Biology subjects

Novak, R.

Publications and source records attributed to Novak, R..

10 recordsLinked to original sources

bioRxiv2026

Generation and MHC class II loading of an endogenous influenza epitope revealed by a T cell receptor-like antibody

CD4+ T cells coordinate immune responses to infections and cancers and initiate many autoimmune diseases, yet the intracellular pathways that generate the peptide antigens they recognize remain incompletely understood. Progress has been limited in part by the scarcity of reagents that directly detect defined peptide:MHC class II (pMHC-II) complexes. Here, we established an mRNA vaccine-based pipeline to generate and characterize T cell receptor (TCR)-like antibodies. One result was 1D6, a monoclonal antibody specific for NA25:Ab, an influenza A/PR8 neuraminidase-derived epitope presented by MHC-II. 1D6 bound NA25:Ab with high affinity and specificity. 1D6 recognizes NA25:Ab through binding determinants partially distinct from those used by the cognate TCR. Using this reagent, we confirmed the proteasome dependence of NA25 presentation and showed that NA25:Ab accumulates in intracellular MHC-II loading compartments without a major requirement for canonical macroautophagy, pointing to an unconventional mode of antigen presentation. These findings establish TCR-like antibodies as powerful tools for dissecting noncanonical MHC-II antigen processing pathways. One Sentence SummaryAn mRNA immunization strategy generated a highly specific antibody to study how a noncanonical natural epitope from influenza virus is produced and loaded onto MHC-II.

immunology↗

bioRxiv2024

Eliminating Aggressive Cancers via PROTAC-like Inducers of Ferroptosis

Aggressive and therapy-resistant cancers present a significant challenge to treatment and are associated with poor patients survival. Identifying molecular pathways and compounds that target these pathways is critical for improving patient outcomes. RNF4, an E3-ubiquitin ligase, is pivotal in oncoprotein stabilization and DNA repair, enhancing cancer cell survival driving tumorigenesis. Elevated RNF4 levels are associated with poor prognosis in cancer patients. Here, we describe the development of R4VPs, proteolysis-targeted chimeras-like (PROTACs-like). R4VPs promote RNF4 degradation and reduce the levels of its stabilized oncoproteins. Notably, R4VPs induce ferroptotic cell death selectively in cancer cells, sparing non-tumorigenic and primary cells. Surprisingly, R4VPs-induced ferroptosis is independent of RNF4 but preferentially targets tumor-driving mutations, particularly those in the EGFR pathway, while not affecting PI3K-transformed cells. R4VPs effectively induce cell death in therapy-resistant melanoma and sarcomas including patient-derived sarcoma tumor cells. Our findings highlight the potential of ferroptosis inducers such as R4VPs as a therapeutic strategy for therapy resistance, aggressive, and hard-to-treat cancers. TeaserR4VPs induce ferroptotic death of melanoma and sarcoma cells including patient-derived tumor cells sparing non-transomed cells.

cancer biology↗

bioRxiv2023

Multiplexed Digital Characterisation of Misfolded Protein Oligomers via Solid-State Nanopores

Misfolded protein oligomers are of central importance in both the detection and treatment of Alzheimers and Parkinsons diseases. However, accurate high-throughput methods to identify and quantify oligomer populations are currently lacking. We present here a single-molecule approach for the detection of oligomeric species. The approach is based on the use of solid state nanopores and multiplexed DNA barcoding to identify and characterise oligomers from multiple samples. We study -synuclein oligomers in the presence of several small molecule inhibitors of -synuclein aggregation, as an illustration of the applicability of this method to assist the development of diagnostic and therapeutic methods for Parkinsons disease.

biophysics↗

bioRxiv2023

Identification of a pharmaceutical biostasis inducer that slows metabolism in multiple vertebrates that do not hibernate

Drugs that induce reversible slowing of metabolic and physiological processes would have great value for organ preservation, especially for organs with high susceptibility to hypoxia-reperfusion injury, such as the heart. Using whole-organism screening of metabolism, mobility, and development in Xenopus, we identified an existing drug, SNC80, that rapidly and reversibly slows biochemical and metabolic activities while preserving cell and tissue viability. Although SNC80 was developed as a delta opioid receptor activator, we discovered that its ability to slow metabolism is independent of its opioid modulating activity as a novel SNC80 analog (WB3) with almost 1,000 times less delta opioid receptor binding activity is equally active. Metabolic suppression was also achieved using SNC80 in microfluidic human organs-on-chips, as well as in explanted whole porcine hearts and limbs, demonstrating the cross-species relevance of this approach and potential clinical relevance for surgical transplantation. Pharmacological induction of physiological slowing in combination with organ perfusion transport systems may offer a new therapeutic approach for tissue and organ preservation for transplantation, trauma management, and enhancing patient survival in remote and low-resource locations.

bioengineering↗

bioRxiv2022

Target-agnostic discovery of Rett Syndrome therapeutics by coupling computational network analysis and CRISPR-enabled in vivo disease modeling

Many neurodevelopmental genetic disorders, such as Rett syndrome, are caused by a single gene mutation but trigger changes in expression and regulation of numerous other genes. This severely impair functions of multiple organs and organ systems beyond the central nervous system (CNS), adding to the challenge of developing broadly effective treatments based on a single drug target. This challenge is further complicated by the lack of sufficiently broad and biologically relevant drug screens, and the inherent complexity in identifying clinically relevant targets responsible for diverse phenotypes. Here, we combined human gene regulatory network-based computational drug prediction with in vivo screening in a population-level diversity, CRISPR-edited, Xenopus laevis tadpole model of Rett syndrome to carry out target-agnostic drug discovery, which rapidly led to the identification of the FDA-approved drug vorinostat as a potential repurposing candidate. Vorinostat broadly improved both CNS and non-CNS (e.g., gastrointestinal, respiratory, inflammatory) abnormalities in a pre-clinical mouse model of Rett syndrome. This is the first Rett syndrome treatment to demonstrate pre-clinical efficacy across multiple organ systems when dosed after the onset of symptoms, and network analysis revealed a putative therapeutic mechanism for its cross-organ normalizing effects based on its impact on acetylation metabolism and post-translational modifications of microtubules. Although traditionally considered an inhibitor of histone deacetylases (HDAC), vorinostat unexpectedly restored protein acetylation across both hypo- and hyperacetylated tissues, suggesting non-HDAC-mediated therapeutic mechanisms supported by proteomic analysis.

neuroscience↗

bioRxiv2021

Enhancers of host immune tolerance to bacterial infection discovered using linked computational and experimental approaches

Current therapeutic strategies against bacterial infections focus on reduction of pathogen load through antibiotics; however, stimulation of host tolerance to infection might offer an alternative approach. Here we used computational transcriptomics and a Xenopus embryo infection model to rapidly discover infection response pathways, identify potential tolerance inducer drugs, and validate their ability to induce broad tolerance. Xenopus embryos exhibit natural tolerance to A. baumanii, K. pneumoniae, S. aureus, and S. pneumoniae bacteria, whereas A. hydrophila and P. aeruginosa produce infection that leads to death. Transcriptional profiling led to definition of a 20-gene signature that allows for discrimination between tolerant and susceptible states, as well as identification of active and passive tolerance responses based on the degree of engagement of gene transcription modulation. Upregulation of metal ion transport and hypoxia pathways reminiscent of responses observed in primate and mouse infection models were identified as tolerance mediators, and drug screening in the susceptible A. hydrophila infection model confirmed that a metal chelator (deferoxamine) and HIF-1 agonist (1,4-DPCA) increase embryo survival despite high pathogen load. These data demonstrate the value of combining the Xenopus embryo infection model with multi-omics analyses for mechanistic discovery and drug repurposing to induce host tolerance to bacterial infection.

immunology↗

bioRxiv2020

Mechanosensation Mediates Long-Range Spatial Decision-Making in an Aneural Organism

The unicellular protist Physarum polycephalum is an important emerging model for understanding how aneural organisms process information toward adaptive behavior. Here, we reveal that Physarum can use mechanosensation to reliably make decisions about distant objects its environment, preferentially growing in the direction of heavier, substrate-deforming but chemically-inert masses. This long-range mass-sensing is abolished by gentle rhythmic mechanical disruption, changing substrate stiffness, or addition of a mechanosensitive transient receptor potential channel inhibitor. Computational modeling revealed that Physarum may perform this calculation by sensing the fraction of its growth perimeter that is distorted above a threshold strain - a fundamentally novel method of mechanosensation. Together, these data identify a surprising behavioral preference relying on biomechanical features and not nutritional content, and characterize a new example of an aneural organism that exploits physics to make decisions about growth and form. HighlightsO_LIThe aneural Physarum makes behavioral decisions by control of its morphology C_LIO_LIIt has a preference for larger masses, which it can detect at long range C_LIO_LIThis effect is mediated by mechanosensing, not requiring chemical attractants C_LIO_LIMachine learning reveals that it surveys environment and makes decision in < 4 hours C_LIO_LIA biophysical model reveals how its pulsations enable long-distance mapping of environmental features C_LI

animal behavior and cognition↗

bioRxiv2019

A robotic platform for fluidically-linked human body-on-chips experimentation

Here we describe of an Interrogator instrument that uses liquid-handling robotics, a custom software package, and an integrated mobile microscope to enable automated culture, perfusion, medium addition, fluidic linking, sample collection, and in situ microscopic imaging of up to 10 Organ Chips inside a standard tissue culture incubator. The automated Interrogator platform maintained the viability and organ-specific functions of 8 different vascularized, 2-channel, Organ Chips (intestine, liver, kidney, heart, lung, skin, blood-brain barrier (BBB), and brain) for 3 weeks in culture when fluidically coupled through their endothelium-lined vascular channels using a common blood substitute medium. When an inulin tracer was perfused through the multi-organ Human Body-on-Chips (HuBoC) fluidic network, quantitative distributions of this tracer could be accurately predicted using a physiologically-based multi-compartmental reduced order (MCRO) in silico model of the experimental system derived from first principles. This automated culture platform enables non-invasive imaging of cells within human Organ Chips and repeated sampling of both the vascular and interstitial compartments without compromising fluidic coupling, which should facilitate future HuBoc studies and pharmacokinetics (PK) analysis in vitro.

bioengineering↗

bioRxiv2018

Human bone marrow disorders recapitulated in vitro using organ chip technology

Understanding human bone marrow (BM) pathophysiology in the context of myelotoxic stress induced by drugs, radiation, or genetic mutations is of critical importance in clinical medicine. However, study of these dynamic cellular responses is hampered by the inaccessibility of living BM in vivo. Here, we describe a vascularized human Bone Marrow-on-a-Chip (BM Chip) microfluidic culture device for modeling bone marrow function and disease states. The BM Chip is comprised of a fluidic channel filled with a fibrin gel in which patient-derived CD34+ cells and bone marrow-derived stromal cells (BMSCs) are co-cultured, which is separated by a porous membrane from a parallel fluidic channel lined by human vascular endothelium. When perfused with culture medium through the vascular channel, the BM Chip maintains human CD34+ cells and supports differentiation and maturation of multiple blood cell lineages over 1 month in culture. Moreover, it recapitulates human myeloerythroid injury responses to drugs and gamma radiation exposure, as well as key hematopoietic abnormalities found in patients with the genetic disorder, Shwachman-Diamond Syndrome (SDS). These data establish the BM Chip as a new human in vitro model with broad potential utility for studies of BM dysfunction.

bioengineering↗

bioRxiv2018

Complex human gut microbiome cultured in anaerobic human intestine chips

The diverse bacterial populations that comprise the commensal microbiota of the human intestine play a central role in health and disease, yet no method is available to sustain these complex microbial communities in direct contact with living human intestinal cells and their overlying mucus layer in vitro. Here we describe a human Organ-on-a-Chip (Organ Chip) microfluidic platform that permits control and real-time assessment of physiologically-relevant oxygen gradients, and which enables co-culture of living human intestinal epithelium with stable communities of aerobic and anaerobic human gut microbiota. When compared to aerobic co-culture conditions, establishment of a transluminal hypoxia gradient sustained higher microbial diversity with over 200 unique operational taxonomic units (OTUs) from 11 different genera, and an abundance of obligate anaerobic bacteria with ratios of Firmicutes and Bacteroidetes similar to those observed in human feces, in addition to increasing intestinal barrier function. The ability to culture human intestinal epithelium overlaid by complex human gut microbial communities within microfluidic Intestine Chips may enable investigations of host-microbiome interactions that were not possible previously, and serve as a discovery tool for development of new microbiome-related therapeutics, probiotics, and nutraceuticals.

bioengineering↗