Biology subjects

Nelson, C.

Publications and source records attributed to Nelson, C..

24 records · Page 2Linked to original sources

bioRxiv2019

HCMV glycoprotein B nucleoside-modified mRNA vaccine elicits antibody responses with greater durability and breadth than MF59-adjuvanted gB protein immunization

A vaccine to prevent maternal acquisition of human cytomegalovirus (HCMV) during pregnancy is a primary strategy to reduce the incidence of congenital disease. Similarly, vaccination of transplant recipients against HCMV has been proposed to prevent transplant-associated HCMV morbidity. The MF59-adjuvanted glycoprotein B protein subunit vaccine (gB/MF59) is the most efficacious tested to-date for both indications. We previously identified that gB/MF59 vaccination elicited poor neutralizing antibody responses and an immunodominant response against gB antigenic domain 3 (AD-3). Thus, we sought to test novel gB vaccines to improve functional antibody responses and reduce AD-3 immunodominance. Groups of juvenile New Zealand White rabbits were administered 3 sequential doses of full-length gB protein with an MF59-like squalene adjuvant (analogous to clinically-tested vaccine), gB ectodomain protein (lacking AD-3) with squalene adjuvant, or lipid nanoparticle (LNP)-packaged nucleoside-modified mRNA encoding full-length gB. The AD-3 immunodominant IgG response following human gB/MF59 vaccination was closely mimicked in rabbits, with 78% of binding antibodies directed against this region in the full-length gB protein group compared to 1% and 46% in the ectodomain and mRNA-LNP-vaccinated groups, respectively. All vaccines were highly immunogenic with similar kinetics and comparable peak gB-binding and functional antibody responses. Although gB ectodomain subunit vaccination reduced targeting of non-neutralizing epitope AD-3, it did not improve vaccine-elicited neutralizing or non-neutralizing antibody functions. gB nucleoside-modified mRNA-LNP-immunized rabbits exhibited enhanced durability of IgG binding to soluble and cell membrane-associated gB protein as well as HCMV-neutralizing function. Furthermore, the gB mRNA-LNP vaccine enhanced breadth of IgG binding responses against discrete gB peptide residues. Finally, low-magnitude gB-specific T cell activity was observed in the full-length gB protein and mRNA-LNP vaccine groups, though not in ectodomain-vaccinated rabbits. Altogether, these data suggest that the gB mRNA-LNP vaccine candidate, aiming to improve upon the partial efficacy of gB/MF59 vaccination, should be further evaluated in preclinical models.\n\nAuthor summaryHuman cytomegalovirus (HCMV) is the most common infectious cause of infant birth defects, resulting in permanent neurologic disability for one newborn child every hour in the United States. Furthermore, this virus causes significant morbidity and mortality in immune-suppressed transplant recipients. After more than a half century of research and development, we remain without a clinically-licensed vaccine or therapeutic to reduce the burden of HCMV-associated disease. In this study, we sought to improve upon the glycoprotein B protein vaccine (gB/MF59), the most efficacious HCMV vaccine evaluated in clinical trial, via targeted modifications to either the protein structure or vaccine formulation. An attempt to alter the protein structure to focus the immune response on vulnerable epitopes ( gB ectodomain) had little effect on the quality or function of the vaccine-elicited antibodies. However, a novel vaccine platform, nucleoside-modified mRNA formulated in lipid nanoparticles, increased the durability and breadth of vaccine-elicited immune responses. We propose that an mRNA-based gB vaccine may ultimately prove more efficacious than the gB/MF59 vaccine and should be further evaluated for its ability to elicit antiviral immune factors that can prevent both infant and transplant-associated disease caused by HCMV infection.

immunology↗

bioRxiv2019

C. elegans LIN-28 controls temporal cell-fate progression by regulating LIN-46 expression via the 5’UTR of lin-46 mRNA

Human Lin28 is a conserved RNA-binding protein that promotes proliferation and pluripotency and can be oncogenic. Lin28 and C. elegans LIN-28 bind to precursor RNAs of the conserved, cellular differentiation-promoting, microRNA let-7 and inhibits production of mature let-7 microRNA. Lin28/LIN-28 also binds to and regulates many mRNAs in various cell types. However, the determinants and consequences of these LIN-28-mRNA interactions are not well understood. Here, we report that LIN-28 in C. elegans represses the expression of LIN-46, a downstream protein in the heterochronic pathway, via the 5 UTR of the lin-46 mRNA. We show that both LIN-28 and the 5UTR of lin-46 are required to prevent LIN-46 expression in the L1 and L2 stages, and that precocious LIN-46 expression is sufficient to skip L2 stage proliferative cell-fates, resulting in heterochronic defects similar to the ones observed in lin-28(0) animals. We propose that the lin-46 5UTR mediates LIN-28 binding to and repression of the lin-46 mRNA. Our results demonstrate that precocious LIN-46 expression alone can account for lin-28(0) phenotypes, demonstrating the biological importance of regulation of individual target mRNAs by LIN-28.

developmental biology↗

bioRxiv2019

Musashi expression in intestinal stem cells attenuates radiation-induced decline in intestinal homeostasis and survival in Drosophila

Exposure to genotoxic stress by environmental agents or treatments, such as radiation therapy, can diminish health span and accelerate aging. We have developed a Drosophila melanogaster model to study the molecular effects of radiation-induced damage and repair. Utilizing a quantitative intestinal permeability assay, we performed an unbiased GWAS screen (using [~]150 strains from the DGRP reference panel) to search for natural genetic variants that regulate radiation-induced gut permeability. From this screen, we identified the RNA binding protein, Musashi (msi).Msi overexpression promoted intestinal stem cell proliferation, which increased survival after irradiation and rescued radiation-induced gut permeability. We identified that a novel role of Msi in ISC proliferation a novel role for Msi in enhancing ISC function following radiation-induced gut damage, which identifies Msi as a potential therapeutic target.

molecular biology↗

bioRxiv2019

Microextrusion Printing Cell-Laden Networks of Type I Collagen with Patterned Anisotropy and Geometry

Type I collagen self-assembles into three-dimensional (3D) fibrous networks. These dynamic viscoelastic materials can be remodeled in response to mechanical and chemical cues to form anisotropic networks, the structure of which influences tissue development, homeostasis, and disease progression. Conventional approaches for fabricating anisotropic networks of type I collagen are often limited to unidirectional alignment over small areas. Here, we describe a new approach for engineering cell-laden anisotropic networks of type I collagen fibers using 3D microextrusion printing of a collagen-Matrigel ink. By adding molecular crowders, we demonstrate hierarchical control of 3D-printed collagen with the ability to spatially pattern collagen fiber anisotropy and geometry. Our data suggest that collagen anisotropy results from a combination of molecular crowding in the ink and shear and extensional flows present during 3D-printing. We demonstrate that human breast cancer cells cultured on 3D-printed collagen orient along the direction of collagen fiber alignment. We also demonstrate the ability to simultaneously bioprint epithelial cell clusters and control the alignment and geometry of collagen fibers surrounding cells in the bioink. The resulting cell-laden constructs consist of epithelial cell clusters fully embedded in aligned networks of collagen fibers. We foresee that cell-laden collagen-Matrigel constructs with spatially-patterned anisotropy and geometry will be broadly useful for the fields of developmental biology, tissue engineering, and regenerative medicine.

bioengineering↗

bioRxiv2018

Trans-splicing of the C. elegans let-7 primary transcript developmentally regulates let-7 microRNA biogenesis and let-7 family microRNA activity

let-7 is a microRNA whose sequence and roles as a regulator of developmental progression are conserved throughout bilaterians. In most systems, transcription of the let-7 locus occurs relatively early in development, whilst processing of let-7 primary transcript into mature microRNA arises later and is associated with cellular differentiation. In C. elegans and other animals, the RNA binding protein LIN-28 post-transcriptionally inhibits let-7 biogenesis at early developmental stages. The mechanisms by which LIN-28 and other factors developmentally regulate let-7 biogenesis are not fully understood. Nor is it understood how the developmental regulation of let-7 might influence the expression or activities of other microRNAs of the same seed family. Here we show that in C. elegans, the primary let-7 transcript (pri-let-7) is trans-spliced to SL1 splice leader at a position downstream of the let-7 precursor stem-loop, producing a short, polyadenylated downstream mRNA. The trans-splicing event negatively impacts the biogenesis of mature let-7 microRNA in cis, likely by destabilizing the upstream pri-let-7 fragment. Moreover, the trans-spliced downstream mRNA contains complimentary sequences to multiple members of the let-7 seed family (let-7fam), and thereby serves as a sponge to negatively regulate let-7fam function in trans. Thus, this study provides evidence for a mechanism by which splicing of a microRNA primary transcript can negatively regulate said microRNA in cis as well as other microRNAs in trans.\n\nHIGHLIGHTSO_LIThe let-7 primary transcript is trans-spliced to produce an RNA that functions as a sponge that negatively regulates the let-7-family microRNAs.\nC_LIO_LITrans-splicing of this RNA negatively impacts let-7 microRNA biogenesis.\nC_LIO_LILIN-28 regulates this trans-splicing event\nC_LI

molecular biology↗

bioRxiv2017

Campylobacter jejuni transcriptome changes during loss of culturability in water

BackgroundThe natural environment serves as a potential reservoir for Campylobacter, the leading cause of bacterial gastroenteritis in humans. However, little is understood about the mechanisms underlying variations in survival characteristics between different strains of C. jejuni in natural environments, including water.\n\nResultsWe identified three Campylobacter jejuni strains that exhibited variability in their ability to retain culturability after suspension in water at two different temperatures (4{degrees}C and 25{degrees}C). Of the three, strains C. jejuni M1 exhibited the most rapid loss of culturability whilst retaining viability. Using RNAseq transcriptomics, we characterised C. jejuni M1 gene expression in response to suspension in water by analyzing bacterial suspensions recovered immediately after introduction into water (Time 0), and from two sampling time/temperature combinations where considerable loss of culturability was evident, namely (i) after 24 h at 25{degrees}C, and (ii) after 72 h at 4{degrees}C. Transcript data were compared with a culture-grown control. Some gene expression characteristics were shared amongst the three populations recovered from water, with more genes being up-regulated than down. Many of the up-regulated genes were identified in the Time 0 sample, whereas the majority of down-regulated genes occurred in the 25{degrees}C (24 h) sample.\n\nConclusionsVariations in expression were found amongst genes associated with oxygen tolerance, starvation and osmotic stress. However, we also found upregulation of flagellar assembly genes, accompanied by down-regulation of genes involved in chemotaxis. Our data also suggested a switch from secretion via the sec system to via the tat system, and that the quorum sensing gene luxS may be implicated in the survival of strain M1 in water. Variations in gene expression also occurred in accessory genome regions. Our data suggest that despite the loss of culturability, C. jejuni M1 remains viable and adapts via specific changes in gene expression.

microbiology↗