a sequential regimen, markedly prolongs survival without overt toxicity. Our findings identify a BNIP3-mTOR signaling axis as a critical mediator of resistance to MET inhibition and provide a mechanistic rationale for combined MET and mTOR targeting as a promising therapeutic strategy in GBM. Statement of Translational RelevanceGlioblastoma (GBM) remains a highly aggressive and treatment-resistant brain tumor with limited therapeutic options. Our study identifies a BNIP3-mTOR signaling axis as a key mediator of resistance to MET inhibition. We show for the first time that combined MET and mTOR inhibition exhibits synergistic effects against GBM in vitro and in vivo. This combination prolongs survival without overt toxicity, providing a strong preclinical rationale for clinical evaluation in GBM patients with high MET expression and offering a promising strategy to overcome adaptive resistance.

cancer biology↗

bioRxiv2025

Dynamic evolution of EZHIP, an inhibitor of the Polycomb Repressive Complex 2 in mammals

The Polycomb Repressive Complex 2 (PRC2) is an ancient, conserved chromatin-interacting complex that controls gene expression, facilitating differentiation and cellular identity during development. Its regulation is critical in most eukaryotes. EZHIP was recently characterized as a PRC2 inhibitor and oncohistone mimic in mammals. Although EZHIP expression is typically restricted to the germline, its aberrant expression in pediatric brain tumors inhibits PRC2-mediated H3K27 methylation, driving disease progression. To gain a deeper understanding of its normal functions, we systematically examined EZHIP evolution across mammals using comparative genomics, synteny analyses, and motif discovery. Extending previous work, we find that EZHIP originated on the X chromosome and was retained there in most placental mammals, except in Afrotheria. In addition to the highly conserved H3K27M-like histone mimic motif, our motif analyses reveal six previously unidentified EZHIP motifs, including a putative nuclear localization signal, a serine-enriched region, and tandem repeats that are largely well-conserved in placental mammals. We hypothesize that these motifs are also critical to EZHIPs functions, including in PRC2 interaction and inhibition. We show that EZHIP has evolved under strong diversifying selection in primates and underwent dynamic expansions and losses across species. Some paralogs, such as EZHIP2 in primates, also evolved under positive selection. Based on its evolutionary attributes and germ-cell expression, we propose that EZHIP arose and evolved rapidly due to inter-parental conflict over fetal development in utero in placental mammals. Our work provides a foundation for further investigations into EZHIPs multifaceted roles in mammalian reproduction and disease. SignificanceHistone modifications regulate genes to orchestrate cell differentiation and development. Their precise regulation is essential for normal development and growth. The Polycomb Repressive Complex 2 (PRC2) deposits the repressive H3K27 methylation mark, whereas EZHIP antagonizes PRC2 to de-repress gene silencing mediated by H3K27 methylation. While aberrant EZHIP activity in cancers is well documented, its normal germline functions, evolutionary origins, and divergence remain unclear. We show that EZHIP is a placental, X-linked innovation that diversified through positive selection and recurrent gene duplications, yielding germline-specific paralogs. We discover conserved motifs that may have critical roles in PRC2 control. Our findings provide an evolutionary model - parental control over in utero reproduction - that drove the origin and innovation of EZHIPs in placental mammals.

evolutionary biology↗

bioRxiv2025

From Metabolism to Malignancy: Profiling Diabetes-Related Genes in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) and diabetes mellitus both affect the liver, a key metabolic organ. This study uses bioinformatics to explore genetic links between Type 1 Diabetes (T1D) and HCC prognosis. Eleven HCC gene expression datasets from GEO and one TCGA-LIHC dataset were analyzed. Gene Set Enrichment Analysis (GSEA) identified up- and downregulated genes after data normalization in R. Four datasets (GSE64041, GSE78737, GSE107170, TCGA) revealed increased expression of T1D-related genes. Ten genes, including HLA-DOB and HLA-DPB1, were consistently upregulated. Statistical analysis (Kruskal-Wallis and Mann-Whitney U tests) showed these two genes were significantly associated with tumor grade and T-stage, with p-values ranging from 0.008 to 0.019. Co-expression analysis with 96 literature-curated T1D genes identified 23 related genes. Survival analysis using Kaplan-Meier curves highlighted five genes (IL7R, CD69, CCR5, RUNX3, PRF1), with CD69 showing strong associations with T-stage and disease-free survival. PRF1, RUNX3, and CCR5 were also linked to survival outcomes. Seven diabetes-related GEO datasets were used for validation. GSEA showed T1D gene enrichment in two datasets (GSE228267, GSE232310), with HLA-DOB significantly expressed in GSE228267 (p = 0.004). These findings suggest that HLA-DOB, HLA-DPB1, and three other T1D-related genes may serve as potential biomarkers for understanding the genetic connection between T1D and HCC. Though computational, this study lays the groundwork for future experimental validation.

bioinformatics↗

bioRxiv2025

Shaker it OFF: Biophysical Characterization of an Inactivating Potassium Conductance Mediating Object Segmentation in a Collision-Detecting Neuron

Homologous ion channels are expressed in sensory neurons across species where they shape responses to varied sensory stimuli, on a wide range of timescales. In grasshoppers, visual detection of looming stimuli which simulate an approaching predator involves the sub-cellular expression pattern of a newly characterized Shaker channel in a single identified neuron, discovered using a newly sequenced genome and single cell RNA sequencing. This channel shapes selectivity for approaching threats and was characterized with electrophysiological recordings, RNA interference, pharmacology and biophysical compartmental simulations. Our results explain how a slowly activating and inactivating potassium conductance common in neuronal dendrites contributes to visual object segmentation and implements a complex neural computation within a single neuron.

neuroscience↗

bioRxiv2025

UNC-45A Drives ATP-Independent Microtubule Destabilization via Defect Recognition and Repair Inhibition Contributing to Neurite Dystrophy

UNC-45A is the only known ATP-independent microtubule severing protein. Using in vitro reconstitution and TIRF microscopy, we show that, unlike canonical severing enzymes such as katanin, spastin, and fidgetin, which hydrolyze ATP to remove tubulin dimers and promote lattice repair, UNC-45A selectively binds to pre-existing microtubule defects and inhibits GTP-tubulin incorporation. This mechanism prevents the formation of stabilized hot spots that typically protect microtubules from disassembly, resulting in persistent lattice damage and net microtubule loss, even in the presence of physiological levels of free GTP-tubulin. We further demonstrate that UNC-45A localizes near amyloid deposits in both mouse models and human cases of Alzheimers disease (AD). In cultured neurons, UNC-45A accumulates in axonal swellings--regions of pronounced microtubule disruption and experimental surrogates for dystrophic neurites in AD--and exacerbates their size and number, particularly under conditions mimicking microtubule damage. Notably, this is the first report of a microtubule severing protein that both localizes near amyloid plaques in tissue and accumulates in neurite swellings in cultured neurons, where it modulates their pathology. Together, our findings establish the mechanism of ATP-independent, damage-responsive severing pathway that couple defects recognition to repair inhibition, defining a new paradigm in microtubule quality control with broad implications for cytoskeletal integrity and remodeling in health and disease.

cell biology↗

bioRxiv2025

RHOV is a Detachment-Responsive Rho GTPase Necessary for Ovarian Cancer Peritoneal Metastasis

All ovarian cancer subtypes spread via transcoelomic metastasis, where cells disseminate into the peritoneal fluid, resist anoikis, and form multicellular aggregates that invade the peritoneum. This represents the main driver of morbidity and mortality for peritoneal cancer patients. Mechanisms necessary for cancer cells to survive matrix detachment and initiate transcoelomic metastasis remain poorly defined. To address this, we identified a conserved detachment-sensitive gene signature activated shortly after matrix-detachment across multiple ascites-derived cancer cell lines. RHOV, an atypical, constitutively active and understudied member of the Rho GTPase family, emerged as a top upregulated transcript, which was confirmed in patient ascites-derived tumor cells. Functionally, loss of RHOV impairs anoikis resistance, multicellular aggregate integrity, migration and invasion, and completely abolishes transcoelomic tumor progression in vivo. RHOV enhances c-Jun signaling and cytoskeletal remodeling, which is dependent on both RHOV GTP-binding and membrane localization. These findings define RHOV as a novel detachment-sensitive Rho GTPase and establish RHOV as a critical regulator of peritoneal metastasis for the first time.

cancer biology↗

bioRxiv2025

Genomic analysis reveals the interplay between ABA-GA in determining dormancy duration in groundnut

Groundnut is an important leguminous crop however; its productivity and seed quality are frequently reduced due to lack of fresh seed dormancy (FSD). To address this challenge, a mini-core collection of 184 accessions was phenotyped to identify donors in each agronomic type, in addition to analysing data on whole genome re-sequencing and multi-season phenotypic evaluations to identify stable marker-trait associations (MTAs) associated with FSD. Phenotypic analysis revealed substantial variability in dormancy durations, with days to 50% germination (DFG) ranging from 1 to 30 days. Multi-locus genome-wide association studies (ML-GWAS) identified 27 MTAs in individual seasons and 12 MTAs in pooled seasons data, respectively. Key candidate genes identified included Cytochrome P450 superfamily proteins, protein kinase superfamily proteins, and MYB transcription factors involved in the Abscisic acid (ABA) pathway, as well as F-box interaction domain proteins, ATP-binding ABC transporters, associated with the Gibberellic acid (GA) pathway. SNP-based KASP (Kompetitive Allele-Specific Polymerase chain reaction) markers for 12 SNPs were developed and validated, of these 6 markers (snpAH00577, snpAH00580, snpAH00582, snpAH00585, snpAH00586 and snpAH00588) showed polymorphism between dormant and non-dormant lines. Incorporating favourable dormant alleles into breeding strategies could enable the development of high-yielding cultivars with a dormancy period of 2-3 weeks.

genomics↗

bioRxiv2024

WRAD core perturbation impairs DNA replication fidelity promoting immunoediting in pancreatic cancer

It is unclear how cells counteract the potentially harmful effects of uncoordinated DNA replication in the context of oncogenic stress. Here, we identify the WRAD (WDR5/RBBP5/ASH2L/DPY30) core as a modulator of DNA replication in pancreatic ductal adenocarcinoma (PDAC) models. Molecular analyses demonstrated that the WRAD core interacts with the replisome complex, with disruption of DPY30 resulting in DNA re-replication, DNA damage, and chromosomal instability (CIN) without affecting cancer cell proliferation. Consequently, in immunocompetent models, DPY30 loss induced T cell infiltration and immune-mediated clearance of highly proliferating cancer cells with complex karyotypes, thus improving anti-tumor efficacy upon anti-PD-1 treatment. In PDAC patients, DPY30 expression was associated with high tumor grade, worse prognosis, and limited response to immune checkpoint blockade. Together, our findings indicate that the WRAD core sustains genome stability and suggest that low intratumor DPY30 levels may identify PDAC patients who will benefit from immune checkpoint inhibitors.

cancer biology↗

bioRxiv2024

Characterization of the novel SmsHSP24.1 Promoter: Unveiling its abiotic stress-inducible expression in transgenic Eggplant (Solanum melongena L.)

Promoters play a pivotal role in regulating gene expression, orchestrating vital processes in plants, including their responses to various environmental stresses. In this study, we focus on the comprehensive characterization of the SmsHSP24.1 promoter, a novel cis-acting element, within the context of transgenic Eggplant (Solanum melongena L.). This detailed analysis shed light on the intricate mechanisms governing SmsHSP24.1 promoter-driven gene regulation, particularly in response to adverse environmental challenges such as heat, salt and drought stressors offering valuable insights into its role in plant stress adaptation. The advances in our understanding of promoter-driven gene regulation also contribute to the broader goal of enhancing crop resilience to abiotic stresses, positioning the SmsHSP24.1 promoter as a promising tool in agricultural biotechnology applications. HighlightsO_LIDemonstrated that the full-length 2.0 kb SmsHSP24.1 promoter significantly enhances gene expression under heat stress, with an observable decline in expression with promoter truncation. C_LIO_LIIdentified specific regulatory elements within the SmsHSP24.1 promoter that are decisive for inducible expression in response to abiotic stresses such as heat, salt, and drought. C_LIO_LIHighlighted the utility of the SmsHSP24.1 promoter in crop improvement programs, offering a tool for developing transgenic plant tolerance to combined stresses. C_LI

plant biology↗

bioRxiv2024

Long non-coding RNAs regulate the expression of cell surface receptors in plants

Plants are exposed to a variety of growth, developmental, and environmental cues during their lifespan. To survive and thrive, plants have developed sophisticated ways of responding to these signals that involve regulation at the transcriptional, post-transcriptional, translational, and post-translational levels. Leucine-rich repeat receptor-like kinases are the largest family of receptor-like kinases in plants and respond to a range of external and internal stimuli. They act as crucial regulators of plant growth, development, and immunity. To fully understand LRR-RLK function, it is essential to understand how their expression is regulated under different conditions. While there have been numerous studies on post-translational regulation of LRR-RLKs through phosphorylation and ubiquitination, there is little known about the mechanisms of transcriptional and post-transcriptional regulation of LRR-RLKs. In this study, we show that natural antisense transcript long non-coding RNAs are central regulators of LRR-RLK expression at the transcriptional and post-transcriptional levels. LRR-RLK genes are almost universally associated with cis-NATs and we confirm cis-NAT expression in planta using strand-specific RT-PCR. We leverage several well-studied LRR-RLKs to demonstrate that cis-NATs regulate LRR-RLK expression and function. For cis-NATs to fine-tune LRR-RLK expression, their expression and regulatory activity must be tightly controlled and cell autonomous. Using a combination of GUS reporter assays and tissue-specific promoters, we provide evidence that cis-NATs have these characteristics, positioning them as key regulators of LRR-RLK function. We also demonstrate that the association of LRR-RLK genes with cis-NATs is conserved across much of plant evolution, suggesting that this previously unexplored regulatory mechanism serves an important and ancient purpose.

plant biology↗

bioRxiv2024

Extended culture of 2D gastruloids to model human mesoderm development

Micropatterned human pluripotent stem cells (hPSCs) treated with BMP4 (2D gastruloids) are among the most widely used stem cell models for human gastrulation. Due to its simplicity and reproducibility, this system is ideal for high throughput quantitative studies of tissue patterning and has led to many insights into the mechanisms of mammalian gastrulation. However, 2D gastruloids have only been studied up to 48h. Here we extended this system to 96h. We discovered a phase of highly reproducible morphogenesis during which directed migration from the primitive streak-like region gives rise to a mesodermal layer beneath an epiblast-like layer. Multiple types of mesoderm arise with striking spatial organization including lateral mesoderm-like cells on the colony border and paraxial mesoderm-like further inside the colony. Single cell transcriptomics showed strong similarity of these cells to mesoderm in human and non-human primate embryos. However, our data suggest that the annotation of the reference human embryo may need to be revised. This illustrates that extended culture of 2D gastruloids provides a powerful model for human mesoderm differentiation and morphogenesis. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=44 SRC="FIGDIR/small/585753v1_ufig1.gif" ALT="Figure 1"> View larger version (13K): org.highwire.dtl.DTLVardef@6411fborg.highwire.dtl.DTLVardef@1d8a834org.highwire.dtl.DTLVardef@10afa27org.highwire.dtl.DTLVardef@1ad1f2e_HPS_FORMAT_FIGEXP M_FIG Graphical Abstract C_FIG

developmental biology↗

bioRxiv2024

IN VITRO 5-LOX INHIBITORY POTENTIAL AND ANTIOXIDANT ACTIVITY OF NEW ISOXAZOLE DERIVATIVES

5-Lipoxygenase (5-LOX) is a key enzyme involved in the biosynthesis of pro-inflammatory leukotrienes, leading to asthma. Developing potent 5-LOX inhibitors are highly attractive. In this research the previously synthesized isoxazole derivatives has been investigated against 5-Lox inhibitory and antioxidant in vitro assay. The percent inhibition for C3 were 89.93{+/-}1.73, 85.94{+/-}0.91, 81.90{+/-}1.32, 77.51{+/-}0.59 and 74.80{+/-}1.41 at various concentrations with IC50 of 8.47 {micro}M. The investigated compounds C5 also exhibited good 5-LOX inhibitory effect. The non-significant percent inhibition for C5 were demonstrated as 91.30{+/-}1.42, 87.78{+/-}0.45, 84.44{+/-}0.86, 79.72{+/-}1.89 and 75.29{+/-}1.64 at various concentration (1000-62.5 {micro}g/ml). The IC50 demonstrated for C5 was 10.48. Among the 10 synthesized compounds, the potential 5-LOX inhibitory effect was reported for C6. The most potent compound which showed excellent free radical scavenging effect was C3 with different percent inhibitions of 92.51{+/-}0.62, 87.65{+/-}0.70, 82.25{+/-}0.55, 79.37{+/-}0.69 and 75.72{+/-}0.51 having IC50 value of 10.96 {micro}M. The next most potent antioxidant activity was reported for C5 which non-significantly showed free radical scavenging effect. The DPPH percent inhibition reported for C5 was 92.63{+/-}0.64, 88.45{+/-}0.55, 83.53{+/-}0.41, 79.42{+/-}0.46 and 76.10{+/-}0.64 at different ranges of (1000, 500, 250, 125 and 62.5 {micro}g/mL) concentrations, respectively. The IC50 value observed for C5 was 13.12 {micro}M. Compound C6 also showed potent dose dependent antioxidant effect with IC50 value of 18.87 {micro}M having percent inhibition of 91.63{+/-}0.55, 88.45{+/-}0.49, 83.53{+/-}0.45, 78.42{+/-}0.66 and 73.72{+/-}0.64 at concentration 1000-62.5 {micro}g/mL respectively. Among the tested compounds, C6 was found most potent which showed significant 5-LOX percent inhibition assay and also reported the minimum IC50 value comparable to the reference drug. The in vitro 5-Lox enzymes inhibition assays of C5 and C3 also showed non-significant percent inhibition and good potency next to C6. We concluded that amongst the investigated designed molecules the C3 was found best potent and showed significant dose dependent antioxidant activity against DPPH screening. The IC50 value reported for C3 was found good as compared to standard drug. Moreover, C5 and C6 also showed excellent free radical scavenging effect against DPPH assay.

pharmacology and toxicology↗

bioRxiv2023

The complement pattern recognition molecule CL-11 promotes invasion and injury of respiratory epithelial cells by SARS-CoV-2.

Collectin-11 is a soluble C-type lectin produced at epithelial surfaces to initiate pathogen elimination by complement. Given the respiratory epithelium is a source of CL-11 and downstream complement-pathway components, we investigated the potential of CL-11 to impact the pathogenicity of SARS-CoV-2. While the SARS-CoV-2 spike trimer could bind CL-11 and trigger complement activation followed by MAC formation, the virus was resistant to lysis. Surprisingly, virus production by infected respiratory epithelial cells was enhanced by CL-11 opsonisation of virus but this effect was fully inhibited by sugar-blockade of CL-11. Moreover, SARS-CoV-2 spike protein expressed at the bronchial epithelial cell surface was associated with increased CL-11 binding and MAC formation. We propose that SARS-CoV-2 pathogenicity is exacerbated both by resistance to complement and CL-11 driven respiratory cell invasion and injury at the portal of entry. Contrary to expectation, CL-11 blockade could offer a novel approach to limit the pathogenicity of SARS-CoV-2.

immunology↗

bioRxiv2023

Loss of Nkd1 is dominant over loss of Axin2 in regulating Wnt signaling

Wnt signaling is a crucial developmental pathway involved in early development as well as stem cell maintenance in adults and its misregulation leads to numerous diseases. Thus, understanding the regulation of this pathway becomes vitally important. Axin2 and Nkd1 are widely utilized negative feedback regulators in Wnt signaling where Axin2 functions to destabilize cytoplasmic {beta}-catenin, and Nkd1 functions to inhibit the nuclear localization of {beta}-catenin. Here, we set out to further understand how Axin2 and Nkd1 regulate Wnt signaling by creating axin2-/-, nkd1-/- single mutants and axin2-/-;nkd1-/- double mutant zebrafish using sgRNA/Cas9. All three Wnt regulator mutants were viable and had impaired heart looping, neuromast migration defects, and behavior abnormalities in common, but there were no signs of synergy in the axin2-/-;nkd1-/- double mutants. Further, Wnt target gene expression by qRT-PCR, and RNA-seq analysis and protein expression by mass spectrometry demonstrated that the double axin2-/-;nkd1-/- mutant resembled the nkd1-/- phenotype demonstrating that Axin2 functions upstream of Nkd1 and that loss of Nkd1 is epistatic to the loss of Axin2. In support of this, the data further demonstrates that Axin2 uniquely alters the properties of {beta}-catenin-dependent transcription having novel readouts of Wnt activity compared to nkd1-/- or the axin2-/-;nkd1-/- double mutant. We also tested the sensitivity of the Wnt regulator mutants to exacerbated Wnt signaling, where the single mutants displayed characteristic heightened Wnt sensitivity, resulting in an eyeless phenotype. Surprisingly, this phenotype was rescued in the double mutant, where we speculate that cross-talk between Wnt/{beta}-catenin and Wnt/Planar Cell Polarity pathways could lead to altered Wnt signaling in some scenarios. Collectively, the data emphasizes both the commonality and the complexity in the feedback regulation of Wnt signaling.

developmental biology↗