Biology subjects

Putnam, D.

Publications and source records attributed to Putnam, D..

9 recordsLinked to original sources

bioRxiv2025

Seq2Karyotype (S2K): A Method for in-silico Karyotyping Using Single-Sample Whole-Genome Sequencing Data

DNA abnormalities characterized by cytogenetic imaging at the single cell resolution, i.e. karyotyping, have long served as cancer diagnostic and prognostic biomarkers. To enable in-silico karyotyping using unpaired whole-genome sequencing data, we developed Seq2Karyotype (S2K), a tool that fits karyotype models with clonality estimation based on read-depth and allelic imbalance in a bulk sample and supports visualization-guided refinement. Analysis on 19 adult and pediatric cancer cell lines revealed unexpected intratumoral heterogeneity involving multiple copy number variation (CNV) states including whole-genome duplication, which were validated by imaging and single-cell omics profiling. Analyses on patient samples showed high concordance with clinical cytogenetic reports for acute myeloid leukemia, and revealed evolutionary trajectories from multi-region metastatic neuroblastomas implicating reversion. These findings highlight extensive and dynamic intratumoral heterogeneity contributed by CNV in both cell line models and patient samples, which may inform future research on tumor evolution under selective pressure such as drug exposure.

bioinformatics↗

bioRxiv2025

Programing Immunogenicity of Dengue EDIII Vaccine Antigens Using Engineered Outer Membrane Vesicles (OMVs)

Dengue is a mosquito-borne viral infection and is more prevalent in the world with no therapeutics and suboptimal vaccine performance against all four serotypes of the dengue virus. Hence, there is an urgent requirement for a non-infectious and non-replicative vaccine candidate that can elicit a balanced and serotype-specific immune response. In this study, we have engineered bacterial outer membrane vesicles (rOMVs) that display EDIII antigens (EDIII rOMVs). The current formulation modulates the expression of costimulatory molecules on antigen-presenting cells (APCs) as well as enhances the uptake and presentation. Subsequently, the EDIII rOMVs elicited a strong antigen-specific polyfunctional response from CD4+ and CD8+ T cells. The robust antibody response was facilitated by a germinal center reaction characterized by high T follicular helper (Tfh) and B cell response levels in the mice that received EDIII rOMVs. Notably, the produced antibodies demonstrated the ability to neutralize all four dengue virus serotypes in an in vitro infection model, indicating its potential role in protective immunity. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=140 SRC="FIGDIR/small/640071v1_ufig1.gif" ALT="Figure 1"> View larger version (42K): org.highwire.dtl.DTLVardef@689d81org.highwire.dtl.DTLVardef@3c878aorg.highwire.dtl.DTLVardef@1e6b1aaorg.highwire.dtl.DTLVardef@9a5180_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2024

Programmable protein degraders enable selective knockdown of pathogenic β-catenin subpopulations in vitro and in vivo

Aberrant activation of Wnt signaling results in unregulated accumulation of cytosolic {beta}-catenin, which subsequently enters the nucleus and promotes transcription of genes that contribute to cellular proliferation and malignancy. Here, we sought to eliminate pathogenic {beta}-catenin from the cytosol using designer ubiquibodies (uAbs), chimeric proteins composed of an E3 ubiquitin ligase and a target-binding domain that redirect intracellular proteins to the proteasome for degradation. To accelerate uAb development, we leveraged a protein language model (pLM)-driven algorithm called SaLT&PepPr to computationally design "guide" peptides with affinity for {beta}-catenin, which were subsequently fused to the catalytic domain of a human E3 called C-terminus of Hsp70-interacting protein (CHIP). Expression of the resulting peptide-guided uAbs in colorectal cancer cells led to the identification of several designs that significantly reduced the abnormally stable pool of free {beta}-catenin in the cytosol and nucleus while preserving the normal membrane-associated subpopulation. This selective knockdown of pathogenic {beta}-catenin suppressed Wnt/{beta}-catenin signaling and impaired tumor cell survival and proliferation. Furthermore, one of the best degraders selectively decreased cytosolic but not membrane-associated {beta}-catenin levels in livers of BALB/c mice following delivery as a lipid nanoparticle (LNP)-encapsulated mRNA. Collectively, these findings reveal the unique ability of uAbs to selectively eradicate abnormal proteins in vitro and in vivo and open the door to peptide-programmable biologic modulators of other disease-causing proteins.

bioengineering↗

bioRxiv2022

Imaging optically thick tissues simply and reproducibly: a practical guide to Lightsheet Macroscopy

Lightsheet microscopy offers an ideal method for imaging of large (mm-cm scale) biological tissues rendered transparent via optical clearing protocols. However the diversity of clearing technologies and tissue types, and how these are adapted to the microscope can make tissue mounting glitchy and somewhat irreproducible. Tissue preparation for imaging can involve glues and or equilibration in a variety of expensive and/or proprietary formulations. Here we present practical advice for mounting and capping cleared tissues in optical cuvettes for macroscopic imaging, providing a standardized 3D cell that can be imaged routinely and relatively inexpensively. We show that acrylic cuvettes should be non-aberrating with objective numerical apertures less than 0.65, and present an inexpensive tool for alignment and calibration of standard lightsheet parameters. Mouse embryo, liver and heart imaging are demonstrated as examples with practical recommendations for acquisition and post-processing.

bioengineering↗

bioRxiv2021

Genomics Characterization of an Engineered Corynebacterium glutamicum in Bioreactor Cultivation under Ionic Liquid Stress

Corynebacterium glutamicum is an ideal microbial chassis for the production of valuable bioproducts including amino acids and next-generation biofuels. Here we resequence engineered isopentenol (IP) producing C. glutamicum BRC-JBEI 1.1.2 strain and assess differential transcriptional profiles using RNA sequencing under industrially relevant conditions including scale transition and compare the presence vs. absence of an ionic liquid, cholinium lysinate ([Ch][Lys]). Analysis of the scale transition from shake flask to bioreactor with transcriptomics identified a distinct pattern of metabolic and regulatory responses needed for growth in this industrial format. These differential changes in gene expression corroborate altered accumulation of organic acids and bioproducts, including succinate, acetate, and acetoin that occur when cells are grown in the presence of 50mM [Ch][Lys] in the stirred-tank reactor. This new genome assembly and differential expression analysis of cells grown in a stirred tank bioreactor clarify the cell response of a C. glutamicum strain engineered to produce IP.

systems biology↗

bioRxiv2021

A modular platform for on-demand vaccine self-assembly enabled by decoration of bacterial outer membrane vesicles with biotinylated antigens

Engineered outer membrane vesicles (OMVs) derived from laboratory strains of bacteria are a promising technology for the creation of non-infectious, nanoparticle vaccines against diverse pathogens. As mimics of the bacterial cell surface, OMVs offer a molecularly-defined architecture for programming repetitive, high-density display of heterologous antigens in conformations that elicit strong B and T cell immune responses. However, antigen display on the surface of OMVs can be difficult to control and highly variable due to bottlenecks in protein expression and localization to the outer membrane of the host cell, especially for bulky and/or complex antigens. To address this shortcoming, we created a universal approach called AddVax (avidin-based dock- and-display for vaccine antigen cross (x)-linking) whereby virtually any antigen that is amenable to biotinylation can be linked to the exterior of OMVs whose surfaces are remodeled with multiple copies of a synthetic antigen receptor (SNARE) comprised of an outer membrane scaffold protein fused to a member of the avidin family. We show that SNARE-OMVs can be readily decorated with a molecularly diverse array of biotinylated subunit antigens, including globular and membrane proteins, glycans and glycoconjugates, haptens, lipids, and short peptides. When the resulting OMV formulations were injected in wild-type BALB/c mice, strong antigen-specific antibody responses were observed that depended on the physical coupling between the antigen and SNARE-OMV delivery vehicle. Overall, these results demonstrate AddVax as a modular platform for rapid self-assembly of antigen-studded OMVs with the potential to accelerate vaccine generation, respond rapidly to pathogen threats in humans and animals, and simplify vaccine stockpiling.

synthetic biology↗

bioRxiv2020

MethylationToActivity: a deep-learning framework that reveals promoter activity landscapes from DNA methylomes in individual tumors

Although genome-wide DNA methylomes have demonstrated their clinical value as reliable biomarkers for tumor detection, subtyping, and classification, their direct biological impacts at the individual gene level remain elusive. Here we present MethylationToActivity (M2A), a machine learning framework that uses convolutional neural networks to infer promoter activities (H3K4me3 and H3K27ac enrichment) from DNA methylation patterns for individual genes. Using publicly available datasets in real-world test scenarios, we demonstrate that M2A is highly accurate and robust in revealing promoter activity landscapes in various pediatric and adult cancers, including both solid and hematologic malignant neoplasms.

genomics↗

bioRxiv2018

The Nucleome of Developing Murine Rod Photoreceptors

The nuclei of rod photoreceptors in mice and other nocturnal species have an unusual inverted chromatin structure: the heterochromatin is centrally located to help focus light and improve photosensitivity. To better understand this unique nuclear organization, we performed ultra-deep Hi-C analysis on murine retina at 3 stages of development and on purified rod photoreceptors. Predicted looping interactions from the Hi-C data were validated with fluorescence in situ hybridization (FISH). We discovered that a subset of retinal genes that are important for retinal development, cancer, and stress response are localized to the facultative heterochromatin domain. We also used machine learning to develop an algorithm based on our chromatin Hidden Markov Modeling (chromHMM) of retinal development to predict heterochromatin domains and study their dynamics during retinogenesis. FISH data for 264 genomic loci were used to train and validate the algorithm. The integrated data were then used to identify a developmental stage- and cell type-specific core regulatory circuit super-enhancer (CRC-SE) upstream of the Vsx2 gene, which is required for bipolar neuron expression. Deletion of the Vsx2 CRC-SE in mice led to the loss of bipolar neurons in the retina.

neuroscience↗

bioRxiv2017

VCF2CNA: A tool for efficiently detecting copy-number alteration in VCF genotype data

VCF2CNA is a web interface tool for copy-number alteration (CNA) analysis of VCF and other variant file formats. We applied it to 46 adult glioblastoma and 146 pediatric neuroblastoma samples sequenced by Illumina and Complete Genomics (CGI) platforms respectively. VCF2CNA was highly consistent with a state-of-the-art algorithm using raw sequencing data (mean F1-score=0.994) in high-quality glioblastoma samples and was robust to uneven coverage introduced by library artifacts. In the neuroblastoma set, VCF2CNA identified MYCN high-level amplifications in 31 of 32 clinically validated samples compared to 15 found by CGIs HMM-based CNA model. The findings suggest that VCF2CNA is an accurate, efficient and platform-independent tool for CNA analyses without accessing raw sequence data.

genomics↗